White matter impairment in chronic heroin dependence: A quantitative DTI study

Exposure to addictive drugs has been associated with disrupted brain white matter integrity. A few studies have examined the white matter deficits in heroin users; however, the results were influenced by the use of substitution drugs such as methadone and buprenorphine. The present study assessed the alteration in white matter integrity and heroin-related neuropathology in heroin dependents who had not received any replacement therapy using quantitative diffusion tensor imaging (DTI). The study comprised 17 heroin-dependent (HD) subjects and 15 matched healthy controls (HC). Fractional anisotropy (FA) and eigenvalues (lambda(perpendicular to), lambda(parallel to)) of white matter in the whole brain were measured and compared using a voxel-based analysis. The correlation between DTI measurements in identified regions and history of heroin exposure was tested by partial correlation analysis. Compared with HCs, HD subjects displayed decreased FA in the bilateral frontal lobe sub-gyrus, cingulate gyms, medial frontal gyms, extra-nuclear, left temporal lobe sub-gyms and right superior frontal gyrus. Among these regions, the HD group had significantly increased lambda(perpendicular to) in the bilateral frontal lobe subgyms, thngulate gyrus and extra-nuclear relative to the HC group. There were no group differences in lambda(parallel to). In addition, there were no significant correlations between duration of heroin use or accumulated dosage and FA or lambda(perpendicular to) values. In conclusion, chronic heroin-dependent subjects had widespread disruption of white matter structural connectivity located mainly in anterior and superior regions of the brain. Damage to myelin other than axons was the primary pathological feature in the brain of the heroin user. (C) 2013 Elsevier B.V. All rights reserved.