Teens' Heavy Drinking May Lead to Changes in the Cerebellum

Binge drinking in adolescence and young adulthood appears to be associated with an altered cerebellum when individuals are in their 20s, a new MRI-based Finnish study reports.

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These peer-reviewed findings (Kekkonen et al., 2021) by researchers at the University of Eastern Finland and Kuopio University Hospital appear in the May issue of the journal Alcohol. "Our results suggest changes in the cerebellum in healthy young adults with a history of heavy drinking from adolescence," the authors write.

This study's total sample included two groups of teenagers: 33 heavy-drinking and 25 light-drinking participants who were followed for about a decade. When they were between ages 21 and 28, study participants underwent MRI brain scans that measured cerebellar brain volume using the CERES (CEREbellum Segmentation tool).

"The heavy-drinking participants were highly functional young adults without alcohol use disorder, but with a history of regular heavy alcohol consumption," Kekkonen and co-authors note.

Cerebellar Differences Between Heavy Drinkers and Light Drinkers

In heavy-drinking study participants, MRI neuroimaging and CERES segmentation data revealed differences in the volume of posterior cerebellar lobules compared to age-matched study participants consuming little or no alcohol.

Notably, the MRI brain scans showed that the gray matter volume of the Crus II subregion was smaller in the heavy-drinking group. However, the relative volume of the VIIIB lobule in the right cerebellar was larger in the heavy-drinking group. (See "Why Gray Matter Volume in All 4 Brain Hemispheres Matters.")

"These [cerebellar] areas of the brain are associated with motor and cognitive functions. However, further research is needed in order to assess the significance and implications of these findings," first author Virve Kekkonen said in a news release.

Close-up detail of a sagittal section of the cerebellum

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What Does the Posterior Crus II Region of the Cerebellum Do?

A recent meta-analysis (Van Overwalle, Ma, & Heleven, 2020) of bilateral Crus II cerebellar areas identified that this subregion of the cerebellum is "specialized for social mentalizing and emotional self-experiences." The authors note: "[Our] present findings show that a domain-specific social mentalizing functionality is supported in the cerebellar Crus II. This has important implications for theories of the social cerebellum focusing on sequencing of social actions and for cerebellar neurostimulation treatments."

Previous alcohol consumption research has shown that excessive, long-term heavy drinking can cause frontal lobe shrinkage and damage to the cerebellum in adulthood.

Decades ago, researchers (Kubota et al., 2001) identified that alcohol-related brain atrophy is associated with reduced cerebral blood flow, impaired cognitive functions, and antisocial behavior. "Light to moderate alcohol consumption did not increase the rate of frontal lobe shrinkage, whereas heavy drinkers had significantly shrunken frontal lobes compared with abstainers," the authors wrote.

Another meta-analysis of alcohol's effects on cerebellum structure (Sullivan et al., 1995) based on postmortem examinations of older adults with alcohol-related substance use disorder, noted that "cerebellar atrophy, shrinkage, or both can occur in the absence of clinical signs such as ataxia or clinically detectable cognitive impairment." Another study (Victor et al. 1989) concluded that "cerebellar shrinkage is most notable in older alcoholics with at least a 10-year duration of alcoholism."

To sum up: Until recently, there's been very little data on how drinking in adolescence and young adulthood might affect cerebellar brain volume. While more research is needed, the latest findings by Kekkonen et al. suggest that heavy drinking as a teenager or young adult may alter the cerebellum and cause shrinkage in the Crus II area, making this subregion of the so-called "little brain" even smaller.

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