Editorial

Women and men are biologically different and have very different life experiences so it is surprising that until recently there has been little research into gender differences in mental health. This may have reflected concerns about the ethics of including women of childbearing age in aetiological or treatment research due to the potential risks of investigations such as neuroimaging or drug treatments on an unknown pregnancy. However, before the 1990s, there also appears to have been a ‘gender-blind’ approach to the understanding of, and development of new treatments for mental illness (Kulkarni, 2007). There is now growing evidence, from neuroscience to epidemiology and health services research, that investigation of gender differences in mental health can help us understand the aetiological determinants of mental disorders and lead to more tailored treatments for men and women. This special issue on gender and mental health is therefore both timely and exciting as it is a great opportunity to update readers on the developments in our understanding of gender differences in mental health and how this can be reflected in gender-specific treatments. This issue is not only about biological and epidemiological differences – we also include a thought-provoking paper by Andermann (2010) on the social construction of gender and how the interdisciplinary study of the complex factors related to culture and society, power and politics is necessary to be able to find solutions to gender disparities in mental health.

We have included comprehensive reviews of gender differences in the major mental disorders commonly seen by psychiatrists: schizophrenia (Abel et al., 2010), bipolar disorder (DiFlorio & Jones, 2010) and depression (Parker & Botchie, 2010). Recent meta-analyses have clearly demonstrated that the traditional assumption of no gender differences in the incidence of psychosis was based on a very limited evidence base. Abel et al. (2010) report that when more methodologically rigorous studies using stringent diagnostic criteria are included in meta-analyses, there is a mean ratio of male:female schizophrenia incidence of 1.4. It has been well recognized for some time that there are also gender differences in the age of onset, symptomatology and course of schizophrenia, but the mechanisms for this have been unclear. Abel et al. suggest that the factors that contribute to the normal sexual dimorphisms of the developing and adult brain may be the same factors that result in sex-specific brain abnormalities in schizophrenia, with implications for treatment response.

DiForio & Jones (2010) report on the recently recognized gender differences in type and course of bipolar disorder, including an increased risk of bipolar II, rapid cycling and mixed episodes in women. They also highlight the impact of childbirth on bipolar disorder which is associated with a very marked increase in risk of puerperal psychosis (see also Leight et al., 2010). This comprehensive review finds little evidence of gender differences in response to treatment but this may reflect the relative lack of research in this area.

Parker & Brotchie (2010) review the evidence for the female preponderance in depression and report that while artefactual factors make some contribution, there is evidence for a higher-order biological factor (variably determined neuroticism, ‘stress responsiveness’ or ‘limbic system hyperactivity’) that contributes to the gender differentiation in some expressions of both depression and anxiety, and reflects the impact of gonadal steroid changes at puberty. They also discuss the role of environmental variables and conclude with a diathesis-stress model, which can account for differential epidemiological findings, with implications for gender differences in treatment response.

The impact of childbirth on a broad range of mental disorders is reviewed by Leight et al. (2010). It is now well-recognized that the postpartum period is a time when women are more likely to develop a psychotic episode than at any other time in their lives. The authors also explore the current evidence base on the impact of pregnancy on pre-existing disorders (including obsessive compulsive disorder and eating disorders), and implications for management, not only by psychiatric services but also maternity services. The perinatal period is a time of frequent contact with maternity care and therefore offers a unique opportunity for professionals to identify and treat mental disorders and improve outcomes for women and their families.

An increasingly recognized determinant of mental disorders in women is domestic violence and we review the current evidence base on prevalence and interventions for domestic violence experienced by people with mental disorders (see Howard et al., 2010). There has been considerably less research on gender differences in the experience of violence in people with severe mental illness; men and women with severe mental illness are at significantly increased risk of violent victimization, but the gender pattern for this has not been systematically examined. In the general population, men are at higher risk of overall and physical victimization, whilst women are at increased risk of domestic and sexual violence. Khalifeh and Dean's review (2010) finds that, compared to the general population, women with severe mental illness are at greater excess risk than men, leading to a narrowing in the ‘gender gap’, with implications for prevention and research.

No review of gender differences in mental health can ignore gender discrimination, gender inequality, and gender disparities (also referred to as gender disadvantage) as these are major determinants of common mental disorders. The global impact of gender disadvantage is reviewed by Chandra and Satyanarayana (2010) and they highlight that gender disadvantage among women includes poverty, discrimination, powerlessness, limited access to resources and restricted choices (e.g. choice of marriage, decision making in the marriage or workplace issues), infant gender preference and violence. Many of these factors co-exist (such as poverty and food insecurity) and hence compound the impact of disadvantage on mental health. Psychosocial, educational and preventive interventions to enhance women's mental health therefore need to be both gender and culture sensitive.

Drug treatments also need to take gender into account and we have therefore included some excellent reviews of gender differences in response to antidepressants (Keers & Aitchison, 2010) and antipsychotics (Smith, 2010). Both these papers provide up-to-date reviews of gender differences in pharmacokinetics and pharmacodynamics, but are also highly practical in helping prescribers to tailor treatment to women and men appropriately, taking age as well as gender into account.

I am sure you will find these reviews as intriguing and informative as I have. This special issue demonstrates that knowledge of gender differences in mental health, using a biopsychosocial framework, is of central importance in understanding mental disorders. The relevance of research into gender and mental health is no longer in doubt and these articles will be an invaluable resource to mental health professionals and researchers.