That's because women are more likely to internalize their emotions, which can bring on withdrawal, loneliness and depression, whereas men externalize them, becoming aggressive and impulsive, the researchers showed.

The results mean that mental illness prevention efforts that focus on each gender's "core psychological processes" are likely to affect the development of multiple disorders, the researchers wrote.

The study was published online Monday (Aug. 15) in the Journal of Abnormal Psychology.

Men and women

Researchers analyzed the answers to interview questions given by 43,093 U.S. adults during a 2001 National Institutes of Health survey. The participants were representative of the age, race/ethnicity and gender distributions of the U.S. population in the 2000 census, the researchers said.

When it came to depression, 22.9 percent of women said they had had the condition during their lifetime; 13.1 percent of men said they had.

The study showed 7.2 percent of women had panic disorder, and 5.8 percent had generalized anxiety disorder, while just 3.7 and 3.1 percent of men had those conditions, respectively.

Among conditions more common in men were alcohol dependence and antisocial personality. The findings showed that 17.4 percent of men had alcohol dependence and 5.5 percent had antisocial personalities, while 8 percent and 1.9 percent of women had those conditions, respectively.

The condition that displayed the biggest gender difference in prevalence was "specific phobia," a condition in which a person has an unreasonable fear of a specific object or situation. Among women, 12.4 said they had the condition, while 6.2 percent of men did. (The researchers statistical analysis took into account not only the percentage of each gender that has a condition, but also how common it is, making this difference slightly larger than that of depression.)

Different genders need different treatments

The findings show that prevention and treatment efforts should be gender-based, the researchers said.

"In women, treatment might focus on coping and cognitive skills to help prevent rumination from developing into clinically significant depression or anxiety," said study researcher Nicholas Eaton, of the University of Minnesota. "In men, treatment for impulsive behaviors might focus on rewarding planned actions and shaping aggressive tendencies into nondestructive behavior."

Past research also indicated that women report more neuroticism and more frequent stressful life events than men do before the onset of a disorder, indicating that environmental stressors may also contribute to internalizing, the report said.

The research also suggests that the revision of the psychiatry textbook the Diagnostic and Statistical Manual of Mental Disorders (DSM) that is now under way should take gender into account when defining psychiatric conditions, the researchers said.

The study was limited in that it relied on interviews conducted by people who were trained but who were not psychological clinicians, and that it investigated only common mental disorders, leaving out more rare ones such as schizophrenia, the researchers said.

Pass it on: Women's tendency to internalize their emotions, and men's tendency to externalize them, contributes to gender differences in mental illnesses.