Women are more likely than men to have depression, and genetics may play a big role in that disparity

Feelings of persistent sadness, loss of interest in previously pleasurable activities, having trouble finding motivation and being fatigued – these are all common symptoms of depression, sometimes called major depression.

Depression – which affects 280 million people worldwide, including 23 million children – differs from just feeling low or having the blues. It often lasts longer, requires treatment and sometimes recurs throughout life.

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And research shows that girls and women are twice as likely to have depression than men, often emerging with the onset of puberty. How to account for these gender differences with major depression is not fully understood.

But a large, new international study has found that much of the gender and sex differences with depression may come down to genetics.

Genes play a much larger role in depression in women than in men – with women having about "twice as many genetic 'flags'" for depression than men, according to the study published in Nature Communications.

"Unpacking the shared and unique genetic factors in males and females gives us a clearer picture of what causes depression — and opens the door to more personalized treatments," Jodi Thomas, who helped lead the research, said in a news release.

The study drew on data from five cohorts in the United States, United Kingdom, Australia and the Netherlands. Researchers analyzed the data of 500,000 people, including nearly 135,000 women with depression and 65,000 men with depression.

The researchers identified about 7,000 DNA changes that cause depression for women and men – and another 6,000 DNA changes that could cause depression in women only.

Additionally, the study found some genetic differences that could explain why adolescent and adult women are more likely than men to experience weight changes and fatigue when depressed.