The study population consisted of 110 Japanese subjects (53 men, 48.2%) and was recruited from Yokosuka, Kanagawa, Japan. Subjects were aged 20 to 59 (mean age ± SD, 36.7 ± 10.5 years). All were healthy without apparent history of physical and psychiatric illness, determined by questionnaires about health status and past medical history. A questionnaire was used to quantify the subjects’ alcohol use and to evaluate the family history of alcohol-related problems. Most of them were social drinkers but included small percentage of heavy drinkers who drink more than 4 drinks on any day or 14 per week in men (3 drinks on any day or 7 per week in women) as shown in Table 1. We compared initial response, which will be defined in the following, to alcohol between social and heavy drinkers. Because we did not find any 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
