Gender differences in depression diagnosis and symptoms start to appear around the age of 12, a new study reports.
"We found that twice as many women as men were affected. Although this has been known for a couple of decades, it was based on evidence far less compelling than what we used in this meta-analysis," said study co-author Janet Hyde. She is a professor of psychology and gender and women's studies at the University of Wisconsin-Madison.
The study was published online in the Psychological Bulletin.
Feeling blue most of the time
"We want to stress that although twice as many women are affected, we don't want to stereotype this as a women's disorder. One-third of those affected are men," Hyde said in a university news release.
For the study, the researchers spent two years reviewing existing studies that involved a total of about 3.5 million people from more than 90 countries.
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The study authors looked at diagnoses of major depression as well as symptoms based on self-reported measures, which may not meet the criteria for major depression, such as a person reporting that they feel blue most of the time.
Overall, the investigators found that depression affects significantly more women than men.
The study also found the gender gap appears two to three years earlier than previously thought.
Social environment changes
"We used to think that the gender difference emerged at 13 to 15 years, but the better data we examined has pushed that down to age 12," Hyde said.
The gap tapers off after adolescence but remains nearly twice as high for women, the researchers pointed out. Puberty could help explain this trend, the study authors noted.
"Hormonal changes may have something to do with it, but it's also true that the social environment changes for girls at that age. As they develop in puberty, they face more sexual harassment, but we can't tell which of these might be responsible," Hyde said.
"We need to start before age 12 if we want to prevent girls from sliding into depression. Depression is often quite treatable. People don't have to suffer and face increased risk for the many related health problems," she added.
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