Higher diffusion in striatum and lower fractional anisotropy in white matter of methamphetamine users

Abstract

Methamphetamine (METH) users showed structural and chemical abnormalities on magnetic resonance (MRI) studies, particularly in the frontal and basal ganglia brain regions. Diffusion tensor imaging (DTI) may provide further insights regarding the microstructural changes in METH users. We investigated diffusion tensor measures in frontal white matter and basal ganglia of 30 adult METH users and 30 control subjects using a 3 T MR scanner. Compared with healthy control subjects, METH users showed lower fractional anisotropy (FA) in right frontal white matter, and higher apparent diffusion coefficient (ADC) in left caudate and bilateral putamen. Higher left putamen ADC was associated with earlier initiation of METH use, greater daily amounts, and a higher cumulative lifetime dose. Similarly, higher right putamen ADC was associated with greater daily amounts and a higher cumulative lifetime dose. The lower FA in the right frontal white matter suggests axonal injury in these METH users. The higher ADC in the basal ganglia suggests greater inflammation or less myelination in these brain regions of those with younger age of first METH use and greater METH usage.

Fig. 1

Axial views of regions of interest (ROI) placement on the fractional anisotropy (FA) maps for measurement of FA, ADC and the diffusion eigenvalues. All FA and diffusion values were measured bilaterally in these brain regions, except for the genu of the corpus callosum and the cerebellar vermis.

Fig. 2

Compared with healthy non-drug users, METH users showed higher apparent diffusion coefficients (ADC) in the left caudate nucleus and bilateral putamen (A), and lower fractional anisotropy (FA) in bilateral frontal white matter (B). Error bars represent standard deviations.

Fig. 3

Putamen diffusivity correlated with METH use. Left putamen ADC was higher in participants with younger age of first use, higher average grams of METH used per day, and higher cumulative lifetime dose. Similarly, right putamen ADC was higher in those with higher average grams of METH used per day, and higher cumulative lifetime dose of METH used.