Updated: Tuesday, April 29, 2014, 4:40 AM
NEW YORK (Reuters Health) - The widely reported difference in depression rates between men and women may be exaggerated by men's tendency to under-report their depressive symptoms, new research suggests.
Women may be up to 70% more likely to suffer depressive symptoms, according to the National Institute of Mental Health. But the difference in depression rates flipped when researchers changed the words "depression inventory" to "well-being inventory" on the CES-D, a self-reported depressive symptoms questionnaire.
Men reported more depressive symptoms when they thought the questionnaire was evaluating their well-being, the study found.
The findings may call into question the reliability of such questionnaires, Joshua Swanson, who led the research, told Reuters Health by email.
Swanson, an undergraduate psychology student at Carnegie Mellon University in Pittsburgh, Pennsylvania presented data from the study on April 23 at the annual meeting of the Society of Behavioral Medicine conference in Philadelphia.
"When practicing physicians go to evaluate depressive symptoms in men, it is important that they keep this response bias in mind," Swanson says.
The study included 111 students who were randomized to fill out one of the two surveys, either the unchanged CES-D or the modified version that swapped the word "depression" for "well-being." While men reported significantly more depressive symptoms on the "well-being" questionnaire, the women's rate did not vary.
"These findings highlight potential explanations for the long-documented disparity in depression rates between men and women, suggesting that men may respond differently to traditional and commonly used measures to assess depression," said Dr. Gareth Dutton of the University of Alabama at Birmingham, who was not involved in the study.
"This is consistent with some of the previous research on gender differences in depression but provides a unique and innovative perspective by artificially manipulating the purpose of a depression screening instrument," Dutton told Reuters Health.
The implications of the findings may not be clear-cut, however. When the researchers conducted the same test online with 116 different participants the differences disappeared. The wording of the questionnaires did not appear to influence the responses from either men or women.
"We hypothesized that either the anonymity of being online reduced their need to alter their responses to be socially desirable, or that the participants were less attentive taking an online study. We are currently working on a third in-lab study where we are also manipulating perceived anonymity to see exactly what is going on," Swanson says.