Why is depression more prevalent in women?

Hard to say, but there’s some evidence that hormones could play a role. One line of evidence suggesting this is that young women are at the greatest risk^[1] for major depression and mental disorders starting at puberty, when prevalence of depression^[2] is doubled in women compared to men for ages 14-25. However, other social factors around this age could equally play a role. What’s more confusing is that a reduction in estrogen also looks to be linked to depression. In the time right before menopause, when estrogen levels begin to decrease in an irregular fashion, the risk of depression^[3] appears to increase, and studies^[4] suggest that hormone replacement therapy (particularly estrogen) may prevent or alleviate depression experienced during the transition. In fact, women using oral contraceptives^[5], especially the monophasic (same amount of hormones in each pill) type, reported reduced rates of depression and anxiety in comparison to non-users. Unfortunately, since researchers suspect hormonal fluctuations can influence depression, most studies tend to avoid women participants for this reason, so not much human data is available.