Sex and gender in psychotrauma research

ABSTRACT

Background: Posttraumatic stress disorder (PTSD) is two to three times more common in women than in men. To better understand this phenomenon, we need to know why men, women, and possibly individuals with other sex/gender identities respond differently to trauma. To stimulate sex and gender sensitive research, the European Journal of Psychotraumatology (EJPT) was the first journal to adopt a gender policy. In addition, a call for papers entitled Integrating and Evaluating Sex and Gender in Psychotrauma Research was announced.

Objective: This special issue synthesizes the past five years of psychotrauma research with regard to sex/gender differences.

Method: Seventy-seven articles were identified from EJPT archives, including five systematic reviews. These articles examined sex differences and/or gender differences in exposure to trauma, posttraumatic stress responses, or how sex and gender impacts (mental) health outcomes or treatment responses.

Results: Findings from these studies outlined that: 1. sex and gender still need to be more clearly defined, also in relation to the context that codetermine trauma responses, like other ‘diversity’ variables; 2. in most studies, sex and gender are measured or reported as binary variables; 3. sex and gender are important variables when examining trauma exposure, responses to these events, symptoms trajectories, and mental and physical health outcomes across the life span; and 4. in PTSD treatment studies, including a meta-analysis and a systematic review, sex and gender were not significant predictors of treatment outcome.

Conclusion: Future research must focus on sex and gender as important and distinct variables; they should include sex and gender in their statistical analyses plan to better clarify associations between these variables and (responses to) psychotrauma. To enhance reporting of comparable data across studies, we provide suggestions for future research, including how to assess sex and gender.

HIGHLIGHTS

• Sex and gender are increasingly introduced as important and distinct variables in the field of psychotrauma, but there is a need to move beyond the binary conceptualization.

• Concrete suggestions on how to assess sex and gender are provided.

• Sex and gender both influence the rates of specific types of traumatic events, responses to these events, longitudinal symptoms trajectories, and mental and physical health outcomes across the life span.

• Sex and gender may play a minor role in the effectiveness of psychological treatments for PTSD.

Antecedentes: El trastorno de estrés postraumático (TEPT) es dos a tres veces más común en mujeres que en hombres. Para entender mejor este fenómeno, necesitamos saber por qué hombres, mujeres y posiblemente individuos con otras identidades de sexo o género responden de forma diferente al trauma. Para estimular investigación sensible al sexo y género, la European Journal of Psychotraumatology (EJPT) fue la primera revista en adoptar una política de género. Además, se anunció una convocatoria de artículos llamada ‘Integrando y evaluando el sexo y el género en investigación en psicotrauma’.

Objetivo: Este número especial sintetiza los últimos cinco años de investigación en psicotrauma en relación a diferencias de sexo y género.

Métodos: Setenta y siete artículos fueron identificados en los archivos EJPT, incluyendo cinco revisiones sistemáticas. Estos artículos examinaron diferencias de sexo y/o de género en la exposición al trauma, respuestas de estrés postraumático, o cómo el sexo y género impactan los resultados de salud (mental) o respuestas al tratamiento.

Resultados: Los resultados de estos estudios describen que: 1. El sexo y el género aún necesitan definirse de forma más clara, también en relación al contexto que codetermina las respuestas al trauma, como otras variables de ‘diversidad’; 2. en la mayoría de los estudios, el sexo y el género se miden o reportan como variables binarias; 3. el sexo y género son variables importantes a la hora de examinar exposición al trauma, respuestas a estos eventos, trayectorias de síntomas y resultados de salud física y mental a lo largo del ciclo vital; y 4. en estudios sobre tratamiento de TEPT, incluyendo un meta-análisis y una revisión sistemática, el sexo y el género no fueron predictores significativos de resultados de tratamiento.

Conclusiones: La investigación futura debe enfocarse en el sexo y género como variables distintivas e importantes; deberían incluir sexo y género en sus planes de análisis estadísticos para clarificar mejor las asociaciones entre estas variables y las respuestas al psicotrauma. Para aumentar el reporte de datos comparables entre estudios, entregamos sugerencias para futuras investigaciones, incluyendo cómo evaluar sexo y género.

KEYWORDS:

• Sex difference
• gender difference
• psychotraumatology
• research

PALABRAS CLAVE:

• Diferencias de sexo
• diferencias de género
• psicotraumatología
• investigación

1. Introduction

Sex and gender have been associated with experiencing specific types of stressors, with the early responses to these events, and with the mental and physical health outcomes of these events (e.g. Christiansen & Hansen, 2015; Olff, 2017; Olff et al., 2007) across the life span (e.g. Grenier et al., 2019; Hiscox, Bray, et al., 2023; Rezayat et al., 2020). PTSD, for instance, is typically two to three times more common in women than in men (Tortella-Feliu et al., 2019). Sex and gender may also impact the effectiveness of trauma interventions (e.g. Békés et al., 2016; Hiscox, Sharp, et al., 2023; Wade et al., 2016).

Sex is defined as a biological construct that is rooted in genetics, anatomy, and physiology. The term gender refers to the psychological, behavioural, social, and cultural aspects of being a woman, a man, or holding another gender identity. For posttraumatic stress disorder (PTSD) and acute stress disorder, sex/gender information was not included in the Diagnostic and Statistical Manual of Mental Disorder, 4th edition (DSM-IV, American Psychiatric Association [APA], 1994). In the DSM-5 (APA, 2013) these two disorders are reported to be more common in women. However, much less is known about how this female preponderance in trauma-related disorders emerges, and why this increased risk is not consistently found across populations (Street & Dardis, 2018).

Because more consistently and systematically collected information considering sex and gender in all aspects of psychotrauma research was needed, several years ago, the European Journal of Psychotraumatology (EJPT) adopted a gender policy (Olff, 2016). Authors were asked to at least report the sex of research subjects, justify single sex studies, discriminate between sex and gender (mostly for human research), analyse how sex or gender impact the results, and discuss sex and gender issues when relevant. The policy guidelines allowed authors to check whether sex and gender issues were properly addressed in their manuscript and encouraged and supported the journal editors and peer reviewers when considering these issues throughout the review process. To further encourage research on the topic a call for papers entitled ‘Integrating and evaluating sex and gender in psychotrauma research’ was announced. Authors were invited to submit papers on research that enhance our understanding of the ways in which sex and gender may function independently or together to influence (mental) health after trauma exposure, and how they may inform the psychosocial care continuum, from public health campaigns to specialized treatment.

In this editorial, we evaluate the progress made in the past five years of research on aspects that may help to explain why PTSD is more prevalent in women than in men, how sex and gender relates to trauma exposure and posttraumatic stress responses, and how both sex and gender may impact (mental) health outcomes and treatment experiences and responses.

2. In this special issue

Articles published between 1 January 2018 and 1 January 2024 were identified from the EJPT archives. Search terms included sex differences OR gender differences. Additional filters were used to limit the search to empirical studies and reviews. Eligible articles for this section met the following inclusion criteria: (1) must include sex and/ or gender differences in the study aim and/ or hypotheses, and/ or (2) must report in the statistical analysis section that analyses by sex or gender were conducted (e.g. sex-specific subgroup analyses had to be pre-defined). Studies including sex or gender as one of the covariates or predictors (alongside other demographic factors) in regression analyses were excluded, unless analyses of sex and/or gender as predictor(s) were explicitly mentioned as a study aim in the introduction, the reasoning behind the choice to include gender as a covariate or predictor was explained or was specified in the statistical analysis section. Studies only including one sex or gender were also excluded since the focus was on papers evaluating sex and/ or gender differences. Furthermore, symposium abstracts, editorials, and study protocols were excluded. All selected articles were described briefly in the text focusing on the findings related to sex and/ or gender differences.

We paid special attention to the assessment and operationalization of sex and gender and the language used to report on these two concepts. For example, did the author(s) specify how participants were asked about sex and gender? How many papers used ‘sex’ and/ or ‘gender’, ‘male’ and ‘female’ or ‘men’ and ‘women’? Were non-binary approaches used? We chose that approach because, in scientific research, these terms and concepts are often confused or used interchangeably even though meaningful differences exist between them. Although the terms ‘sex’ and ‘gender’ are related, they are not equivalent. Distinguishing between sex and gender is particularly important for individuals who have a gender identity that does not correspond to their sex assigned at birth. In addition, by adopting a binary approach to sex and gender (e.g. male vs. female; men vs. women) research findings are not reported in a sex- and/ or gender sensitive way. We expected room for improvement concerning the measurement of sex and gender in psychotrauma research.

In this special issue, we have collected 77 papers, including five systematic reviews, that met the inclusion criteria. For an overview of the characteristics of the studies retrieved through the search, please see Table 1. Because there was a lot of variation in research themes, the identified studies were roughly classified into different subgroups based on their topic and study design. We applied a life course perspective, grouping studies with children and adolescents and those with adults. The following seven topics were covered: trauma and its consequences; course of symptoms; treatment; high risk professions; neurobiological factors; sexual orientation; and measures. Before we describe study findings, we first discuss how sex and gender were reported or assessed.

