Definition and Diagnosis
Delusional disorder is characterized by the presence of one or more delusions persisting for at least a month, in the absence of the broader symptom picture of schizophrenia, with functioning outside the direct impact of the delusion often relatively well preserved.
Epidemiology
Delusional disorder is uncommon, with an estimated lifetime prevalence of around 0.2%, and onset is typically in middle to late adulthood, somewhat later than schizophrenia.
Risk Factors
Risk factors include social isolation, sensory impairment (particularly hearing loss), family history of psychotic disorders, and certain personality traits such as suspiciousness.
Symptoms and Subtypes
The central feature is one or more non-bizarre or bizarre delusions (such as persecutory, jealous, erotomanic, grandiose, or somatic types), typically without prominent hallucinations, disorganized speech, or marked negative symptoms.
Diagnosis
DSM-5-TR requires the presence of one or more delusions for a month or longer, criterion A for schizophrenia never having been met (apart from possible related hallucinations), and functioning not markedly impaired outside the impact of the delusion itself.
Treatment
Treatment can be challenging due to limited insight; antipsychotic medication may reduce symptom intensity, and building a strong therapeutic alliance along with supportive psychotherapy is important for engagement and management.
Prognosis
Course is often chronic, though some individuals experience periods of remission; overall functioning tends to be better preserved than in schizophrenia given the more circumscribed nature of the symptoms.
Reference
Sadock, B. J., Sadock, V. A., & Ruiz, P. Kaplan & Sadock's Synopsis of Psychiatry (11th ed.).