Mental illness is a term that refers to all the different types of mental disorders, including disorders of thought, mood, or behavior. To be classified as a mental illness, the condition must cause distress and result in a reduced ability to function psychologically, socially, occupationally, or interpersonally.

This means that someone who has a mental illness may have trouble coping with emotions, stress and anger, for instance; and trouble handling such things as daily activities, family responsibilities, relationships, or work and school responsibilities. A person can have trouble, to a greater or lesser degree, with one area or all of them, and can have more than one type of mental illness at the same time.

Classifications of Mental Illness

Mood disorders.

These include disorders that affect how you feel, such as persistent sadness or feelings of euphoria. They include major depression and bipolar disorder.

Anxiety disorders.

Anxiety is an emotion characterized by the anticipation of future danger or misfortune accompanied by a feeling of being ill at ease. Examples include panic disorder, obsessive-compulsive disorder, specific phobias, and generalized anxiety disorder.

Substance-related disorders.

These include problems associated with the misuse of alcohol, nicotine, caffeine and illicit drugs.

Psychotic disorders.

These disorders impair your sense of reality. The most notable example of this is schizophrenia, although other classes of disorders can be associated with psychosis at times.

Cognitive disorders.

These disorders affect your ability to think and reason. They include delirium, dementia and memory problems. Perhaps the most well-known of these disorders is Alzheimer's disease.

Developmental disorders.

This category covers a wide range of problems that usually first begin to make themselves known in infancy, childhood or adolescence. They include autism, attention-deficit/hyperactivity disorder and learning disabilities. But just because they're all grouped in this category doesn't necessarily mean they share a common cause or that there's a relationship among the disorders.

Personality disorders.

A personality disorder is an enduring pattern of inner experience and behavior that is dysfunctional and leads to distress or impairment. Examples include borderline personality disorder and antisocial personality disorder.

Other disorders.

These include disorders of impulse control, sleep, sexual functioning and eating. Also included are dissociative disorders, in which a person's sense of self is disrupted, and somatoform disorders, in which there are physical symptoms in the absence of a clear physical cause, such as hypochondriasis.

Is mental illness simply whatever a culture or society defines it as?

Behaviors that are approved of or frowned upon can vary greatly from culture to culture. But research shows a surprising consistency in the prevalence of serious mental illness across all cultures. Schizophrenia, for instance, occurs in about 1 percent of all populations worldwide. Major depression also has a consistent prevalence in countries around the world. This information supports the idea that serious mental illnesses have a biological basis common to all humans.

Important Facts About Recovery

The best treatments for serious mental illnesses today are highly effective; between 70 and 90 percent of individuals have significant reduction of symptoms and improved quality of life with a combination of pharmacological and psychosocial treatments and supports.

With appropriate effective medication and a wide range of services tailored to their needs, most people who live with serious mental illnesses can significantly reduce the impact of their illness and find a satisfying measure of achievement and independence. A key concept is to develop expertise in developing strategies to manage the illness process.

Early identification and treatment is of vital importance. By ensuring access to the treatment and recovery supports that are proven effective, recovery is accelerated and the further harm related to the course of illness is minimized.