['Sensitivity to the skin flush effect of niacin is reduced in a portion of patients with schizophrenia. Though this peripheral physiological abnormality has been widely replicated, its relevance to neuropsychiatric manifestations of the illness has been unclear. The goal of this study was to determine if the niacin response abnormality in schizophrenia is associated with functional impairment.', "Following psychiatric assessment, a Global Assessment of Functioning (GAF) score was assigned to each of 40 volunteers with schizophrenia. For each subject, the blood flow responses to several concentrations of topical methylnicotinate were recorded. Blood flow was measured objectively, using laser Doppler flowmetry. From the dose-response data, EC(50) values were derived. GAF scores were assigned without knowledge of the participants' niacin response data.", 'There was a significant negative correlation between GAF scores and EC(50) values for methylnicotinate (Pearson r=-0.42; p=0.007).'] Is niacin subsensitivity associated with functional impairment in schizophrenia?