Heavy alcohol consumption produces 'deleterious' effects on adolescents' white matter

Heavy alcohol consumption during adolescence appeared associated with deleterious effects on white matter microstructural integrity, according to results of a case-control study published in JAMA Psychiatry.

“Widespread [fractional anisotropy] alteration has been observed in adolescents who initiated binge drinking,” Qingyu Zhao, PhD, of the department of psychiatry & behavioral sciences at Stanford University School of Medicine, and colleagues wrote. “Affected fiber systems include the corpus callosum, superior longitudinal fasciculus, internal and external capsule, brainstem, and cortical projection fibers. Disruption of these systems may degrade neural signal transmission and the capacity for certain cognitive functions, resulting in enhanced impulsivity, poor inhibitory control and restricted working memory capacity.”

The researchers aimed to pinpoint disrupted adolescent microstructural brain development associated with drinking onset, as well as to evaluate whether younger adolescents have a more pronounced disruption vs. older adolescents. They analyzed data of 451 participants aged 12 to 21 years at baseline who were included in the National Consortium on Alcohol and Neurodevelopment in Adolescence cohort. Participants had two or more usable magnetic resonance diffusion tensor imaging scans and up to five examination visits across 4 years. Those with a youth-adjusted Cahalan score of zero were considered no-to-low drinkers, and those with a score greater than one for two or more consecutive visits as heavy drinkers. The researchers conducted an exploratory analysis between no-to-low and heavy drinkers, as well as a between-group analysis between age- and sex-matched youths and a within-participant analysis before and after drinking. Self-reported alcohol consumption in the past year summarized by categorical drinking levels served as the exposure. Main outcomes and measures included diffusion tensor imaging measurement of fractional anisotropy in the whole brain and fiber systems, which quantified each participant’s development change as a slope.

Results showed 291 (64.5%) no-to-low drinkers and 160 (35.5%) heavy drinkers indicated a potential for deleterious effects of alcohol on microstructural development. Of the no-to-low drinkers, 48.4% were boys with mean age of 16.5 years, 51.2% were girls with mean age of 16.5 years and 66% were white. Of heavy drinkers, 53.8% were boys with mean age of 20.1 years, 46.3% were girls with mean age of 20.5 years and 88.8% were white. Per group analysis results, the researchers noted a fractional anisotropy reduction in heavy-drinking youth vs. age- and sex-matched controls. This reduction’s slope correlated with log of days of drinking since the baseline visit. Drinking onset appeared associated with and potentially preceded white matter integrity disruptions, according to results of the within-participant analysis. Based on age-alcohol interactions observed for the fractional anisotropy, alcohol-associated disruption was greater among youth vs. older adolescents and was most pronounced in the genu and body of the corpus collosum, which are known to continue developing throughout adolescence.

“Taken together, our results bolster the emerging evidence for the period of early adolescence and its rapid neurodevelopment as a possible magnifier of vulnerability of the brain's [white matter] communication systems to the risks of heavy alcohol consumption,” Zhao and colleagues wrote.