Previous epidemiologic studies of psychiatric disorders in the United States have reported an overall 12-month prevalence of any mental illness to be in the range of 30% of the population. However, “significant questions about the disability associated with these syndromes remain,” according to Thomas R. Insel, MD, Director of the National Institute of Mental Health. “How severe are the disorders reported to be present in 30% of the population? What is the economic and public health impact of these conditions? How long is the delay between onset and diagnosis? And to what extent have we made progress in providing appropriate evidence-based treatment to those who are ill?”

Four articles in the June Archives of General Psychiatry address these questions. The quartet represents the initial findings from the National Comorbidity Survey Replication (NCS-R) study. In a commentary on the studies, Dr. Insel and Wayne S. Fenton, MD, noted that the NCS was the first study to estimate the prevalence of DSM-III-R mental disorders in a nationally representative US sample.

The NCS-R used the International World Health Organization–Composite International Diagnostic Interview to generate DSM-IV diagnoses from data collected in a household survey of 9,282 respondents ages 18 and older (70.9% response rate). Methodologic innovations included an expanded set of diagnoses, in-depth clinical validation of field research diagnoses, inclusion of subthreshold diagnostic syndromes, and assessment of disability and impairment, as well as assessments of service use, treatment barriers, and adequacy of treatment, Drs. Insel and Fenton noted. The disorders were categorized into four groups: anxiety disorders (panic disorder, posttraumatic stress disorder, and obsessive-compulsive disorder), mood disorders (major depressive disorder, bipolar disorder), impulse control disorders (oppositional defiant disorder, attention-deficit/hyperactivity disorder, and intermittent explosive disorder), and substance use disorders (drug and alcohol abuse and dependence).

Though the study is not without its limitations—including the exclusion of schizophrenia and autism, the requirement that all participants speak English and belong to a household, and the retrospective nature of its age-at-onset data acquisition—Drs. Insel and Fenton acknowledged that “the results described in these four articles raise several important issues that should concern [psychiatrists.]”

TREATMENT DELAYS

“Failure to make prompt initial treatment contact is a pervasive aspect of unmet need for mental health care in the US,” according to Philip S. Wang, MD, DrPH. Based on analysis of the NCS-R data, the majority of people with lifetime mental disorders eventually seek treatment if the disorder persists; however, long delays are the norm, reported Dr. Wang and colleagues.

More people with mood disorders (mean 91.15%) seek treatment than do persons with anxiety (mean 61.3%), impulse control (mean 42.85%), or substance use disorders (mean 64.8%). Delay in making treatment contact ranged from six to eight years for persons with mood disorders to nine to 23 years for those with anxiety disorders. Even longer delays or outright failure to make initial treatment contact was associated with patients with early onset of disease, those in an older cohort, males, married patients, those with limited formal education, and members of a racial/ethnic minority.

“The findings reported here suggest that more effort is needed to increase prompt initial treatment contacts among people with incident episodes of mental disorders,” said Dr. Wang, of the Department of Health Care Policy, Harvard Medical School, Boston. “Additional large-scale public education programs ... and expanded use of National Screening Days continue to hold great promise for hastening detection and treatment. School-based screening programs using brief self-report and/or informant scales may be needed to detect early-onset mental disorders. Demand management and other outreach strategies could also help reduce critical delays and failures in initial help-seeking once mental disorders are identified.” However, “a range of interventions may ultimately be needed to alleviate the burdens and hazards from untreated mental disorders,” he concluded.

LIFETIME PREVALENCE AND AGE AT ONSET

Ronald C. Kessler, PhD, principal investigator of the NCS-R study, and colleagues determined that about half of Americans will meet the criteria for a DSM-IV diagnosis of a mental disorder over the course of their lifetime, with first onset usually in childhood or adolescence. Based on their analysis of data from the NCS-R, lifetime prevalences for the different classes of disorders were: anxiety disorder, 28.8%; mood disorders, 20.8%; impulse control disorders, 24.8%; substance use disorders, 14.6%; and any disorder, 46.4%.

Median age at 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, and three fourths by age 24, noted Dr. Kessler, of the Department of Health Care Policy at Harvard Medical School in Boston. Later-onset disorders usually occur as comorbid conditions, and the estimated lifetime risk of any disorder at age 75 is only slightly higher (50.8%) than the observed lifetime prevalence. The findings were stable among sociodemographic groups.

“The NCS-R results clearly document that mental disorders are highly prevalent, that lifetime prevalence is, if anything, underestimated, that age-at-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 concluded. “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.”

TWELVE-MONTH RESULTS

Dr. Kessler and colleagues also analyzed 12-month data from the NCS-R for prevalence, severity, and treatment. They determined that the 12-month prevalence for any disorder was 26.2%, with a 12-month prevalence of anxiety disorders of 18.1%; mood disorders, 9.5%; impulse control disorders, 8.9%; and substance use disorders, 3.8%. Of the cases, 22.3% were classified as serious—characterized by a 12-month suicide attempt with serious lethality intent, work disability or substantial limitation, nonaffective psychosis, bipolar disorder, substance dependence with serious role impairment, or an impulse control disorder with serious repeated violence. Additionally, 37.3% were classified as moderate—characterized by suicidal ideation, plan, or gesture; substance dependence without serious role impairment; moderate work limitations; or moderate impairment on the Sheehan Disability Scale. The remaining 40.4% of cases were classified as mild.

Fifty-five percent of individuals with a disorder met the criteria for only one disorder; 22%, for two diagnoses; and 23%, for three or more diagnoses, noted Dr. Kessler. “Although mental disorders are widespread, serious cases are concentrated among a relatively small proportion of cases with high comorbidity,” the authors concluded.

In terms of treatment during the 12-month period, the investigators determined that only 41.1% of individuals with symptoms qualifying them for a diagnosis of a mental disorder were likely to receive any treatment. Of those who did receive treatment, 12.3% were treated by a psychiatrist, 16% by another mental health specialist, 22.8% by a general practitioner, 8.1% by a human services professional, and 6.8% by either a complementary or alternative medical provider.

More patients in specialty than general medical care 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,” Dr. Wang wrote.

“Three broad types of intervention are suggested by the results,” he added, echoing his earlier conclusion. “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.”

FIRST FRUITS

“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,” Drs. Insel and Fenton asserted. “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.”

—C. Justin Romano

Suggested Reading
Insel TR, Fenton WS. Psychiatric epidemiology: it’s not just about counting anymore. Arch Gen Psychiatry. 2005;62:590-592.
Kessler RC, Berglund P, Demler O, et al. Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the National Comorbidity Survey Replication. Arch Gen Psychiatry. 2005;62:593-602.
Kessler RC, Chiu WT, Demler O, Walters EE. Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication. Arch Gen Psychiatry. 2005;62:617-627.
Wang PS, Berglund P, Olfson M, et al. Failure and delay in initial treatment contact after first onset of mental disorders in the National Comorbidity Replication Survey. Arch Gen Psychiatry. 2005;62:603-613.
Wang PS, Lane M, Olfson M, et al. Twelve-month use of mental health services in the United States: results from the National Comorbidity Survey Replication. Arch Gen Psychiatry. 2005;62:629-640.

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