What Is Mental Illness?

A comprehensive look at mental illness starting with an explanation of mental illness is and the different types of mental illness, psychiatric disorders.

An explanation of mental illness and psychiatric disorders


The term "mental illness" actually encompasses numerous psychiatric disorders, and just like illnesses that affect other parts of the body, they can vary in severity. Many people suffering from mental illness may not look as though they are ill or that something is wrong, while others may appear to be confused, agitated, or withdrawn.


The term "mental illness" is an unfortunate one because it implies a distinction between "mental" disorders and "physical" disorders. Research shows that there is much "physical" in "mental" disorders and vice-versa. For example, the brain chemistry of a person with major depression is different from that of a nondepressed person, and antidepressant medication can be used (often in combination with psychotherapy) to bring the brain chemistry back to normal. Similarly, a person who is suffering from hardening of the arteries in the brain--which reduces the flow of blood and thus oxygen in the brain--may experience such "mental" symptoms as confusion and forgetfulness.



What is mental illness? Read this explanation of mental illness and psychiatric disorders.Recognized mental illnesses are described and categorized in the book Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. This book is compiled by the American Psychiatric Association and updated periodically. It can be purchased through the American Psychiatric Press Inc.

Some of the more commonly known psychiatric disorders are depression; manic depression (also known as bipolar disorder); anxiety disorders, including specific phobias (such as fear of heights), social phobia, panic disorder, agoraphobia, obsessive-compulsive disorder, and generalized anxiety disorder; schizophrenia and other psychotic disorders, such as delusional disorder; substance abuse and disorders related to substance abuse; delirium; dementia, including Alzheimer's disease; eating disorders, such as bulimia and anorexia; sleep disorders; attention-deficit/hyperactivity disorder; learning disorders; sexual disorders; dissociative disorders, such as multiple personality disorder; and personality disorders, such as borderline personality disorder and antisocial personality disorder.

For comprehensive information on mental illness, here is the Mental Illness Table of Contents with all the information you need to know.


next: A Picture of Mental Illness and the Types of Mental Illness

back to: Psychiatric Disorders Definitions Index

APA Reference
Writer, H. (2009, January 3). What Is Mental Illness?, HealthyPlace. Retrieved on 2019, May 20 from

Last Updated: 2017, March 29

Medically reviewed by Harry Croft, MD