Parental PTSD and school performance in 16-year-olds – a Swedish national cohort study

Abstract

Aim: Posttraumatic stress disorder (PTSD) in parents can have severe consequences also for their children. Prevalence of PTSD is high among refugees. Refugee children have been reported to perform poorly in school. The aim of this study was to investigate the impact of PTSD in refugee and native Swedish parents on children’s school performance and to compare the impact of PTSD with that of other major psychiatric disorders.

Methods: Register study where multiple regression models were used to analyse school performance in 15–16-year-olds in a national cohort (n = 703,813). PTSD and other major psychiatric disorders (bipolar, depression and/or psychotic disorders) were identified from out- and in-patient hospital care.

Results: Maternal and paternal PTSD were associated with lower grades, with adjusted effects of 0.30–0.37 SD in refugee and 0.46–0.50 SD in native Swedish families. Impact of PTSD was greater than that of other psychiatric disorders and comorbidity to PTSD did not increase this impact. Although the impact of PTSD on grades was greater in children in native Swedish families, consequences with regard to eligibility to secondary education were greater for children in refugee families, where 35% of these children were ineligible.

Conclusions: Parental PTSD has major consequences for children’s school performance and contributes to the lower school performance in children in refugee families in Sweden. Identification and treatment of PTSD in refugee parents is important for offspring educational achievement. Psychiatric clinics and treatment centres need to have a strategy for support, including educational support, to the offspring of their patients with PTSD.

Keywords:

• Posttraumatic stress disorder
• refugee families
• intergenerational transmission of trauma
• school performance
• register data

Introduction

Intergenerational effects of psychological trauma have been investigated in a great number of empirical studies since the 1970s, particularly in offspring of Holocaust survivors. In a meta-analysis in 2003, van Ijzendoorn summarised 32 studies of mental health in children of Holocaust survivors and concluded that negative consequences were found only in children of psychiatric patients [1]. Posttraumatic stress disorder (PTSD) is the psychiatric disorder most specifically associated with psychological trauma, although depression is also commonly diagnosed after psychological trauma. Lifetime prevalence of PTSD in the Swedish population has been estimated to about 6%, with the highest PTSD risk associated with sexual and physical assault, robbery and multiple trauma experiences [2]. Traumatic experiences of war and torture may have long-term sequelae in the form of poor mental health and psychiatric disorders, such as anxiety, depression and PTSD, and previous studies have demonstrated a high prevalence of these conditions in refugees resettled in Western countries. PTSD has been shown to be up to ten times more prevalent among resettled refugees than in age-matched general populations [3]. Refugees often have especially complex conditions due to difficult experiences before and during flight in combination with adverse social and socioeconomic circumstances in the new society. In addition, the asylum process often constitutes a long period of uncertainty and insecurity, and refugees often lack social networks and experience stigmatisation or discrimination [4–6]. This emphasizes the importance of considering the family context, which may contribute to differences between refugee and non-refugee families.

Using data from Swedish national registers, we have previously demonstrated higher levels of school failure in children of parents who have been hospitalized due to psychiatric disorders or substance abuse [7,8]. Such associations are probably explained by a number of complex and interrelated environmental and genetic mechanisms. The obvious environmental factors involved in the development of PTSD may indicate that genetic factors are less important than for psychiatric disorders like schizophrenia and bipolar disorder [9,10]. On the other hand, many of the symptoms of PTSD, including re-experiencing the traumatic event with persistent, intrusive memories, irritability and lack of emotional presence can be hypothesised to interfere in the interaction between parent and child [11,12].

Research on intergenerational effects of PTSD has mainly been focused on psychological symptoms. A previous meta-analysis demonstrated an association between parents’ PTSD symptoms and children’s psychological distress and behavioural problems, with type of trauma being a significant moderator. The effect size was highest for children of parents with histories of interpersonal trauma, including family violence, community violence and traumatic loss [13]. A recent review, examining the impact of PTSD on parenting behaviour and children’s outcomes in military and veteran families demonstrated that PTSD symptoms in parents have an effect on internalising and externalising symptoms in their children, including depression, anxiety, and adjustment problems [14]. This review also indicated an association between parental PTSD symptoms and parent–child functioning difficulties, such as communication problems and less positive parental engagement [14]. Another systematic review focusing on intergenerational effects of trauma in refugee families demonstrate that the effect on children was diverse but mostly negative [15]. The majority of studies showed that children in refugee families, where a parent suffers from psychological consequences after having experienced trauma, are at increased risk of adverse psychological outcomes and vulnerability to psychosocial stress, including posttraumatic stress, mood, and anxiety disorder symptoms, and at greater risk of abuse and neglect [15]. Children in families of traumatised torture victims have also been shown to display more symptoms of anxiety, depression, posttraumatic stress, attention deficits and behavioural disturbances compared to children in the comparison group [16].

