What You Can Change _. And What You Can't - Martin E. Seligman [52]
Epidemic
It is very important to know that this kind of depression is rampant today and that its usual victim is a woman.
In the late 1970s, under the leadership of the visionary biological psychiatrist Gerald Klerman, the United States government sponsored two major studies of mental illnesses; the findings were startling. In the first, 9,500 people were randomly picked as a cross section of adult Americans. Each was given the same diagnostic interview that a troubled patient who walks into a knowledgeable professional’s office would get.
Because such a large number of adults of different ages were interviewed, the study gave an unprecedented picture of mental illness over many years and made it possible to trace the changes that had taken place over the twentieth century.3 One of the most striking changes was in the lifetime prevalence of depression, that is, the percentage of the population that has had it at least once. Obviously, the older you are, the more chance you have to get the disorder. The lifetime prevalence of broken legs, for instance, goes up with age, since the older you are, the more opportunities you have to break a leg.
It was expected that the earlier in the century a person was born, the higher would be the person’s lifetime prevalence for depression—that is, the more episodes of depression she would have had. Someone born in 1920 would have had more chances to suffer depression than someone born in 1960. Before the statisticians looked at the findings, they would have stated confidently that if you were twenty-five years old at the time you were interviewed for the study—which meant that you were born around 1955—there was, say, about a 6 percent chance that you had had at least one episode of severe depression, and that if you were between twenty-five and forty-four years old, your risk of depression would have climbed—say, to about 9 percent—as any sensible cumulative statistic should.
When the statisticians actually looked at the findings, though, they saw something odd. The findings showed that the people born around 1925 hadn’t suffered much depression; not 9 percent but only 4 percent had had an episode. And when the statisticians looked at the findings for people born even earlier—before World War I—they found something even odder: Again, the lifetime prevalence had not climbed; in fact, it had nosedived to a mere 1 percent. This meant that people born in the second half of the century were ten times likelier to suffer depression than people born in the first half.
One study, however—even one as well done as this—does not entitle scientists to shout “epidemic.” Fortunately, another major study was done at the same time. This time, the people were not randomly selected; they were chosen because they had close relatives who had been hospitalized for depression.4
Again, the findings turned expectations upside down. They showed a strong increase in depression over the course of the century—again, more than ten to one. For instance, when the women of the World War I generation were thirty (the age women born during the Korean War now were), only 3 percent of them had ever suffered a severe depression, while by the time the women born during the Korean War period had turned thirty, 60 percent of them had had an episode of depression—a twentyfold difference. The statistics for the men in the study showed the same surprising reversal. Though the men suffered only about half as much depression as the women (a crucial fact I’ll discuss in a moment), they also displayed the same strong percentage increase over the decades.
Not only is severe depression much more common now; it also attacks its victims much earlier in their lives. If you were born in the 1930s and at any point thereafter had a depressed relative, your own first depression, if you had one, would strike between the ages of thirty and thirty-five, on average. If you were born in 1956, your first depression would