Alterations in neural structure have been reported in both cocaine‐use disorder and gambling disorder, separately, suggesting similarities across addiction diagnoses. Individual variation in neural structure has also been associated with impulsivity...
Alterations in neural structure have been reported in both cocaine‐use disorder and gambling disorder, separately, suggesting similarities across addiction diagnoses. Individual variation in neural structure has also been associated with impulsivity, a dimensional construct implicated in addictions. This study combines categorical (diagnosis‐based) and dimensional (transdiagnostic) approaches to identify neural structural alterations linked to addiction subtypes and trait impulsivity, respectively, across individuals with gambling disorder (n = 35), individuals with cocaine‐use disorder (n = 37) and healthy comparison individuals (n = 37). High‐resolution T1‐weighted data were analyzed using modulated voxel‐based morphometry (VBM). Statistical analyses were conducted using whole‐brain general‐linear models, corrected for family‐wise error (pFWE < .05). Categorical analyses indicated a main effect of diagnostic group on prefrontal (dorsal anterior cingulate and ventromedial prefrontal cortex) gray matter volumes (GMVs), involving decreased GMVs among cocaine‐use disorder participants only. Dimensional analyses indicated a negative association between trait impulsivity and cortical (insula) and subcortical (amygdala and hippocampus) GMVs across all participants. Conjunction analysis indicated little anatomical overlap between regions identified as differentiating diagnostic groups and regions covarying with impulsivity. These data provide first evidence of neural structural differences between gambling disorder and an illicit substance‐use disorder. They further indicate dissociable effects of diagnostic groupings and trait impulsivity on neural structure among individuals with behavioral and drug addictions. Study findings highlight the importance of considering both categorical and dimensional (e.g. Research Domain Criteria; RDoC) analysis approaches within the context of addictions research.
Between‐group analyses indicated reduced prefrontal cortical gray matter among individuals with cocaine‐use disorder (n = 37) versus individuals with gambling disorder (n = 35) and healthy controls (n = 37). Regression analyses indicated a negative association between trait impulsivity and gray matter within cortical (insula) and subcortical (amygdala and hippocampus) regions across all participants. Conjunction analyses indicated little anatomical overlap between regions identified as differentiating diagnostic groups versus those identified as covarying with impulsivity, raising the possibility of dissociable anatomical substrates of diagnosis and impulsivity in addictions.