Long-Term Treatment With Long-Acting Injectable Antipsychotic in Schizophrenia Patients With and Without Dopamine Supersensitivity Psychosis A 6-Year Retrospective Comparative Study

Background Dopamine supersensitivity psychosis (DSP) is an unstable psychotic state in patients with schizophrenia due to an upregulation of dopamine D2 receptors induced by antipsychotic medication. Long-acting antipsychotic injectable (LAI) could be advantageous for controlling the dopamine supersensitivity state, but it is not known if long-term treatment with LAI might ultimately lead to development or exacerbation of DSP. Methods The present study included 58 patients who had been treated with LAI for at least 3 years, with medical records for the 3 years before its introduction. Those records were used to classify patients as having DSP (n = 30, DSP group) or not (n = 28, non-DSP group). The effects of LAI treatments on the clinical course during the 3 years after the LAI introduction were compared between the 2 groups. Results Both groups demonstrated significant decreases in antipsychotic dosage (combined LAI and oral antipsychotics) and a significant improvement measured by clinical global impression-improvement. These indicators did not differ between them, suggesting similar efficacy of LAI for both groups. On average, the DSP group was treated with a higher dose of antipsychotics (1004.8 mg) before the LAI introduction compared with the non-DSP group but reduced them to within the standard dose range (662.0 mg) after the introduction of LAI. Conclusions Our results indicated the effectiveness of LAI treatment for at least 3 years for patients with DSP, suggesting that this treatment strategy is unlikely to worsen DSP. The efficacy might be explained by the large decrease in the total antipsychotic dose with the introduction of LAI.