significant differences in initial response to alcohol between them, we combined social and heavy drinkers and performed subsequent analyses. Exclusion criteria included apparent medical history of renal, hepatic, cardiovascular, pulmonary, or gastrointestinal disease; a personal history of any DSM-IV (American Psychiatric Association, 1994) axis I disorder, including alcohol-related disorders; homozygous for inactive aldehyde dehydrogenase 2 (ALDH2) allele (ALDH2*2/*2) because of the possibility of acute intoxication caused by ALDH deficiency. The Ethics Committee of the National Hospital Organization Kurihama Alcoholism Center approved the protocol, and all subjects gave written informed consent before participation.
