Capgras syndrome is the belief that a familiar person has been replaced by an imposter. Capgras syndrome is a member of the unspecified type of delusional disorders. There are variants of Capgras syndrome such as the delusion that familiar persons can assume the guise of strangers (Frégoli’s phenomenon) and the very rare delusion that familiar persons can change themselves into other persons at will (intermetamorphosis). Patients with Cotard syndrome (also known as délire de négation or nihilistic delusional disorder) complain of having lost not only possessions, status, and strength, but also their heart, blood, and intestines. Each delusional disorder of the unspecified type is not only rare but may be associated with schizophrenia, dementia, epilepsy, and other organic disorders.

Olfactory reference syndrome is a subcategory of delusional disorder, somatic type, in which the patient has delusions of foul body odors or halitosis. It differs from other delusions of the somatic type in that it has an earlier age of onset (mean of 25 years), male predominance, unmarried, and absence of past psychiatric treatment.

Conjugal paranoia is a delusional disorder of infidelity in which the patient has delusions that a spouse is being unfaithful. The eponym Othello syndrome has been used to describe morbid jealousy that can arise from multiple concerns. The delusion usually affects men, often those with no prior psychiatric illness. It may appear suddenly and serve to explain a host of present and past events involving the spouse’s behavior. The condition is difficult to treat and may diminish only on separation, divorce, or death of the spouse.

The course of brief psychotic disorder is found in the diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR). It is a psychotic episode that lasts more than 1 day but less than 1 month, with eventual return to premorbid level of functioning. Approximately 50 percent patients diagnosed with brief psychotic disorder retain this diagnosis; the other 50 percent evolve into either schizophrenia or a major affective disorder. There are no apparent distinguishing features among brief psychotic disorder, acute-onset schizophrenia, and mood disorders with psychotic features on initial presentation. Several prognostic features have been proposed to characterize the illness, but they are inconsistent across studies. The good prognostic features are similar to those found in schizophreniform disorder, including acute onset of psychotic symptoms, confusion or emotional turmoil at the height of the psychotic episode, good premorbid functioning, the presence of affective symptoms, and a short duration of symptoms. There is a relative dearth of information on the recurrence of brief psychotic episodes, however, so the course and prognosis of this disorder have not been well characterized.

Sharing rapid onset of symptoms, brief psychotic disorder must be differentiated from substance-induced psychotic disorders and psychotic disorders due to a general medical condition. A thorough medical evaluation, including a physical examination, laboratory studies, and brain imaging, helps rule out many of those conditions. With only cross-sectional information, brief psychotic disorder is difficult to differentiate from other types of functional psychosis.

The relationship between brief psychotic disorder and both schizophrenia and affective disorders remains uncertain. The DSM-IV-TR has made the distinction between brief psychotic disorder and schizophreniform disorder clearer by now requiring a full month of psychotic symptoms for the latter. If psychotic symptoms are present longer than 1 month, the diagnoses of schizophreniform disorder, schizoaffective disorder, schizophrenia, mood disorders with psychotic features, delusional disorder, and psychotic disorder not otherwise specified need to be entertained. If psychotic symptoms of sudden onset are present for less than 1 month in response to an obvious stressor, the diagnosis of brief psychotic disorder is strongly suggested. Other diagnoses to differentiate include factitious disorder, malingering, and severe personality disorders, with consequent transient psychosis possible.

Good prognostic features for brief psychotic disorders include good premorbid adjustment, few premorbid schizoid traits, a severe precipitating stressor, the sudden onset of symptoms, affective symptoms, confusion and perplexity during psychosis, little affective blunting, a short duration of symptoms, and the absence of schizophrenic relatives.

The case of Mrs. P demonstrates a “classic” presentation of schizoaffective disorder. Schizoaffective disorder has features of both schizophrenia and mood disorders. Patients are diagnosed with schizoaffective disorder if they fit into one of six categories: (1) patients with schizophrenia who have mood symptoms, (2) patients with mood disorder who have symptoms of schizophrenia even when euthymic, (3) patients with both mood disorder and schizophrenia, (4) patients with a third psychosis unrelated to schizophrenia and mood disorder, (5) patients whose disorder is on a continuum between schizophrenia and mood disorder, and (6) patients with some combination of the above. In the case of Mrs. P, clear depressive and hypomanic episodes are present in combination with continuous psychotic illness.

Schizophreniform disorder is an acute psychotic disorder that has a rapid onset and lacks a long prodromal phase. Symptoms must last at least 1 month but less than 6 months. In the case of Mrs. P, symptoms presented for more than 6 months and include depressive and manic symptoms that are not indicated in the diagnostic criteria for schizophreniform disorder. Delusional disorder is diagnosed when a person exhibits nonbizarre delusions for at least 1 month’s duration that cannot be attributed to other psychotic disorders. The mood of patients with delusional disorders is consistent with the content of the delusions (i.e., a person with persecutory delusions is suspicious). Mrs. P experiences depressive and manic episodes that do not appear to coincide with the content of her delusions. Brief psychotic disorder is a psychotic condition that involves the sudden onset of psychotic symptoms and lasts 1 day or more but less than 1 month. It can also include the presence of marked stressors (i.e., war, torture, serious medical illness). Mrs. P’s symptoms present too long to qualify for this diagnosis. Acute and transient psychotic disorders are defined as psychotic conditions with an onset within 2 weeks and full remission within 1 to 3 months. It is also a nonaffective psychotic disorder; therefore, Mrs. P’s mood symptoms and the duration of the illness rule out acute and transient psychotic disorders.

The course and the prognosis of schizoaffective disorder are variable. As a group, patients with this disorder have a prognosis intermediate between patients with schizophrenia and patients with mood disorders. Patients with schizoaffective disorder, bipolar type, typically have a better prognosis. A poor prognosis is associated with the depressive type of schizoaffective disorder. A poor prognosis is also associated with the following variables: no precipitating factor, a predominance of psychotic symptoms, early or insidious onset, a poor premorbid history, and a positive family history of schizophrenia.

Folie á deux is another name for shared psychotic disorder. Other references for the disorder are shared paranoid disorder, induced psychotic disorder, folie impose, and double insanity. The disorder is characterized by the transfer of delusions from one person to another. The key features of the disorder are the unquestioning acceptance of the other individual’s delusional beliefs and the temporal sequence of development of the disorder, with one of the individuals having an earlier onset. Both persons are closely associated for a long time and typically live together in relative social isolation. Shared psychotic disorder usually involves two individuals but may involve more than two individuals, including entire family units. Persecutory delusional beliefs are most commonly seen in shared psychotic disorder, comprising about 70 percent of patients in one study; however, religious, grandiose, and somatic delusions may also be observed.

Psychotherapy for nondelusional members of the patient’s family is usually not necessary. Clinical reports vary, but the prognosis is guarded—recovery rates have been reported to be as low as 10 percent. The submissive person often requires treatment with antipsychotic drugs, as does the dominant person. Separation of the submissive person from the dominant person is the primary intervention. The submissive person and the dominant person usually move back together after treatment.