Psychosis

Before the careful classification of mental illnesses, anyone exhibiting psychotic behavior was thought to be schizophrenic, which is the mental illness most frequently associated with psychosis. Schizophrenia is a mental illness that is characterized by delusions, hallucinations, thought disorders, disorganized speech and behavior, and sometimes catatonic behavior. Emotions tend to flatten out and it becomes increasingly more difficult for the person to function normally in society. It is estimated that 1% of the American population is currently affected by this illness, which means there are about 1.5 million people who are ill from this disease.

In certain states of manic-depressive illness, or bipolar disorder, a patient may also suffer psychotic symptoms of delusions, hallucinations, and thought disorder. Unlike schizophrenia, those who suffer from manic-depressive illness are involved in a mood disorder, while schizophrenia is considered more of a thought disorder. In schizophrenia the mood is flat, but in manic-depression the mood can swing from great excitability to deep depression and feelings of hopelessness. In both phases of manic-depressive illness, many patients also experience delusions and hallucinations, which lead to misperceptions of reality.

Other psychiatric illnesses that produce psychotic episodes are delusional disorders, brief psychotic disorders that may remit within a month, substance-induced psychotic disorders, psychotic disorders due to a general medical condition, and a number of others given separate classification in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), a publication that presents guidelines for the diagnosis of serious mental illnesses. Diagnosis is based both on the nature of the psychosis and its duration.