Table 1. Study characteristics.

Authors (year)	Study design	Sex/Gender	Sample (N; % female, country)	Sex/Gender differences found
Trauma and its consequences in children and adolescents
Bruckmann et al. (2020)	Cross-sectional	Gender (male, female?); how measured is not explicitely stated.	145 foster children and adolescents ages 10–19 years (30.3% female, Austria)	Yes
De Haan et al. (2019)	Cross-sectional	Sex (male, female)	114 participants ages 7–16 years after accidental trauma (43.9% female, Switzerland) and 113 participants ages 6–17 years after interpersonal trauma (70.8% female, Germany)	Yes
Ford et al. (2022)	Cross-sectional	Gender (male, female)	507 children and adolescents ages 7–18 years in mental health treatment (49.0% female, United States of America [USA])	No
Haselgruber et al. (2020)	Cross-sectional	Gender (male, female)	135 trauma-exposed foster children ≤ 18 years (31.1% female, Austria)	Yes
Hiscox et al. (2021)	Cross-sectional	Self-reported sex (male, female)	797 adolescents ages 13–17 years (62.2% female, South Africa)	Yes
Lenferink et al. (2020)	Longitudinal (data was derived from the Prospective studies of Acute Child Trauma and Recovery (PACT/R) Data Archive, an international archive including studies from the USA, UK, Australia, and Switzerland)	Use both sex and gender (boys, girls)	Data from 21 longitudinal studies in which self-reported ASD symptoms by children were assessed within 30 days after trauma; 2287 children and adolescents ages 5–18 years (36.4% girls)	Yes
Sadeh et al. (2022)	Cross-sectional (based on medical records)	Gender child (male, female); abstracted from electronic health records	Caregivers of 374 children 0–18 years of age who were admitted to a pediatric rehabilitation department after pediatric traumatic medical events (40.9% female, Israel)	No
Van Duin et al. (2018)	Case study	Gender (boys, girls)	44 substantiated extrafamilial sexual abuse cases (31.8% female, The Netherlands)	Yes
Trauma and its consequences in adults
Authors (year)	Study design	Sex/Gender	Sample (N; % female, country)
Amstadter et al. (2023)	Longitudinal (based on 23 years of data from the Swedish National Registries)	Sex (male, female); obtained from the Total Population Register	Everyone born between 1975 and 1990 (n = 1,541,883 for the self-medication model and n = 1,540,979 for the susceptibility model; 49.0% female) and for the second set of analyses individuals born between 1960 and 1990 (n = 3,829,660; 49.0% female)	Yes
Ásgeirsdóttir et al. (2018)	Stress And Gene Analysis (SAGA) cohort study	Gender (male, female; men, women); how measured is not explicitely stated.	922 adults (56.0% female, Iceland), including women attending a cancer screening programme and a random sample of men from the general population	Yes
Bahati et al. (2023)	Cross-sectional	Gender (male, female)	343 refugees residing in Mbarara City (42.3% female, Uganda)	Yes
Bountress et al. (2021)	Cross-sectional (based on date from the fifth cohort of The Spit for Science project)	Sex assigned at birth (male, female)	897 undergraduate students (78.6% female, USA)	Yes
Charny et al. (2023)	Cross-sectional (online)	Gender (male, female)	488 citizens (no % female available, Israel)	No
Dalgaard et al. (2021)	Archival	Gender (male, female)	1249 survivors of torture and organized violence treated in a specialist outpatient clinic (19.9% female; Denmark)	Yes
Dashorst et al. (2019)	Systematic review	Parental gender (father, mother)	23 quantitative studies (13 included males and females, the other studies consisted of only women)	Yes
Dashorst et al. (2022)	Cross-sectional, clinical	Gender (male, female)	98 adult offspring of World War Two survivors in treatment in one of two clinics specialized in mental health services for war victims (57.0% female, The Netherlands)	Yes
Exenberger et al. (2019)	Cross-sectional, mixed-method	Gender (male, female)	185 German-speaking adults recruited via snowball sampling (66.5% female)	No
Goldberg et al. (2019)	Cross-sectional	Sex (male, female); how measured is not explicitely stated	165 outpatients with major depressive disorder (69.5% female, Spain)	Yes
Haahr-Pedersen et al. (2020)	Nationally representative household sample	Sex (male, female); how measured is not explicitely stated	1,839 adults (52% female, USA)	Yes
Harb et al. (2023)	Longitudinal	Gender (male and female; men and women)	113 individuals who identified as Black/African American in a Emergency Department at a Level I Trauma Center (61.1% female, USA)	No
Hennemann et al. (2023)	Cross-sectional	Gender (male, female)	1337 bereaved adults with symptoms of prolonged grief disorder (76.1% female; United States of America: 62.3%, Turkey/Iran: 24.2%, Cyprus/Greece: 13.5%)	Yes
Ho et al. (2021)	Nationally representative sample	Gender (male, female); Use gender and sex interchangeably.	1,020 adults (51.0% female, Ireland)	Yes
Jin et al. (2022)	Cross-sectional	Use both sex and gender (male, female)	3,479 sexual abuse survivors, university students (51.2% female, China)	Yes
Johnsen et al. (2023)	Longitudinal	Gender (male, female)	89 close friends of those killed on Utøya on 22 July 2011 (76.4% female, Norway)	Yes
Krahé et al. (2023)	Longitudinal	Gender (male, female, or other); also men and women in text	588 university students (52.4% female, Germany)	No
Lonnen and Paskell (2024)	Systematic review	Sex (based on anatomy and typically assigned at birth) or gender (one’s own identity and internal sense of self, which exists on a non-binary spectrum and which may or may not correspond with sex); search terms: 1. Gender, 2. Sex, 3. Nonbinary, 4. Male, 5. Female, 6. Men, 7. Women	12 qualitative or quantitative empirical study using child or adult clinical or non-clinical samples and presented CPTSD separated by gender or sex, or in one gender or sex only	Yes
Mellor et al. (2021)	Systematic review	Gender (male, female); how measured is not explicitely stated	13 empirical studies in refugee and displaced treatment seeking or general populations	No
Nordström et al. (2022)	Cross-sectional (based on the fourth data collection eight years after the Utøya terror attack)	Gender (male, female)	88 bereaved parents and 34 siblings aged 19 and above (59.8% female, Norway)	Yes
Pociunaite et al. (2023)	Longitudinal data from the data-archive of the Measurement Archive of Reactions to Bereavement from Longitudinal European Studies (MARBLES) project	Gender (male, female)	398 bereaved adults (64.2% female, Denmark & The Netherlands)	No
Rasmusson et al. (2018)	Cross-sectional	Gender (male, female)	112 patients in treatment for substance use disorders and 112 matched controls with mild to moderate mental health disorders (each group 43.8% female, Norway)	Yes
Schenker et al. (2023)	Cross-sectional	Sex, biologically (use both male, female and men, women; none of the participants indicated their sex as ‘other’)	41 non-treatment seeking, trauma exposed young adults aged 18–50 years (75.6% female, Australia)	Yes
Søegaard et al. (2021)	Cross-sectional	Self-reported gender (men, women)	110 traumatized patients attending a mental health outpatient clinic (61.8% female, Norway)	Yes
Stelzer et al. (2019)	Cross-sectional	Gender (men, women)	50 bereaved widow(er)s and parents (58% female; USA)	Yes
Wilker et al. (2021)	Cross-sectional	Sex (male, female)	Four civilian post-conflict samples from different countries: Northern Uganda (N = 1665; 54.0% female), Rwanda (N = 433; 46.5% female), Syria (N = 974; 49.3% female) and Sri Lanka (N = 165; 46.5% female)	No
Zhang et al. (2020)	Cross-sectional	Gender parent and gender deceased child (male, female); gender of the child was obtained from the Register of Population Statistics provided by the Health Family Planning Commission of China	149 Chinese Shidu parents who had lost their only child (60.4% female)	Yes
Longitudinal courses children and adolescents
Authors (year)	Study design	Sex/Gender	Sample (N; % female, country)
Glad et al. (2023)	Longitidunal	Sex (men, women); how measured is not explicitely stated	289 survivors of the Utøya Island attack (51.2% female, Norway)	Yes
Hlodversdottir et al. (2018)	Population-based prospective cohort	Gender parent (male, female), gender child (boy, girl)	Children's parents; 1,148 (52.7% female) in the exposed area and 510 (49.0% female) from the non-exposed area (Iceland)	Yes
Porcheret et al. (2022)	Longitudinal	Sex (male, female) at the time of the attack was determined from social security numbers	336 survivors of the Utøya Island attack who completed the study 2.5 and 8.5 years after the attack (47–51% female, Norway)	No
Raymond et al. (2022)	Longitudinal	Sex (boys, girls)	84 children ages 9–14 years (50.0% female, Canada)	Yes
Zhang et al. (2022)	Longitudinal	Gender (male, female); how measured is not explicitely stated.	217 children and adolescents ages 8–17 years at four emergency departments exposed to single-event trauma (42.9% female, England)	No
