According to a recent study by Yale University, higher levels of estrogen may enhance feelings of stress, thereby making women more susceptible to depression, posttraumatic stress disorder, and other mental illnesses. Researchers exposed male and female rats to various stressors and then tested their abilities to complete a short-term memory task. Without stress, both the male and female rats performed at the same level. After being exposed to high levels of stress, both genders had difficulty performing the task.
After moderate levels of stress, however, the female rats were impaired while the male rats were not. The researchers were also able to show that the female rats only showed this impairment while in a high-estrogen phase. These findings support the higher incidence of depression in women than in men. They may also explain why the prevalence of depression begins in women?s pubescent years and declines in postmenopausal years. (The findings were published in Molecular Psychiatry, March 2004.)