What is the recommended management—including assessment, first‑line low‑dose atypical antipsychotic dosing and cognitive‑behavioral therapy—for an adult patient with delusional disorder who has no significant medical contraindications?

Management of Delusional Disorder

Start with a low-dose atypical antipsychotic as first-line pharmacotherapy, specifically risperidone 0.5-2 mg/day or aripiprazole 5-10 mg/day, combined with cognitive-behavioral therapy targeting insight and coping strategies, while recognizing that approximately 50% of patients will show meaningful improvement with this approach. 1, 2, 3

Initial Assessment

Diagnostic Confirmation

• Verify the presence of one or more non-bizarre delusions lasting at least 1 month (experiences that could conceivably occur in real life, such as being followed, having a disease, being loved at a distance, having an unfaithful partner, or possessing inflated worth). 4
• Confirm that functioning impairment is consistent with the delusion itself rather than global deterioration. 4
• Exclude schizophrenia (absence of prominent hallucinations, disorganized speech, or negative symptoms), mood disorder with psychotic features, substance-induced psychosis, and medical causes (thyroid disease, neurological conditions, medication toxicity). 4
• Document the specific subtype: persecutory, somatic, erotomanic, jealous, or grandiose, as this may influence treatment selection. 4, 1

Comorbidity Screening

• Screen for comorbid depression, which occurs frequently in delusional disorder and may require concurrent treatment with antidepressants. 3
• Assess for cognitive deficits, as their presence may predict differential treatment response. 1

First-Line Pharmacotherapy

Atypical Antipsychotic Selection and Dosing

Risperidone is a well-established first-line option:

• Start at 0.5 mg orally once daily (typically at bedtime). 5
• Titrate to 1-2 mg/day based on response and tolerability. 5, 1
• Maximum effective dose is typically 2-4 mg/day; doses above 6 mg/day increase extrapyramidal side effect risk substantially. 5
• Available as oral disintegrating tablet for patients with adherence concerns. 5
• Reduce dose in older patients and those with severe renal or hepatic impairment. 5

Aripiprazole is an excellent alternative with superior tolerability:

• Start at 5 mg orally once daily. 5, 2
• Average effective dose is 10-15 mg/day (range 5-15 mg). 2
• Clinical response typically occurs within 5-7 weeks. 2
• Particularly well-tolerated with lower risk of metabolic side effects and extrapyramidal symptoms compared to other antipsychotics. 2
• May cause headache, agitation, anxiety, or insomnia initially. 5

Olanzapine as a third option:

• Start at 2.5-5 mg orally at bedtime. 5, 1
• Titrate to 5-10 mg/day based on response. 5
• More sedating than risperidone or aripiprazole, which can be advantageous for agitated patients. 5
• Higher risk of metabolic effects (weight gain, diabetes, dyslipidemia) with long-term use. 5
• Available as oral disintegrating tablet. 5

Treatment Duration and Monitoring

• Continue antipsychotic treatment for at least 8-12 weeks before declaring treatment failure, as response may be gradual. 2, 3
• Approximately 50% of patients will show positive response to antipsychotic medication regardless of which agent is used. 3
• Monitor for extrapyramidal side effects, metabolic changes, and QTc prolongation at baseline and periodically. 5
• Use medications at the lowest effective dose for the shortest time necessary to control symptoms. 5

Cognitive-Behavioral Therapy

CBT Components for Delusional Disorder

• Implement CBT targeting insight development, reality testing, and coping strategies for managing delusional beliefs. 4
• Focus on functional impairment and quality of life rather than directly challenging the delusion initially. 4
• Address comorbid depression and anxiety through standard CBT techniques. 3
• Work on medication adherence, as patients typically lack awareness of the psychiatric nature of their condition. 4

Special Considerations

Treatment-Resistant Cases

• Consider switching to clozapine for truly treatment-resistant cases, though evidence is limited. 1, 3
• Long-acting injectable antipsychotics may improve adherence in patients with poor medication compliance. 1
• Partial D2 agonists (aripiprazole, brexpiprazole) may be more effective than full antagonists in some patients. 1

Somatic Subtype Considerations

• Historically, pimozide was considered the drug of choice for somatic-type delusional disorder, but modern atypical antipsychotics (risperidone, olanzapine, aripiprazole) are equally or more effective with better tolerability. 1, 2
• Patients with somatic delusions often present to dermatologists, internists, or surgeons rather than psychiatrists. 4

Common Pitfalls to Avoid

• Avoid using haloperidol or typical antipsychotics as first-line treatment, as atypical antipsychotics offer superior efficacy for negative symptoms, cognitive impairment, and mood symptoms, with lower risk of tardive dyskinesia and extrapyramidal side effects. 6
• Do not start with excessively high doses, as delusional disorder often responds to lower doses than schizophrenia (e.g., risperidone 0.5-2 mg/day vs. 4-6 mg/day for schizophrenia). 5, 1
• Do not declare treatment failure prematurely—allow at least 8-12 weeks at therapeutic doses before switching agents. 2, 3
• Do not overlook comorbid depression, which is common and may require concurrent antidepressant treatment. 3
• Do not ignore adherence issues—patients typically lack insight into their condition and may discontinue medication; consider long-acting injectables or oral disintegrating tablets. 4, 1