Date Published: May 10, 2018
Publisher: Oxford University Press
Author(s): Liam Mahedy, Matt Field, Suzanne Gage, Gemma Hammerton, Jon Heron, Matt Hickman, Marcus R Munafò.
The study aimed to examine the association between adolescent alcohol use and working memory (WM) using a large population sample.
Data from the Avon Longitudinal Study of Parents and Children were used to investigate the association between alcohol use at age 15 years and WM 3 years later, assessed using the N-back task (N ~ 3300). A three-category ordinal variable captured mutually exclusive alcohol groupings ranging in order of severity (i.e. low alcohol users, frequent drinkers and frequent/binge drinkers). Differential dropout was accounted for using multiple imputation and inverse probability weighting. Adjustment was made for potential confounders.
There was evidence of an association between frequent/binge drinking (compared to the low alcohol group) and poorer performance on the 3-back task after adjusting for sociodemographic confounding variables, WM at age 11 years, and experience of a head injury/unconsciousness before age 11 years (β = −0.23, 95% CI = −0.37 to −0.09, P = 0.001). However, this association was attenuated (β = −0.12, 95% CI = −0.27 to 0.03, P = 0.11) when further adjusted for baseline measures of weekly cigarette tobacco and cannabis use. Weaker associations were found for the less demanding 2-back task. We found no evidence to suggest frequent drinking was associated with performance on either task.
We found weak evidence of an association between sustained heavy alcohol use in mid-adolescence and impaired WM 3 years later. Although we cannot fully rule out the possibility of reverse causation, several potential confounding variables were included to address the directionality of the relationship between WM and alcohol use problems.
Alcohol consumption during adolescence is a major public health concern, in particular because the brain is still developing and undergoing considerable structural and functional changes (De Bellis et al., 2000). One area of research that has received considerable attention is the association between alcohol use and working memory (WM) performance. WM is critical to higher order cognitive functioning, such as decision making and planning (Miller and Cohen, 2001) and deficits in WM make it more difficult to respond in a controlled and planned manner to alcohol stimuli (Grenard et al., 2008; Peeters et al., 2012). Furthermore, WM may be more susceptible to damage from heavy alcohol use during adolescence than in adulthood (De Bellis et al., 2000) as it is not fully developed until young adulthood (De Luca et al., 2003; Boelema et al., 2014).
In this study, we found weak evidence of a prospective association between alcohol use at age 15 years and impaired WM performance 3 years later in a general population birth cohort. This association was evident in adolescents who were frequent and binge drinkers for the more demanding 3-back version of the task (assessed using the d′) after adjusting for a number of sociodemographic confounding variables, measure of WM at age 11 years and participants who had a head injury/unconsciousness before age 11 years. However, this association was attenuated when controlling for measures of cigarette smoking and cannabis use. When examining specific indices of WM, false alarms showed the strongest association, suggesting that performance on the task was affected by poor accuracy in rejecting non-targets rather than poor accuracy in detecting targets. There was insufficient evidence for an association between moderate drinking practices (i.e. frequent drinking only) and WM performance 3 years later for either the 2- or 3-back versions.
Our findings contribute to the understanding of the relationship between alcohol use and WM in adolescents, and provide evidence that regular binge drinking in mid-adolescence is associated with impaired WM 3 years later, after adjusting for confounding variables. These findings have clinical and public health implications. For example, interventions aimed at preventing alcohol use in adolescents (Koning et al., 2009) might be effective in reducing impairments in WM. In particular, a combined parent and student intervention was the most effective in reducing the onset of weekly alcohol use and frequency of drinking. One advantage is that interventions can yield beneficial effects on alcohol-related outcomes for adolescents even when delivered at young ages (Tanner-Smith and Lipsey, 2015). Although it is difficult to quantify the meaning of the deficit in WM in practical terms, deficits in WM have been shown to be related to academic achievement (Gathercole et al., 2004), and impulsivity and risk-taking behaviours (Khurana et al., 2013; Khurana et al., 2015) in adolescents. Given the impact that cigarette and cannabis use had on the association between alcohol use and WM, it may be important to include these in future studies. Future research should explore possible mechanisms underlying this association and examine whether these associations persist into adulthood.