Duke University psychologists Terrie Moffitt, Avshalom Caspi and colleagues used a long-term tracking study of more than 1,000 New Zealanders from birth to the age 32 to conclude that people vastly under-report the degree of mental illness they have suffered.
But such self-reporting from memory is the basis of much of what we know about the prevalence of anxiety, depression and alcohol dependence.
Longitudinal studies like the Dunedin Study in New Zealand that track people over time are rare and expensive, Moffitt said.
“If you start with a group of children and follow them their whole lives, sooner or later almost everybody will experience one of these disorders,” said Moffitt, professor of psychology at Duke.
The Great Smoky Mountains Study, a similar effort based at Duke, tracked 1,400 American children from age 9-13 into their late 20s and found similar patterns, said
“I think we’ve got to get used to the idea that mental illness is actually very common,”
Similarly, the survey studies have reported a six to 17 percent lifetime rate of alcohol dependence between the ages 18-32, versus nearly 32 percent in the Dunedin Study.
Moffitt and Caspi’s findings appeared online in Psychological Medicine.