Previous studies investigating cognitive functioning in refugee children conclude that difficulties faced by children with a refugee background often include exposure to traumatic events, the need to acquire a new language, and adverse effects on family relations and family functioning [17]. Such difficulties affect cognitive functioning, learning and academic performance. Previous studies investigating school performance in refugee children are, however, scarce. As far as we know, no previous studies have investigated the impact of parental PTSD on offspring school performance, even though children in refugee families in Sweden have been found to be at particular risk for school failure [5,18]. One Swedish study, however, described lower levels on IQ-test in children in refugee families where parents were treated for consequences of torture trauma, compared with age-matched children with a similar migrant background but without PTSD in the family [19].

The aim of this study was to investigate whether PTSD in parents is associated with lower school performance in their offspring; and if so, if the association is as strong as for major psychiatric disorders such as psychotic and bipolar disorders, similar for paternal and maternal PTSD, and the same for children in refugee and native Swedish families.

Materials and methods

This study was based on data from Swedish national registers. The study population consisted of all children who finished compulsory school during the years 2004–2009, whose mother and father could be identified in the Multi-Generation Register (n = 703,813). The Multi-Generation Register contains parental identification numbers and children and parents can be linked to each other through this register. Record-linkage of different registers is made possible through the unique personal identity number assigned to all Swedish residents at birth or time of immigration. In datasets available to researchers, the personal identity numbers are replaced by random reference numbers and all data are analysed anonymously. This study was approved by the Stockholm Region Ethics Committee in 2016 (Dnr 2016/1610-31/5).

Post-traumatic stress disorder

Information on PTSD in parents was retrieved from the National Hospital Discharge Register and defined as at least one outpatient care visit (during 2002–2009) or a hospital admission (during 1997–2009) with an International Classification of Diseases (ICD-10) diagnosis indicating PTSD (F43.1).

School performance

Information on school performance at age 15–16 (ninth grade – the final compulsory school year in Sweden) was obtained from the National School Register. School performance was analysed as grade points (maximum rating 320 points), scores on national mathematics tests (maximum test score 75), and eligibility for secondary level education programmes (yes/no). Grade points summarize performance during the final compulsory school year, and the mathematics tests score was based on the sum of four national tests in mathematics. Having completed primary school with passing grades in core subjects (Swedish, English and Mathematics) is required to be eligible for continued studies in secondary level.

Covariates

A number of sociodemographic and socioeconomic variables (year of birth, gender, country/region of birth, geographic residency, parental education, family income and social welfare recipiency) were retrieved from the Longitudinal Integration Database for Health Insurance and Labour Market Studies. Parental country/region of birth was categorized as Sweden, Europe, EU15¹, former Yugoslavia, outside of Europe and missing. Based on the parents’ country/region of birth, the study population was also categorized as probable refugee or non-refugee. In order to be categorized as a probable refugee, both parents had to been born outside of Europe or in former Yugoslavia. Information on major psychiatric disorders in the parents was retrieved separately for mothers and fathers, and defined as at least one recorded case with a main diagnosis of depression (ICD10-code F32-F35 and F-38-F39), psychosis (ICD10-code F2) and bipolar disorder (ICD10-code F30 and F31), using information from the Hospital Discharge Register in inpatient care for the years 1997–2009 and outpatient care for 2002–2009.

Statistical analysis

Z-scores of mean grade points and scores on national mathematics tests were calculated in order to calibrate these two measures of school performance and analysed in linear regression models. Logistic regression models were used to analyse the effect of parental PTSD on eligibility for secondary education. PTSD in mothers and fathers, respectively, were included as two independent variables in the models to test for their independent effects (adjusted for the other). Data were analysed in two different models. Model 1 included year of graduation and gender. Model 2 adjusted further for geographic residency, income and other parental psychiatric disorders (e.g. depression, psychosis and bipolar disorder). We did not adjust for parental education because of the systematic underestimation of education in immigrants with a non-European background. However, in a sensitivity analysis among children of Swedish-born parents, we adjusted additionally for parental educational level.

