In order to ensure the GPS were predictive of alcohol problems above and beyond levels of consumption, which are genetically correlated but distinct phenotypes [53], we estimated the effect of GPS while accounting for either drinking or intoxication frequency. GPS were significantly related to AD symptoms after statistically controlling for drinking frequency (b = 0.085, P < 0.01) or intoxication frequency (b = 0.075, P < 0.01; see Supporting information, Table S2). Finally, we estimated the polyserial correlation between GPS and relationship status (ρ = 0.005, P > 0.05) to assess the possibility of gene–environment correlation.
