Intelligence, alcohol consumption, and adverse consequences. A study of young Norwegian men

IQ in high school as a predictor of midlife alcohol drinking patterns

AIMS

The aim of the present study was to assess the relationship between adolescent IQ and midlife alcohol use and to explore possible mediators of this relationship.

METHODS

Study data were from 6300 men and women who participated in the Wisconsin Longitudinal Study of high-school students graduating in 1957. IQ scores were collected during the participants' junior year of high school. In 2004, participants reported the number of alcoholic beverages consumed (past 30 days) and the number of binge-drinking episodes. A multinomial logistic regression was conducted to determine the relationship between adolescent IQ and future drinking pattern (abstainer, moderate drinker, or heavy drinker), and Poisson regression was used to examine the number of binge-drinking episodes. Two mediators-income and education-were also explored.

RESULTS

Every one-point increase in IQ score was associated with a 1.6% increase in the likelihood of reporting moderate or heavy drinking as compared to abstinence. Those with higher IQ scores also had significantly fewer binge-drinking episodes. Household income, but not education, partially mediated the relationship between IQ and drinking pattern.

CONCLUSIONS

The present study suggests that higher adolescent IQ may predict a higher likelihood of moderate or heavy drinking in midlife, but fewer binge-drinking episodes. The study also suggests that this relationship is mediated by other psychosocial factors, specifically income, prompting future exploration of mediators in subsequent studies.

The moderation of the genetic risk for alcohol and drug use disorders in a Swedish national sample by the genetic aptitude for educational attainment

BACKGROUND

Does the genetic aptitude for educational attainment (GAEA) moderate the genetic risk for alcohol use disorder (AUD) and drug use disorder (DUD)?

METHODS

In the native Swedish population, born 1960-1980 and followed through 2017 (n = 1 862 435), the family genetic risk score (FGRS) for AUD and DUD and GAEA were calculated from, respectively, the educational attainment and risk for AUD and DUD, of 1st through 5th degree relatives from Swedish national registers. Analyses utilized Aalen's linear hazards models.

RESULTS

Risk for AUD was robustly predicted by the main effects of FGRSAUD [b = 6.32 (95% CI 6.21-6.43), z = 64.9, p < 0.001) and GAEA [b = -2.90 (2.83-2.97), z = 44.1, p < 0.001] and their interaction [b = -1.93 (1.83-2.03), z = 32.9, p < 0.001]. Results were similar for the prediction of DUD by the main effects of FGRSDUD [b = 4.65 (CI 4.56-4.74), z = 59.4, p < 0.001] and GAEA [-2.08 (2.03-2.13), z = 46.4, p < 0.001] and their interaction [b = -1.58 (1.50-1.66)), z = 30.2, p < 0.001]. The magnitude of the interactions between GAEA and FGRSAUD and FGRSDUD in the prediction of, respectively, AUD and DUD was attenuated only slightly by the addition of educational attainment to the model.

CONCLUSIONS AND RELEVANCE

The genetic propensity to high educational attainment robustly moderates the genetic risk for both AUD and DUD such that the impact of the genetic liability to AUD and DUD on the risk of illness is substantially attenuated in those with high v. low GAEA. This effect is not appreciably mediated by the actual level of educational attainment. These naturalistic findings could form the basis of prevention efforts in high-risk youth.