A delusion is a fixed false belief based on an inaccurate interpretation of an external reality despite evidence to the contrary. The belief is not congruent with one’s culture or subculture, and almost everyone else knows it to be false.
The diagnosis of a delusional disorder occurs when a person has one or more non-bizarre (situations that can take place in real life, although not real but are possible) delusional thought for one month or more, that has no explanation by another physiological, substance-induced, medical condition or any other mental health condition. An individual's cultural beliefs merit consideration before coming to the diagnosis. Cultural beliefs also impact the content of delusions.
Other than the delusions(s) the functionality is not impacted, and behavior is not obviously bizarre.
Some of the most frequently encountered types of delusions are:
Delusional disorder is relatively rare, has a later age of onset as compared to schizophrenia and does not show a gender predominance. The patients are also relatively stable. The exact cause of delusional disorder is unknown.
Many biological conditions like substance use, medical conditions, neurological conditions can cause delusions. Delusional disorder involves the limbic system and basal ganglia in those with intact cortical functioning.
Hypersensitive persons and ego defense mechanisms like reaction formation, projection and denial are some psychodynamic theories for delusional disorder. Social isolation, envy, distrust, suspicion, and low self-esteem are some of the factors which when becoming intolerable leads to a person seeking an explanation and thus form a delusion as a solution.
Immigrants with language barrier, deaf and visually impaired persons as well as the elderly are special populations who are more vulnerable to delusions.
The lifetime morbid risk of delusional disorder in the general population has been estimated to range from 0.05 to 0.1 percent, based on data from various sources including case registries, case series, and population-based samples. According to the DSM-V, the lifetime prevalence of delusional disorder is about 0.02%. The prevalence of delusional disorder is much rarer than other conditions like schizophrenia, bipolar disorder, and other mood disorders; this may be in part due to underreporting of delusional disorder as those with delusional disorder may not seek mental health attention unless forced by family or friends. Age mean age of onset is about 40 years, but the range is from 18 years to 90 years. The persecutory and jealous type of delusion is more common in males, while the erotomanic variety is more common in females.
Generally, global functioning is more or less preserved as compared to other disorders. Impairment can be significant in one's occupation. There may be social isolation. A unique finding is apparent normal psychological functioning and appearance when not discussing the specific delusion.
Delusional disorder in the partner of an individual with the delusional disorder: This is also known as a shared psychotic disorder.
General description: Patients usually well-nourished, appropriately groomed. May seem odd, suspicious, can be litigious. Patients seek an ally in the clinician, but it is important not to accept the delusion as it eventually results in confusing the patient’s reality and leads to distrust.
Mood: Mood is usually congruent with the delusion, for example, a grandiose patient may be euphoric, or a paranoid patient may be anxious. Mild depressive symptoms are present.
Perceptions: Usually no abnormal perceptions are present. Auditory hallucinations may be present in some.
Thought: This is the primary abnormality in delusional disorder. The delusions are not bizarre and are clear as well as systematic for example a cheating spouse, persecutory delusions. It is essential to check the patient's belief before concluding it to be a delusion. Some patients are verbose and circumstantial when describing their delusion. Bizarre delusions more likely correlate with schizophrenia.
Cognition: Memory and cognition are usually intact, and patients are oriented unless there is a specific delusion about person, place or time.
Impulse control: It is important to evaluate for suicidal or homicidal ideations and plan. If there is a history of aggression with adverse action, then hospitalization should be considered.
Insight and judgment: Most commonly patients have no insight regarding their delusion. Judgment is assessable by a history of past behavior and future plan.
Although there is no set of labs required for delusional disorder like most other psychiatric disorders. Imaging or laboratory tests should be considered to rule out any organic causes. Substance-induced conditions should be ruled out by getting a urine drug screen. After an organic cause is ruled out a clinical exam should be completed. A clinician would do an assessment and ask further questions about their delusions. During the assessment a complete mental status exam should be done. Interviewing family members and friends should be considered because they can provide further details about the delusions and more importantly a time line of the presenting symptoms.
The treatment of the delusional disorder is difficult considering the lack of insight. A good doctor-patient relationship is key to treatment success. Treatment includes psychotherapy by establishing trust and building a therapeutic alliance.
Patient's history of medication compliance is the best guide to select appropriate antipsychotic medication. An antipsychotic should be started for a trial period of 6 weeks after which there is an evaluation of the effectiveness of the medication. Start a low dose and titrate up as needed. Another drug from another class can be tried after six weeks if no benefit is noted from initial treatment.
Though not a primary indication drugs like lithium, valproic acid and carbamazepine can be considered as adjunct treatment if monotherapy with antipsychotics fails.
Treatment response is better when combining psychotherapy with psychopharmacology.
The prognosis of delusional disorder is better with treatment and medication compliance. Almost 50% of patients have a full recovery; more than 20% of patients report a decrease in symptoms and less than 20% of patients report minimal to no change in symptoms. A good prognosis is also related to higher social and occupational functioning, early onset before age 30 years, female, sudden onset of symptoms and short duration.
Patients with a delusional disorder may first have their first encounter with the nurse practitioner or primary care physician. It is important to refer these patients to a mental health counselor or a psychiatrist because the management is complex. Many of these patients lack insight into their disorder and consequently refuse treatment. Despite treatment, relapses are frequent. The biggest obstacle to treatment is in treatment compliance. A mental health nurse should follow up on these patients because many eventually run into legal and work-related problems. An interprofessional team approach will ultimately result in the best patient outcomes. [Level V]
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