Cortical thickness and brain aging in individuals engaging in unhealthy alcohol use

Background: The relation of alcohol use to different health outcomes is a longtime and controversial classic. Most previous studies reported associations between higher self-reported alcohol use and poorer brain health. However, inconclusiveness remains due to methodological heterogeneity and alcohol use was often not validated using gamma-glutamyltransferase (gamma-GT) levels. This study aimed to comprehensively examine several aspects of brain health using magnetic resonance imaging (MRI) in individuals regularly exceeding recommended limits of moderate drinking versus those who don’t.Methods: This cross-sectional analysis was based on the population-based cohort of the BiDirect Study. Participants aged between 35 and 65 years were randomly sampled from the local population register of the city of Münster (Germany) and invited to participate in a comprehensive examination program that included a 3 Tesla MRI of the brain and a blood collection. Unhealthy alcohol use was defined as the regular intake of at least three units of alcohol (one unit = 0.2L beer or 0.1L wine or 2cl spirits) per occasion at least two times a week. Regional cortical thickness was extracted from T1-weighted images in participants who underwent MRI. In addition, brain-predicted age differences (brain age gaps) were estimated with support vector machines based on regional cortical thickness. Associations between unhealthy alcohol use, cortical thickness, and brain age gaps were analyzed using multiple regression models adjusted for age, sex, lifetime smoking status, education, and childhood trauma.Results: Significantly higher gamma-GT levels were observed in participants engaging in unhealthy alcohol use. This behavior was furthermore associated lower regional cortical thickness across all four lobes of the brain. In addition, we observed a higher brain age gap (+ 1.02 years) in individuals engaging in unhealthy alcohol use compared to those who don’t.  Conclusions: The results of this study indicate that unhealthy alcohol use, operationalized as the regular exceedance of recommended levels of alcohol intake, is related to poorer brain health as reflected by lower regional cortical thickness and advanced brain aging. The findings underscore the potentially adverse effects of alcohol on brain health, which are increasingly relevant in view of recent global trends in alcohol use.