Prevalence and severity of mental illness in the United States

06/02/05

Four related studies, based on data from the National Comorbidity Survey Replication, appear in the June issue of Archives of General Psychiatry.

Over the course of the previous 12 months, more than one-fourth of adults reported having symptoms that would qualify them for a diagnosis of a mental disorder; and most of those disorders can be classified as serious or moderate, according to a study in the June issue of Archives of General Psychiatry, one of the JAMA/Archives journals.

Although previous epidemiological surveys have estimated prevalence of mental disorders in the U.S. as high as 30 percent, information on severity and comorbidity (individuals with symptoms that meet criteria for two or more mental disorders at the same time) has not previously been available, according to background information in the article.

Ronald C. Kessler, Ph.D., of Harvard Medical School, and colleagues analyzed information on mental disorders in the United States collected from the U.S. National Comorbidity Survey Replication (NCS-R), a nationally representative face-to-face household survey conducted between February 2001 and April 2003 using the World Health Organization World Mental Health Survey Initiative version of the Composite International Diagnostic Interview. The researchers determined the 12-month prevalence of different types of mental disorders (the percentage of individuals reported having symptoms that would represent a particular mental disorder in the course of the previous 12 months) as well as the level of severity of the disorder in that 12-month period and the likelihood that an individual qualifying in that 12-month period for a diagnosis for one mental disorder would also meet the criteria for at least one other (comorbidity).

The disorders were divided into four classes: anxiety disorders, including panic disorder, post-traumatic stress disorder and obsessive-compulsive disorder; mood disorders, including major depressive disorder and bipolar disorder; impulse control disorder, including oppositional defiant disorder, attention deficit/hyperactivity disorder and intermittent explosive disorder; and substance abuse disorder, defined as alcohol and drug abuse and dependence. Severity was divided into three levels: serious, which might be defined by criteria including a serious suicide attempt or substantial work limitations as result of the disorder; moderate, which might defined by criteria including suicide ideation or substance abuse without serious impairment of functioning; and mild.

Based on data obtained from 9,282 adult respondents to the survey, the researchers determined that the 12-month prevalence for any disorder was 26.2 percent, with a 12-month prevalence of anxiety disorders of 18.1 percent; mood disorders, 9.5 percent; impulse control disorders, 8.9 percent and substance abuse disorders, 3.8 percent. Of the cases, 22.3 percent were classified as serious; 37.3 percent as moderate and 40.4 percent as mild. Fifty-five percent of individuals with a disorder met the criteria for only one disorder, 22 percent for two diagnoses and 23 percent for three or more diagnoses.

"Although mental disorders are widespread, serious cases are concentrated among a relatively small proportion of cases with high comorbidity," the authors conclude.

(Arch Gen Psychiatry. 2005; 62:617-627. Available post-embargo at www.archgenpsychiatry.com)

Editor's Note: The National Comorbidity Survey Replication (NCS-R) is supported by grants from the National Institute of Mental Health, the National Institute of Drug Abuse, the Substance Abuse and Mental Health Services Administration, Bethesda, Md., the Robert Wood Johnson Foundation, Princeton, N.J., and John W. Alden Trust, Boston. See the paper for complete funding information.

Lifetime Prevalence and Age of Onset of Mental Illness in the United States

Ronald C. Kessler, Ph.D., of Harvard Medical School, and colleagues determined that about half of Americans reported having symptoms that would qualify them for a diagnosis of a mental disorder over the course of their lifetime (lifetime prevalence), with most mental illness beginning in childhood or adolescence, based on their analysis of data from the National Comorbidity Survey Replication (NCS-R). Lifetime prevalence for the different classes of disorders were: anxiety disorder, 28.8 percent; mood disorders, 20.8 percent; impulse-control disorders, 24.8 percent; substance use disorders, 14.6 percent and lifetime prevalence for any disorder, 46.4 percent. Median age of onset is much earlier for anxiety and impulse-control disorders (11 years for both) than for substance use (20 years) and mood disorders (30 years), the researchers found. Half of all lifetime cases start by age 14 years and three fourths by age 24 years.

"…the NCS-R results clearly document that mental disorders are highly prevalent, that lifetime prevalence is, if anything, underestimated, that age-of-onset distribution for most of the disorders considered herein are concentrated in a relatively narrow age range during the first two decades of life, and that later onset disorders occur in large part as temporally secondary comorbid conditions," the authors conclude. "Given the enormous personal and societal burdens of mental disorders, these observations should lead us to direct a greater part of our thinking about public health interventions to the child and adolescent years and, with appropriately balanced considerations of potential risks and benefits, to focus on early interventions aimed at preventing the progression of primary disorders and the onset of comorbid disorders."

