Origins and consequences of age at first drink. 1. Associations with substance-use disorders, disinhibitory behavior and psychopathology, and P3 amplitude

Background: Although an early age at first drink has been repeatedly associ ated with substantially elevated rates of alcoholism, the mechanisms underl ying this association remain unclear. We investigated whether the associati on of age at first drink (AFD) with alcoholism was more consistent with the hypothesis that the former causes the latter or the hypothesis that both a re manifestations of some common vulnerability. Methods. We investigated whether substance use and mental health disorders, education, IQ, and personality were associated with AFD in a sample of 267 0 adults; whether P3 amplitude was associated with AFD in a sample of 1127 17 year olds; and whether indicators of disinhibitory psychopathology asses sed at age I I predicted AFD by age 14 in a sample of 1343 adolescents. Results: In adults, AFD was associated not only with alcohol dependence, bu t also with a broad array of indicators of disinhibitory behavior and psych opathology including nicotine dependence, illicit drug abuse and dependence , conduct disorder, antisocial personality disorder, underachievement in sc hool, and the personality trait of constraint. In 17 year olds, AFD was als o associated with reduced P3 amplitude, a well-documented psychophysiologic al marker of alcoholism risk. Finally, in the early-adolescence sample, mea sures of behavioral disinhibition, including oppositionality, hyperactivity /impulsivity, and inattentiveness assessed at age 11 predicted drinking ons et by age 14. Conclusions: Our findings indicated that AFD is not specifically associated with alcoholism but rather is correlated with a broad range of indicators of disinhibited behavior and psychopathology. Moreover, individuals who fir st drink at a relatively early age manifest elevated rates of disinhibitory behavior and psychopathology before they first try alcohol. Taken together , these findings suggest that the association of AFD with alcoholism reflec ts, at least in part, a common underlying vulnerability to disinhibitory be havior. Whether an early AFD directly influences risk of adult alcoholism r emains unclear.