The impact of alcohol and tobacco on the white matter integrity during adolescence and young adulthood neurodevelopment

Alcohol and tobacco consumption is socially accepted and widespread among adolescents. Adolescence is a very sensitive period for neurodevelopment, characterized by significant changes in cognitive and emotional functioning, and by the morphological maturation of brain tissues, especially of the white matter (WM). Research using advanced diffusion neuroimaging has revealed that alcohol and tobacco use during adolescence and young adulthood can have detrimental effects on neurodevelopmental trajectories of WM, by delaying the growth of this brain tissue and disrupting its integrity. Specifically, alcohol consumption has been associated with reduction of fractional anisotropy (FA) mainly in corpus callosum and fronto-temporal networks, unveiling compromised connectivity and reduced cognitive functioning. Similarly, nicotine exposure from tobacco use has been linked to decreased FA in critical brain regions, potentially impairing cognitive processes like attention, inhibition and emotional codification. Furthermore, these effects appear to be dose-dependent and gender-dependent, with heavier and more frequent substance use leading to more pronounced alterations in WM integrity according to biological gender. Additionally, the adolescent brain is particularly vulnerable to the neurotoxic effects of alcohol and tobacco, as it is still undergoing significant neurodevelopment, including myelination of WM tracts. Understanding the precise mechanisms underlying these neurodevelopmental changes and their long-term consequences on cognitive and behavioral outcomes is an ongoing area of research. Given the potential long-lasting impacts of alcohol and tobacco use on WM during adolescence and young adulthood, preventive efforts and early interventions are essential to mitigate the potential harm and promote healthy brain development in this vulnerable population.