The prevalence of mental illness in the United States continues to be high despite increases in mental health awareness, new medications, changes in public perceptions about mental illness, and advances in treatment financing, according to a national mental health tracking study.

The results of the latest National Comorbidity Survey Replication (NCS-R) indicate that most Americans experience mental illness at some point in their lives, and many go untreated. Additionally, those who eventually seek treatment often receive substandard care, survey director Ronald C. Kessler, Ph.D., said in a press teleconference sponsored by Harvard Medical School and the National Institute of Mental Health.

Led by Harvard, the University of Michigan Institute for Social Research, and NIMH, the NCS-R is a nationally representative, face-to-face household survey taken every 10 years to assess the mental health of the country. The survey examined anxiety, mood, impulse control, and substance abuse disorders and quantified lifetime prevalence, age of onset, delay in treatment seeking, prevalence and severity in a given year, treatment and quality of care in a given year, and barriers to treatment.

In one of four papers analyzing the survey results from 9,282 English-speaking respondents, Dr. Kessler and his colleagues at Harvard Medical School, Boston, reported that about half of the population met the criteria for a DSM-IV disorder sometime in their lives, with first onset usually in childhood or adolescence. The lifetime prevalence estimates for anxiety and impulse control disorders were highest, at 29% and 25%, respectively, and the median age of onset for both was 11 years.

The lifetime prevalence estimates for mood disorders and substance use disorders were 21% and 15%, respectively, and the median age of onset was 30 years for mood disorders and 20 years for substance use disorders (Arch. Gen. Psychiatry 2005;62:593–640).

Because first onset so often occurs in childhood or adolescence, “prevention and treatment interventions have to focus on youth,” Dr. Kessler stressed. “Early interventions should be aimed at preventing the progression of primary disorders in the child and adolescent years” as a way to mitigate the societal and personal burdens associated with mental disorders into adulthood, he said.

Analyses of the 12-month prevalence, severity, and comorbidity data showed that more than 26% of adults had symptoms meeting the criteria for a DSM-IV mental disorder in the previous 12 months, but he said most of the cases were mild (40.4%) or moderate (37.3%). Impulse-control disorders, which have been neglected in previous epidemiologic studies, according to Dr. Kessler, were found in nearly one-third of individuals meeting diagnostic criteria, “and these cases were typically more serious than the other disorders,” he said.

More than 40% of the 12-month cases had more than one disorder, “and severity was strongly related to comorbidity,” Dr. Kessler said.

The latter findings suggest that public health interventions should take the presence of comorbidities into account when considering treatment for specific populations, he said.

Regarding the 12-month mental health service utilization data, “most people with mental disorders in the United States remain either untreated or poorly treated,” said Philip S. Wang, M.D., also of Harvard. Less than 42% of people with a mental disorder received treatment for that disorder within the 12-month period prior to the survey.

Of those who received treatment, 12.3% were treated by a psychiatrist, 16% by a nonpsychiatrist mental health specialist, 22.8% by a general medical provider, 8.1% by a human service provider, and 6.8% by a complementary and alternative medical provider.

Of particular interest, noted Dr. Wang, was that patients treated in the mental health specialty sector received more visits than those treated in the general medical sector, and more patients in the specialty sector, compared with the general medicine sector received treatment that exceeded a minimal threshold of adequacy. Not surprising was the finding that the unmet need for treatment continued to be greatest in traditionally underserved groups, including the elderly, racial and ethnic minorities, the uninsured, and residents of rural areas, he said.

The cumulative lifetime probability curves derived from the survey data showed that the majority of people with lifetime mental health disorders eventually get some sort of treatment, but the time it took to actually make treatment contact after first onset of a mental disorder ranged from 6 to 8 years for mood disorders, 9 to 23 years for anxiety disorders, 4 to 13 years for impulse-control disorders, and 5 to 9 years for substance disorders.

Predictors of treatment delay included early age of onset, being in an older cohort, and various sociodemographic characteristics, including being male, racial/ethnic minority, poorly educated, and married, Dr. Wang said at the teleconference.

Although the data show that there is a significant need for interventions that speed initial treatment contact to reduce the later burdens of untreated mental health disorders, it is not enough to design and test prevention and treatment interventions, according to Dr. Kessler.

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