The mental status examination (including cognitive examination) in delusional disorder is usually normal other than the presence of abnormal delusional beliefs.

In general, patients are well groomed and well-dressed without evidence of gross impairment. Speech, psychomotor activity, and eye contact may reflect the emotional state associated with delusions, but are otherwise normal.

Mood and affect are consistent with delusional content; for example, patients with persecutory delusions may be suspicious and anxious. Mild dysphoria may be present without regard of type of delusions.

Tactile and olfactory hallucinations may be notably present if they are related to the delusional theme (eg, the sensation of being infested by insects, the perception of body odor). [19] Systemic or focal CNS causes of tactile and olfactory hallucinations, such as substance intoxication and/or withdrawal, temporal lobe epilepsy, should be ruled out. Auditory or visual hallucinations stereotypically characteristic of more severe psychotic disorders (eg, schizophrenia) are not consistent with a diagnosis of delusional disorder.

Memory and cognition are intact. Level of consciousness is unimpaired.

Patients usually have little insight and impaired judgment regarding their delusions. Police, family members, coworkers, and physicians other than psychiatrists are usually the first to suspect delusional disorder and often encourage the patient to seek psychiatric consultation. Seeking corroborative collateral information is often crucial. Recall that it is permissible to seek collateral history and that collateral history should not be withheld from the patient.

Assessment of homicidal or suicidal ideation is extremely important in evaluating patients with delusional disorder. The presence of homicidal or suicidal thoughts related to delusions should be actively assessed and the risk of carrying out violent plans should be ascertained. A review by researchers revealed a 8–21% risk of suicidal ideation and behavior in the persecutory and somatic subtypes. [20] Reid pointed out that some types of delusional disorder—erotomanic, jealous, and persecutory—are associated with higher risk for violence than others. [21] History of previous violent acts as well as history of how aggressive feelings were managed in the past may help to assess the risk. Access to weapons needs to be explored.

Erotomanic type

Related terms include erotomania, psychose passionelle, Clerambault syndrome, and old maid's insanity. [11, 4, 10]

The central theme of delusions is that another person, usually of higher social status, is in love with the patient. The object of delusion is usually married, geographically and/or socially distant, or otherwise unavailable. [22, 10]

Patients with this type of delusion are usually female, although males predominate in forensic samples. [1, 10]

Erotomania is usually intense. Signs of denial of love by the delusionally desired love object are frequently paradoxically, falsely interpreted as affirmation of love. [11, 10]

Patients may attempt to contact the object of the erotomanic delusion by initiating email and other elcectronic communications, making telephone calls, sending letters and gifts, making unwanted visits, and even stalking. Some cases lead to assaultive behaviors as a result of attempts to pursue the object of delusional love or attempting to "rescue" her/him from some imagined danger. [1]

Grandiose type

Patients believe that they possess some great and unrecognized talent, have made some important discovery, have a special relationship with a prominent person, and/or have special religious insight. [1]

Grandiose delusions in the absence of a manic episode are relatively uncommon. Many patients with paranoid type show some degree of grandiosity in their delusions. [4]

Grandiosity in narcissistic personality disorder is by definition nonpsychotic and not directly and solely related to hypomanic or manic episodes, as in bipolar disorder. Narcissistic personality disorder patients will concurrently show a lack of empathy, exploitative social behavior, jealousy, and/or a sense of entitlement, in addition to grandiosity.

Jealous type

Related terms include conjugal paranoia, Othello syndrome, and pathological or morbid jealousy. [3, 6, 23, 24]

The main theme of the delusions is that the patient's spouse or lover is unfaithful. Some degree of infidelity may in fact occur; however, patients with delusional jealousy support their accusation with delusional interpretation of "evidence" that may be innocuous (e.g., disarrayed clothing, spots on the sheets). [1, 4]

Patients may attempt to confront their spouses and intervene in imagined infidelity situations. Jealousy may evoke anger and empower the jealous individual with a sense of righteousness to justify acts of aggression towards the spouse/partner and/or the imagined paramour. Both the intimate partner and the (perceived) lover may be the targets of aggression and violence. This disorder can lead to acts of violence, including suicide and homicide. [4]

Persecutory type

This is the most common type of delusional disorder. [5, 25]

Patients with this type believe that they are being persecuted and harmed. [4] In contrast to persecutory delusions of schizophrenia, which may be fundamentally bizarre, the delusions are systematized, coherent, and defended with clear logic. Otherwise, no deterioration in social functioning and/or personality is observed. [11]

Patients may pursue formal litigation against their perceived persecutors. Munro [22] refers to an article by Freckelton who identified the following characteristics of delusional litigants: determination to succeed against all odds, tendency to identify barriers to justice as conspiracies, and endless drive to right a wrong, quarrelsome behaviors, and "saturating the field" with multiple complaints and suspiciousness. [22]

Patients often experience some degree of emotional distress such as irritability, anger, and resentment. [4] In extreme situations, they may resort to violence against those who they believe are threatening and/or hurting them. [1]

The distinction between normality, overvalued ideas, and delusions can be difficult to make in some cases. [4]

Somatic type

The core beliefs of this type are delusions around bodily functions and sensations. The most common are beliefs that one is infested with insects or parasites, that one is emitting a foul odor, that parts of the body are not functioning, that the body or parts of the body are misshapen or ugly, or the reduplication of body parts. [1, 13]

Patients are strongly convinced in the "physical" nature of this disorder, as opposed to patients with a hypochondriacal presentation who may be able to admit that their fear of having a serious illness is groundless. [11]

Patients are usually first seen by dermatologists, plastic surgeons, urologists, gastroenterologists, and other medical specialists. [4]

Sensory experiences associated with somatic delusions (e.g., sensation of parasites crawling under the skin) are viewed as components of systemized delusions. [4] This must be distinguished from bizarre somatic delusions occasionally seen in schizophrenia (e.g., a delusion that a "colony of lobsters" is living in the patient’s stomach).

Mixed type

Patients exhibit more than one of the delusions simultaneously [4] , and no one delusional theme predominates. [1]

Unspecified type

Delusional themes fall outside the above specific categories and/or cannot be clearly determined. [1]

Misidentification syndromes such as Capgras syndrome (characterized by a belief that a familiar person has been replaced by an identical "impostor") or Fregoli syndrome (a belief that a familiar person is "disguised" as someone else) fall into this category. These misidentification syndromes are rare and frequently, when present, associated with other neuropsychiatric conditions (e.g., schizophrenia, neurocognitive disorders, epilepsy, post-CVA). [4]

Another unusual syndrome is Cotard syndrome, in which patients believe that they have lost all their possessions, status, and strength as well as their entire being, including their organs. [4] Described first in the 19th century, it is a rare condition, which is usually considered a precursor to a psychotic or depressive episode. [11]