THE NIACIN CHALLENGE TEST - CLINICAL MANIFESTATION OF ALTERED TRANSMEMBRANE SIGNAL-TRANSDUCTION IN SCHIZOPHRENIA

Several lines of evidence implicate altered phospholipid-dependent sig nal transduction (PDST) in the pathophysiology of schizophrenia, Niaci n induces vasodilation through mechanisms requiring intact PDST. Thus, an altered response to a challenge dose of niacin may reflect disturb ances in these signalling processes in this disorder. In the present s tudy, niacin-induced vasodilation was estimated quantitatively in schi zophrenic and comparison bipolar affective disorder and healthy subjec ts using thermocouple sensors to measure the change in skin temperatur e relative to core body and ambient room temperature. Twelve (42.9%) o f 28 schizophrenic subjects did not vasodilate in response to a 200-mg niacin challenge dose, whereas only 1 of 18 (6%) bipolar disorder sub jects and none of 28 controls showed impaired response (Fisher's Exact Test, p < .0001), These findings support the notion that the schizoph renic syndromes are biochemically heterogeneous and suggest the existe nce of a subgroup of schizophrenic subjects in whom phospholipid-depen dent signalling responses may be impaired, (C) 1997 Society of Biologi cal Psychiatry.