Neural Correlates of Hazardous Alcohol Use Examined Via Structural and Functional Neuroimaging

Abstract

Introduction: Substance use disorders are often associated with widespread structural and functional abnormalities in the brain. The primary aim of this thesis was to reduce existing ambiguity and explore novel topics in the field of addictions neuroscience by conducting three human neuroimaging studies. Results: In the first study, individuals who used alcohol were found to have significant inverse associations between drinks in past week, frequency of heavy drinking, and cortical thickness in a majority of regions examined via MRI. These regions included the dorsolateral prefrontal cortex, the inferior frontal gyrus, and the precentral gyrus. In the second study, when we employed a novel MRI pulse sequence to examine intracortical myelin (ICM) in people with alcohol use disorder, we found that the alcohol use disorder group in fact had greater ICM signal than the control participants, leading us to hypothesize a potential inflammation response in the brain from the prolonged use of alcohol. Finally, in the third study, when we explored large-scale brain activity in a sample of people who use alcohol alone or in combination with other substances, we found that those who used three or more substances displayed the least amount of activation in the salience and temporal networks of the brain. A peculiar finding, however, was that dual users of alcohol and cannabis were found to have the most activation in these networks. Conclusions: Results demonstrate that, indeed, alcohol use is associated with structural and functional abnormalities in the brain. These studies have demonstrated cortical thinning and increased ICM signal in relation to alcohol use broadly. As well, this work has shown that polysubstance use is associated with alterations in various large-scale resting state brain networks. Future research should seek to conduct longitudinal work in order to clarify whether structural and functional brain abnormalities are a cause or a consequence of substance use.