Schizophrenia is a long-term mental disorder that affects how a person thinks, feels, and behaves.  Signs and symptoms of schizophrenia are variable and include changes in perception, emotion, cognition, thinking, and behavior. A diagnosis of schizophrenia requires continuous signs of the disturbance for at least 6 months, during which time the individual’s level of functioning is markedly below their norm in work, interpersonal relations, or self-care. When the onset is in childhood or adolescence, the person fails to achieve an expected level of interpersonal, academic, or occupational functioning. The 6-month period must include at least two of the symptoms below that are active for a significant portion of time during a period of 1 month. At least one of these must be from the first three in the list:

1. Delusions
2. Hallucinations
3. Disorganized speech
4. Grossly disorganized or catatonic behavior
5. Negative symptoms, such as diminished emotional expression

A diagnosis of schizophrenia requires ruling out schizoaffective disorder and depressive or bipolar disorder with psychotic features. In addition, the symptoms cannot be attributable to the physiological effects of a substance (e.g., a drug of abuse or medication) or another medical condition.

Epidemiology

• The lifetime prevalence of schizophrenia in the United States is about 1 percent.
• Schizophrenia is equally prevalent in men and women. Onset of the illness, however, is earlier in men than in women. The peak ages of onset are 10 to 25 years for men and 25 to 35 years for women.
• Individuals with schizophrenia have a higher mortality rate from accidents and natural causes than the general population.
• Patients with a diagnosis of schizophrenia are reported to account for 15 to 45 percent of homeless Americans.
• Substance abuse is common among people with schizophrenia. The lifetime prevalence of any drug abuse (other than tobacco) is greater than 50 percent.

What is Schizoaffective Disorder?

Schizoaffective disorder has features of both schizophrenia and mood disorders. A diagnosis of schizoaffective disorder is given with the following requirements:

• An uninterrupted period of illness during which time there is a major mood episode (major depressive or manic) concurrent with symptoms of schizophrenia.
• Delusions or hallucinations for 2 or more weeks in the absence of a major mood episode (depressive or manic) during the lifetime duration of the illness.
• Symptoms that meet the criteria for a major mood episode present for the majority of the illness, whether active or residual.
• Symptoms are not attributable to the effects of a substance (e.g., a drug of abuse or medication) or another medical condition.

What is Schizophreniform Disorder?

The symptoms of schizophreniform are similar to those of schizophrenia; however, with schizophreniform disorder, they last less than 6 months (but at least 1 month). Patients with this disorder return to their baseline level of functioning after the disorder has resolved. If the disorder lasts longer than 6 months, it is diagnosed as schizophrenia.

A diagnosis of schizophreniform disorder must rule out schizoaffective disorder and depressive or bipolar disorder with psychotic features. In addition, symptoms cannot be attributable to the effects of a substance (e.g., a drug of abuse or medication) or another medical condition.