Longitudinal courses adults
Authors (year)	Study design	Sex/Gender	Sample (N; % female; country)
Boersma-van Dam et al. (2021)	Longitudinal multi-centre	Gender (male, female)	111 partners of adult burn survivors (80.2% female; Belgium and The Netherlands)	No
Diamond et al. (2022)	Meta-analysis	Sample sex distribution (% male)	78 studies, representing 79 independent samples (an overall average of 53.0% male)	Yes
Nissen et al. (2019)	Longitudinal	Gender (male, female)	2108 ministerial employees who had been exposed to a terrorist attack on 22 July 2011 in Oslo, Norway (56.5% female)	Yes
Opaas et al. (2022)	Longitudinal	Gender (male, female)	54 trauma-affected refugee patients (35.2% female; Norway)	Yes
Swart et al. (2020)	Longitudinal	Gender (male, female)	85 adult patients referred to a specialized mental health clinic (71.8% female; The Netherlands)	Yes
Van Zuiden et al. (2022)	Longitudinal	Biological sex (men, women)	554 adults from a multi-centre prospective cohort of emergency department patients with suspected severe injury (37.5% female, The Netherlands)	Yes
Treatment children and adolescents
Authors (year)	Study design	Sex/Gender	Sample (N; % female)
Jensen et al. (2022)	Naturalistic observational study (pre-post)	Sex; how measured is not stated	73 youth referred to one of 23 Norwegian child and adolescent mental health clinics that fulfilled the criteria for PTSD or CPTSD according to ICD-11 (89.0% female)	No
Pfeiffer et al. (2020)	Secondary analysis of two RCT studies in Norway and Germany	Gender (male, female)	52 therapists (78.8% female) and 153 patients (72.3% female)	No
Treatment adults
Authors (year)	Study design	Sex/Gender	Sample (N; % female)
Barawi et al. (2020)	Systematic review	Gender (male, female); how measured is not explicitely stated	25 randomized controlled trials (RCTs)	No
Bauer et al. (2021)	Feasibility study, mixed-method	Gender (identified as male, female)	80 trauma-exposed rural Veterans (66.50% female, USA)	No
Lely et al. (2019)	Systematic review and meta-analysis	Gender (male, female); how measured is not explicitely stated	16 RCTs (N = 947; 48.2% female)	No
Nordin & Perrin (2019)	Pilot; pre-post with 9-month follow-up	Gender (male, female); how measured is not explicitely stated	276 patients at a clinic for a highly specialized treatment programme for refugee survivors of torture or other organized violence (38.4% female, Denmark)	No
Therapist characteristics
Authors (year)	Study design	Sex/Gender	Sample (N; % female)
Gossmann et al. (2021)	Online experiment	Gender (male, female)	768 licenced psychotherapists (73.4% female, 0.7% diverse, Germany)	No
Lueders et al. (2022)	Cross-sectional, online	Gender (male, female, diverse)	148 outpatient medical and psychological psychotherapists in Saxony, Germany (79.7% female)	Yes
High risk professions
Authors (year)	Study design	Sex/Gender	Sample (N; % female)
Behnke et al. (2019)	Cross-sectional	Biological sex (male, female)	102 rescue workers (35.3% female, Germany)	Did not interpret
Blais et al. (2021)	Meta-analysis	Sex (male, female); how measured is not explicitely stated. In the analyses % females.	37 cross-sectional studies (N = 18,766; 27.29% female)	No
Frank et al. (2018)	Cross-sectional	Gender (male, female)	5,980 regular force or reserve force personnel who had been deployed at least once (11.1% female)	Yes
Kindermann et al. (2020)	Cross-sectional	Gender (male, female)	71 emergency call-takers and dispatchers who work in an emergency control centre (14.1 female, Germany)	No
Leshem et al. (2023)	Cross-sectional	Gender of the parent (father, mother)	56 veterans, mothers and fathers; ‘directly active veterans’ and ‘indirectly active veterans’	Yes
Rentmeesters & Hermans (2023)	Cross-sectional (web-based survey)	Gender (male, female)	1,465 police officers (28.9% female, Belgium)	No
Shin et al. (2023)	Cross-sectional	Gender (male, female)	483 firefighters (8.1% female; South Korea)	No
Stevelink et al. (2019)	Cross-sectional	Gender (male, female)	1,448 serving and ex-serving personnel of the armed forces who self-reported a stress, emotional or mental health problem in the past 3 years (15.1% female, United Kingdom)	Yes
(Neuro)biological factors
Authors (year)	Study design	Sex/Gender	Sample (N: % female)
Ancelin et al. (2020)	Cross-sectional (based on a longitudinal study ofneuropsychiatric disorders in community-dwelling French elderly, the Esprit study)	Sex (male, female); how measured is not explicitely stated	377 community-dwelling older adults (≥ 65 years of age); 165 no trauma (57.6% female), 137 trauma without re-experiencing (43.8% female), 75 trauma with re-experiencing (64.0% female)	Yes
Engel et al. (2020)	Prospective	Sex (male, female)	100 participants, including 54 men, 27 women using hormonal contraception, and 19 cycling women (The Netherlands)	Yes
Gultig et al. (2023)	Birth cohort	Sex (male, female)	439 term-born singleton adults 71–74 years of age (54.2% female; The Netherlands)	Yes
Llorens et al. (2023)	Cross-sectional	Sex (male, female)	53 adolescents ages 14–17 years with attention deficit and hyperactivity disorder (35.8% female, Spain)	Yes
Sexual orientation
Authors (year)	Study design	Sex/Gender	Sample (N; % female)
Van der Watt et al. (2023)	Case-case-control	Sex (male, female, intersexual)	2,022 university students (71.7% female, 0.1% intersex); 886 individuals who endorsed current PTSS (South Africa) in relation to a single specific non-marital romantic relationship dissolutions (RRD) event (casegroup 1), 592 individuals who endorsed PTSS in relation to a single specific DSM-5 congruent event for PTSD (casegroup 2), 544 individuals who endorsed PTSS in relation to another single stressful event (not an RRD and not a DSM-5 criterion A event)	Yes
Measures
Authors (year)	Study design	Sex/Gender	Sample (N & % female; country)
Anderson et al. (2023)	Cross-sectional	Gender identity (cisgender women, cisgender men, genderfluid or nonbinary). Analysis restricted to cisgender women vs. cisgender men.	91 women and men seeking detoxification treatment (41.8% cisgender women); 310 cisgender women at a rural college (USA)	Yes
Bondjers et al. (2019)	Prospective	Gender (male, female); how measured is not explicitely stated	186 adults who had experienced a potentially traumatic event (79.0% female; Sweden)	No
Carmassi et al. (2021)	Cross-sectional	Sex / Gender (male, female); how measured is not explicitely stated	265 health care workers who repeatedly experienced the deaths of patients during COVID-19 emergency (68.3% female; Italy)	Yes
Fresno et al. (2023)	Cross-sectional	Gender (male, female)	275 young adults (74.2% female, Chile)	Yes
Frewen et al. (2021)	Cross-sectional	Sex (male, female)	1,268 via the website of the Global Collaboration on Traumatic Stress (84.4% female); 1,378 actively via Amazon’s MTurk (42.1% female; international ‘English speaking’)	Yes
Hoppen et al. (2022)	Cross-sectional	Sex / Gender (male, female)	209 individuals between 18 and 70 years old seeking treatment for childhood trauma-related PTSD (76.6% female); 556 adults who had suffered at least one traumatic life event reporting different levels of PTSD symptoms (61.8% female); 156 healthy adults (79.5% female; Netherlands, Germany, and Australia)	Yes
Leuchter et al. (2021)	Cross-sectional	Sex / Gender (male, female)	140 individuals (≥ 18 years) from the general population (80.0% female, Germany)	Yes
Nielsen et al. (2023)	Cross-sectional	Gender (male, female)	490 treatment-seeking refugees (41.8% female; Denmark)	Yes
Stevenson et al. (2023)	Cross-sectional	Sex at birth (male, female)	6,765 adults, including 3,625 adults with a diagnosis of schizophrenia, schizoaffective disorder, bipolar disorder, or psychosis ‘not otherwise specified’ (39.3% female, South Africa)	Yes
Van der Feltz-Cornelis & De Beurs (2023)	Cross-sectional	Gender (male, female); how measured is not explicitely stated (‘both genders’)	298 patients with anxiety and depressive disorders (56.3% female); 234 patients with somatics symptom and related disorders (61.4% female; The Netherlands)	No

2.1. Measurement of sex and gender

Most papers failed to report findings in a sex- and/or gender-sensitive way. As shown in Table 1, in most papers, sex and gender were divided into two distinct categories (male vs. female; boys vs. girls; men vs. women), thereby excluding intersex individuals and gender diverse individuals. Furthermore, researchers frequently failed to specify how participants were asked about their sex and/ or gender. In some papers, both the terms ‘sex’ and ‘gender’ were used interchangeably, without mentioning if the participants’ genders corresponded with their sex. Finally, relatively few studies did measure participant’s gender identity or gender role (orientation). In the text about the study results, we followed the terms sex and gender as introduced by the study’s authors.

