Mental Illness Rates in the United States

(HealthDay News) -- A sweeping look at mental illness in the United States has uncovered a continued high prevalence of psychological disorders, with about half of all chronic cases beginning by the age of 14. The findings show that anxiety disorders were the most prevalent of all disorders.

While most cases of mental illness are mild and will not need professional intervention, people with more serious cases tend to delay treatment and, when they do seek help, tend to receive inadequate care. The results of the massive survey on the prevalence of common mental disorders appear in four papers in the June 6 issue of the Archives of General Psychiatry.

"This new study demonstrates clearly these really are chronic disorders of young people in this country," said Dr. Thomas R. Insel, director of the National Institute of Mental Health (NIMH), which funded the study. "These disorders cause a high degree of disability, with nearly six percent of the population showing serious disability. That is really extraordinary. Those are the kinds of numbers we didn't have before."

The reach of mental illness is similar in magnitude to that of diabetes and cardiovascular disease, the difference being that the latter two diseases tend to occur in older people while mental disorders strike people in the prime of life, added Ronald C. Kessler, director of the surveys and a professor of health-care policy at Harvard Medical School.

For the surveys, 300 professional interviewers traveled 8 million miles over a five-year period to question nearly 9,300 U.S. adults.

Here are some of the key findings of the study, which examined anxiety disorders, mood disorders, impulse-control disorders and substance abuse disorders:

Half of all lifetime cases of mental illness begin by age 14, while three-quarters begin by age 24. Anxiety disorders tend to begin in late childhood, mood disorders in late adolescence and substance abuse in the early 20s. "This interferes with accomplishing major social, educational and occupational milestones, and can cause lifelong disability," said Kathleen Ries Merikangas, lead NIMH collaborator on the study and chief of the NIMH's section on developmental genetic epidemiology.

The majority of Americans will, at some point in their lifetime, meet the diagnostic criteria for one or more mental disorders. About one quarter (26 percent) of the general population reported symptoms sufficient for diagnosing such a disorder during the past year. Most of these disorders, however, were mild and likely to resolve without treatment. "Snake phobia is a mental illness but if you live on the 35th floor of a building in Manhattan, it doesn't get in the way of life very much," Kessler said. "We need to do a better job of which mild and moderate cases are likely to become seriously debilitating."

Six percent of Americans have a severe mental health disorder, reporting a mean of 88.3 days during the past year when they felt they were unable to carry out their normal daily activities.

Anxiety disorders were the most prevalent (affecting 28.8 percent of Americans at some time in their life), followed by impulse-control disorders (24.8 percent), mood disorders (20.8 percent) and substance use disorders (14.6 percent).

In any given year, 18.1 percent of the adult population suffered anxiety disorders, 9.5 percent experienced mood disorders, 8.9 percent experienced impulse-control disorders and 3.8 percent suffered substance use disorders.

In the United States, females have higher rates of mood and anxiety disorders, while males have higher rates of substance abuse and impulse disorders.

For almost all mental disorders, individuals delayed getting treatment. The median delay was about 10 years. For social phobia and separation anxiety, the delay was 20 to 23 years and, for mood disorders, six to eight years. Almost half of all lifetime cases of substance use and impulse control disorders never obtained treatment. "Early-onset disorders are, in general, more persistent and more severe than those that start later," Kessler explained.

Roughly 80 percent of people overall do eventually seek treatment, the survey found:

The earlier in life a disorder begins, the slower an individual is in seeking treatment.

Forty-five percent of people with one mental disorder met the criteria for two or more disorders. "The severity of the mental illness is associated with the degree to which people manifest more than one disorder," Ries Merikangas said. "Services are often separate for different disorders so people fall through the cracks. Our findings illustrate the importance of integrating services and treating the people rather than the disorder."

Overall, use of mental health services is low, with only 41 percent of cases within any given year getting treatment. The proportion of people who are getting help has improved over the last decade, however.

Existing treatments are also inadequate, said Philip Wang, a psychiatrist at Harvard who led the study on treatment. Only about one-third of therapies meet minimal standards for adequacy established in national guidelines.

Only 12.3 percent of individuals with mental health disorders are treated by a psychiatrist, versus 22.8 percent by a general medical provider. "If you see a mental health professional, you are more likely to get adequate treatment," Kessler pointed out.

Minority groups have lower rates of mental illness than the majority population -- not the first time this finding has come to light. In addition, minority individuals who start living in the majority community begin to have more mental illness. "Clearly it's not genes," Kessler said. "There are cultural advantages. There is a sense of belongingness that minorities have that many other people don't have."

It is possible that part of the increase in prevalence is due to people becoming more willing to discuss these issues. Regardless, the system still has many kinks that need to be worked out, the researchers said.

"There is general recognition that our services system is lagging behind," said NIMH deputy director Richard Nakamura. "We need an iterative process of destigmatizing mental illness, improving overall treatment and making services more widely available."

The surveys are part of a larger, international effort. So far, the United States has the highest prevalence of mental disorders of any developed country in the world. Again, however, it's not clear if this is because Americans are more willing to talk about mental illness or if the prevalence really is higher.

For more on mental health and mental disorders, see the Mental Health Center