Alterations in surface-based brain morphometry in men with opioid use disorder

<i>Background:</i> Cortical differences in thickness, folding, and complexity may reflect synaptic pruning and myelination alterations. Individuals with opioid use disorder (OUD) may demonstrate differences in these cortical metrics due to neurodevelopmental aberrations or early opioid exposure.<i>Objectives:</i> We compared the cortical metrics between individuals with OUD and controls. The influence of age and duration of opioid exposure were considered indirect evidence for preexisting or opioid-exposure-based structural aberrations.<i>Methods:</i> Sixty-nine treatment-naïve men with OUD (52 heroin, 17 non-heroin) and 25 age and education-matched non-drug-using male controls were recruited from a treatment center and community, respectively. 3-Tesla Siemens Magnetom Verio scanner and Computational Anatomy Toolbox 12 were used for image acquisition and processing. Cortical parcellation was performed using Destrieux atlas. Surface-based morphometry (SBM) metrics were cortical thickness, sulcal depth, fractal dimension, and gyrification index.<i>Results:</i> Only two cortical areas survived corrections for multiple comparisons: persons with OUD had greater sulcal depth in the right lateral orbital sulcus (<i>p</i> = .0003, Glass's delta = 0.98) and lower gyrification index in the left frontal middle gyrus (<i>p</i> = .0005, Glass's delta = 0.67) than controls. The group-by-age interaction effect on the cortical thickness was non-significant. Lower age of initiation of opioid use was associated with larger cortical thickness in the inferior frontal (<i>r</i> = -0.36, <i>p</i> = .002) and anterior cingulate (<i>r</i> = -0.35, <i>p</i> = .003) regions. Duration of OUD negatively correlated with cortical thickness in frontal and occipital areas (<i>r</i> > -.30, <i>p</i> = .004-.007).<i>Conclusion:</i> Cortical abnormalities may stem from altered synaptic pruning and myelination, possibly due to neurodevelopmental aberrations or early opioid exposure.