ments in methodology and instrumentation. However, differences in diagnostic criteria may also account for some of the difference in the estimates. The ECA study defined active disorder as a disorder for which criteria (codified in the third edition of the Diagnostic and Statistical Manual of Mental Disorders [American Psychiatric Association, 1980]) had been met at some time in the person's life and at least one symptom (or one episode) had been present in the year prior to interview.
Mental disorders can occur throughout the life span, but the type and nature of the illnesses vary with age. At least 12 percent (or about 7.5 million) of our nation's 63 million children and adolescents suffer from one or more mental disorders—including autism, attention deficit hyperactivity disorder, severe conduct disorder, depression, and alcohol and psychoactive substance abuse and dependence (DHHS, 1991; IOM, 1989; OTA, 1986). Based on a review of seven epidemiological studies, the Office of Technology Assessment (OTA, 1991) reported that the prevalence of diagnosable mental disorders among individuals under age 20 may be closer to 20 percent. In 1990, suicide ranked as the third leading cause of death among 15- to 24-year-olds (National Center for Health Statistics, 1993). The American Academy of Child and Adolescent Psychiatry (1990) reported that growing numbers of children and adolescents are at exceptionally high risk for developing a mental disorder: for example, 1.5 million children and adolescents are reported abused or neglected each year, 300,000 are in the foster care system, and 7 million live with an alcoholic parent. In addition, more than 18,500 children and adolescents have been left motherless by the HIV/AIDS epidemic, and that number will more than double by 1995 (Michaels and Levine, 1992). Toward the other end of the life span are the 4 million older Americans who, according to a National Institute on Aging estimate, are likely to be suffering from Alzheimer 's disease (Evans, Scherr, Cook, Albert, Funkenstein, Smith et al., 1990) and the 15 to 25 percent of the elderly in nursing homes who are clinically depressed (NIH Consensus Development Panel on Depression in Late Life, 1992).
Mental illness of this magnitude places an extraordinary burden on the financial and social resources of this country. Current expenditures in this area include not only core costs such as direct costs for treatment and indirect costs for lost worker productivity, but also related costs such as those resulting from investment of time while caring for mentally ill family members. One estimate put our annual total economic cost of drug abuse, alcohol abuse, and mental illness at just over $218 billion in 1985, of which $44 billion was for drug abuse, $70 billion for alcohol abuse, and $103 billion for other mental illness (Rice, Kelman, Miller, and Dunmeyer, 1990). Based on this study, using