Brain white matter microstructural integrity differences between pre-post buprenorphine-naloxone treated individuals with opioid use disorder: Evidence from a DTI study.

Opioid use disorder (OUD) has been linked to alterations in brain white matter microstructure, but evidence comparing pre-treatment and six-month buprenorphine-naloxone (BNX) treatment remains limited. This study examined changes in brain diffusion tensor imaging (DTI) metrics before and after six months of BNX treatment in individuals with OUD and assessed the influence of concurrent cannabis and tobacco use. This pre-post study included 25 individuals with OUD initiating BNX treatment and 25 healthy controls. All participants underwent 3-Tesla brain DTI scans at baseline and at six-month follow-up. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were quantified across 48 regions of interests defined by JHU White Matter Atlas. Linear mixed-effects models were applied to examine group and time effects. At follow-up, the OUD group demonstrated widespread increases in MD, AD, RD compared with baseline and healthy controls, involving commissural, projection, and association tracts. Compared with healthy controls, the OUD group at baseline showed lower FA in key commissural and projection pathways. White matter changes after 6-month BNX treatment are modest overall but might be influenced by continued cannabis and tobacco use. Addressing concurrent substance use may be important for optimizing neurobiological recovery during buprenorphine treatment.