|This group of disorders is characterized by the development either of a single delusion or of a set of related delusions which are usually persistent and sometimes lifelong. The delusions are highly variable in content. Often they are persecutory, hypochondriacal, or grandiose, but they may be concerned with litigation or jealousy, or express a conviction that the individual's body is misshapen, or that others think that he or she smells or is homosexual. Other psychopathology is characteristically absent, but depressive symptoms may be present intermittently, and olfactory and tactile hallucinations may develop in some cases. Clear and persistent auditory hallucinations (voices), schizophrenic symptoms such as delusions of control and marked blunting of affect, and definite evidence of brain disease are all incompatible with this diagnosis. However, occasional or transitory auditory hallucinations, particularly in elderly patients, do not rule out this diagnosis, provided that they are not typically schizophrenic and form only a small part of the overall clinical picture. Onset is commonly in middle age but sometimes, particularly in the case of beliefs about having a misshapen body, in early adult life. The content of the delusion, and the timing of its emergence, can often be related to the individual's life situation, e.g. persecutory delusions in members of minorities. Apart form actions and attitudes directly related to the delusion or delusional system, affect, speech, and behaviour are normal.|
Delusions constitute the most conspicuous or the only clinical characteristic. They must be present for at least 3 months and be clearly personal rather than subcultural. Depressive symptoms or even a full-blown depressive episode may be present intermittently, provided that the delusion persists at times when there is no disturbance of mood. There must be no evidence of brain disease, no or only occasional auditory hallucinations, and no history of schizophrenic symptoms (delusions of control, thought broadcasting, etc.).