2.2. Trauma and its consequences in children and adolescents

Eight papers focused on sex differences or gender differences in trauma type and/ or in symptoms presentation or diagnosis in (young) children and adolescents.

Van Duin et al. (2018) examined gender differences in the psychological sequelae for children sexually abused at a very young age (infants or toddlers) in a sample of substantiated child abuse cases. Three years after the extrafamilial abuse disclosure, 30% of the children exhibited clinically significant sexual behaviour problems, 24% internalizing problems, and 27% attachment insecurity; 18% were diagnosed with a psychiatric disorder (including PTSD). In this rather small sample, boys exhibited more internalizing problems and avoidant insecure attachment than girls.

Lenferink et al. (2020) identified three latent classes (i.e. homogeneous subgroups) of children exposed to a single-incident trauma based on the number of DSM-5 Acute Stress Disorder symptoms. This study found that, compared to children in the low symptoms class, those in the intermediate or high severity class were more likely to be girls. Among the 21 longitudinal studies included in this paper was that of De Haan et al. (2019).

De Haan et al. (2019) showed that trauma type needs to be considered when assessing the impact of sex/gender on posttrauma adjustment in children and adolescents. They found a significant difference between an accidental trauma sample and an interpersonal trauma sample in the association between the child’s sex and depression, but not PTSD. In the interpersonal trauma sample, female sex predicted increased childhood depression. The authors note that the differences between samples might not only be related to trauma types, but also to factors such as the complexity of trauma history, time since the trauma, and the presence of acute or chronic PTSD.

Two other studies focused on the role of gender in the prevalence, symptoms structure, and predictors of (Complex) PTSD in traumatized Austrian foster children and adolescents. The study of Bruckmann et al. (2020) showed that girls had 2.93 times higher odds of presenting with an ICD-11 diagnosis of PTSD; the odds were 4.55 times higher for girls compared to boys when using the DSM-5. In addition, Haselgruber et al. (2020) found that girls reported significantly higher rates of exposure to sexual abuse, sexual assault, and sudden/violent death of a close person. Girls also exhibited significantly higher rates of PTSD and symptoms of disturbances in self-organization.

In addition, Ford et al. (2022) evaluated whether distinct subgroups of children with predominant Developmental Trauma Disorder (DTD), predominant PTSD, and combined PTSD + DTD symptoms profiles could be identified, and if so, whether these subgroups differ in their patterns of traumatic antecedents and internalizing and externalizing disorder comorbidity, or in their gender or racial/ethnic composition. As hypothesized, the authors did not find differences in the three classes with respect to gender or race and ethnicity.

Using a sample of adolescents from an impoverished community in South Africa Hiscox et al. (2021) examined the contribution of self-reported sex on the conditional risk of PTSD and posttraumatic symptoms. The authors found support for sex differences in rates of PTSD during adolescence, with a higher rate of PTSD in female adolescents. However, this study among adolescents in a peri-urban community in Cape Town, South Africa, where exposure to trauma can be both frequent and persistent, also showed that exposure to interpersonal trauma overrules any specific female vulnerability.

Finally, Sadeh et al. (2022) focused on caregivers of children after pediatric medical events. They used latent profile analysis to identify psychological risk profiles in these caregivers. Gender of the child did not predict membership of risk profiles (low, above-average, high), but ethnicity and type of injury did.

In sum, most but not all studies described above did report sex differences or gender differences in trauma type and/ or in presentation of symptoms or diagnosis in (young) children and adolescents.

2.3. Trauma and its consequences in adults

Twenty-seven papers focused on sex or gender differences in trauma types and/ or in presentation of symptoms or diagnosis in adults. For the sake of overview, we organized the studies by their main focus: a variety of traumatic events (3 papers); a variety of trauma-exposed populations (3 papers); childhood adversity and childhood maltreatment (5 papers); CPTSD prevalence and clinical presentation (2 papers); grief experiences and Prolonged Grief Disorder (6 papers); trauma and substance use (3 papers); and other topics, including intergenerational consequences (1 paper), PTSD symptom variability and sleep (1 paper), COVID-19 (1 paper), posttraumatic growth (1 paper), and sensory responsiveness (1 paper).

2.3.1. A variety of traumatic events (3 papers)

Ho et al. (2021) evaluated gender-specific relationships between different types of traumatic events, Complex PTSD (CPTSD), and psychotic-like symptoms in a nationally representative sample of Irish adults. The authors found differences between men and women in their likelihood of reporting experiences of different traumatic events. For example, men reported more often having experienced life threats with a weapon, war and combat, life threatening accidents, and having caused extreme suffering and death compared to women. Compared to men, women reported more often sexual harassment, sexual assault, being stalked, and emotional abuse and neglect. Although there were differences between men and women in their likelihood of experiencing different traumatic events, the relationship between these events and CPTSD and psychotic-like symptoms was generally not moderated by gender, except in the case of elevated levels of psychosis in men reporting sexual abuse by a parent or guardian.

Søegaard et al. (2021) studied gender differences in a wide range of trauma symptoms after the two different trauma types, namely victimization trauma (i.e. different types of physical violence and sexual assault, war-related trauma, murder of a close relative, captivity, and torture) and accidental trauma (i.e. accidental, coincidental, and non-intentional human traumas such as natural disasters or motor vehicle accidents). The study showed significant symptom differences between men and women. Men with a history of victimization reported more and different trauma symptoms than men who experienced accidental trauma. This difference in range of trauma symptoms depending on trauma type was much smaller for women.

In addition, Dashorst et al. (2022) focused on indirectly experienced traumatic events. They aimed to identify personal characteristics such as gender, education level, trait dissociation, affect intensity, attentional control, mental imagery, fantasy proneness, and current psychopathology that could be associated with reports of intrusions following indirectly experienced traumatic events This study, with a clinical sample of adult offspring of World War II survivors, showed that gender was associated with direct intrusions (i.e. intrusions about self-experienced traumatic events), but not indirect intrusions. Women reported more frequent direct intrusions compared to men.

2.3.2. A variety of trauma-exposed populations (3 papers)

Wilker et al. (2021) evaluated sex differences in PTSD risk in four different post-conflict populations (North Uganda, Rwanda, Syria, Sri Lanka) differing in rates of trauma exposure. They did not find substantial support for the general assumption of the increased risk of PTSD in women. Across all four samples, the association between trauma load and PTSD risk was strong for both women and men.

Dalgaard et al. (2021) used archival data from 27 years of clinical practice with refugees with PTSD to explore associations between torture, gender, and ethnic minority status. Gender differences were observed in self-reported torture exposure, with men reporting more types of torture, while women more often reported sexual torture. Regarding ethnicity, they found that ethnic minority status in one’s country of origin was associated with reports or more types of torture for both genders.

And finally, in their study of Black/African American individuals, Harb et al. (2023) observed that experiences of racial discrimination increased the risk for peritraumatic dissociation during the index trauma injury, which in turn increased the risk for future PTSD symptomatology. They also found no gender difference in this indirect effect. Experiences of racial discrimination increased vulnerability to PTSD after traumatic injury via peritraumatic dissociation in both Black/African American women and men.

2.3.3. Childhood adversity and childhood maltreatment (5 papers)

Haahr-Pedersen et al. (2020) investigated whether distinct profiles of childhood adversities exist for men and women in a nationally representative sample of US adults. They also evaluated whether profiles characterized by co-occurrent Adverse Childhood Events (ACE) would be associated with poorer mental health and social and emotional well-being outcomes in adulthood. Regarding the profiles of childhood adversities, they found that women reported more complex and varied patterns of ACEs, and that these patterns were associated with a range of adverse outcomes. These findings demonstrate the importance of considering specific combinations of childhood adversities when investigating the links between ACEs and adverse outcomes among men and women.

Ásgeirsdóttir et al. (2018) found an increased risk of lifetime suicidality among individuals reporting lifetime interpersonal, childhood, and sexual trauma for both genders, with a higher risk for men than for women. In addition, the authors found an association between reports of non-interpersonal trauma and suicidality among men, but not among women.

