Original articleDopamine supersensitivity psychosis and delay of clozapine treatment in patients with treatment-resistant schizophreniaMasumo, Yutoa,b; Kanahara, Nobuhisac,d; Kogure, Masanobua; Yamasaki, Fumiakia; Nakata, Yusukea; Iyo, Masaomia Author Information aDepartment of Psychiatry, Chiba University Graduate School of Medicine, Chiba bDepartment of Psychiatry, Naoki-kai Isogaya Hospital, Ichihara cDivision of Medical Treatment and Rehabilitation, Center for Forensic Mental Health, Chiba University, Chiba dShirayuri-kai Ichihara Tsuruoka Hospital, Ichihara, Japan Received 11 June 2022 Accepted 21 September 2022 Correspondence to Nobuhisa Kanahara, MD, PhD, Division of Medical Treatment and Rehabilitation, Chiba University Center for Forensic Mental Health, 1-8-1 Inohana, Chuou-ku, Chiba-shi, Chiba 260-8670, Japan, Tel: +81 43 226 2148; fax: +81 43 226 2150; e-mail: [email protected] International Clinical Psychopharmacology: November 11, 2022 - Volume - Issue - 10.1097/YIC.0000000000000442 doi: 10.1097/YIC.0000000000000442 Buy PAP Metrics Abstract Both the underutilization of clozapine and treatment resistance of patients to clozapine are serious problems worldwide. Identifying clinical markers predicting response to clozapine would help clinicians more effectively utilize clozapine treatment. The present study retrospectively assessed dopamine supersensitivity psychosis (DSP) in addition to other measures such as age at disease onset and delay of clozapine introduction for a total of 47 treatment-resistant schizophrenia (TRS) patients. The response to clozapine was judged with CGI-C at 1 and 2 years from clozapine introduction. Results revealed that the DSP group tended to have a longer delay between designation of TRS and introduction of clozapine and continued to have slightly more severe psychopathology after treatment with clozapine, showing only slight improvement. The logistic regression analysis showed that the age at disease onset was the only significant indicator, predicting responsiveness to clozapine: patients with an onset age <20 years had a significantly better response to clozapine than patients with an onset age ≥20 years. The present study suggests that DSP might be related to a longer delay in clozapine introduction and the persistence of refractory symptoms despite clozapine treatment, whereas early age of disease onset might be related to a better response to clozapine. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.