The combination of PTSD and major psychiatric disorders in parents were further analysed by categorising parents as having 1) no psychiatric disorder (i.e. no hospital care with a diagnosis of PTSD, depression, bipolar disorder or psychosis), 2) major psychiatric disorder without PTSD (i.e. hospital admission with one or several of the following diagnosis: depression, bipolar disorder or psychosis, but without a PTSD diagnosis), 3) PTSD without major psychiatric disorder and 4) PTSD and at least one major psychiatric disorder. All analyses were performed separately for children from families with a probable refugee background and for children from non-refugee families.

In further sensitivity analyses in the probable refugee population only, we created a new parental exposure variable for PTSD, indicating that at least one of the parents had been in hospital care with a diagnosis of PTSD. In analyses with this exposure, we created two models of linear and logistic regression in analyses with mean grades and eligibility for secondary education. The first model was adjusted for sex and year of graduation only and a second model was adjusted further for age on arrival in Sweden in three categories (born in Sweden, 0–6 years and 7–13 years) and country/region of birth of parents in five categories (former Yugoslavia, Iraq, Iran, East Africa and others). In a final sensitivity analysis in the probable refugee population, these two outcomes were compared between Swedish and foreign-born children. In order to estimate the strength of the effect, we also calculated Cohen’s d [20], where 0.2 is considered small, 0.5 medium and 0.8 large.

All analyses were conducted using SAS version 9.4 (SAS Institute Inc., Cary, NC).

Results

In total, 4004 children (0.5%) in the study population had a parent who had been in hospital care with a PTSD diagnosis. Characteristics of the study population among probable refugee and non-refugee families according to parental PTSD are presented in Table 1. Children from probable refugee families constituted 9.1% of the study population, and parental PTSD was much more common in parents in these families. In the probable refugee families, 1.8% had a mother and 1.7% a father with a PTSD diagnosis, compared with 0.2 and 0.1% in the rest of the population.

Table 1. Characteristics of the study population according to parental PTSD, %.

	Probable refugee families		Non-refugee families
	No PTSD	Parental PTSD	No PTSD	Parental PTSD
Total number (%)	61 690 (96.7)	2 111 (3.3)	638 119 (99.7)	1 893 (0.3)
Sex
Girls	48.4	46.8	48.8	46.6
Boys	51.6	53.2	51.2	53.4
Not born in Sweden	44.0	64.8	1.0	3.5
Age at arrival among non-Swedish born children
0–6 years	55.1	40.2	45.8	31.7
7–12 years	31.2	37.9	31.8	38.3
≥13 years	13.7	21.9	22.5	30.0
Parental country/region of birth
Sweden	–	–	96.8	87.8
Foreign-born non-refugee	–	–	3.2	12.2
Former Yugoslavia	26.1	38.5	–	–
Iraq	16.8	22.7	–	–
Iran	8.5	8.2	–	–
East Africa	5.7	1.6	–	–
Other	42.9	29.0	–	–
Mother’s highest education
Compulsory school	43.5	53.3	10.2	19.6
Upper secondary school	36.9	32.3	52.6	60.6
University	19.6	14.5	37.1	19.8
Father’s highest education
Compulsory school	34.5	40.0	19.4	27.5
Upper secondary school	40.1	40.7	51.6	57.3
University	25.4	19.2	29.0	15.2
Income
1st quintile (lowest 20%)	52.5	56.9	16.4	23.4
2nd quintile (2nd lowest 20%)	18.2	16.0	20.1	20.1
3rd quintile (middle 20%) middle)	13.7	15.4	20.6	23.5
4th quintile (2nd highest 20%)	10.1	8.4	21.0	22.2
5th quintile (highest 20%)	5.1	3.0	21.7	10.7
Missing	0.4	0.3	0.2	0.3
Social welfare recipiency	32.2	58.5	5.7	25.8
Other psychiatric disorders
Mother psychosis	1.0	3.4	0.5	2.3
Mother bipolar disorder	0.3	1.7	0.6	5.6
Mother depression	5.7	33.2	3.4	39.0
Father psychosis	0.9	6.1	0.4	3.8
Father bipolar disorder	0.2	0.6	0.4	2.3
Father depression	2.6	24.3	2.0	18.2

Major psychiatric disorders were more common among parents with PTSD, compared with parents without this diagnosis (Table 1). PTSD and depression were especially comorbid; overall in the study population 45.6% of fathers with PTSD had also been diagnosed with depression, and corresponding number in mothers with PTSD was 53.3%.