Goldberg et al. (2019) examined whether a sex-specific approach may be relevant when evaluating the association between childhood maltreatment and history of suicide attempts among patients with major depressive disorder (MDD). They found support for sex-related differences in the impact of childhood maltreatment on suicide attempts. When testing the model separately in the group of female patients and in the group of male patients, the effect of childhood maltreatment on suicide attempts remained for females, whereas for males, age of MDD onset and Childhood Trauma Questionnaire minimization–denial scale were predictive variables. The authors note that this finding points to the relevance of including sex/gender into models of mechanisms underlying the prediction of suicide attempts.

Two other studies focused on sex/gender differences in symptoms or diagnosis among survivors of child sexual abuse (CSA). Jin et al. (2022) examined associations between PTSD symptoms and other psychiatric symptoms among CSA victims using a network analysis approach, also to explore sex differences in the symptoms model. Male victims were more likely to have psychosis, while female victims were more likely to report depression, anxiety, and PTSD. No significant differences in the network global strength were found, meaning that the associations between depression, anxiety, psychosis, and PTSD symptoms were similar between male and female participants. In addition, in their longitudinal study based on a large sample of university students with three data waves covering 23 months, Krahé et al. (2023) showed that the associations with later sexual victimization and perpetration held for both female and male victims of CSA.

2.3.4. CPTSD prevalence and clinical presentation (2 papers)

Lonnen and Paskell (2024) indicated in their systematic review that most reviewed papers used a binary approach to sex and gender, with only one of the twelve selected papers including non-binary gender options and differentiating between cisgender and gender diverse participants. Among the twelve papers included in the review were those of Ho et al. (2021) and Søegaard et al. (2021). Of the nine papers reporting prevalence rates, eight found no sex and/or gender differences in CPTSD rates, whereas one paper reported higher rates among women. Results regarding the clinical presentation were mixed: of the four papers found, two used single sex and/or gender samples. Of the other two papers, one found higher overall CPTSD symptom scores among women, without specifying which symptoms. The other study found higher scores in two symptom clusters, namely negative self-perception (e.g. shame and guilt) and alterations in systems of meaning (e.g. despair, negative change in existential beliefs) in men compared to women.

In the other systematic review, Mellor et al. (2021) examined gender differences in CPTSD prevalence in refugees and forcibly displaced populations. The authors found that of the thirteen studies included in their review, five reported on gender as a predictor of CPTSD. Four out of the five studies did not find an association with gender, with only one recording CPTSD to be more prevalent in women than men.

2.3.5. Grief experiences and prolonged grief disorder (6 papers)

Based on previous research, Hennemann et al. (2023) expected both a higher prevalence of somatic symptoms distress, and a stronger association between somatic symptoms distress and symptoms of Prolonged Grief Disorder (PGD) in women compared to men. This intercultural study among bereaved adults indeed found that mean somatic symptoms distress were significantly higher in female participants. Further support for their hypothesis was found with PGD symptoms being a significant predictor of self-reports of somatic symptoms distress in female, but not in male participants.

Zhang et al. (2020) examined PGD in Chinese Shidu parents who had lost their only child. Female gender of the parent was found to be one of the prominent risk factors for the development of PGD.

Stelzer et al. (2019) studied gender differences in adjustment to loss through linguistic markers in grief narratives in a sample of 50 bereaved widow(er)s and parents. They found support for gender differences in self-reported adjustment, but not in discussing grief experiences. Various linguistic markers were associated with increased depression levels in females, but not males.

In the fourth paper, Nordström et al. (2022) cross-sectionally studied gender differences in symptoms levels of prolonged grief, posttraumatic stress, and functional impairment in parents and siblings eight years after the terrorist attack in Utøya, Norway, on 22 July 2011. They found that women reported significantly higher levels of prolonged grief and posttraumatic stress symptoms compared to men. Functional impairment did not differ between women and men.

Johnsen et al. (2023) focused on gender differences in the relationships between grief reactions, the need for help, and help received over a period of 8.5 years for close friends of those killed in Utøya on 22 July 2011. Findings showed that women needed more help and received more help than men, which could be explained by different grieving patterns and tendencies. Female participants had higher levels of complicated grief reactions at baseline. In addition, received help was not associated with a decrease in grief symptoms.

Pociunaite et al. (2023) expected gender differences in latent DSM-5-TR PGD trajectories with female showing an increased likelihood of belonging to trajectories that experienced more severe PGD. In contrast to many other studies, gender did not have a role in predicting the different trajectories of PGD symptoms levels within the first five years after loss in their sample of bereaved adults, possibly due to the increase of Type II error due to the overrepresentation of women in the sample.

2.3.6. Trauma and substance use (3 papers)

Bahati et al. (2023) investigated gender differences in problematic use of alcohol and other substances among refugees residing in Mbarara City, in Southwestern Uganda. The refugees were mostly from Democratic Republic of Congo, Rwanda, Burundi, and Somalia, with a few from South Sudan. No gender difference in problematic alcohol use was found, but male refugees more often reported moderate to severe substance use compared to female refugees, (45% versus 37% respectively). Alcohol and other substances use was correlated with the severity of depressive symptoms.

Rasmusson et al. (2018) focused on gender differences in the relationship between childhood trauma and substance use disorders (SUD). They observed that female patients in SUD treatment reported more severe and varied forms of childhood trauma than male patients, and that the relationship between childhood trauma and SUD was particularly strong in female.

Amstadter et al. (2023) sought to clarify why PTSD and drug use disorder (DUD) often co-occur while examining sex differences with two hypotheses: the self-medication hypothesis (i.e. PTSD leads to DUD via drug use to cope with trauma-related symptoms) vs. the susceptibility hypothesis (i.e. DUD broadly affects the risk for PTSD via increased likelihood of trauma exposure associated with substance use behaviours). The authors used 23 years of longitudinal data from the Swedish National Registries (N > 1.5 million) to look at the prospective relationships between PTSD and DUD, and vice versa. They demonstrated a bidirectional risk whereas having one disorder increased the future risk for the other disorder. However, the effect sizes were higher for PTSD risk on future DUD, and some patterns differed by sex. For instance, the self-medication pathway may be more pronounced for women, whereas the susceptibility pathway may be more pronounced for men.

2.3.7. Other topics (5 papers)

Five papers focused on sex and gender differences related to a variety of other topics, including intergenerational consequences of trauma, day-to-day PTSD symptoms variability and sleep, domains of COVID-19 impact, posttraumatic growth, and sensory responsiveness.

In their systematic review of mechanisms of intergenerational consequences of the Holocaust, Dashorst et al. (2019) found that the gender of the survivor parent influenced the mental well-being of their offspring. Compared to fathers, Holocaust survivor mothers appeared to be more influential for the well-being of their offspring.

Schenker et al. (2023) examined the relationship between a range of day-to-day PTSD symptoms variability and sleep in non-treatment-seeking trauma-exposed young adults, using both objective and subjective measures. Exploratory analyses indicated that sex moderated the bi-directional relationships between night-time sleep and day-time PTSD symptoms, with longer sleep onset latency and lower sleep efficiency being related to worse PTSD symptoms the next day in women, but not in men.

Bountress et al. (2021) evaluated domains of COVID-19 impacts in a sample of undergraduate students and also if sex or race predicted these domains of impact. Regarding sex, women reported significantly more COVID-related worry and more food/housing instability than men. Men reported more changes than women in substance use due to COVID, namely a significant increase in such use compared to pre-COVID.

Exenberger et al. (2019) used a mixed-method design to examine the phenomenon of posttraumatic growth in a selected German-speaking sample. The quantitative data were used to investigate gender and age differences in perceived growth. There were no significant gender differences in experienced growth, but less growth experiences were observed in older participants.

Lastly, Charny et al. (2023) assessed a sample of Israeli citizens using an online survey for sensory modulation and trauma-related symptoms during rocket attacks to evaluate the contribution of sensory modulation difficulties to trauma-related symptomatology profile types above and beyond gender and other risk factors, such as age, history of mental disorder, perceived threat, and perceived social support. Although the factor gender was related to elevated trauma-related symptoms during the peritraumatic phase, it was not significant when exploring the contribution of all study variables to membership to the high symptoms profile. Study findings highlighted that both male and female individuals who suffer from high sensory responsiveness may be more susceptible to elevated levels of distress during exposure to trauma.

Overall, with regard to this diverse set of papers that focused on sex differences or gender differences in trauma type and/ or in presentation of symptoms or diagnosis in adults, sex and gender appeared to be important variables associated with the outcomes of interest.

2.4. Course of symptoms

2.4.1. Course of symptoms in children and adolescents

Five studies focused on the longitudinal course of symptoms in children and adolescents after a variety of stress or trauma exposures.

