Mental Health and Illness - How Many People Are Mentally Ill?

It is difficult to determine how many people suffer from mental illness because of changing definitions of mental illness and difficulties classifying, diagnosing, and reporting mental disorders. There are social stigmas attached to mental illness, such as being labeled "crazy," being treated as a danger to others, and being denied jobs or health insurance coverage, that keep some sufferers from seeking help, and many of those in treatment do not reveal it on surveys. Some patients do not realize that their symptoms are caused by mental disorders. Because knowledge about the way the brain works is relatively narrow, mental health professionals must continually reassess how mental illnesses are defined and diagnosed. In addition, what might be considered, for example, delusional thinking in one culture may well be widely accepted in another; the symptoms of mental illness are notoriously fluid, and diagnosis may be skewed by cultural differences or other bias on the part of both patient and practitioner.

The Surgeon General's report estimated that 20 percent of the U.S. population was affected by mental disorders and that 15 percent use some type of mental health service every year. Table 8.1 shows the estimated prevalence of mental health disorders among Americans age eighteen to fifty-four. Approximately 22.1 percent of Americans ages eighteen and older, about one in five adults, have diagnosable mental disorders in a given year, according to the National Institute of Mental Health (NIMH). Also, of the ten leading causes of disability, four are mental disorders—major depression, bipolar disorder, schizophrenia, and obsessive-compulsive disorder. It is common for someone to have more than one mental disorder at a given time.

Not All People Need or Seek Treatment

The NIMH observes that not all mental disorders require treatment because many people with mental disorders have relatively brief, self-limiting illnesses that are not disabling enough to warrant treatment. As much as 70 percent of mental illness goes untreated, and many cases are believed to resolve spontaneously. Among people seeking

TABLE 8.1
Best estimate one-year prevalence rates of mental disorders based on ECA* and NCS*, ages 18–54, 1999

	ECA prevalence (%)	NCS prevalence (%)	Best estimate (%)
Any anxiety disorder	13.1	18.7	16.4
Simple phobia	8.3	8.6	8.3
Social phobia	2.0	7.4	2.0
Agoraphobia	4.9	3.7	4.9
GAD	(1.5)	3.4	3.4
Panic disorder	1.6	2.2	1.6
OCD	2.4	(0.9)	2.4
PTSD	(1.9)	3.6	3.6
Any mood disorder	7.1	11.1	7.1
MD episode	6.5	10.1	6.5
Unipolar MD	5.3	8.9	5.3
Dysthymia	1.6	2.5	1.6
Bipolar I	1.1	1.3	1.1
Bipolar II	0.6	0.2	0.6
Schizophrenia	1.3	—	1.3
Nonaffective psychosis	—	0.2	0.2
Somatization	0.2	—	0.2
ASP	2.1	—	2.1
Anorexia nervosa	0.1	—	0.1
Severe cognitive impairment	1.2	—	1.2
Any disorder	19.5	23.4	21.0
Notes: Numbers in parentheses indicate the prevalence of the disorder without any comorbidity. These rates were calculated using the NCS data for GAD and PTSD, and the ECA data for OCD. The rates were not used in calculating the any anxiety disorder and any disorder totals for the ECA and NCS columns. The unduplicated GAD and PTSD rates were added to the best estimate total for any anxiety disorder (3.3%) and any disorder (1.5%)
*Key to abbreviations: ECA, Epidemiologic Catchment Area; NCS, National Comorbidity Study; GAD, generalized anxiety disorder; OCD, obsessive-compulsive disorder; PTSD, post-traumatic stress disorder; MD, major depression; ASP, antisocial personality disorder.
SOURCE: "Table 2-6. Best Estimate 1-Year Prevalence Rates Based on ECA and NCS, Ages 18–54," in Mental Health: A Report of the Surgeon General, U.S. Department of Health and Human Services, Substance Abuse and Mental Health Services Administration, Center for Mental Health Services, National Institutes of Health, National Institute of Mental Health, Rockville, MD, 1999 [Online] http://www.surgeongeneral.gov/library/mentalhealth/toc.html# chapter2 [accessed March 15, 2004]

help, about half see their primary care physicians; the balance visit psychiatrists, clinical psychologists, clinical social workers, or other trained mental health professionals.

Because primary care physicians are often the first professionals to encounter people with mental disorders, NIMH encourages all primary care practitioners, who often lack special training to recognize these disorders, to send patients who seek help to mental health professionals for screening to ensure that mental disorders are properly diagnosed and treated. Further, NIMH recommends that general physicians receive more training to improve recognition and treatment of psychiatric disorders.

One likely explanation for the relatively small number of people seeking help from psychiatrists, clinical psychologists, or other mental health professionals is the high cost of these services and the reluctance of insurance companies to cover treatment of mental health disorders or problems. Many private insurance policies offer only limited coverage for mental health services. In addition, mental health practitioners and facilities covered by insurance are unevenly distributed throughout the country. In January 1998, however, Congress made significant progress toward more equitable access to mental health treatment when the Mental Health Parity Act of 1996 (PL 104-204) took effect. The act requires that mental health benefits be comparable to medical/surgical benefits in health plans that cover groups of fifty or more employees.

Types of Disorders

Psychiatrists have identified a wide range of mental disorders, from phobias to depression to schizophrenia. Psychiatric diagnoses are made based on criteria described in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Some disorders are relatively mild and affect an individual's life in only a minor way. Others can be overwhelming, completely debilitating, and life-threatening.

Anxiety disorders, which include phobias (intense, irrational, and persistent fears), and depression are the two most common mental disorders. About twenty million Americans report at least one phobia serious enough to affect their daily routines, and depression afflicts nearly nineteen million people each year. The medical community also classifies substance abuse as a mental disorder. Alcoholism affects close to fourteen million people (one in thirteen) a year. Many people suffer from more than one mental disorder at a time (comorbidity)—millions of Americans suffer from substance (drug or alcohol) abuse combined with one or more other mental disorders.