Table 2 presents information on mean Z-scores of grades, mean Z-scores on mathematics tests and percentages of children ineligible for secondary education, in relation to parental PTSD in children from families with a probable refugee background and in children from non-refugee families. In children of parents without a PTSD diagnosis, Z-scores were lower in the probable refugee population, −0.30, compared to 0.03 in the non-refugee population with a similar pattern for math test scores, −0.41 vs. 0.04. Not being eligible for secondary education was more than twice as common in children from probable refugee families (22.8% vs. 9.3%). Parental PTSD was associated with considerably lower mean grades and lower scores on mathematic tests among non-refugee children as well as among children in probable refugee families, with the lowest scores seen in the latter group. The unadjusted effect size (Cohen’s D) of parental PTSD (mother or father) on mean school grades was 0.31 among children from refugee families and 0.51 among children from non-refugee families. The effect size of PTSD on mathematic tests scores was 0.22 in children from refugee families and 0.38 in children from non-refugee families.

Table 2. School performance in relation to parental PTSD and other psychiatric disorders.

	Grades, z-scores (Z-score)	Math tests, z-scores (Z-score)	Ineligible for secondary education, %
All individuals	0	0	10.5
Probable refugee families
Parental PTSD
No PTSD	−0.30	−0.41	22.4
Father PTSD	−0.65	−0.64	35.1
Mother PTSD	−0.63	−0.59	33.5
Mother psychiatric disorders
No psychiatric disorders	−0.29	−0.41	22.5
Mother psychosis	−0.43	−0.54	17.3
Mother bipolar disorder	−0.25	−0.35	21.9
Mother depression	−0.48	−0.54	26.4
Father psychiatric disorder
No psychiatric disorders	−0.30	−0.41	22.5
Father psychosis	−0.49	−0.57	26.4
Father bipolar disorder	−0.17	−0.26	20.3
Father depression	−0.50	−0.55	27.4
Non-refugee families
Parental PTSD
No PTSD	0.03	0.04	9.3
Father PTSD	−0.51	−0.39	21.8
Mother PTSD	−0.50	−0.31	19.9
Mother psychiatric disorders
No psychiatric disorders	0.05	0.05	8.9
Mother psychosis	−0.31	−0.23	19.9
Mother bipolar disorder	−0.31	−0.17	15.4
Mother depression	−0.37	−0.24	17.3
Father psychiatric disorder
No psychiatric disorders	0.04	0.05	9.1
Father psychosis	−0.40	−0.26	27.4
Father bipolar disorder	−0.13	−0.07	12.5
Father depression	−0.32	−0.21	16.2

Among children from families with a probable refugee background where a parent had a PTSD diagnosis, 35% were not eligible for secondary education, compared with 20% in non-refugee children with PTSD in the family. School performance in offspring of parents in hospital care with major psychiatric diagnoses was also lower than for children whose parents who had not been in hospital care with these psychiatric diagnoses, but not as low as for children to parents with PTSD (Table 2). Ineligibility for secondary education among children who had a mother and/or a father with a major psychiatric disorder was 17% in non-refugee children and 26% in children from probable refugee families.

In Table 3, beta-coefficients of z-scores of mean grades and mathematical tests are presented. Parental PTSD was associated with lower z-scores of mean grades and lower scores on mathematics tests both among children from probable refugee families and in children from non-refugee families, but the associations were stronger in children in non-refugee populations. Adjusting for income and geographic residency in Model 2 had a marginal effect on these estimates of the associations.

Table 3. Beta-coefficients of z-scores of grade points and mathematical tests scores, by parental PTSD and major psychiatric disorders.

