A psychotic disorder is a mental illness that causes abnormal and irrational thinking and perceptions. Psychotic illnesses alter a person's ability to think clearly, make good judgments, respond emotionally, communicate effectively, understand reality, and behave appropriately. People with psychotic disorders have difficulty staying in touch with reality and often are unable to meet the ordinary demands of daily life.
The most obvious symptoms of a psychotic disorder are hallucinations and delusions. Hallucinations are sensory perceptions of things that aren't actually present, such as hearing voices, seeing things that aren't there, or feeling sensations on the skin even though nothing is touching the body. Delusions are false beliefs that the person refuses to give up, even in the face of contradictory facts. Schizophrenia is an example of a psychotic disorder.
Shared psychotic disorder, also known as folie a deux ("the folly of two"), is a rare condition in which an otherwise healthy person (secondary case) shares the delusions of a person with a psychotic disorder (primary case), such as schizophrenia. An example: A person with a psychotic disorder believes aliens are spying on him or her. The person with shared psychotic disorder will also begin to believe in spying aliens. The delusions are induced in the secondary case and usually disappear when the people are separated. Aside from the delusions, the thoughts and behavior of the secondary case usually are fairly normal.
Shared psychotic disorder usually occurs only in long-term relationships in which one person is dominant and the other is passive. In most cases, the person in whom the delusions are induced is dependent on or submissive to the person with the psychotic disorder. The people involved often are reclusive or otherwise isolated from society and have close emotional links with each other. The disorder also can occur in groups of individuals who are closely involved with a person who has a psychotic disorder.
What Are the Symptoms of Shared Psychotic Disorder?
The person with shared psychotic disorder has delusions that are similar to those of someone close who has a psychotic disorder.
What Causes Shared Psychotic Disorder?
The cause of shared psychotic disorder is not known; however, stress and social isolation are believed to play a role in its development.
How Common Is Shared Psychotic Disorder?
The number of cases is unknown, but shared psychotic disorder is rarely seen in clinical settings, such as hospitals, outpatient clinics, or doctors' offices. In many cases, only one of the affected individuals seeks treatment, making a diagnosis of shared psychotic disorder difficult. As a result, many cases might go undetected.
How Is Shared Psychotic Disorder Diagnosed?
If symptoms of shared psychotic disorder are present, the doctor will perform a complete medical history and physical exam. Although there are no laboratory tests to specifically diagnose shared psychotic disorder, the doctor might use various diagnostic tests, such as brain imaging (e.g., MRI scans)and blood tests, to rule out physical illness or a drug reaction as the cause of the delusions.
If the doctor finds no physical reason for the shared psychotic disorder symptoms, he or she might refer the person to a psychiatrist or psychologist, health care professionals who are trained to diagnose and treat mental illnesses. Psychiatrists and psychologists use specially designed interview and assessment tools to evaluate a person for a psychotic disorder. The doctor or therapist bases his or her diagnosis on the person's report of symptoms and his or her observation of the person's attitude and behavior. A diagnosis is made if a person develops a delusion as the result of a close association with another person who has an already-established delusion.