Structural MRI and cognitive brain measures in methamphetamine dependence

Abstract

MRI studies suggest that chronic psychostimulant abuse is associated with changes in white matter integrity and striatal volume. We tested 12 HIV-negative, and 5 HIV-positive, patients with methamphetamine dependence and 17 age matched healthy controls.  MRI scans included eight-direction Diffusion Tensor Imaging (DTI), T2-weighted spin echo and FLAIR (Fluid Attenuated Inversion Recovery) and T1-weighted 3D volumetric scan.  T1 weighted images were used for volume determinations and in intersubject registrations of the DTI data for voxelwise analyses. Fractional anisotropy (FA), a measure of white matter integrity, was analyzed using voxelwise t tests with false discovery rate correction. Computerized cognitive tests using the Cogtest® battery were used to evaluate attention, response inhibition, facial emotion recognition, verbal working memory, spatial working memory, set shift and tapping speed. Combined volume of caudate and nucleus accumbens was similar across groups and no gross white matter damage was noted based on the presence of white matter hyperintensities (FLAIR). However, methamphetamine patients showed significantly lower FA in the white matter of the corpus callosum and superior longitudinal fasciculi bilaterally as well as in the left superior frontal and fusiform gyri and the right posterior cingulate gyrus. Methamphetamine patients also showed significantly higher FA in the left ventral tegmental area and mediodorsal thalamus and in the right subcallosal fasciculus.  Methamphetamine patients showed cognitive deficits in attention, set shift, spatial and verbal memory, and finger tapping speed. Lower voxelwise FA in methamphetamine users in the corpus callosum and fasciculi paralleled findings in active cocaine abusers. Correlations of cognitive deficits with changes in FA will be presented.