Accuracy of Niacin Skin Flush Test for Diagnosing Schizophrenia

 This study aims to investigate niacin sensitivity in schizophrenia patients compared to healthy people and examine the accuracy of niacin skin flush test in diagnosing schizophrenia.

 This diagnostic study was conducted in 2018 in Zanjan, Iran. Three niacin concentrations (0.001 M, 0.01 M, and 0.1 M) was first applied topically to the skin of 36 schizophrenia patients and 33 healthy controls. Flush responses were evaluated at 10 and 15 min after application. Sensitivity, specificity, Positive Predictive Value (PPV), and Negative Predictive Value (NPV) of the test were measured for each niacin concentration and evaluation time. 

 At 10 min, the highest test accuracy was reported when 0.001 M niacin solution was used (Sensitivity=94%, specificity=50%, PPV= 51%, and NPV= 94%). At 15 min, the highest test accuracy was observed at 0.01 concentration (Sensitivity=52%, specificity=92%, PPV=79%, and NPV=77%).

 Flush responses to niacin is more impaired in patients with schizophrenia. Therefore, niacin can be considered as a biological marker of schizophrenia and can be used for its diagnosis.