Niacin skin flushing in schizophrenic and depressed patients and healthy controls

This study compares the skin reactions to the niacin flushing test of 16 schizophrenic patients with those of 17, depressed patients and 16 healthy controls. Methyl nicotinate (niacin) in a concentration of 0.1 M was applied to the forearm for 5 min. Significant differences could be observed between the group of schizophrenic patients (less flushing) in comparison to the other groups. There were no statistical differences in niacin flushing between patients with depression and healthy controls. Gender, age and the use of antipsychotic agents did not appear to be confounders. The differences in flushing within the group of schizophrenic patients were striking, however. Most patients showed little or no flushing, but some patients reacted strongly. Although the three groups could be differentiated by the niacin flushing test, to develop a reliable clinical application of this test, further research is necessary. (c) 2005 Elsevier Ireland Ltd. All rights reserved.