Regarding the heavy drinking composite, a significant time by impulsivity trajectory group interaction was found, F(12, 476) = 1.78, p < 0.05. As with the alcohol QF findings, follow-up contrasts suggested that compared to all other impulsivity classes, Class 3 exhibited the steepest decreases in heavy drinking from ages 18 to 25 [F(1, 476) = 8.92, p < 0.01; see Fig. 2]. Additional contrasts suggested that Class 3, versus Class 4, displayed significantly steeper decreases in heavy drinking from ages 18 to 25 [F(1, 476) = 4.33, p < 0.05; see Fig. 2].