Raymond et al. (2022) studied the effects of socio-emotional vulnerability on COVID-related psychological distress in a sample of healthy children. This Canadian longitudinal study (June 2020 to March 2021) assessed socio-emotional vulnerability to psychopathology via personality traits (i.e. anxiety sensitivity, anxiety trait, intolerance to uncertainty, and rumination) measured before the pandemic or at its early stages. The study showed that healthy youth experiencing high levels of socio-emotional vulnerability to psychopathology have a higher risk of reporting posttraumatic stress and anxiety symptoms, but not depressive symptoms in the year following the COVID-19 pandemic. The study also revealed that girls and adolescents reported greater symptomatology compared to boys and younger children.

Zhang et al. (2022) evaluated gender differences in the developmental courses of PTSD and depression symptoms in children and adolescents in the initial months following a single-event trauma. In this study, both gender and age did not predict PTSD or depression.

Hlodversdottir et al. (2018) studied the effects of the 2010 Eyjafjallajökull volcano eruption in Iceland on children’s physical and mental health. In their prospective cohort study children living in the exposed area were assessed at 6–9 months and three years after the volcano eruption, using a non-exposed comparison group in a rural area. Gender-specific analysis revealed an increased risk of anxiety or worries in exposed girls and boys, whereas only exposed boys, not girls, were more likely to experience headache(s) and sleep disturbances compared to non-exposed children.

Two other papers focused on survivors of the terrorist attack on the Utøya Island 8.5 years after the attack. Porcheret et al. (2022) examined the long-term impact of trauma exposure on survivors’ insomnia. They also explored sex differences in survivors’ insomnia who were adolescents or young adults (≤ 30 years of age) at the time of the attack. Eight and a half year after the terrorist attack, nearly half of the survivors (47.7%) reported insomnia; no significant sex difference emerged.

In another study Glad et al. (2023) focused on the type, frequency, intensity, and duration of trauma reminders experienced by survivors 8.5 years after the attack. They explored the association between sex and frequency of exposure to reminders, and found that women reported experiencing trauma reminders significantly more often than men.

2.4.2. Course of symptoms in adults

In addition, six other papers focused on sex/gender aspects in longitudinal symptoms courses in adulthood.

Diamond et al. (2022) conducted a meta-analysis of 78 studies on the two-year course of recovery from PTSD following a variety of traumatic events (essentially single-incident), and the factors that influence that recovery. The authors found sex differences in PTSD prevalence and change over time. Female sex was associated with higher PTSD rates at 1 month. In addition, a larger reduction in PTSD over time was observed among females versus males which, according to the authors, may be partly explained by higher initial levels of PTSD among females, with baseline PTSD levels being a strong predictor of recovery.

Opaas et al. (2022) examined predictors of the long-term course of mental health and quality of life in trauma-affected refugee patients; they found gender differences. Indeed, in this 10-year longitudinal study, female patients significantly improved in symptoms of PTSD, anxiety, depression, and quality of life, while male patients appeared relatively unchanged.

Swart et al. (2020) tested gender differences in the two-year course of (comorbid) trauma-related, dissociative and personality disorders in adult patients referred to a specialized mental health clinic. The authors found support for gender differences in the course of psychopathology (general psychopathology, dissociative symptoms, personality problems), indicating that female patients improved significantly more than male patients. No gender differences were found in received minutes of treatment, days of hospitalization or treatment setting (i.e. inpatient, outpatient) and treatment focus (i.e. trauma, personality).

Van Zuiden et al. (2022) showed that it is not just the prevalence of PTSD that differs between women and men, but also their PTSD symptoms trajectories. One-year after admission to emergency departments, they found that a recovering trajectory is more prevalent in women, while men more often showed a delayed symptoms onset. The authors used sex-disaggregated Bayesian latent growth mixture modelling analysis of PTSD symptoms development.

Boersma-van Dam et al. (2021) showed that gender may play a minor role in the PTSD symptoms course of partners of adult burn survivors up to 18 months post-burn. The authors mentioned that partners of male patients were more likely to participate in the longitudinal study than partners of female patients, resulting in a predominantly female sample that may have been underpowered to find significant gender effects.

Nissen et al. (2019) examined whether perceived safety at work was associated with views on security measures and emergency preparedness among ministerial employees who had been exposed to a terrorist attack in Oslo, Norway. The authors also aimed to evaluate whether gender and education altered the expected longitudinal associations between employees’ knowledge of emergency procedures and perceived safety at work. For this, the sample was split by gender. Results showed that both between- and within-subject associations were more than twice as large for males than for females.

Overall, most studies focusing on the longitudinal course of symptoms after a variety of experiences of exposure to stress or trauma reported sex or gender differences across samples of children, adolescents, and adults.

2.5. Treatment studies

2.5.1. Treatment of children and adolescents

Two papers focused on the role of sex or gender in the treatment of children and adolescents.

Pfeiffer et al. (2020) examined the impact of therapists’ characteristics (gender, theoretical background, clinical experience) on outcomes in trauma-focused cognitive behavioural therapy (TF-CBT) for children and adolescents. The authors found no clear evidence of a significant therapist’s gender effect on treatment outcome.

Jensen et al. (2022) evaluated whether TF-CBT is helpful for youth who have complex PTSD, supporting its use in both male and female youth. CPTSD patients experienced a significant decline in symptoms, did not seem to need an extended number of sessions, and did not drop out more than youth with PTSD.

2.5.2. Treatment of adults

Six papers focused on the role of sex or gender in the treatment of adults.

Two systematic reviews focused on potential gender effects in the treatment of traumatized adults. In their review and meta-analysis of the effectiveness of narrative exposure therapy, Lely et al. (2019) hypothesized that female gender and older age would predict larger treatment effects on depression and PTSD symptoms. Based on results of 16 randomized controlled trials including 947 participants, their hypothesis was confirmed for age but not gender.

Barawi et al.’s (2020) systematic review of factors associated with the outcomes of psychological treatments for PTSD highlighted that of the 126 randomized controlled trials (RCTs) eligible, 25 RCTs reported on factors associated with treatment outcome; seven of them included participants’ gender. None of those found a significant effect of gender on treatment outcomes.

Two other papers focused on gender differences in outcomes of specific types of treatment approaches. Nordin and Perrin (2019) investigated gender differences in outcomes in multimodal treatment, targeting PTSD, depression, anxiety, somatic complaints, and social difficulties, for tortured and traumatized refugees. They did not find that gender predicted treatment outcome.

Bauer et al. (2021) evaluated the feasibility and effectiveness of webSTAIR, a web-based skills training programme, paired with home-based telehealth sessions in trauma-exposed rural veterans with clinically elevated symptoms of either PTSD or depression, including women veterans and those who have experienced military sexual trauma (MST). The results support the feasibility and effectiveness of this integrated telehealth web-based skills training programme for both male and female veterans as well as for those with and without MST.

In addition, two papers focused on therapists’ characteristics, including gender. In an online nationwide study based on randomly presented case vignettes, an experimental design was used to assess which PTSD patients’ characteristics influenced treatment readiness among licensed psychotherapists in Germany (Gossmann et al., 2021). In the case vignettes, the authors randomly manipulated gender (female vs. male), among other variables. Results showed that therapists’ characteristics like fears/ doubt or trauma-specific training were more relevant for the treatment readiness of patients with PTSD symptoms than patients’ characteristics such as gender.

Lueders et al. (2022) conducted exploratory analyses to evaluate the effects of therapists’ characteristics like gender, own traumatic events, length of work experience, and theoretical orientation on trauma assessment. Results indicated that characteristics of therapeutic fit (e.g. same gender, similar age) were in general rated as relatively irrelevant, whereas therapists’ characteristics like gender, own traumatic events, length of work experience, and theoretical orientation affected trauma assessment. For example, regarding requirements for trauma assessment, male therapists agreed more with the statement ‘Therapist has similar traumatic experience’ than female therapists, whereas female therapists rated the characteristic ‘Severe trauma should be treated exclusively by trauma therapists’ as more relevant than male therapists. Concerning addressing traumatic events, female therapists reported greater frequency in patients reporting traumatic events of their own accord than male therapists.

Overall, the studies described above, including one meta-analysis and one systematic review, do not support sex differences and gender differences in treatment outcomes for both children and adolescents and adults. However, it is difficult to draw firm conclusions from these studies as most of those integrating participant’s sex and/ or gender examined treatment outcomes for specific types of treatment approaches. In addition, only a small proportion of studies in a review on factors associated with outcomes of psychological treatments for PTSD included gender as a factor of interest.

2.6. High-risk professions

One meta-analysis and seven studies focused on sex/gender as a risk factor for posttrauma psychopathology in high-risk professions.

In their meta-analytic review of 38 cross-sectional studies on the relationship between PTSD and social support in U.S. veterans and military service members, Blais et al. (2021) tested sex of the individual as a moderator. Results showed that social support in the home environment and received from civilians were associated with less long-term PTSD symptom severity than social support received from military sources; sex did not moderate this relationship.

