Heavy Teen Drinking Linked to Reduced Brain Volume

Megan Brooks

December 14, 2016

Heavy alcohol use during adolescence has been linked to a reduction in brain volume in young adults, new research shows.

"Even though the alcohol use of our heavy-drinking participants did not meet the diagnostic criteria of a substance use disorder, it was still connected to brain structural changes, with reductions in gray matter volume especially in the areas of the cingulate gyrus and insula," study investigator Noora Heikkinen, a PhD student at University of Eastern Finland, told Medscape Medical News.

The study was published online November 19 in Addiction.

Harm Reduction

The study included 62 healthy young adults aged 22 to 28 years who are participating in the longitudinal Youth Wellbeing Study, which is monitoring Finnish adolescents' health and alcohol use.

They were 13 to 18 years old at the start of the study. On the basis of questionnaires completed at three time points during a 10-year period, 35 participants were identified as being heavy drinkers throughout their adolescence, consuming roughly 6 to 9 units about once a week, and 27 were categorized as "light-drinking" persons, who served as controls in the study.

Brain MRI conducted at the last time point revealed that among heavy drinkers, gray matter volumes were significantly smaller in the bilateral anterior cingulate cortex, the right orbitofrontal and frontopolar cortex, the right superior temporal gyrus, and the right insular cortex as compared to the control group (P < .05), the investigators report.

The cingulate cortex plays a key role in impulse control, and volumetric changes in this area may play a part in the development of a substance use disorder later in life, they note. Structural changes in the insula may reflect a reduction in sensitivity to alcohol's negative subjective effects, which could contribute to the development of a substance use disorder.

"Our study has a longer follow-up period as compared to earlier studies. Very few studies have recorded the alcohol use for more than a few years, whereas we followed up the adolescents for 10 years using questionnaires," Heikkinen told Medscape Medical News.

"One weakness of our study is that our imaging data come from only one time point, which was at the end of this study. We hope to be able to conduct follow-up imaging on the participants in a few years," she said.

"An important message of our study," said Heikkinen, "is that it seems that heavy alcohol use that has begun early in adolescence is connected to altered brain structure even when the alcohol use does not reach the criteria for substance use disorder. It would be very important to prevent and reduce both alcohol experimentation and use during the vulnerable years of social, psychic, and biological development."

Toxic Effects

Commenting on the study for Medscape Medical News, Lindsay Squeglia, PhD, of the Addiction Sciences Division, Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, in Charleston, said: "It's nice to see replication of previous findings that suggest alcohol use during teen years and early adulthood appears to interfere with normal brain development. The brain continues to develop into the mid 20s, so interference with this normal development could have long-term effects."

Dr Squeglia cautioned that because this study utilized brain scans at only one time point, "we can't say the volume decreased over time, only that heavy drinkers show less brain volume than light drinkers. But we don't know if they had less volume to begin with because we don't have a baseline scan. Other studies have shown a decrease in volume from baseline, though."

Richard Saitz, MD, MPH, addiction expert and professor and chair of the Department of Community Health Sciences, Boston University School of Public Health, Massachusetts, said the study is "a bit difficult to interpret" because it is not clear how much the adolescents drank and in what pattern. However, "it is known that heavy drinking is associated with brain differences, particularly among adolescents with alcohol use disorder," said Dr Saitz.

"What I think we can extract from the paper," he noted, "is that adolescents with unhealthy alcohol use...had lower gray matter volumes in particular areas. This is important because it suggests those with unhealthy alcohol use who do not have alcohol addiction or alcohol use disorder have what appear to be detrimental/toxic effects on brain.

"What it does not tell us is which came first, the chicken or the egg, the drinking or the brain changes, though the observations over time strengthen the possibility that these data reflect the alcohol came first," Dr Saitz said. "Alcohol's effects go way beyond the brain, but knowing the exact risky level in youth could be helpful for youth who are going to drink at all."

The study had no commercial funding. The authors have disclosed no relevant financial relationships.

Addiction. Published online December 8, 2016. Abstract

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