A national report reveals that 45.9 million American adults aged 18 or older, or 20 percent of this age group, experienced mental illness in the past year. The rate of mental illness was more than twice as high among those aged 18 to 25 (29.9 percent) than among those aged 50 and older (14.3 percent). Adult women were also more likely than men to have experienced mental illness in the past year (23 percent versus 16.8 percent).
Mental illness among adults aged 18 or older is defined as having had a diagnosable mental, behavioral, or emotional disorder (excluding developmental and substance use disorders) in the past year, based on criteria specified in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).
The Substance Abuse and Mental Health Services Administration’s (SAMHSA) National Survey on Drug Use and Health also shows that 11.4 million adults (5 percent of the adult population) suffered from serious mental illness in the past year. Serious mental illness is defined as one that resulted in serious functional impairment, which substantially interfered with or limited one or more major life activities.