Stevelink et al. (2019) evaluated differences in help-seeking patterns among 1448 male and female UK armed forces personnel who reported a mental health, stress or emotional problem occurring during the past three years. Findings indicated that most participants sought some form of help, including informal help only, non-medical support and formal medical support. Women were more likely than men to access formal medical support (70% vs. 51%).

Frank et al. (2018) examined gender differences in the association between deployment-related trauma and lifetime PTSD while controlling for non-deployment trauma using data from the 2013 Canadian Forces Mental Health Survey. In this study, women had higher odds of reporting PTSD compared to men. Findings suggested that trauma experienced while on deployment was positively associated with the odds of PTSD, and that there were no gender differences in this association. In addition, findings provided some evidence that exposure to non-deployment trauma, in particular interpersonal trauma, contributed to the observed gender differences in PTSD.

Leshem et al. (2023) investigated PTSD symptoms in war veterans and secondary traumatic stress (STS) among their parents five years after the 2014 Israel-Gaza military conflict. Five years after the war, active war veterans had about twice as higher scores of PTSD symptoms than those who did not actively participate in the war. Also, parents of active veterans reported higher STS symptoms with mothers reporting higher symptoms than fathers.

Rentmeesters and Hermans (2023) evaluated the prevalence and the impact of exposure to traumatic events in a sample of Belgian police officers. The 1-month prevalence of probable PTSD, complex PTSD, and subclinical PTSD were determined and the effects of demographic factors (i.e. gender, age, seniority, police zone size and police service), cumulative traumatic events, and trauma characteristics on the prevalence of these three PTSD groups were evaluated. No gender effect were identified in the prevalence of trauma exposure and the 1-month prevalence of PTSD, of complex PTSD, and of subclinical PTSD.

Shin et al. (2023) used gender, age, years of service, and shift pattern as factors that may influence the latent class classification of PTSD levels and posttraumatic growth (PTG) levels in a sample of firefighters. One of the study hypotheses was that firefighters who are female, older, or have worked for a longer period of time would be more likely to belong to a group with a higher level of PTG than other groups. Study findings did not support this hypothesis for gender and age.

Behnke et al. (2019) aimed to examine whether the revised sense of coherence is a potential resilience factor against PTSD, depressive, and somatic symptoms in rescue workers. Findings indicated that female rescue workers reported more severe PTSD symptoms and somatic symptoms than male rescue workers, but the authors did not interpret these effects as biological sex was disproportionately distributed in the sample and systematically confounded with relevant occupational-demographic etiological factors: the female rescue workers were younger, had less work experienced, and had been exposed to less occupational trauma than their male colleagues.

Kindermann et al. (2020) investigated the prevalence of secondary traumatic stress (STS) and screened for PTSD, and depressive and anxiety disorders in Emergency Call-takers and Dispatchers (ECDs) who work in an emergency control centre in Germany. A further aim was to identify risk factors for higher STS symptoms load. Findings indicated that STS resulting from exposure to traumatic emergency caller content was rather common with a prevalence of 8.5% for moderate STS and 2.8% for severe STS. A total of 11.3% of the ECDs screened positive for PTSD, 15.5% for depression and 7.0% for anxiety disorders. The findings of the cross-sectional study did not support the hypothesis that female gender would be associated with higher STS symptoms load, but indicated that a higher number of children and the absence of a secure attachment style were significantly related with higher STS symptoms load.

The studies described above showed mixed results with regard to sex/gender as a risk factor for posttrauma psychopathology in high-risk professions.

2.7. Neurobiological factors

Four papers focused on sex differences in (neuro)biological factors that may play a role in posttraumatic stress symptoms development.

Llorens et al. (2023) examined the relationship between hair cortisol concentrations (HCCs) and cognitive factors (i.e. attention and memory, and executive functioning) in adolescents with attention deficit and hyperactivity disorder (ADHD), and the moderating effects of sex and childhood trauma. Childhood trauma did not moderate the relationships but sex did, with better performance in attention and memory tasks for boys with ADHD with higher HCCs.

Engel et al. (2020) found that the prognostic effects of cortisol suppression and resting oxytocin on PTSD symptoms severity were sex and hormonal contraception use dependent. Stronger cortisol suppression upon dexamethasone ingestion was associated with higher PTSD symptoms at 1.5 months in women using hormonal contraception, but with lower PTSD symptoms at 1.5 months in men. In women using hormonal contraception, higher oxytocin concentrations were also associated with higher PTSD symptoms up to 6 months posttrauma.

In their study of non-institutionalized older participants (≥65 years of age) Ancelin et al. (2020) evaluated if lifetime history of trauma and re-experiencing symptoms are associated with specific alterations in grey matter volumes, independently of comorbidity, and if so, whether this varies according to serotonergic genetic vulnerability. The authors found a significant sex interaction for the amygdala, with larger amygdalae in trauma-exposed participants without re-experiencing compared to non-traumatized and trauma-exposed participants with re-experiencing in female carriers of the SS 5-HTTLPR genotype. According to the authors, the small number of SS re-experiencing women (n = 14) precluded drawing a definite conclusion.

Finally, in a study using the Dutch famine birth cohort, a historical birth cohort of individuals born around the time of the Dutch famine of 1944–1945, by Gultig et al. (2023), exploratory sex-specific analyses were performed to evaluate whether prenatal famine exposure and genetic variation in the glucocorticoid receptor (GR) moderated the associations between childhood trauma or adulthood trauma and PTSD symptoms severity later in life. The authors found that participants exposed to famine during early gestation, but only those not carrying the GR Bcll haplotype, showed a significantly stronger association between adulthood trauma and PTSD symptoms severity compared to non-exposed controls. The observed effects, indicating increased PTSD susceptibility following later life trauma, were more pronounced in men exposed to prenatal adversity than in women exposed to prenatal adversity.

This diverse set of papers focusing on sex differences in (neuro)biological factors showed mixed results regarding a variety of outcome measures.

2.8. Sexual orientation

Van der Watt et al. (2023) determined whether being female, having been exposed to trauma, having an anxious-ambivalent attachment style, having a non-heterosexual orientation, and being single were positively correlated with scores on the Posttraumatic Stress Checklist (PCL-5) in a sample of 2,022 university students. It examined posttraumatic stress symptoms (PTSS) following a non-marital romantic relationship dissolution or PTSS following a DSM-5 Criterion A traumatic event. As hypothesized, female sex was associated with higher levels of PTSS, but the effect size was small (§ = 0.03). Other significant factors included attachment style, sexual orientation, and monthly income level.

2.9. Measures

Ten papers focused on possible sex and/ or gender differences in (accuracy of) measures assessing experiences of violence or trauma and trauma-related psychopathology.

Stevenson et al. (2023) evaluated the psychometric properties of the Life Events Checklist for the DSM-5 (LEC-5) among a large sample of adults in South Africa. The authors reported the prevalence of traumatic events as measured by individual items on the measure by sex. Men reported more traumatic events (by both cumulative types of events and by ≥1 exposure) than women. Furthermore, men reported more physical assault and women reported more sexual assault.

Van der Feltz-Cornelis and De Beurs (2023) assessed the psychometric properties of the Dutch version of the10-item Adverse Childhood Experiences International Questionnaire (ACE-IQ-10) in two clinical samples. The first five items of the ACE-IQ assess childhood abuse and the second five items assess signs of household dysfunction. A confirmatory factor analysis supported a two-factor structure. No gender differences were observed in overall ACE-IQ-10 score and in experiencing childhood abuse or household dysfunction.

Anderson et al. (2023) compared the accuracy of three different measures for assessing a history of sexual violence, namely a general trauma screening questionnaire (LEC-5) and two behaviour-specific questionnaires, including the Childhood Trauma Questionnaire (CTQ) and the 2007 Sexual Experiences Survey (SES). Based on their two high-risk substance use samples, one of 91 individuals seeking detoxification treatment, and another of 310 women at a rural college, they found that the specialized sexual violence measures were more accurate than the general trauma questionnaire in detecting cases in college women and in men.

Frewen et al. (2021) assessed the psychometric properties of the Global Psychotrauma Screen (GPS) in two internet-based studies. Findings of the study provided initial support for the validity of the English version of the GPS as a screener for the concurrent measurement of several transdiagnostic outcomes of traumatic stressors. In addition, no prominent gender differences at the total symptoms or risk factor levels were found, but item-level analyses showed that, compared to men, women more often endorsed cognitive and affective symptoms of depression, avoidance, anxiety, and specific risk factors.

