A similar pattern of cross-sectional findings for those observed for alcohol QF emerged for heavy drinking. At age 18, cross-sectional analyses suggested that Class 3 displayed significantly higher levels of heavy drinking compared to Class 1 (p < 0.01) and Class 2 (p < 0.05) but was not significantly different from Class 4 or Class 5. At age 25, Class 3 was significantly lower in heavy drinking compared to Class 4 (p < 0.01) but not Classes 1, 2, or 5 (see Fig. 2).
