For many decades, delusional disorder (DD) has been considered a treatment-resistant disorder, with antipsychotics acknowledged as the best, though imperfect, treatment. It is possible that the discovery of the right drug could turn treatment resistance into treatment response. The goal of this narrative review is to provide a historical perspective of the treatment of DD since the introduction of antipsychotics 70 years ago. The following search terms were used to scan the literature: antipsychotics AND "delusional disorder". Findings were that therapy for DD symptoms has changed over time. Initial reports suggested that the drug of choice was the antipsychotic pimozide, and that this drug was especially effective for the somatic subtype of DD. Subsequent studies demonstrated that other antipsychotics, for instance, risperidone and olanzapine, were also highly effective. Treatment response may vary according to the presence or absence of specific symptoms, such as cognitive defect and depression. Clozapine, partial D2 agonists, and long-acting injectable drugs may be more effective than other drugs, but the evidence is not yet in. Because of the absence of robust evidence, treatment guidelines for the optimal management of DD are not yet available.
Keywords: optimizing treatment; partial D2 agonists; pimozide; schizophrenia spectrum.