Researchers supported by the National Institute of Mental Health (NIMH) have found that half of all lifetime cases of mental illness begin by age 14, and that despite effective treatments, there are long delays — sometimes decades — between first onset of symptoms and when people seek and receive treatment. The study also reveals that an untreated mental disorder can lead to a more severe, more difficult to treat illness, and to the development of co-occurring mental illnesses.

The landmark study is described in four papers that document the prevalence and severity of specific mental disorders. The papers provide significant new data on the impairment — such as days lost from work — caused by specific disorders, including mood, anxiety, and substance abuse disorders. These measures will allow researchers to determine the degree of disability and the economic burden caused by mental illness, as well as trends over time.

The papers are reported in the June 6 issue of the Archives of General Psychiatryby Ronald Kessler, Ph.D., and colleagues. The study was a collaborative project between Harvard University, the University of Michigan, and the NIMH Intramural Research Program.

This study, called the National Comorbidity Survey Replication (NCS-R), is a household survey of 9,282 English-speaking respondents, age 18 and older. It is an expanded replication of the 1990 National Comorbidity Survey, which was the first to estimate the prevalence of mental disorders (using modern psychiatric standards) in a nationally representative sample. The expansion includes detailed measures that will significantly improve estimates of the severity and persistence of mental disorders, and the degree to which they impair individuals and families, and burden employers and the U.S. economy.

“These studies confirm a growing understanding about the nature of mental illness across the lifespan,” says Thomas Insel, M.D., Director of the National Institute of Mental Health. “There are many important messages from this study, but perhaps none as important as the recognition that mental disorders are the chronic disorders of young people in the U.S.”