Neural and cognitive biomarkers of binge and heavy drinking

BACKGROUND: Theories suggest two motivations that drive people to consume alcohol at pathological levels: (1) seeking of short-term pleasurable effects and (2) alleviation of unpleasant states. The former is associated with binge drinking (BD; i.e. high intake during fewer occasions) and the latter with heavy drinking (HD; substantial intake during more occasions). Although direct comparisons have not been made, BD has been associated with impairments in top-down executive control (related to frontal-parietal regions) and HD has been linked to bottom-up changes in internal mentation (related to the default mode network anatomical structure and function). This dissertation compares the two drinking patterns with the goal of testing for differential neurocognitive and neuroanatomical characteristics that would be indicative of two disorder subtypes. METHODS: The sample consisted of adult participants with a history of adolescent onset: BD (N = 16), HD (N = 15), and Healthy Controls (HC; N = 21). All groups were equated on age, education, amount of lifetime alcohol consumed (BD and HD groups), as well as other factors. The study compared group performance on an affective go/no go task and group differences in brain volume and cortical thickness based on structural MRI. RESULTS: Behavioral results showed a higher number of errors for the HD group, in comparison to other groups. Volumetric results indicated a smaller bilateral ventral diencephalon in both BD and HD, in comparison to the HC, and smaller bilateral globus pallidus in BD only. Cortical thickness analyses revealed a thinner left superior parietal region (overlapping with the dorsal attention and fronto-parietal networks) in BD, whereas a left medial occipito-parietal region was thicker in HD (overlapping mainly with the visual network). CONCLUSION: These data, interpreted in the context of prior studies, suggest that BD findings might be indicative of an executive control dysregulation that could contribute to continued BD. HD findings might be indicative of tissue damage due to frequent drinking. Prior research has found the occipital region to have the highest concentration γ-Aminobutyric acid receptors that are affected by alcohol, which might explain the thicker occipital region findings in the HD group