Mental Disorders and Illness

Mental Illness

Mental illnesses are health conditions involving changes in emotion, thinking or behavior (or a combination of these). Mental illnesses are associated with distress and/or problems functioning in social, work or family activities. A mental illness is a disease that causes mild to severe disturbances in thought and/or behavior, resulting in an inability to cope with life’s ordinary demands and routines.

Mental illness is common. In a given year:

• nearly one in five (19 percent) U.S. adults experience some form of mental illness
• one in 24 (4.1 percent) has a serious mental illness*
• one in 12 (8.5 percent) has a diagnosable substance use disorder