	Z-scores of grades		Z-scores of mathematics tests scores
	Model 1 OR (95% CI)	Model 2 OR (95% CI)	Model 1 OR (95% CI)	Model 2 OR (95% CI)
Probable refugee families
Mother
No psychiatric disorder	0	0	0	0
Major psychiatric disorder, no PTSD	−0.15 (−0.19, −0.12)	−0.16 (−0.20, −0.13)	−0.12 (−0.15, −0.09)	−0.13 (−0.16, −0.09)
PTSD, no major psychiatric disorder	−0.35 (−0.44, −0.25)	−0.31 (−0.41, −0.21)	−0.22 (−0.31, −0.13)	−0.19 (−0.28, −0.10)
PTSD and other psychiatric disorder	−0.31 (−0.40, −0.22)	−0.30 (−0.39, −0.21)	−0.18 (−0.26, −0.09)	−0.17 (−0.25, −0.08)
Father
No psychiatric disorder	0	0	0	0
Major psychiatric disorder, no PTSD	−0.15 (−0.20, −0.10)	−0.17 (−0.22, −0.12)	−0.11 (−0.16, −0.07)	−0.13 (−0.17, −0.08)
PTSD, no major psychiatric disorder	−0.39 (−0.48, −0.29)	−0.37 (−0.46, −0.27)	−0.26 (−0.35, −0.17)	−0.25 (−0.34, −0.16)
PTSD and other psychiatric disorder	−0.32 (−0.42, −0.23)	−0.31 (−0.41, −0.22)	−0.20 (−0.29, −0.11)	−0.19 (−0.28, −0.10)
Non-refugee families
Mother
No psychiatric disorder	0	0	0	0
Major psychiatric disorder, no PTSD	−0.40 (−0.41, −0.39)	−0.38 (−0.39, −0.37)	−0.29 (−0.30, −0.27)	−0.27 (−0.28, −0.25)
PTSD, no major psychiatric disorder	−0.50 (−0.58, −0.42)	−0.46 (−0.54, −0.38)	−0.35 (−0.44, −0.27)	−0.32 (−0.40, −0.23)
PTSD and other psychiatric disorder	−0.58 (−0.65, −0.51)	−0.54 (−0.61, −0.47)	−0.38 (−0.46, −0.31)	−0.35 (−0.43, −0.28)
Father
No psychiatric disorder	0	0	0	0
Major psychiatric disorder, no PTSD	−0.35 (−0.36, −0.33)	−0.34 (−0.35, −0.32)	−0.25 (−0.27, −0.24)	−0.25 (−0.26, −0.23)
PTSD, no major psychiatric disorder	−0.55 (−0.66, −0.43)	−0.51 (−0.63, −0.40)	−0.46 (−0.58, −0.34)	−0.44 (−0.56, −0.32)
PTSD and other psychiatric disorder	−0.53 (−0.64, −0.42)	−0.49 (−0.59, −0.38)	−0.43 (−0.54, −0.32)	−0.40 (−0.51, −0.29)

Model 1 is adjusted for year of graduation and gender.

Model 2 is adjusted also for geographic residency and income.

Table 4 presents the ORs for ineligibility for secondary education. These results demonstrate that PTSD was associated with a higher proportion of individuals not being eligible for secondary education in children of parents with PTSD or with a combination of PTSD and major psychiatric disorders, compared with children of parents without psychiatric disorders, and also lower than children of parents with major psychiatric disorders but no PTSD. This pattern was particularly pronounced in children in non-refugee families but also present in children with probable refugee parents.

Table 4. Parental PTSD and other psychiatric disorder and OR of ineligibility for secondary education.

	Model 1 OR (95% CI)	Model 2 OR (95% CI)
Probable refugee families
Mother
No psychiatric disorder	1	1
Major psychiatric disorder, no PTSD	1.14 (1.06–1.23)	1.17 (1.08–1.26)
PTSD, no major psychiatric disorder	1.77 (1.47–2.12)	1.66 (1.38–2.00)
PTSD and other psychiatric disorder	1.70 (1.44–2.02)	1.71 (1.44–2.02)
Father
No psychiatric disorder	1	1
Major psychiatric disorder, no PTSD	1.16 (1.05–1.29)	1.23 (1.11–1.36)
PTSD, no major psychiatric disorder	2.07 (1.74–2.47)	2.02 (1.69–2.41)
PTSD and other psychiatric disorder	1.68 (1.40–2.01)	1.69 (1.41–2.03)
Non-refugee families
Mother
No psychiatric disorder	1	1
Major psychiatric disorder, no PTSD	2.08 (2.01–2.16)	2.01 (1.94–2.07)
PTSD, no major psychiatric disorder	2.42 (1.97–2.98)	2.28 (1.85–2.80)
PTSD and other psychiatric disorder	2.62 (2.18–3.13)	2.47 (2.06–2.96)
Father
No psychiatric disorder	1	1
Major psychiatric disorder, no PTSD	1.95 (1.87–2.03)	1.92 (1.84–2.00)
PTSD, no major psychiatric disorder	2.78 (2.09–3.69)	2.63 (1.97–3.49)
PTSD and other psychiatric disorder	2.77 (2.12–3.61)	2.54 (1.94–3.31)

Model 1 is adjusted for year of graduation and gender.

Model 2 is adjusted also for geographic residency and income.

