Shared Microstructural Features of Behavioral and Substance Addictions Revealed in Areas of Crossing Fibers

Abstract

BackgroundSimilarities between behavioral and substance addictions exist. However, direct neurobiological comparison between addictive disorders is rare. Determination of disorder specificity (or lack thereof) of alterations within white matter microstructures will advance understanding of the pathophysiology of addictions. MethodsWe compared white matter microstructural features between individuals with gambling disorder (GD) (n = 38), cocaine use disorder (n = 38), and healthy comparison (n = 38) participants, as assessed using diffusion-weighted magnetic resonance imaging. To provide a more precise estimate of diffusion within regions of complex architecture (e.g., corticolimbic tracts), analyses were conducted using a crossing-fiber model incorporating local-orientation modeling (tbss_x). Anisotropy estimates for primary and secondary fiber orientations were compared using analyses of variance corrected for multiple comparisons across space using threshold-free cluster enhancement (pfamilywise error < .05). ResultsA main effect of group on anisotropy of secondary fiber orientations within the left internal capsule, corona radiata, forceps major, and posterior thalamic radiation involving reduced anisotropy among GD and cocaine use disorder participants in comparison with healthy comparison participants. No differences in anisotropy measures were found between GD and cocaine use disorder individuals. ConclusionsThis is the first study to compare diffusion indices directly between behavioral and substance addictions and the largest diffusion-weighted magnetic resonance imaging study of GD. Our findings indicate similar white matter microstructural alterations across addictions that cannot be attributed solely to exposure to drugs or alcohol and thus may be a vulnerability mechanism for addictive disorders.