In 2010, an estimated 20% of adults aged 18 years and older in the United States – almost 46 million adults – had experienced "any mental illness" in the past year, with those aged 18-25 years, women, and the unemployed among the groups most affected, according to a report issued Jan. 19 by the Substance Abuse and Mental Health Services Administration (SAMHSA).

A "relatively high" prevalence rate of mental illness during the previous year, a strong association between mental illness during the previous year and substance abuse, as well as a "substantial unmet need" for mental health care during the previous year are among the key findings, the report concluded.

The report also found that that 8% of adolescents aged 12-17 years (almost 2 million individuals) had experienced a major depressive episode in the past year, and that illicit drug use was more than twofold greater among these adolescents than among those who had not used illicit drugs (37% vs. 18%). In addition, 12% of people in this age group (almost 3 million individuals) had received treatment or counseling for emotional or behavioral problems in an inpatient or outpatient mental health setting. "Feeling depressed" was the most common reason for using these services, in almost 50% of cases, the report said.

The SAMHSA report defined "any mental illness" as having had, at the current time or at any time during the past year, "a diagnosable mental, behavioral, or emotional disorder (excluding developmental and substance use disorders) of sufficient duration to meet diagnostic criteria" specified in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), regardless of functional impairment. The 20% figure in adults was similar to the rate of the previous year. Nearly 30% of the adults aged 18-25 years and 22% of those aged 26-49 years had had a mental illness in the past year, compared with 14% of those aged 50 years and older. Unemployed people were also more likely to have had a mental illness in the past year (28%), compared with people who worked full time (17%) or part time (23%).

The rate of "serious mental illness" – which was defined the same way as "any mental illness," but one that was "of sufficient duration" to meet diagnostic DSM-IV criteria and had "resulted in serious functional impairment, which substantially interferes with or limits one or more major life activities" – followed a similar pattern.

An estimated 5% of adults aged 18 years and older (about 11.4 million adults) had had a serious mental illness, similar to the rate of the previous year. The rate of serious mental illness was highest among those aged 18-25 years (8%), followed by those aged 26-49 years (6%), compared with 3% of those aged 50 years and older. Almost 8% of unemployed adults had a serious illness, compared with 4% of those who were employed full time and 6% of those who were employed part time.

Women were more likely to be affected than men by any mental illness (23% vs. 17%) and serious mental illness (7% vs. 3%).

Less than 40% of the adults who had experienced any mental illness and almost 61% of those with a serious mental illness had received mental health services during the past year.

Substance abuse was more than threefold higher among adults who had had any mental illness in the past year: 20% of the adults who had had any mental illness and 25% of those who had had a serious mental illness met the criteria for substance abuse or dependence, compared with 6% of those who had not had any mental illness during that time.

Among the other findings included in the report was that almost 4% of adults had had serious thoughts about suicide, similar to the rate of the previous year. The rates were about the same for men and women, but were higher among the younger age groups: 7% in those aged 18-25 years, 4% in those aged 26-49 years, and 2.5% in those aged 50 and older.

"Mental illness is a significant public health problem in itself, but also because it is associated with chronic medical diseases such as cardiovascular disease, diabetes, obesity, and cancer, as well as several risk behaviors including physical inactivity, smoking, excessive drinking, and insufficient sleep," Ileana Arias, Ph.D., principal deputy director of the Centers for Disease Control and Prevention, said in a SAMHSA statement announcing the report on Jan. 19. The report, she added, "provides further evidence that we need to continue efforts to monitor levels of mental illness in the United States in order to effectively prevent this important public health problem and its negative impact on total health."

The results are based on the mental health–related results from the 2010 National Survey on Drug Use and Health (NSDUH), an annual survey of about 67,500 people aged 12 years and older in the United States.

Survey: 20% of Adults Report Mental Illness