In sensitivity analyses among children with Swedish-born parents, beta-coefficients of z-scores of mean grades were 0.28 (−0.34 and −0.22) in relation to PTSD in mothers and −0.40 (−0.50 and −0.29) in relation to PTSD in fathers. After additional adjustment for parental educational level, beta-coefficients were attenuated to 0.20 (−0.25 and −0.15) (mother PTSD) and −0.26 (−0.36 and −0.17) (father PTSD). ORs for ineligibility for secondary education among children with Swedish-born parents were 1.60 (1.36–1.88) in relation to PTSD in mothers and 2.00 (1.52–2.64) in relation to PTSD in fathers, and adjustment for parental education attenuated these OR’s to 1.43 (1.21–1.69) and 1.69 (1.28–2.24), respectively.

Table 5 presents Z-scores of mean grades and ORs of not being eligible for secondary education by country of birth of parents, and in the probable refugee group also by age of arrival in Sweden. Both outcomes differed greatly by parental country of birth with children in families with parents born in Iran having very similar outcomes as children with Swedish-born parents while outcomes in offspring of children in families from Iraq and East Africa having much lower grades and much higher percentage not being eligible for secondary education.

Table 5. School performance by parental country/region of birth and age at arrival in Sweden.

		Grade, mean points		Ineligible for secondary education
	N	No PTSD (Z-score)	Parental PTSD (Z-score)	No PTSD (%)	Parental PTSD (%)
Parental country/region of birth
Sweden	549,007	0.05	−0.52	8.7	20.4
Foreign-born non-refugee	18,548	−0.08	−0.60	16.4	25.6
former Yugoslavia	16,957	−0.24	−0.68	18.3	33.7
Iran	5458	0.00	0.33	13.0	24.7
Iraq	10,870	−0.60	−0.86	37.0	46.9
East Africa	3559	−0.41	−0.82	24.1	32.4
Other probable refugee	27,202	0.26	−0.53	19.3	28.0
Age at arrival in Sweden in children with Foreign-born parents
Born in Sweden	49,992	−0.15	−0.51	15.8	25.1
0–6 years	26,451	−0.18	−0.44	16.9	23.9
7–13 years	5018	−0.69	−0.93	43.7	49.5

A higher percentage of children in probable refugee families with PTSD were themselves foreign-born, 65%, compared with probable refuge families without parental PTSD, 45%. In a sensitivity analysis children in the refugee population, Beta-coefficients of z-scores of mean grades in relation to PTSD in any parent were slightly lower in foreign-born children, −0.29 (−0.35 and −0.23), compared to those born in Sweden, −0.33 (−0.41 and −0.26), after adjustment for gender, year of graduation and parental country of birth. A similar pattern was seen for ineligibility for secondary education with an OR of 1.60 (1.42–1.79) for foreign-born children and 1.85 (1.57–2.19) for Swedish-born children in relation to parental PTSD. In interaction analyses, these differences between being born in and outside Sweden were found to be significant on the p < .01 level.

For children in probable refugee families, mean grades and ineligibility for secondary school were analysed in a sensitivity analysis with refugee specific co-variates. In relation to PTSD in any parent, beta-coefficients of z-scores of mean grades were −0.35 (−0.40 and −0.30) with adjustment for gender and year of graduation only in a first model, and attenuated to −0.24 (−0.28 and −0.19) after adjustment also for age at arrival and parental country of birth as refugee specific factors in a second model. The OR for ineligibility for secondary education, 1.83 (1.67–2.00) was attenuated to 1.45 (1.31–1.60) with these same adjustments.

Girls were generally doing better in school than boys, with higher grades and a lower proportion of individuals not being eligible for secondary education. However, only minor differences were seen between girls and boys with regard to the impact of parental PTSD on school performance. Furthermore, there were only minimal differences in impact of parental PTSD depending on if the mother or the father who had been diagnosed with PTSD (see Tables 3 and 4).

Discussion

This national cohort study of 700,000 Swedish 15–16-year-olds is, to our knowledge, the first study to investigate links between parental PTSD and their children’s school performance. PTSD in both mothers and fathers was associated with poorer school performance with lower mean grades, lower scores on math tests and higher proportions of children being ineligible for secondary education. The effect sizes of parental PTSD were greater in children in native Swedish families, where they were moderate according to Cohen’s criteria compared to the small effect sizes in offspring of probable refugees. The consequences for eligibility to secondary education were, however, more severe for children in refugee families because of the general lower school performance in this population, with 35% of children from refugee families with experience of PTSD not being eligible for secondary education.

