White Matter Differences in Early-Stage Alcohol Use Disorder: Diffusion Tensor and Neurite Orientation Dispersion and Density Measures of Structural Integrity

Background. Alcohol use disorder (AUD) is prevalent during young adulthood, and this risk may be linked to aberrations in neurodevelopmental processes. Prior studies examining white matter (WM) integrity in young adult individuals with AUD have shown considerable variability. This is due in part because traditional tensor related metrics such as fractional anisotropy are subject to limitations in estimation precision at sites of crossing or curving fibres. In response, to better understand differences in WM integrity of young adults with AUD, this study sought to uniquely employ two WM integrity measurement domains. Methods. Twenty-five participants (n = 14 female) diagnosed with AUD and 33 social drinkers (n = 19 female) underwent structural and diffusion-weighted imaging. Diffusion-weighted images were processed to extract diffusion tensor (DTI) and neurite orientation dispersion and density (NODDI) metrics in major WM tracts for comparison between the two groups. Results. We identified decreased axial diffusivity in portions of frontolimbic and corticostriatal WM tracts, and increased orientation dispersion at overlapping tracts in participants with AUD relative to social drinkers. Conclusions. These results may represent early-stage neural immune system activation and axonal reorganization targeting frontolimbic and corticostriatal WM tracts, therein associated with behaviours linked to AUD. This is the first study combining DTI and NODDI metrics to identify early-stage indicators of alcohol-related neurobiological pathology in young adults with AUD compared to social drinkers.