Life events as predictors for depression in men and women: A Finnish twin study

Abstract Background Depression is more common in women than in men, but reasons for the sex/gender difference are not fully known. We analyzed sex/gender differences in the association of past life events (LE) with depression, and if the associations are independent of genetic liability. Methods In the 2011 survey of the Finnish Twin Cohort (participation 72%, n = 8410, 45% men, mean age 60 yrs), depression was assessed using the Center for Epidemiologic Studies Depression (CES-D) scale (cut off value ≥20) showing depression in 13% (11% in men, 15% in women). LE were assessed as negative, positive, and serious (traffic accident, other accident, fire and natural catastrophe, physical abuse, sexual abuse, violent crime, and parental divorce) ones in childhood and/or in adulthood. Pearson’s chi-squared test and age- and sex-adjusted logistic regressions were used to model the strength of associations. The effect of familial factors was tested using conditional logistic regression in 176 genetically identical (MZ) twin pairs (38% male) discordant for depression. Results Women experienced more both negative LE (50%/42%, p < 0.001) and positive LE (60%/40%, p < 0.001) than men. Accidents, physical abuse and violent crime were reported more by men, but women reported more sexual abuse (14%/1%, p < 0.01). All LEs were associated with depression (adjusted Odds Ratios [OR] from 1.24, 95% Confidence Intervals [CI] 1.09 - 1.42 to OR 6.91, 95% CI 3.88 - 12.30). Women with physical abuse or violent crime in childhood or in adulthood were more vulnerable for depression than men. High magnitude of negative LEs in both sexes, low rates of positive LE in women, and physical abuse in women remained significantly associated with depression within MZ pairs suggesting independence from familial factors and genetic liability. Conclusions We found sex difference in LE prevalence and in vulnerability for depression. These do not appear to be accounted for by familial effects. Key messages We found differences between women and men in life event prevalence and in vulnerability for depression. Differences in life experiences and exposures between women and men should be considered in prevention and treatment of depression.