Shared Psychotic Disorder

The main characteristic of Shared Psychotic Disorder (Folie à Deux) is a delusion that develops in an individual who is involved in a close relationship with someone who has a psychotic condition.

The diagnostic criteria is as follows:

• A delusion develops in an individual in the context of a close relationship with another person(s), who has an already-established delusion.

• The delusion is similar in content to that of the person who already has the established delusion.

• The disturbance is not better accounted for by another Psychotic Disorder (e.g., Schizophrenia) or a Mood Disorder With Psychotic Features and is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition.

Individuals who come to share delusional beliefs are often related by blood or marriage and have lived together for a long time, sometimes in relative social isolation. If the relationship with the primary case is interrupted, the delusional beliefs of the other individual usually diminish or disappear. Although most commonly seen in relationships of only two people, Shared Psychotic Disorder can occur among a larger number of individuals, especially in family situations in which the parent is the primary case and the children, sometimes to varying degrees, adopt the parent's delusional beliefs. Individuals with this disorder rarely seek treatment and usually are brought to clinical attention when the primary case receives treatment.

Associated Features

Aside from the delusional beliefs, behavior is usually not otherwise odd or unusual in Shared Psychotic Disorder. Impairment is often less severe in the individual with Shared Psychotic Disorder than in the primary case.

Diagnostic criteria summarized from:

American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders, fourth edition. Washington, DC: American Psychiatric Association.