Psychologists continue to broach a subject considered verboten in many circles: intrinsic differences between men and women, with particular regard to mental health.

Writing in TIME magazine, Daniel Freeman, a psychologist at Oxford University, says it's true that men are more likely to develop problems with alcohol and drugs — or to engage in antisocial behaviors — but that women tend to suffer mental illness at much higher rates, as shown by empirical data.

A large and representative sample of the American population, known as the National Comorbidity Survey Replication, shows that 9 percent of women suffered depression during the past year, compared to 5 percent of men. Moreover, nearly one in four women experienced an anxiety disorder in comparison to 14 percent of men.

"This data isn't illusory: it shows that huge numbers of people are struggling with psychological problems — and the majority of them are female," Freeman wrote. "Some would say that men experience just as much mental illness as women: they just don't admit it. But the scientific evidence to back up such an assertion simply isn't there."

Freeman, who co-wrote The Stressed Sex: Uncovering the Truth about Men, Women, and Mental Health with his brother Jason Freeman, says the data shows that in any given year women suffer mental illnesses at a rate 20-40 percent higher than men.

Putting aside blatant sexism as a root cause, Freeman says women may suffer mental illnesses at higher rates than men because of the stressful roles they play in society, as they often juggle lower-paying jobs along with childcare and family responsibilities. They are also more likely to be survivors of childhood sexual abuse, "a trauma that leaves lasting psychological damage," Freeman writes.

To any modern feminists or others offended by the discussion, Freeman enjoins everyone to "have these awkward conversations" in the hopes of solving mental health problems, rather than allowing it to fester. Researchers should investigate root causes of mental illness while paying close attention to the role gender may play, he writes.