Assessing white matter integrity as a function of abstinence duration in former cocaine-dependent individuals

Abstract

Current cocaine-dependent users show reductions in white matter (WM) integrity, especially in cortical regions associated with cognitive control that have been associated with inhibitory dysfunction. A key question is whether these white matter differences are present following abstinence from drug use. To address this, WM integrity was examined using diffusion tensor imaging (DTI) obtained on 43 cocaine abstinent patients (abstinence duration ranged between five days and 102 weeks) and 43 non-using controls. Additionally, a cross-sectional comparison separated the patients into three groups (short-term, mid-term and long-term) based upon duration of cocaine abstinence. The 43 cocaine abstinent patients showed lower fractional anisotropy (FA) in the left anterior callosal fibers, left genu of the corpus callosum, right superior longitudinal fasciculus, right callosal fibers and the superior corona radiata bilaterally when compared against non-using controls. Higher FA in the cocaine abstinent patients was observed in the splenium of the corpus callosum and right superior longitudinal fasciculus. Differences between the cocaine abstinent groups were observed bilaterally in the inferior longitudinal fasciculus, right anterior thalamic radiation, right ventral posterolateral nucleus of the thalamus, left superior corona radiata, superior longitudinal fasciculus bilaterally, right cingulum and the WM of the right precentral gyrus. The results identified WM differences between cocaine abstinent patients and controls as well as distinct differences between abstinent subgroups. The findings suggest that specific white matter differences persist throughout abstinence while other, spatially distinct, differences discriminate as a function of abstinence duration. These differences may, therefore, represent brain changes that mark recovery from addiction.

Figure 1. Brain areas that show differences between all patients and all controls

Blue signifies lower FA and red signifies higher FA in the patient group. Number refers to region (see Table 2). Images are in radiological orientation with left hemisphere shown on the right side of the image.

Figure 2. Brain areas that show differences between abstinence groups

Letter A refers to higher FA with abstinence. Letter B refers to lower FA with abstinence. Letter C refers to higher and then lower FA with abstinence. Letter D refers to lower and then higher FA with abstinence. Number refers to region (see Table 4). Scatterplots show education-adjusted FA values (y-axis) plotted against abstinence duration (x-axis). FA values are scaled from 0–1000. Images are in radiological orientation.