Newswise — Chronic misuse of alcohol can cause damage to the structure and function of the brain, and this in turn can impair decision-making and further exacerbate problem drinking. The cerebral cortex – a folded layer of cells that forms the outer layer of the brain ─is of particular interest, as this is where a majority of information processing takes place. Neuroimaging studies have revealed that greater alcohol intake is associated with a thinner cortex. However, when comparing the thickness of different regions of the cortex, findings have differed across studies ─possibly because of modest sample sizes, and because many studies did not account for potential differences between males and females. Researchers from the McMaster University’s Peter Boris Centre for Addictions Research in Ontario, Canada and the University of Georgia, USA have now published new findings in the journal Alcoholism: Clinical & Experimental Researchon the association between the thickness of different regions of the cortex and alcohol use in a large group of young men and women.

The new analysis was based on data from over 700 young drinkers aged 22 to 37 years who had undergone magnetic resonance imaging (MRI scanning) as part of the Human Connectome Project. This project is systematically mapping the structure and function of the human brain, and provided a unique data resource for this research. Overall, 45% of participants in this analysis reported drinking heavily (5+ drinks per occasion) at least monthly, with men drinking more than women. Consistent with previous studies, the researchers found that reduced thickness in several regions of the cortex was associated with heavier drinking. Thickness of one region ─the left dorsolateral prefrontal cortex (DLPFC) ─ was found to be uniquely associated with both greater weekly alcohol intake and more frequent heavy drinking episodes. Importantly, this and other frontal regions of the brain are involved in cognitive control and decision making, including decisions and planning around drinking. The association of drinking quantity with thickness was also found to be largely limited to men.

These findings from a young and broadly typical sample of drinkers enhance researchers’ understanding of alcohol use and neuroanatomy, and provide further evidence for the importance of frontal regions of the brain in drinking behavior. Because the study was conducted at a single point in time,  it was not possible to establish whether excess alcohol use was a cause or a consequence of a thinner cerebral cortex. However, because this was a younger group of adults without an extensive history of alcohol misuse, the researchers think it more likely that low cortical thickness may serve as a risk factor for alcohol misuse, perhaps through impaired cognitive control. This now needs to be tested in future studies, where young drinkers are followed up with repeated MRI scans over a period of time in an effort to disentangle cause from effect.  


Associations between drinking and cortical thickness in younger adult drinkers: Findings from the Human Connectome Project