Associations between IQ and alcohol consumption in a population of young males: a large database analysis.

Purpose: This study aimed at exploring the relationship between intelligence quotient (IQ) and alcohol consumption in a large sample of young males. This study explored whether IQ influences alcohol drinking and which pathways might be involved. We further hypothesized that IQ differences between lifetime abstainers and former drinkers exist, and that they primarily result from different group characteristics.

Method: Within a psychiatric-epidemiological survey using a cross-sectional design IQ-tests were administered to approximately 50,000 Swiss conscripts at age of about 20 years. The sample was divided into four alcohol consumption categories (rare, occasional, moderate and daily drinking) and two non-drinker categories (former drinking and lifetime abstinence). Probabilities for different levels of consumption or former drinking against lifetime abstention in relation to IQ were estimated using multinomial logistic regression. Models were adjusted for education, disability pension, tobacco/cannabis use, migration, parental alcohol disorders, and mental health.

Results: After adjusting for confounders full-scale IQ displayed positive associations with being a rare (OR 1.13; CI 95 % 1.07-1.19), occasional (OR 1.41; CI 95 % 1.33-1.48), and moderate drinker (OR 1.53; CI 95 % 1.45-1.62), and negative associations with being a former drinker (OR 0.85; CI 95 % 0.79-0.93). Daily drinking was positively associated only with the performance subscale IQ (OR 1.12; CI 95 % 1.02-1.22). Confounders contributed significantly to the IQ-alcohol association and, therefore, highlight the distinction of non-drinkers into lifetime abstainers and former drinkers.

Conclusions: Our data confirmed the positive link between IQ and moderate drinking. Lower IQ in non-drinkers, however, seems to be related to earlier consumption and the presence of other risk factors.