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Mental Health Disorders

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on March 31, 2020.

Mental health disorders are common and affect tens of millions of people each year in the United States. However, overall, only about half of those affected receive treatment. The National Survey on Drug Use and Health (NSDUH) defines a mental illness as:

  • A mental, behavioral, or emotional disorder (excluding developmental and substance use disorders).
  • Diagnosable currently or within the past year.
  • Meets diagnostic criteria specified within the Diagnostic and Statistical Manual of Mental Disorders.

Nearly one in five U.S. adults live with a mental illness, or about 46.6 million people (18.9% of all adults). Women (22.3%) are more highly impacted by mental illness than men (15.1%). Over 11 million adults live with a serious mental health disorder. This number represented 4.5% of all U.S. adults.

A mental illness does not mean one cannot function and live a productive life - treatments can have a profound effect. A mental illness can range in impact from limited impairment to significantly disabling impairment, such as in individuals with serious mental illness. A serious mental illness is defined as individuals with a mental disorder with serious functional impairment which substantially interferes with or limits one or more major life activities.

Common mental health disorders include:

Even though mental disorders are widespread, the main burden of illness lies in serious mental health disorders. These result in serious functional impairment, which substantially interferes with or limits one or more major life activities. These estimates of any mental illness do not include substance use disorders, such as drug- or alcohol-related disorders.

Mental illnesses can take a financial toll on the nation as well as the individual. Major depressive disorder is the leading cause of disability in the U.S. for individuals aged 15 to 44 years. Mental health disorders are also high among the homeless and inmates. Add to that, cuts in government-funded mental health services and psychiatric hospital beds, and the cost of not caring for these patients can skyrocket.

See Also


  • National Institute of Mental Health. Any Mental Illness (AMI) Among U.S. Adults. Accessed March 31, 2020 at
  • National Institute of Mental Health. Mental Illness. Accessed March 31, 2020 at

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.