Psychosis is a loss of contact with reality, usually including false beliefs about what is taking place or who one is (delusions) and seeing or hearing things that aren't there (hallucinations).

A number of substances and medical conditions can cause psychosis, including:

• Alcohol and certain illegal drugs, both during use and during withdrawal
• Brain tumors or cysts
• Dementia (including Alzheimer's disease)
• Degenerative brain diseases, such as Parkinson's disease, Huntington's disease, and certain chromosomal disorders
• HIV and other infections that affect the brain
• Some prescription drugs, such as steroids and stimulants
• Some types of epilepsy
• Stroke

Psychosis is also part of a number of psychiatric disorders, including:

• Bipolar disorder (manic or depressed)
• Delusional disorder
• Depression with psychotic features
• Personality disorders (schizotypal, shizoid, paranoid, and sometimes borderline)
• Schizoaffective disorder
• Schizophrenia

Psychotic symptoms may include:

• Disorganized thought and speech
• False beliefs that are not based in reality (delusions), especially unfounded fear or suspicion
• Hearing, seeing, or feeling things that are not there (hallucinations)
• Thoughts that "jump" between unrelated topics (disordered thinking)

Psychiatric evaluation and testing are used to diagnose the cause of the psychosis.

Laboratory testing and brain scans may not be needed, but sometimes can help pinpoint the diagnosis. Tests may include:

• Blood tests for abnormal electrolyte and hormone levels
• Blood tests for syphilis and other infections
• Drug screens
• MRI of the brain

Treatment depends on the cause of the psychosis. Care in a hospital is often needed to ensure the patient's safety.

Antipsychotic drugs, which reduce hallucinations and delusions and improve thinking and behavior are helpful, whether the cause is a medical or psychiatric disorder.

See: Schizophrenia for more information about the treatment of psychosis.

How well a person does depends on the cause of the psychosis. If the cause can be corrected, the outlook is often good, and treatment with antipsychotic medication may be brief.

Some chronic conditions, such as schizophrenia, may need life-long treatment with antipsychotic medications to control symptoms.

Psychosis can prevent people from functioning normally and caring for themselves. If the condition is left untreated, people can sometimes harm themselves or others.

Call your health care provider or mental health professional if you or a member of your family is losing contact with reality. If there is any concern about safety, immediately take the person to the nearest emergency room to be seen by a doctor.

Prevention depends on the cause. For example, avoiding alcohol abuse prevents alcohol-induced psychosis.

Freudenreich O, Weiss AP, Goff DC. Psychosis and schizophrenia. In: Stern TA, Rosenbaum JF, Fava M, Biederman J, Rauch SL, eds. Massachusetts General Hospital Comprehensive Clinical Psychiatry. 1st ed. Philadelphia, Pa: Mosby Elsevier; 2008:chap 28.