Delusional disorder is characterized by nonbizarre delusions (false beliefs) that persist for at least 1 mo, without other symptoms of schizophrenia.

Delusional disorder is distinguished from schizophrenia by the presence of delusions without other symptoms of schizophrenia. The delusions tend to be nonbizarre and involve situations that could occur, such as being followed, poisoned, infected, loved at a distance, or deceived by one's spouse or lover.

In contrast to schizophrenia, delusional disorder is relatively uncommon. Onset generally occurs in middle or late adult life. Psychosocial functioning is not as impaired as it is in schizophrenia, and impairments usually arise directly from the delusional belief.

When delusional disorder occurs in elderly patients, it is sometimes called paraphrenia. It may coexist with mild dementia. The physician must be careful to distinguish delusions from elder abuse being reported by a mildly demented elderly patient.

Symptoms and Signs

Delusional disorder may arise from a preexisting paranoid personality disorder. In such people, a pervasive distrust and suspiciousness of others and their motives begins in early adulthood and extends throughout life. Early symptoms may include the feeling of being exploited, preoccupation with the loyalty or trustworthiness of friends, a tendency to read threatening meanings into benign remarks or events, persistent bearing of grudges, and a readiness to respond to perceived slights.

Several subtypes of delusional disorder are recognized:

• Erotomanic: Patients believe that another person is in love with them. Efforts to contact the object of the delusion through telephone calls, letters, surveillance, or stalking are common. People with this subtype may have conflicts with the law related to this behavior.
• Grandiose: Patients believe they have a great talent or have made an important discovery.
• Jealous: Patients believe that their spouse or lover is unfaithful. This belief is based on incorrect inferences supported by dubious evidence. They may resort to physical assault.
• Persecutory: Patients believe that they are being plotted against, spied on, maligned, or harassed. They may repeatedly attempt to obtain justice through appeals to courts and other government agencies and may resort to violence in retaliation for the imagined persecution.
• Somatic: The delusion relates to a bodily function; eg, patients believe they have a physical deformity, odor, or parasite.

Diagnosis

Diagnosis depends largely on making a clinical assessment, obtaining a thorough history, and ruling out other specific conditions associated with delusions. Assessment of dangerousness, especially the extent to which patients are willing to act on their delusion, is very important.

Prognosis

Delusional disorder does not usually lead to severe impairment or change in personality, but delusional concerns may gradually progress. Most patients can remain employed.

Treatment

Treatment aims to establish an effective physician-patient relationship and to manage complications. If patients are assessed to be dangerous, hospitalization may be required. Insufficient data are available to support the use of any particular drug, although antipsychotics sometimes suppress symptoms.

A long-term treatment goal of shifting the patient's major area of concern away from the delusional locus to a more constructive and gratifying area is difficult but reasonable.

Last full review/revision June 2008 by Juan R. Bustillo, MD