Age at First Drink Relates to Behavioral Measures of Impulsivity: The Immediate and Delayed Memory Tasks

Background: This study examined the relationship between laboratory-measured impulsivity and age at first drink. Methods: Using a laboratory behavioral measure of impulsivity [Immediate (IMT) and Delayed Memory Tasks (DMT)], we compared two groups of women differing in their self-reported age at first drink (early-onset drinking, age <18 years, n = 40; late-onset drinking, age ≥21 years, n = 23). It was expected that those who first consumed alcohol before the legal drinking age (i.e., early onset) would perform in a more impulsive manner on the laboratory behavioral measure than the late-onset drinkers. Results: The main finding was that the early-onset group (IMT: mean, 28.7%; DMT: mean, 30.4%) had increased commission error rates compared with the late-onset group (IMT: mean, 21.2%; DMT: mean, 15.5%) during both the IMT [ANOVA: F(1,61) = 4.30; p = 0.042; f = 0.27] and DMT [F(1,61) = 10.76; p = 0.002; f = 0.42]. Age at first drink was significantly correlated with DMT commission errors (r = -0.23; p = 0.037), although this was only at the trend level for IMT commission errors (r = -0.20; p = 0.062); these correlations are likely to be underestimates because of range restriction of the age variable. Conclusions: These results demonstrate that differences in impulsive behavioral responding are distinguishable even between groups of alcohol drinkers who are not experiencing clinically significant problems with alcohol.