Why is Depression More Prevalent in Women?
Unnati Shekhar
June 2024
Major depression is a widespread chronic illness that significantly contributes to the global burden of disease. In 2010, depressive disorders were the second leading cause of years lived with disability in Canada, the United States, and across the globe. When considering deaths from suicide and stroke related to depression, it ranks third in the global burden of disease. The overall burden of major depression is increasing, and it is expected to be the leading cause of disease burden by 2030, already holding this position for women worldwide. Between 1990 and 2010, Canada saw a 75% increase in disability-adjusted life years due to major depression, second only to Alzheimer’s disease, while the increase in the U.S. was 43%. The female-to-male ratio of global disability from major depression has remained at 1.7:1. While socioeconomic factors such as abuse, education, and income may influence the higher rate of depression in women, this article focuses on biological contributors to this disparity.
The prevalence of major depression is higher in women than in men. In 2010, the global annual prevalence was 5.5% for women and 3.2% for men, a 1.7-fold difference. In Canada, the prevalence in 2002 was 5.0% for women and 2.9% for men, increasing to 5.8% and 3.6% respectively by 2012. These similar ratios across developed countries suggest that the differential risk is mainly due to biological sex differences rather than social or economic factors. The rate of depression does not appear higher in countries where women have significantly lower socioeconomic status than men. Depression is more than twice as prevalent in young women (ages 14–25) than in men, but this ratio decreases with age. Before puberty, boys and girls have similar depression rates, which decline after age 65, becoming similar between genders. This higher prevalence in women is also reflected in the prescription rates of antidepressants, with women in Canada being prescribed these medications more than twice as often as men. The delay in antidepressant treatment for young adults may contribute to higher depression rates in adolescence and young adulthood.
Depression triggers differ between genders, with women more often experiencing internalizing symptoms and men externalizing symptoms. Studies of dizygotic twins suggest women are more sensitive to interpersonal relationships while men are more sensitive to external career and goal-oriented factors. Women also face specific forms of depression-related illnesses linked to hormonal changes, such as premenstrual dysphoric disorder, postpartum depression, and postmenopausal depression and anxiety. This suggests that hormonal fluctuations, particularly estrogen, may trigger depression in women. However, most preclinical studies focus on males to avoid behavioural variability related to the menstrual cycle. Additionally research on primates has shown that social stress can lead to depression-like symptoms and changes in the serotonin system and hippocampal volume, more pronounced in postmenopausal than ovarian-intact monkeys. Furthermore, hormone replacement therapy during perimenopause has shown promise in preventing postmenopausal depression. Studies indicate that oral contraceptive use may reduce depression and anxiety, suggesting that moderating estrogen cycling could be protective.
Despite the lack of systemic estrogen, men have lower depression rates, possibly due to the conversion of testosterone to estrogen in the male brain, providing consistent protection. Men also have androgen receptors that may offer additional protection. These hormonal and developmental differences in brain circuitry contribute to the lower prevalence of depression in men.
The fundamental genetic differences between men and women, such as the presence of X and Y chromosomes, contribute to the differing depression rates. Societal factors likely have a biological basis, yet even with improving social equality, the female-to-male depression ratio remains unchanged. Biological factors, particularly fluctuations in ovarian hormones and decreases in estrogen, appear to significantly contribute to the higher prevalence of depression in women. Developing treatments that target these biological factors could help mitigate this disparity.
References
Whiteford, H. A., Degenhardt, L., Rehm, J., Baxter, A. J., Ferrari, A. J., Erskine, H. E., Charlson, F. J., Norman, R. E., Flaxman, A. D., Johns, N., Burstein, R., Murray, C. J., & Vos, T. (2013). Global burden of disease attributable to mental and substance use disorders: findings from the Global Burden of Disease Study 2010. Lancet, 382(9904), 1575–1586. https://doi.org/10.1016/s0140-6736(13)61611-6
Ford, D. E., & Erlinger, T. P. (2004). Depression and C-Reactive protein in US adults. Archives of Internal Medicine, 164(9), 1010. https://doi.org/10.1001/archinte.164.9.1010
