Mental Illness

Last Editorial Review: 7/7/2004
Mental Disorders in America

Mental disorders are common in the United States and internationally. An estimated 22.1% of Americans ages 18 and older-about 1 in 5 adults-suffer from a diagnosable mental disorder in a given year. When applied to the 1998 U.S. Census residential population estimate, this figure translates to 44.3 million people. In addition, 4 of the 10 leading causes of disability in the U.S. and other developed countries are mental disorders - major depression, bipolar disorder, schizophrenia, and obsessive-compulsive disorder. Many people suffer from more than one mental disorder at a given time.

In the U.S., mental disorders are diagnosed based on the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV).

Depressive Disorders

  • Depressive disorders encompass major depressive disorder, dysthymic disorder, and bipolar disorder. Bipolar disorder is included because people with this illness have depressive episodes as well as manic episodes.
  • Approximately 18.8 million American adults, or about 9.5 percent of the U.S. population age 18 and older in a given year, have a depressive disorder.
  • Nearly twice as many women (12.0 percent) as men (6.6 percent) are affected by a depressive disorder each year. These figures translate to 12.4 million women and 6.4 million men in the U.S.
  • Depressive disorders may be appearing earlier in life in people born in recent decades compared to the past.
  • Depressive disorders often co-occur with anxiety disorders and substance abuse.


  • In 1997, 30,535 people died from suicide in the U.S.
  • More than 90 percent of people who kill themselves have a diagnosable mental disorder, commonly a depressive disorder or a substance abuse disorder.
  • The highest suicide rates in the U.S. are found in white men over age 85.
  • The suicide rate in young people increased dramatically over the last few decades. In 1997, suicide was the 3rd leading cause of death among 15 to 24 year olds.
  • Four times as many men than women commit suicide; however, women attempt suicide 2-3 times as often as men.


  • Approximately 2.2 million American adults, 2 or about 1.1 % of the population age 18 and older in a given year, 1 have schizophrenia.
  • Schizophrenia affects men and women with equal frequency.
  • Schizophrenia often first appears earlier in men, usually in their late teens or early 20s, than in women, who are generally affected in their 20s or early 30s.

Anxiety Disorders

Anxiety disorders include panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, generalized anxiety disorder, and phobias (social phobia, agoraphobia, and specific phobia).

  • Approximately 19.1 million American adults ages 18 to 54, or about 13.3 percent of people in this age group in a given year, have an anxiety disorder.
  • Anxiety disorders frequently co-occur with depressive disorders, eating disorders, or substance abuse.
  • Many people have more than one anxiety disorder.
  • Women are more likely than men to have an anxiety disorder. Approximately twice as many women as men suffer from panic disorder, post-traumatic stress disorder, generalized anxiety disorder, agoraphobia, and specific phobia, though about equal numbers of women and men have obsessive-compulsive disorder and social phobia.

Eating Disorders

The 3 main types of eating disorders are anorexia nervosa, bulimia nervosa, and binge-eating disorder.

  • Females are much more likely than males to develop an eating disorder. Only an estimated 5 to 15 % of people with anorexia or bulimia and an estimated 35 percent of those with binge-eating disorder are male.
  • In their lifetime, an estimated 0.5 % to 3.7 % of females suffer from anorexia and an estimated 1.1 % to 4.2 % suffer from bulimia.
  • Community surveys have estimated that between 2 % and 5 % of Americans experience binge-eating disorder in a 6-month period.

Attention Deficit Hyperactivity Disorder (ADHD)

  • ADHD, one of the most common mental disorders in children and adolescents, affects an estimated 4.1 % of youths ages 9 to 17 in a 6-month period.
  • About 2-3 times more boys than girls are affected.
  • ADHD usually becomes evident in preschool or early elementary years. The disorder frequently persists into adolescence and occasionally into adulthood.


  • Autism affects an estimated 1 to 2 per 1,000 people.
  • Autism and related disorders (also called autism spectrum disorders or pervasive developmental disorders) develop in childhood and generally are apparent by age 3.
  • Autism is about 4 times more common in boys than girls. Girls with the disorder, however, tend to have more severe symptoms and greater cognitive impairment.

Alzheimer's Disease

  • Alzheimer's disease, the most common cause of dementia among people age 65 and older, affects an estimated 4 million Americans.
  • As more and more Americans live longer, the number affected by Alzheimer's disease will continue to grow unless a cure or effective prevention is discovered.
  • The duration of illness, from onset of symptoms to death, averages 8 to 10 years.

For more information about these conditions, please visit the following areas:
Portions of the above information has been provided with the kind permission of the National Institute of Mental Health, National Institutes of Health (


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