An important aspect of delusional disorder is the identification of the form of delusion from which a person suffers. The most common form of delusional disorder is the persecutory or paranoid subtype, in which the patients are certain that others are striving to harm them.
In the erotomanic form of delusional disorder, the primary delusional belief is that some important person is secretly in love with the sufferer. The erotomanic type is more common in women than men. Erotomanic delusions may prompt stalking the love object and even violence against the beloved or those viewed as potential romantic rivals.
The grandiose subtype of delusional disorder involves the conviction of one’s importance and uniqueness, and takes a variety of forms: believing that one has a distinguished role, has some remarkable connections with important persons, or enjoys some extraordinary powers or abilities.
In the somatic subtype, there is excessive concern and irrational ideas about bodily functioning, which may include worries regarding infestation with parasites or insects, imagined physical deformity, or a conviction that one is emitting a foul stench when there is no problematic odor.
The form of disorder most associated with violent behavior, usually between romantic partners, is the jealous subtype of delusional disorder. Patients are firmly convinced of the infidelity of a spouse or partner, despite contrary evidence and based on minimal data (like a messy bedspread or more cigarettes than usual in an ashtray, for instance). Delusional jealousy sufferers may gather scraps of conjectured “evidence,” and may try to constrict their partners’ activities or confine them to home. Delusional disorder cases involving aggression and injury toward others have been most associated with this subtype.