DETERMINANTS OF P3 AMPLITUDE AND RESPONSE TO ALCOHOL IN NATIVE-AMERICAN MISSION INDIANS

Native Americans have some of the highest rates of alcohol abuse and d ependence, yet potential biological risk factors associated with probl em drinking seen in some tribes remain relatively unknown. The amplitu de of the P3 component relatively unknown. The amplitude of the P3 com ponent of the event-related potential (ERP) is perhaps the most studie d electrophysiological ''marker'' of potential vulnerability to alcoho l dependence, yet it has not been investigated in Native Americans. Fo rty-seven, non-alcohol-dependent Native American Mission Indian men be tween the ages of 18 and 25 years participated in the study. ERPs were collected at 60 minutes following both alcohol (0.56 g/kg) and placeb o intake. No relationship was found between P3 amplitude and degree of Native-American heritage (NAH), or family history (FH) of alcohol dep endence. The results of this study did, however, replicate previous fi ndings that the P3 component of the ERP is sensitive to the effects of alcohol. A reduction in the P3a component across the scalp was found in these Native American men following alcohol when compared with plac ebo ingestion. P3 response to alcohol, although not influenced by a su bject's NAH or FH, was influenced by the presence of a polymorphism in the alcohol metabolizing enzyme alcohol dehydrogenase (ADH). Men with an ADH23 allele had significantly higher amplitude P3 components at placebo and also demonstrated more alcohol-induced reductions in P3 am plitude than men with ADH21 alleles only. In addition, individuals wi th low P3 amplitude in the placebo condition has less of a reduction o r an actual increase in P3a and P3b amplitudes following alcohol intak e. Given than a less intense response to alcohol has been associated w ith greater risk for the development of alcohol-related problems, thes e data suggest the presence of certain biological variables within thi s Native American population that may confer both risk and protection for the future development of alcohol dependence. (C) 1998 American Co llege of Neuropsychopharmacology. Published by Elsevier Science Inc.