to support the notion that the nicotine SNP score increase risk for alcohol use. One might conjecture that it represents a trend for early adults to specialize in their drug use habits and use available resources (e.g., money, time) for drugs of choice at the expense of other substances. However, in an analysis of the SNP score’s relationship with alcohol use frequency in the subsample of current smokers, there was no significant effect at age 24 (regression coefficient = −0.018, Χ2 = 1.3, df = 1, p = 0.25), suggesting that the effect in general may well be spurious.
