According to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition – Text Revision. (DSM-IV-TR), delusional disorders are marked by nonbizarre false beliefs with a plausible basis in reality. Formerly referred to as paranoid disorders, delusional disorders involve erotomanic, grandiose, jealous, somatic, or persecutory themes. Some patients experience several types of delusions, whereas others experience unspecified delusions with no dominant theme.
Delusional disorders commonly begin in middle or late adulthood, usually between the ages of 40 and 55, but they can occur at a younger age. These uncommon illnesses affect less than 1% of the population; the incidence is about equal in men and women.
Typically chronic, these disorders commonly interfere with social and marital relationships but seldom impair intellectual or occupational functioning significantly.
Delusional disorders of later life strongly suggest a hereditary predisposition. At least one study has linked the development of delusional disorders to inferiority feelings in the family.
Some researchers suggest that delusional disorders are the product of specific early childhood experiences with an authoritarian family structure. Others hold that anyone with a sensitive personality is particularly vulnerable to developing a delusional disorder.
Certain medical conditions—head injury, chronic alcoholism, and deafness—and aging are known to increase the risk for delusional disorders. Predisposing factors linked to aging include isolation, lack of stimulating interpersonal relationships, physical illness, and impaired hearing and vision.
Severe stress (such as a move to a foreign country) may also precipitate a delusional disorder.
Signs and symptoms
Aside from behavior related to the patient’s delusions, the psychiatric history of a delusional patient may be unremarkable. This helps distinguish it from disorders that result in behavior more dissociated from reality such as paranoid schizophrenia. (See Delusional disorder or paranoid schizophrenia?)
The delusional patient is likely to report problems with social and marital relationships, including depression or sexual dysfunction. He may describe a life marked by social isolation or hostility. He may deny feeling lonely, relentlessly criticizing, or placing unreasonable demands on others.
Gathering accurate information from a delusional patient may prove difficult. He may deny his feelings, disregard the circumstances that led to his hospitalization, and refuse treatment.
However, his responses and behavior during the assessment interview provide clues that can help to identify his disorder. Family members may confirm observations—for example, by reporting that the patient is chronically jealous or suspicious.
Assessment clue: Communication
The patient’s ability to communicate can be another indicator. He may be evasive or reluctant to answer questions. Or he may be overly talkative, explaining events in great detail and emphasizing what he has achieved, prominent people he knows, or places he has traveled.
The patient may make statements that at first seem logical but later prove irrelevant. Some of his answers may be contradictory, jumbled, or irrational.