are not attributable  to the physiological effects of a su bstance (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 dy smorphic 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 mani a symptom domains is vital for making crit-
ically important distinctions between the va rious schizophrenia spectrum and other psy-
chotic disorders.
Associated Features Supporting Diagnosis
Social, marital, or work problems can result from the delusional beliefs of delusional dis-
order. Individuals with delusional disorder ma y 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 de velop irritable or dysphoric
mood, which can usually be understood as a re action 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. 
Prevalence
The lifetime prevalence of delusional disorder has been estimated at around 0.2%, and the
most frequent subtype is persecutory. Delu sional disorder, jealous type, is probably more
common in males than in females, but there ar e no major gender differences in the overall
frequency of delu sional disorder.
Development and Course
On average, global function is generally better than that observed in schizophrenia. Al-