The origins of sex differences in depressive disorder: bridging the gap

The high prevalence of depressive disorder in women is well established. However, it has not been convincingly explained. This reflects a more general failure of research to provide a comprehensive aetiological account of depression. The examination of the sex difference can be used as a probe to evaluate how far we have gone in substantiating integrated models of depressive disorder. In this paper, I review several lines of investigation in order to assess the relative importance of social, psychological and biological influences on the sex difference in depression. These include the epidemiology of macrosocial variables and age effects, and the exploration of relevant psychological attributes, including temperament, personality, and attributional and coping styles. We must also consider the experience of psychosocial adversity, and in particular the possibility of an increased susceptibility of women to some forms of stress. Both the tendency to affiliation and the requirement for social support seem stronger in women. There is appreciable direct and indirect evidence that the particular strains of the roles available to women may increase their risk of depression. Biological explanations tend to be couched in hormonal terms. However, the most convincing hormonal correlates of depressive disorder relate not to sex hormones but to corticosteroids and their control mechanisms. These do not appear to differ by sex. However, the greatest problem for biological explanations of the sex difference lies in the failure of genetic models to account for it. It is hard to conceive of a biological substrate unaffected by genetic factors. Thus, while there seems no doubt that biological factors are involved in the emergence of depressive disorder, they do not appear to be responsible for the sex difference. All told, the evidence for environmental effects is much better for social than for physical factors, and a plausible case can be made for a developmental perspective involving the interaction of social experience and psychological attributes.