Delusional disorder is characterized by one or more false beliefs that persist for at least 1 month.

• The false beliefs tend to be ordinary things that could occur, such as being deceived by a spouse.
• This disorder may develop in people with a paranoid personality disorder.
• Doctors base the diagnosis mainly on the person's history after they rule out other possible causes.
• People usually remain functional and employed.
• A good doctor-patient relationship is essential to treatment.

Delusional disorder usually first affects people in middle or late adult life. Delusions tend to be nonbizarre and involve situations that could conceivably occur in real life, such as being followed, poisoned, infected, loved at a distance, or deceived by a spouse or lover. Several subtypes of delusional disorder are recognized:

Erotomanic: People believe that another person is in love with them. Efforts to contact the object of the delusion through telephone calls, letters, or even surveillance and stalking may be common. Behavior related to the delusion may cause conflict with the law.

Grandiose: People are convinced that they have some great talent or have made some important discovery.

Jealous: People are convinced that a spouse or lover is unfaithful. This belief is based on incorrect inferences supported by dubious evidence. Under such circumstances, physical assault may be a significant danger.

Persecutory: People believe that they are being plotted against, spied on, maligned, or harassed. People may repeatedly attempt to obtain justice by appealing to courts and other government agencies. Rarely, violence may be resorted to in retaliation for imagined persecution.

Somatic: People are preoccupied with a bodily function or attribute, such as an imagined physical deformity or odor. The delusion can also take the form of an imagined general medical condition, such as a parasitic infection.

Symptoms

A delusional disorder may arise from a preexisting paranoid personality disorder (see Personality Disorders: Schizotypal personality disorder). Beginning in early adulthood, people with a paranoid personality disorder have a pervasive distrust and suspiciousness of others and their motives. Early symptoms of delusional disorder may include feeling exploited, being preoccupied with the loyalty or trustworthiness of friends, reading threatening meanings into benign remarks or events, bearing grudges for a long time, and responding readily to perceived slights.

Diagnosis

After ruling out other specific conditions that are associated with delusions, a doctor bases the diagnosis largely on the person's history. The doctor must assess the degree of dangerousness, particularly the extent to which the people are willing to act on their delusions.

Prognosis and Treatment

Delusional disorder does not usually cause severe impairment. However, people may become progressively more involved with their delusion. Most people are able to remain employed.

A good doctor-patient relationship helps. Hospitalization may be needed if the doctor believes that people are dangerous.

Antipsychotic drugs are not generally used but are sometimes effective in suppressing symptoms. A long-term treatment goal is to shift the person's focus away from the delusion to a more constructive and gratifying area, although this goal is frequently difficult to achieve.

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