Psychology Today~ Delusional disorder refers to a condition associated with one or more nonbizarre delusions of thinking—such as expressing beliefs that occur in real life such as being poisoned, being stalked, being loved or deceived, or having an illness, provided no other symptoms of schizophrenia are exhibited.
Delusions may seem believable at face value, and patients may appear normal as long as an outsider does not touch upon their delusional themes. Mood episodes are relatively brief compared with the total duration of the delusional periods. Also, these delusions are not due to a medical condition or substance abuse.
Themes of delusions may fall into the following types: erotomanic type (patient believes that a person, usually of higher social standing, is in love with the individual); grandiose type (patient believes that he has some great but unrecognized talent or insight, a special identity, knowledge, power, self-worth, or special relationship with someone famous or with God); jealous type (patient believes his partner has been unfaithful); persecutory type (patient believes he is being cheated, spied on, drugged, followed, slandered, or somehow mistreated); somatic type (patient believes he is experiencing physical sensations or bodily dysfunctions—such as foul odors or insects crawling on or under the skin—or is suffering from a general medical condition or defect); mixed type (characteristics of more than one of the above types, but no one theme dominates); or unspecified type (patient's delusions do not fall in described categories).