These results show that offspring of parents with PTSD have a considerably lower school performance than other children. The negative association of PTSD was not mediated through co-morbidity with depression, psychosis or bipolar disorder. School performance in children of parents with PTSD was lower than in children of parents with major psychiatric disorders such as psychosis and bipolar disease, which was quite surprising given the severity of these conditions and the strong association between such parental psychopathology and children’s adverse outcomes [9,10,21–23]. Parental PTSD has previously been shown to have adverse effects on children’s psychological distress and behavioural problems [13,15]. Thus, the children’s own mental health problems could contribute to the lower than average school performance in offspring of patients with PTSD. Furthermore, the children themselves may have experienced traumatic events and many traumatic events, such as family violence, traffic accidents or war related violence, can also be experienced by children and parents together. The finding that the association of parental PTSD in refugee families is even stronger for Swedish-born children in refugee families than those born before settlement in Sweden, seems to somewhat contradict the importance of shared exposure to war and persecution in the refugee populations. A possible contributing explanation to why the association was less pronounced among non-Swedish born children could be that the common suffering in the family, such as experiences of pre-flight difficulties and hardship during flight may foster resilience. However, other individual, relational and contextual factors, such as self-esteem and adaptability, family cohesion and support, and good peer relations have primarily been shown to promote resilience [19,24]. Further studies, with data on the children’s own exposures and mental health, are needed to clarify these important issues.

Our results are congruent with the findings of Daud et al. [19] that offspring of Arabic speaking refugee parents with PTSD in Sweden scored lower on an IQ-test compared with offspring of Arabic-speaking parents without PTSD. As demonstrated in previous research, post-traumatic stress extends beyond the individual to family members and can be experienced as a common trauma in the family, where parents’ reactions to traumatic experiences and the child’s own perception of these experiences may affect the child’s well-being and mental health [15]. Parental experience of traumatic stress may lead to a lack of consistency and stability in the family and has been associated with disconnected and insensitive parenting behaviour and harsh parenting styles [11,12,25,26]. Parental exposure to various forms of trauma has also been associated with an increased risk of violent behaviour and child abuse [27,28]. Previous studies have also shown that children of parents with PTSD often have insecure and/or disorganized attachment patterns [11,12]. The way in which parents with PTSD can have difficulties to meet their children’s need for empathy, sensitivity and presence has previously been discussed as one possible pathway for the intergenerational transmission of trauma [24]. The importance of how families communicate about traumatic experiences is another suggested pathway. An open and positive expression of emotion can foster resilience and serve as a protective factor in coping with stress and mental ill health. On the other hand, children may be affected in a more negative manner in families where parents have an unfiltered way to communicate about their experiences and when communication is characterized by feelings of meaninglessness and alienation [12,24]. Parental support and commitment are important factor for school success. Adding to the existing literature on possible consequences for health and well-being from parental PTSD, our study suggests that parents who suffer from PTSD-related symptoms may be hampered in their ability to motivate, encourage and support their children in schoolwork.

One may speculate about an alternative/complimentary explanation of the intergenerational effect of parental PTSD on offspring school performance through parental education and cognitive competence, which have been shown to be major determinants of offspring school performance [29]. The mechanisms through which parental education and cognitive competence exert influence on offspring school performance most likely include a complex combination of genetic and environmental factors, including effects on IQ, parenting style, parental expectation and engagement [29,30]. Parents with PTSD in this study have a lower educational level than those without. This could possibly be explained by social differences in exposures to violence and other traumatic events involved in the development of PTSD [31].

Our results suggest that parental PTSD may be an important contributing factor explaining the lower grades and higher ineligibility for secondary school seen in children from families with a probable refugee background. Previous studies on the association between parental mental ill health, e.g. depression, and risk for school failure has proposed social pathways, in addition to adverse effects on neurodevelopment and shared genetic liability, as possible mechanisms [32]. The importance of a student’s socioeconomic background for school results in the Swedish primary school has previously been stressed in a report from the Swedish National Agency for Education [33]. In addition to the effect that parental PTSD may have on the quality of parenting and family functioning, social pathways are thus probably also important in the explanation of poor school performance in children in refugee families. Refugee families have been described to have a socioeconomically disadvantaged situation compared with the native population, e.g. with higher rates of unemployment, lower income and residency in low status neighbourhoods [4].

It is possible that PTSD can have negative consequences for the process of integration of refugees in the labour market in the receiving country, through e.g. functional impairment and difficulties in language acquisition, with secondary effects on the socioeconomic situation of the family. Further studies with a longitudinal perspective are needed to study this.

