Replication of the abnormal niacin response in first episode psychosis measured using laser Doppler flowmeter.

Introduction: Impaired sensitivity of the skin flush response to niacin is found in approximately 30% of patients with schizophrenia. Although the niacin response abnormality (NRA) may serve as a useful endophenotype for schizophrenia, few studies have directly replicated NRA in patients with first‐episode psychosis (FEP). Methods: In total, 204 patients with FEP, 16 with psychotic mood disorder (PMD), and 68 healthy controls (HC) were included. The log10(EC50) values represent the concentration of methyl nicotinate required to elicit a half‐maximal blood flow (MBF) response, and the MBF value was calculated. The NRA was defined as having log10(EC50) molar value above the 90% and an MBF value below the 60% of those in the HC group. Results: In total, 13.7% of the FEP, 12.5% of the PMD, and 7.4% of the HC group met the definition of NRA. Significant differences were found in the log10(EC50) values between the FEP and HC groups (p =.014) and in the MBF between the FEP and PMD groups (p =.011). Patients with FEP and NRA had more severe negative symptoms than those with a normal niacin response. Discussion: These data represent the NRA in patients with FEP, defining a small subgroup of patients with early‐phase psychosis possessing a clinically significant phospholipid‐signaling defect. [ABSTRACT FROM AUTHOR]