It is complicated 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% of the United States population was affected by mental disorders and that 15% use some type of mental health service every year. Community surveys estimate that as many as 30% of the adult population in the United States suffer from mental disorders. The National Comorbidity Survey Replication (NCS-R), a nationally representative face-to-face household survey conducted by Harvard University, the University of Michigan, and the National Institute of Mental Health (NIMH) Intramural Research Program, between February 2001 and April 2003 used a structured diagnostic interview of 9,282 randomly selected English-speaking Americans age eighteen and older. Ronald Kessler et al in "Prevalence, Severity, and Comorbidity of 12-Month DSM-IV Disorders in the National Comorbidity Survey Replication" (Archives of General Psychiatry, June 2005) found that more than one-quarter (26.2%) of all FIGURE 8.1 Annual prevalence of mental/addictive disorders for children "Figure 2-6a. Annual Prevalence of Mental/Addictive Disorders for Children," in Mental Health: A Report of the Surgeon General, U.S. Department of Health and Human Services, Substance Abuse and Mental Health Services Administration, with NIH, 1999, http://www.surgeongeneral.gov/library/mentalhealth/chapter2/sec7.html (accessed January 19, 2006)Americans met the criteria for having a mental illness, and fully a quarter of those had a "serious" disorder that significantly disrupted their ability to function day to day. The exhaustive NIMH-sponsored effort also found that the prevalence of U.S. mental illness has not varied significantly in the past decade, unlike previous decades in which the prevalence of mental illness had been slowly increasing.

How Many Children Suffer from Mental Illness?

Studies of prevalence of mental illness, which included mental disorders and addictive disorders, estimate that more than one-fifth (nearly 21%) of U.S. children ages nine to seventeen suffer some degree of impaired functioning resulting from a mental or addictive disorder. (See Figure 8.1 and Table 8.1.) Although the same research found that just 11% of this group suffers from significant impairment, this prevalence estimate translates into four million children and teens for whom difficulties at school and with their families and friends are attributable to mental illness.

Table 8.2 lists the broad categories of mental disorders that begin during childhood and adolescence. Children and teens with mood and anxiety disorders suffer from unfounded fears, prolonged sadness or tearfulness, withdrawal, low self-esteem, and feelings of worthlessness and hopelessness. These children and adolescents often suffer from more than one mental health problem—for example, symptoms of depression and anxiety together.

TABLE 8.1 Children and adolescents age 9-17 with mental or addictive disorders* "Table 3-1. Children and Adolescents Age 9-17 with Mental or Addictive Disorders," in Mental Health: A Report of the Surgeon General, U.S. Department of Health and Human Services, Substance Abuse and Mental Health Services Administration, with NIH, 1999, http://www.surgeongeneral.gov/library/mentalhealth/chapter3/sec1.html (accessed January 19, 2006)

Some Americans Experience Serious Mental Distress

The National Health Interview Survey (NHIS), a continuing, nationwide survey conducted by the National Center for Health Statistics (NCHS) of the Centers for Disease Control and Prevention (CDC), poses six questions about psychological distress. These questions ask how often a respondent experienced certain symptoms of psychological distress during the thirty days preceding the survey. In the first half of 2005, nearly 3% of adults age eighteen and older said they had experienced serious psychological distress during the past thirty days. Figure 8.2 shows that the percent of adults

SOURCE: "Table 3-2. Selected Mental Disorders of Childhood and Adolescence from the DSM-IV," in Mental Health: A Report of the Surgeon General, U.S. Department of Health and Human Services, Substance Abuse and Mental Health Services Administration, with NIH, 1999, http://www.surgeongeneral.gov/library/mentalhealth/chapter3/sec3.html (accessed January 19, 2006)

TABLE 8.2

Selected mental disorders of childhood and adolescence

• Anxiety disorders
• Attention-deficit and disruptive behavior disorders
• Autism and other pervasive developmental disorders
• Eating disorders
• Elimination disorders
• Learning and communication disorders
• Mood disorders (e.g., depressive disorders)
• Schizophrenia
• Tic disorders

reporting serious psychological distress declined from 3.3% in 1997 to 2.4% in 1999 but increased to 3.2% in 2001 and has not varied significantly since.

