Intelligence Moderates the Relationship Between Delay Discounting Rate and Problematic Alcohol Use

Individuals with problematic alcohol use discount larger delayed rewards at higher rates relative to smaller immediate rewards compared with healthy controls. Lower executive function ability, including lower general intelligence quotient (IQ), is associated with both high delay discounting rates and more lifetime alcohol-related problems. Although problematic alcohol use, delay discounting rates, and IQ are all significantly associated, we know little about the nature of their interrelationships. This study tests the hypothesis that IQ moderates the association between delay discounting rates and measures of problematic alcohol use. Lifetime alcohol-related problems, drinking levels over the past 2 weeks, IQ, and delay discounting were assessed in a sample of 617 young adults (303 female). Higher delay discounting rates were associated with more lifetime alcohol problems, more recent alcohol use, and lower IQ. However, analyses also revealed that IQ moderated the association between delay discounting rates and lifetime alcohol problems as well as high levels of recent alcohol use. Delay discounting rates were more strongly associated with both lifetime alcohol problems and higher levels of recent alcohol consumption for those with higher IQ compared with those with lower IQ. Results indicate that discounting rewards at higher rates may indicate an important risk factor for problematic alcohol use in individuals with high IQ, whereas this association may be blunted in individuals with low IQ because of their uniformly elevated discounting rates and higher problematic alcohol use.