October 29, 2019

Frequent alcohol use among adolescents and young adults has the potential to be dangerous for obvious reasons—and now, new research in nonhuman primates shows it can actually slow the rate of growth in developing brains.

Researchers at Oregon National Primate Research Center (ONPRC) at Oregon Health & Science University (OHSU) in Portland, Oregon, measured the brain growth of 71 rhesus macaques via magnetic resonance imaging (MRI). The macaques voluntarily consumed ethanol or beverage alcohol, and the scientists measured their intake, diet, daily schedules and health care, ruling out other factors which tend to confound results in observational studies involving humans.

The study shows heavy alcohol use reduced the rate of brain growth by 0.25 milliliters per year for every gram of alcohol consumed per kilogram of body weight, in addition to reduced growth of cerebral white matter and the subcortical thalamus. These findings help validate previous research examining the effect of alcohol use on brain development in humans.

“Human studies are based on self-reporting of underage drinkers,” said co-author Christopher Kroenke, PhD, an associate professor in the Division of Neuroscience at ONPRC. “Our measures pinpoint alcohol drinking with the impaired brain growth.”

The study is the first to identify normal brain growth in rhesus macaques in late adolescence and early adulthood as occurring at a rate of 1 milliliter per 1.87 years. It also supports previous studies which show a decrease in the volume of distinct brain areas due to voluntary consumption of ethanol.

Lead author Tatiana Shnitko, PhD, a research assistant professor in the Division of Neuroscience at ONPRC, said previous research has shown the brain has a capacity to recover at least in part following the cessation of alcohol intake. However, it’s not clear whether there would be long-term effects on mental functions as the adolescent and young adult brain ends its growth phase. The next stage of research will explore this question.

“This is the age range when the brain is being fine-tuned to fit adult responsibilities,” Shnitko explained. “The question is, does alcohol exposure during this age range alter the lifetime learning ability of individuals?”

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