FIGURE 8.3 Percentage of adults aged 18 and over who experienced serious psychological distress during the past 30 days, by age group and sex, January-June 2005 "Figure 13.2. Percentage of Adults Aged 18 Years and over Who Experienced Serious Psychological Distress during the Past 30 Days, by Age Group and Sex: United States, January-June 2005," in Early Release of Selected Estimates Based on Data from the January-June 2005 National Health Interview Survey, Centers for Disease Control and Prevention, National Center for Health Statistics, December 2005, http://www.cdc.gov/nchs/data/nhis/earlyrelease/200512_13.pdf (accessed January 18, 2006)

The NHIS revealed that persons age sixty-five and older (2.4%) were less likely to have experienced serious psychological distress during the thirty days preceding the survey than persons ages forty-five to sixty-four (3.5%). Among persons ages eighteen to forty-four, women were more likely than men to report serious psychological distress during the thirty days preceding the survey. (See Figure 8.3.)

The percentage of adults that experienced serious psychological distress during the thirty days preceding the survey did not vary significantly by race or ethnicity. The age-sex adjusted prevalence of serious psychological distress was 2.8% for non-Hispanic white persons, and 3.4% for both Hispanic persons and non-Hispanic African-American persons. (See Figure 8.4.)

Not All People Need or Seek Treatment

The NIMH observes that not all mental disorders require treatment, because many people with mental FIGURE 8.4 Age-sex-adjusted percentage of adults aged 18 and over who experienced serious psychological distress during the past 30 days, by race/ethnicity, January-June 2005 "Figure 13.3. Age-Sex-Adjusted Percentage of Adults Aged 18 Years and over Who Experienced Serious Psychological Distress during the Past 30 Days, by Race/Ethnicity: United States, January-June 2005," in Early Release of Selected Estimates Based on Data from the January-June 2005 National Health Interview Survey, Centers for Disease Control and Prevention, National Center for Health Statistic, December 2005, http://www.cdc.gov/nchs/data/nhis/earlyrelease/200512_13.pdf (accessed January 18, 2006)disorders have relatively brief, self-limiting illnesses that are not disabling enough to warrant treatment. As much as 70% of mental illness goes untreated, and many cases are believed to resolve spontaneously. Among people seeking help, about 23% see their primary care physicians and 12.3% visit psychiatrists (June 3, 2005, press conference with Thomas R. Insel, director, National Institute of Mental Health; Ronald C. Kessler, Ph.D., professor, health-care policy, Harvard Medical School; Philip Wang, M.D., assistant professor, health-care policy, Harvard Medical School; Richard Nakamura, Ph.D., deputy director, National Institute of Mental Health; Kathleen Ries Merikangas, Ph.D., chief, section on developmental genetic epidemiology, National Institute of Mental Health).

Philip Wang et al in "Twelve-Month Use of Mental Health Services in the United States" (Archives of General Psychiatry, June 2005) found that less than half of persons in need of mental health treatment receive it. Those who seek treatment generally delay pursuing help for a decade or more, and during this time they are likely to develop additional problems. Nonetheless, the survey revealed that the percent of the population treated for mental illness over a twelve-month period has grown by 4%, from 13% a decade ago to 17% in 2003. The researchers theorized that the increase in persons seeking treatment might be attributable to direct-to-consumer advertisements for antidepressants and other drugs, and to diminishing stigma associated with obtaining mental health treatment. Unfortunately, the survey found that the treatment received is frequently inadequate. The researchers attributed delays in seeking treatment to inattention to early warning signs, insufficient health insurance, and the lingering stigma that surrounds mental illness.

Even among persons with health insurance, 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 many health 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.