(Arch Gen Psychiatry. 2005; 62:593-602. Available post-embargo at www.archgenpsychiatry.com)

Editor's Note: The National Comorbidity Survey Replication (NCS-R) is supported by grants from the National Institute of Mental Health, the National Institute of Drug Abuse, the Substance Abuse and Mental Health Services Administration, Rockville, Md., the Robert Wood Johnson Foundation, Princeton, N.J., and John W. Alden Trust, Boston. See the paper for complete funding information.

Long Delays Common Between Age of Onset and First Treatment of Mental Disorders in the U.S.

Philip S. Wang, M.D., Dr.P.H., of Harvard Medical School, and colleagues determined that failure to make prompt initial treatment contact for mental health care is common in the United States, based on their analysis of data from the National Comorbidity Survey Replication (NCS-R). The researchers found that the vast majority of people with lifetime disorders eventually make treatment contact, particularly for those with mood disorders. Delay in making treatment contact ranges from six to eight years for mood disorders and nine to 23 years for anxiety disorders.

"…the findings reported here suggest that more effort is needed to increase prompt initial treatment contacts among people with incident episodes of mental disorders," the authors write. "Additional large-scale public education programs … and expanded use of National Screening Days continue to hold great promise for hastening detection and treatment. … Interventions to speed initial treatment contact are likely to reduce the burdens and hazards of untreated mental disorder."

(Arch Gen Psychiatry. 2005; 62:603-613. Available post-embargo at www.archgenpsychiatry.com)

Editor's Note: The National Comorbidity Survey Replication (NCS-R) is supported by grants from the National Institute of Mental Health, the National Institute of Drug Abuse, the Substance Abuse and Mental Health Services Administration, Rockville, Md., the Robert Wood Johnson Foundation, Princeton, N.J., and John W. Alden Trust, Boston. See the paper for complete funding information.

Many Individuals with Mental Disorders May Be Untreated or Poorly

Philip S. Wang, M.D., Dr.P.H., of Harvard Medical School, and colleagues determined that only 41.1 percent of individuals with symptoms that qualify them for a diagnosis of a mental disorder in the previous 12 month period (12-month prevalence) were likely to receive any treatment, based on their analysis of data from the National Comorbidity Survey Replication (NCS-R). Of those who received treatment, 12.3 percent were treated by a psychiatrist, 16 percent by another mental health specialist, 22.8 percent by a general practitioner, 8.1 percent by a human services professional and 6.8 percent by a complementary or alternative medical provider. More patients in specialty than general medical treatment received treatment that exceeded a minimal threshold of adequacy. "Unmet need for treatment is greatest in traditionally underserved groups, including elderly persons, racial-ethnic minorities, those with low incomes, those without insurance, and residents of rural areas," the authors write.

"Three broad types of intervention are suggested by the results," the authors conclude. "First, outreach efforts are needed to increase access to and initiation of treatments. … Second, interventions are needed to improve the quality of care delivered to patients with mental disorders. … Third, initiatives are needed to increase the uptake of successful programs and treatment models. Widespread failure to disseminate proved interventions may, in fact, explain why large unmet needs persist in the United States, despite earlier efforts to address this problem."

(Arch Gen Psychiatry. 2005; 62:629-640. Available post-embargo at www.archgenpsychiatry.com)

Editor's Note: The National Comorbidity Survey Replication (NCS-R) is supported by grants from the National Institute of Mental Health, the National Institute of Drug Abuse, the Substance Abuse and Mental Health Services Administration, Rockville, Md., the Robert Wood Johnson Foundation, Princeton, N.J., and John W. Alden Trust, Boston. See the paper for complete funding information.

Editorial: Psychiatric Epidemiology
It's Not Just About Counting Anymore

In an editorial accompanying these studies, Thomas R. Insel, M.D., Director, and Wayne S. Fenton, M.D., Associate Director for Clinical Affairs, of the National Institute of Mental Health (NIMH), write that NIMH supported population-based efforts in psychiatric epidemiology over the last two decades have "demonstrated that mental disorders were highly prevalent in the general population and placed mental illness squarely on the nation's and the world's public health agenda. … Nonetheless, many critical issues were not addressed by earlier studies."

"The findings reported here are the first fruit of what promises to be a bountiful harvest; the NCS-R is one element in a coordinated program of new psychiatric epidemiological studies that will be completed over the next several years," the authors state. "Quantifying the prevalence of mental disorders, the disabilities associated with them, and the adequacy of service provision forms the foundation for national and international mental health policy. But psychiatric epidemiology is no longer just about counting. The NCS-R results will yield much-needed information about the burden of disease, medical comorbidity, and global patterns of illness. Because it includes subthreshold diagnostic information, which we know from studies of hypertension and diabetes can be highly predictive of future diseases, the results may be informative for studying the effect of early intervention."

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
    Published on PsychCentral.com. All rights reserved.

 

 

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