Limitations

The strengths of this study include the use of a large national cohort consisting of more than 700,000 individuals, and the linkage of multiple national registers with high validity and minimal attrition. However, there are also limitations. Information from the national Hospital Discharge Register was used to identify parents with a diagnosis of PTSD, which means that individuals suffering from PTSD who do not seek medical attention and individuals who are treated in primary care and in special treatment centres (e.g. treatment centres run by non-governmental organisations such as The Red Cross) are not included. Furthermore, representativeness may be affected by differences in care-seeking behaviours, for instance because of different ways of understanding and communicating mental distress and psychiatric disorders across cultures, and barriers to care, such as knowledge about the health care system and language skills, which can make it more difficult for individuals with a refugee background to access psychiatric care. Another limitation is the lack of information on children’s mental health and children’s own experiences. Such information would contribute to the understanding of these associations and there is need for future studies where these issues can be studied further.

Since we did not have access to detailed information on whether the parents and/or the child arrived in Sweden as refugees, parental country/region of birth was used as a proxy for refugee background. The population of probable refugees may thus include non-refugee migrants. However, since this most likely would have resulted in a dilution of the associations between parental PTSD in refugee families and consequences for children, this was assumed to be a minor problem. Since the national administrative registers used for this study only include individuals with residence permits, there is no information on individuals without residence permits or individuals seeking asylum.

Because of a systematic underestimation of education in immigrants with a non-European background, another limitation of the current study is that from these administrative register data we cannot further explore the potential contribution of parental education among refugee families to the association between parental PTSD and offspring educational achievement.

The study population consisted of children who finished compulsory school between the years 2004–2009. The Swedish school system has not changed significantly since then, but there has been a larger amount of refugees arriving in Sweden and the number of families where parents suffer from PTSD due to war trauma is probably higher in more recent years. Future studies with more recent data, including also more detailed information on refugees/asylum-seekers, age at arrival and how long the family have lived in Sweden, are therefore needed.

Implications

These results suggest that PTSD may have severe consequences for parents’ ability to support their children’s schoolwork. School failure is a major risk factor for several adverse outcomes in adolescence and young adulthood as well as later in life [34–36]. Grades from primary school are also the main selection criteria for further studies and as such an important predictor of educational achievement and labour market attachment. Thus, prevention of school failure is crucial for creating opportunities for good health, education, and employment, key factors in social participation and integration [37]. School performance overall was considerably poorer among children in families with a probable refugee background. Consequences from parental PTSD may be a contributing factor in explaining higher rates of school failure in children with a refugee background, in addition to the possible contribution of other important factors such as language problems, lack of understanding of the school system, and contextual factors such as neighbourhood and school characteristics. Identifying individuals suffering from PTSD, and their families, as part of the reception of asylum-seekers, assuring that these individuals are diagnosed and receive correct treatment, seems to be an important course of action. Family teams that provide support for children and spouses of patients diagnosed with PTSD have been established at treatment centres for refugees [38] and should be encouraged also within regular psychiatric services. This study shows that educational support should be a priority and integrated to the psychosocial support strategies guiding this work.

Conclusions

PTSD in parents may have substantial consequences also for their children. Our results demonstrated that parental PTSD was associated with lower mean grades and a higher proportion of children being ineligible for secondary education, in comparison with children without PTSD in the family. Thus, the specific symptoms of PTSD and consequences for attachment, parent–child interaction and parenting may not only have consequences for the child’s health and wellbeing, but also for cognitive development and educational achievement. Preventive work must address children of diagnosed patients and there is a need for interventions, such as tutoring programmes, to improve school performance in children from families with parental PTSD.

Notes on contributors

LB and AH conceptualized and designed the study. LB performed the data analyses and drafted the manuscript. LB, SC, EM and AH interpreted the results and revised the manuscript. All authors read and approved the final version of the manuscript.

Disclosure statement

The authors declare that there is no conflict of interest.

Data availability statement

Sharing of data is restricted by Swedish data protection laws and administrative data is made available for specific research projects. Thus, the data used for this study cannot be shared with other researchers.

Note

Additional information

Funding

This work was supported by the research initiative Children, Migration and Integration at Stockholm University, Stockholm, Sweden; the Swedish Research Council for Health, Working Life and Welfare [grant number 2016-07128]; and the Swedish National Board of Health and Welfare.

Notes

1 The EU15 comprise the 15 member countries in the European Union prior to 2004: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, Netherlands, Portugal, Spain, Sweden and the United Kingdom.