In erotomanic type, the central theme of the delusion is that another person is in love with the individual. The person about whom this conviction is held is usually of higher status (e.g., a famous individual or a superior at work) but can be a complete stranger. Efforts to contact the object of the delusion are common. In grandiose type, the central theme of the de- lusion is the conviction of having some great talent or insight or of having made some im- portant discovery. Less commonly, the individual may have the delusion of having a special relationship with a prominent individual or of being a prominent person (in which case the actual individual may be regarded as an impostor). Grandiose delusions may have a religious content. In jealous type, the central theme of the delusion is that of an un- faithful partner. This belief is arrived at without due cause and is based on incorrect infer- ences supported by small bits of "evidence” (e.g., disarrayed clothing). The individual with the delusion usually confronts the spouse or lover and attempts to intervene in the imagined infidelity. In persecutory type, the central theme of the delusion involves the in- dividual’s belief of being conspired against, cheated, spied on, followed, poisoned, mali- ciously maligned, harassed, or obstructed in the pursuit of long—term goals. Small slights may be exaggerated and become the focus of a delusional system. The affected individual may engage in repeated attempts to obtain satisfaction by legal or legislative action. Indi- viduals with persecutory delusions are often resentful and angry and may resort to Vio- lence against those they believe are hurting them. In somatic type, the central theme of the delusion involves bodily functions or sensations. Somatic delusions can occur in several forms. Most common is the belief that the individual emits a foul odor; that there is an in- festation of insects on or in the skin; that there is an internal parasite; that certain parts of the body are misshapen or ugly; or that parts of the body are not functioning.
The essential feature of delusional disorder is the presence of one or more delusions that persist for at least 1 month (Criterion A). A diagnosis of delusional disorder is not given if the individual has ever had a symptom presentation that met Criterion A for schizophre- nia (Criterion B). Apart from the direct impact of the delusions, impairments in psychoso- such as schizophrenia, and behavior is not obviously bizarre or odd (Criterion C). If mood episodes occur concurrently with the delusions, the total duration of these mood episodes is brief relative to the total duration of the delusional periods (Criterion D). The delusions are not attributable to the physiological effects of a substance (e.g., cocaine) or another medical condition (e.g., Alzheimer’s disease) and are not better explained by another men- tal disorder, such as body dysmorphic disorder or obsessive-compulsive disorder (Crite- rion E).
In addition to the five symptom domain areas identified in the diagnostic criteria, the assessment of cognition, depression, and mania symptom domains is vital for making crit- ically important distinctions between the various schizophrenia spectrum and other psy- chotic disorders.
Social, marital, or work problems can result from the delusional beliefs of delusional dis- order. Individuals with delusional disorder may be able to factually describe that others view their beliefs as irrational but are unable to accept this themselves (i.e., there may be ”factual insight” but no true insight). Many individuals develop irritable or dysphoric mood, which can usually be understood as a reaction to their delusional beliefs. Anger and violent behavior can occur with persecutory, jealous, and erotomanic types. The individ- ual may engage in litigious or antagonistic behavior (e.g., sending hundreds of letters of protest to the government). Legal difficulties can occur, particularly in jealous and eroto- manic types.