Nearly 24% of US adults have a lifetime history of major depressive episodes, a prevalence much higher than the 14% who self-report them, researchers reported in the American Journal of Preventive Medicine. The findings are based on a simulation model.
“Major depressive episodes are far more common than we thought,” said study leader Jamie Tam, PhD, at the Yale School of Public Health in New Haven, Connecticut.
“Our model shows that the probability of someone having a first major depressive episode is especially high during adolescence. We also know from other research that having a first major depressive episode increases the likelihood you’ll have a second one,” Dr. Tam explained. “This means that anything we can do to prevent or treat episodes among young people could lead to larger health benefits over the course of their life.”
While major depressive episodes are a leading cause of disability, they are subject to substantial recall bias in survey assessments, researchers explained. To quantify the full burden of major depressive episodes on population health in the United States, they applied a model that simulates under-reporting of past major depressive episodes.
After adjusting for recall error, the study estimated 30.1% of women and 17.4% of men had lifetime histories of major depressive episodes, compared with 17% of women and 10% of men in survey assessments.
Among all adults, failure to report a past major depressive episode occurred with 13.1% of women and 6.6% of men. Among adults aged 65 years or older, under-reporting of a major depressive episode history was estimated at 70%, according to the study.
Given the findings, far more adults would benefit from strategies to prevent depression than what survey estimates have suggested, researchers concluded.
“If you think about chronic health conditions like heart disease, we do a lot to identify people who might be at risk for additional health events like heart attacks because that group would benefit from maintenance treatment and clinical monitoring,” Dr. Tam said.
“We don’t do such a great job when it comes to mental health conditions. So, if we’re able to assess how many people actually have histories of depression, that also tells us that more people are at risk of experiencing more depressive episodes.”