Intelligence, alcohol consumption, and adverse consequences in young Norwegian men: Intelligence was not associated with intoxication frequency at any age

Intelligence, alcohol consumption, and adverse consequences. A study of young Norwegian men. Adrian F. Rogne, Willy Pedersen, Tilmann Von Soest. Scandinavian Journal of Public Health, September 11, 2020.  https://doi.org/10.1177/1403494820944719

Rolf Degen's take: https://twitter.com/DegenRolf/status/1305755292236484609

Abstract
Aims: Research suggests that intelligence is positively related to alcohol consumption. However, some studies of people born around 1950, particularly from Sweden, have reported that higher intelligence is associated with lower consumption and fewer alcohol-related problems. We investigated the relationships between intelligence, alcohol consumption, and adverse consequences of drinking in young men from Norway (a neighboring Scandinavian country) born in the late 1970s.

Methods: This analysis was based on the population-based Young in Norway Longitudinal Study. Our sample included young men who had been followed from their mid-teens until their late 20s (n = 1126). Measures included self-reported alcohol consumption/intoxication, alcohol use disorders (AUDIT), and a scale measuring adverse consequences of drinking. Controls included family background, parental bonding, and parents’ and peers’ drinking. Intelligence test scores—scaled in 9 “stanines” (population mean of 5 and standard deviation of 2)—were taken from conscription assessment.

Results: Men with higher intelligence scores reported average drinking frequency and slightly fewer adverse consequences in their early 20s. In their late 20s, they reported more frequent drinking than men with lower intelligence scores (0.30 more occasions per week, per stanine, age adjusted; 95% CI: 0.12 to 0. 49). Intelligence was not associated with intoxication frequency at any age and did not moderate the relationships between drinking frequency and adverse consequences.

Conclusions: Our results suggest that the relationship between intelligence and drinking frequency is age dependent. Discrepancies with earlier findings from Sweden may be driven by changes in drinking patterns.

Keywords: Intelligence, alcohol, intoxication, Norway, consequences, young adults

Discussion and conclusions

In our sample of Norwegian men born in the 1970s, there was no association between intelligence and frequency of alcohol use when participants were in their early 20s. In their late 20s, we observed a positive association. However, we found no significant link between intelligence and intoxication frequency. Our findings are not consistent with findings from neighboring Sweden, which were based on cohorts born in the 1950s. Rather, our findings resemble those from other recent studies showing a positive association between intelligence and alcohol use, but this association is age-dependent and not very strong. One possible explanation may be that alcohol use in Norway changed considerably in the 1990s and early 2000s, when the so-called weekend binge drinking culture was supplemented by more frequent alcohol consumption. If intelligence is more positively associated with alcohol consumption in cultures with more frequent but less intensive drinking, such changes may have led to an emerging positive (or less negative) association between intelligence and drinking frequency. However, to disentangle these relationships, more research into changes in drinking patterns over time in relation to intelligence is necessary.

The positive association between intelligence and drinking frequency in the late 20s, when most men have entered the labor market, is also consistent with the notion that selection into longer educational programs or high-status jobs may be relevant to this association. Our findings also indicated a small, negative association between intelligence and alcohol related problems at around 22 years of age. While one possible interpretation of this finding is that high intelligence may protect against adverse consequences from drinking, additional analyses (not shown) indicate that the negative association is driven solely by higher adverse consequences scores in the two lowest stanines. Finally, our results do not support the notion that intelligence moderates the relationship between drinking frequency and adverse consequences of drinking.

Our study has several limitations. We cannot rule out the importance of selective attrition, measurement error, and similar survey-related issues. If people with greater cognitive abilities are more reflexive of, and concerned with, potentially adverse consequences of their drinking, they may be more likely to report alcohol use and related problems accurately in surveys [6], which may result in systematic measurement error. The group of nondrinkers may be highly diverse, possibly including both former heavy drinkers and lifetime abstainers [15]. Several of the included control variables in models 3 and 4 may also be affected by intelligence, drinking habits, or adverse consequences, and controlling for these may have introduced overcontrol bias. Our results may also be affected by reverse causation, since heavy alcohol consumption in adolescence may adversely affect cognitive ability [32]. Moreover, our data did not enable us to study women.

In conclusion, studying young Norwegian men born in the 1970s, our findings suggest that the association between intelligence and alcohol consumption is only positive when they are in their late 20s, not when they are in their early 20s. In other words, the association appears to be age dependent. This finding also contrasts with Swedish findings from older cohorts, suggesting that the relationship may also be context-dependent. Our results also suggest that intelligence does not moderate the relationship between frequent drinking and adverse consequences.