Three other studies focused on the psychometric properties of two instruments developed to operationalize the descriptions of ICD-11 PTSD and CPTSD and to facilitate assessment of the disorders: the International Trauma Questionnaire (ITQ) and the International Trauma Interview (ITI). In their study, among a sample of Chilean young adults, Fresno et al. (2023) investigated gender differences in ITQ scores. Findings indicated that women reported higher levels of threat, PTSD, and anxiety than men. Furthermore, Nielsen et al. (2023) examined ITQ differential item functioning related to gender in a cross-cultural sample of treatment-seeking refugees. They found that one PTSD item (i.e. one of the two sense of threat items) did function differentially in relation gender. Regardless of their level of PTSD, female patients were more likely to indicate that they had been bothered by feeling jumpy or easily startled compared to male patients. In addition, Bondjers et al. (2019) evaluated how strongly gender, age, and the types of traumatic events (interpersonal or non-interpersonal) predicted the ITI factors as part of assessing the convergent and discriminant validity of the Swedish version. Based on their structural equation model they found that gender and age were not associated with PTSD or ‘disturbances in self-organization’.

Leuchter et al. (2021) tested their hypothesis of significant gender differences with respect to mother’s and father’s ratings of perceived attachment and the perpetration of abuse on the German version of the Childhood Attachment and Relational Trauma Screen (CARTS) Regarding perceived attachment, mothers were generally rated as being more positive, emotionally available, and a greater source of security and proximity than fathers. Concerning the perpetration of abuse, fathers were reported to be significantly more physically and sexually abusive than mothers. Notably, the authors indicated that gender effects may stem from their predominantly female sample.

Hoppen et al. (2022) examined measurement invariance across gender for the 8-item Guilt and Shame Questionnaire (GSQ-8) in three different samples: a clinical sample, a traumatized sample, and a non-clinical sample. Measurement invariance across gender was mostly established across samples. No gender difference in reports of shame and guilt was found in the clinical sample. In the traumatized sample, women reported more frequently experiencing guilt and shame than men; in the non-clinical sample too, women reported more frequently experiencing shame, which is, according to the authors, in line with the literature.

Finally, Carmassi et al. (2021) conducted a validation study of the Italian version of the Peritraumatic Distress Inventory (PDI) in a sample of healthcare workers exposed to COVID-19-related potentially traumatizing events. They also assessed possible gender differences in mean total scores on the PDI and observed higher scores among women. In addition, as expected, the PDI predicted PTSD symptoms independently from gender or age.

Depending on the study sample and the instrument used, sex and/ or gender differences in (accuracy of) measures assessing experiences of violence or trauma and trauma-related psychopathology were found.

3. Limitations and recommendations

This editorial offered a brief review of sex and gender differences reported in 77 articles (including five systematic reviews) published in EJPT in the past five years. We selected papers based on their clear aims to examine sex or gender. Ideally, all research published in EJPT should have been preregistered in open-source tools such as Open Science Framework (OSF), which involves specifying its aims in advance. However, not all studies were, so we cannot exclude a bias towards studies reporting positive sex differences or gender differences as a post hoc finding.

The EJPT gender policy, in combination with a worldwide trend to recognize diversity in research, may have improved the inclusion of sex and/ or gender as variables of importance in psychotrauma research. Over the years, an increasing number of papers explicitly included sex and/or gender differences in the study aims and/ or hypotheses. For instance, comparing the past five years with a similar time-period before the gender policy was adopted, we see about twice as many articles that have examined sex and/or gender differences. Although single sex studies are to be justified and sometimes needed for good reasons, including more sexes and in particular a wider diversity of genders would better represent the diversity in society. In this editorial, we followed the terms sex and gender as introduced by the authors. Only three studies of the 77 reviewed papers included sex or genders other than male or female in their research. Ideally, research should explore differences in an intersectional perspective, including combinations of socio-demographic features. Most of the reviewed studies have focused on the exploration of the presence or absence of sex and/ or gender differences (hypothesis generating research), leaving unclear what might explain such differences. Several studies were too small to test sex or gender differences or were underpowered to examine associations separately for boys and girls or men and women. Notably, data from such studies can be used to generate hypotheses or contribute to meta-analysis of sex and/ or gender differences. Given the EJPT gender policy, it is worth considering ideal practices versus reality with respect to motivation to explore or test sex and/ or gender differences, as well as power and sample sizes, and pre-specification of analyses including sex and gender in statistical analytic plans.

4. Conclusion and future directions for research

In line with previous research the papers in this special issue confirm that sex and gender may be associated with experiencing specific types of stressors, with the responses to these events, their longitudinal courses and with the mental and physical health outcomes. With regard to treatments studies published in the past five years – including a meta-analysis and a systematic review – there may be little impact of sex and gender on treatment outcomes. The research topics of the studies and the nature of their samples described in this special issue varied widely, but the importance of looking at sex and gender differences in trauma exposure and (treatment) response, and in measures used in psychotrauma research is evident. As expected, most studies focused on self-reported sex or gender, referring to a binary classification of boys and girls and men and women. Adopting a binary approach is not a sex- and/ or gender sensitive way to report research data. Therefore, our knowledge of sex and or gender differences in exposure to trauma and posttraumatic stress responses and how both sex and gender may affect (mental) health outcomes and affect treatment responses is still very limited if not incomplete.

To better understand why there are sex and gender differences in responses to trauma, more research in the field of psychotraumatology that considers sex and gender as important and distinct variables is needed. In sex- and gender-inclusive-based research a binary approach should be avoided; intersex, non-binary, and gender diversity should be measured as well. Because men are not all the same, and neither are women or intersex individuals or gender diverse individuals, ideally, other aspects of intersectionality (i.e. combinations of socio-demographic features) should also be measured.

Sex and gender aspects in (neuro)biological research are, to the best of our knowledge, still based on limited data for women (Bauer, 2023). Until recently, only 2% of neurobiological research has been conducted in females and these were mainly rats, despite evidence that the oestrous cycle does not increase variability in female rodents relative to male rodents (Kaluve et al., 2022). To increase our understanding of sex and gender differences in response types to traumatic stress and in response to psychological and pharmacological treatment, it is important to report differences and similarities between sexes/genders.

Although an increasing number of papers performing analyses by sex or gender were submitted to EJPT after the introduction of the gender policy, more studies are needed to show whether the findings generalize across sexes/genders. Regarding preregistration, both hypothesis-generating (exploratory) research and hypothesis-testing (confirmatory) research are important. A relatively simple way to advance the field is by further encouraging to include sex and/or gender differences in research designs and to report of outcome data from studies disaggregated by sex/gender (Heidari et al., 2016). However, to avoid biased model estimations for the underrepresented sex or gender the use of appropriate statistical techniques is important. Some suggestions for statistical analysis of sex differences in (pre-)clinical studies are provided by Beltz et al. (2019).

Until now few studies did measure participant’s gender identity, and none gender role (orientation); most studies focused on self-reported sex or gender, referring to a dichotomous classification of men and women. Future studies should look at measures that can be used to assess participant’s gender identity or gender role orientation (masculine, feminine). When measuring sex and gender, researchers need to identify relevant and specific aspects in relation to their research question Lindqvist et al. (2021). However, because studies have measured sex and gender differently, it is problematic to bring together the available evidence on the role of sex/gender aspects in psychotraumatology. Any terms we use from now should be ‘mappable’ regarding future specific ontology of sex and gender terms. To encourage reporting of comparable data across studies, we propose the following options for measuring sex and gender:

What sex were you assigned at birth?

1 = male, 2 = female, 3 = intersex, 4 = other, namely, 5 = prefer not to answer

What is your gender identity?

1 = man, 2 = women, 3 = non-binary, 4 = gender queer, 5 = other, namely, 6 = prefer not to answer

Because gender is socially-constructed, our understanding and terminology will continue to evolve. It has been suggested that gender identity may be best categorized using a free-text response as it may feel awkward to respond to questions about one’s ‘gender identity’ when participants have never reflected upon their gender identity – as for most cisgender persons (Lindqvist et al., 2021). Researchers will need to decide whether in their culture this would be more appropriate. In our point of view participants in most cultures would be able to handle this ‘awkwardness’.

Moreover, future studies should also look at measures for assessing gender stereotypes to examine, for instance, whether gender stereotypes may result in underdiagnosis of (sexual) trauma and PTSD in men. For example, masculinity ideologies, especially those prescribing restrictive emotionality could be addressed in interventions for trauma survivors (Kaiser et al., 2020). In addition, integrating more aspects of diversity in addition to sex and gender in psychotrauma research is encouraged. It is critical to understand not only why individuals of different sexes/genders respond differently to trauma, but also the context or circumstances under which they may respond differently or similarly. Therefore, considering sex and gender, in addition to other ‘diversity’ variables such as age, socioeconomic status and ethnicity in the field of psychotraumatology is needed. Because diverse populations of traumatized people from Western and non-Western world regions seek mental health care, it is important that we have (better) knowledge of the role of culture in how individuals conceptualize gender and trauma, and express trauma-related symptoms. Integrating sex/gender in psychotrauma research should increase our understanding of how individuals of different sexes/genders respond to trauma in various circumstances and may improve prevention as well as diagnostics and treatment outcome.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

No empirical data were collected. All articles retrieved from the European Journal of Psychotraumatology are open access available from www.tandonline.com/zept.