of 19. Of the initial sample of 384 participants, 18 (4.7%) were excluded because of severe handicaps (IQ<70 or neurological disorder), 39 (10.2%) were dropouts, 35 (9.1%) refused to participate in blood sampling and 24 (6.3%) had incomplete data. Accordingly, the current investigation included 268 young adults (126 males, 142 females) for whom data on PER2 genotype, stressful life events and alcohol use at age 19 were available. Among these were 131 current regular alcohol users (80 males, 51 females), defined as drinking at least once per week. Loss of subjects was not selective with regard to obstetric or psychosocial risks.
