Chronic Alcohol Drinking Slows Brain Development in Adolescent and Young Adult Nonhuman Primates

Abstract The transition from adolescence to adulthood is associated with brain remodeling in the final stages of developmental growth. It is also a period when a large proportion of this age group engages to binge (occasional consumption of 4-5 drinks leading to intoxication) and heavy (binge drinking on ≥5 days in a month) alcohol drinking. Here we report on magnetic resonance imaging of developmental changes in the brain occurring during late adolescence and early adulthood (3.5-7.5 years) in a rhesus macaque model of alcohol self-administration. Monkeys were imaged prior to alcohol exposure, and following ∼6 and ∼12 months of daily (22 hr/day) access to ethanol and water. The results revealed that the brain volume increases by 1 ml per 1.87 years throughout the late adolescence and early adulthood in controls. Heavy alcohol reduced the rate of brain growth by 0.25 ml/year per 1 g/kg of daily ethanol. Cortical volume increased throughout this period with no significant effect of alcohol drinking on the cortical growth rate. In subcortical regions, age-dependent increases in the volumes of globus pallidus, thalamus, brainstem and cerebellum were observed. Heavy drinking attenuated the growth rate of the thalamus. Thus, developmental brain volume changes in the span of late adolescence to young adulthood in macaques is altered by excessive alcohol, an insult that may be linked to the continuation of heavy drinking throughout later adult life. Significance Statement Alcohol abuse during late adolescence and early adulthood is a risk factor for development of alcohol dependence. This longitudinal study used a macaque model of alcohol self-administration and in vivo MR-imaging to quantify the impact of chronic alcohol on developmental changes occurring within the brain during this period. Chronic alcohol self-intoxication reduced the growth rate of brain, cerebral white matter and subcortical thalamus. Thus, daily alcohol drinking during the critical transition to adulthood significantly impacts critical areas of sensory motor integration, concomitant with a decrease in cortical white matter, documenting in the primate brain neural circuitry implicating in the propagation of alcohol use disorder.