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 (λ┴,λ||) 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 gyrus, medial frontal gyrus, extra-nuclear, left temporal lobe sub-gyrus and right superior frontal gyrus. Among these regions, the HD group had significantly increased λ┴ in the bilateral frontal lobe sub-gyrus, cingulate gyrus and extra-nuclear relative to the HC group. There were no group differences in λ||. In addition, there were no significant correlations between duration of heroin use or accumulated dosage and FA or λ┴ 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.
"For example, Liu et al. (2009) analysed DTI datasets from 16 HDIs and 16 controls and found significantly decreased FA in HDIs in the bilateral frontal sub-gyral, right precentral and left cingulate regions compared with controls . Li et al. (2013) revealed decreased FA value in brain WM of the bilateral frontal lobes, cingulate gyri, medial frontal gyri and right superior frontal gyrus in HDIs. "
[Show abstract][Hide abstract] ABSTRACT: Abstract Background: Diffusion tensor imaging has been used to explore white matter changes in heroin-dependent patients; however, results have been inconsistent. Objectives: The current study meta-analytically examines the neuroimaging findings of all studies published before 2014 using the novel technique of Effect Size Signed Differential Mapping (ES-SDM). Methods: Two independent investigators searched three databases for whole-brain voxel-based fractional anisotropy morphometric studies involving heroin use without comorbid polysubstance abuse. Of 59 initial primary studies, four met stringent inclusion criteria. Results: Results from this preliminary analysis indicate that heroin abusers may have significant reductions in fractional anisotropy in the bilateral frontal sub-gyral regions extending from the limbic structures to the prefrontal association cortices, implicating damage to the cingulum and superior longitudinal fasciculus. Exploratory moderator analyses indicate that the potential damage in the left cingulate gyrus may increase with longer use and decrease after long-term abstinence. Conclusion: These preliminary findings suggest that heroin abuse is significantly associated with damage to white matter integrity. These results are considered preliminary and analyses should be revisited with more primary studies focusing on either long- or short-term abuse as well as abstinence.
The American Journal of Drug and Alcohol Abuse 02/2015; 41(2):1-6. DOI:10.3109/00952990.2014.985829 · 1.78 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abnormal interhemispheric functional connectivity correlates with several neurologic and psychiatric conditions, including depression, obsessive-compulsive disorder, schizophrenia, and stroke. Abnormal interhemispheric functional connectivity also correlates with abuse of cannabis and cocaine. In the current report, we evaluated whether tobacco abuse (i.e., cigarette smoking) is associated with altered interhemispheric connectivity. To that end, we examined resting state functional connectivity using magnetic resonance imaging (MRI) in short term tobacco deprived and smoking as usual tobacco smokers, and in non-smoker controls. Additionally, we compared diffusion tensor imaging (DTI) in the same subjects to study differences in white matter. The data reveal a significant increase in interhemispheric functional connectivity in sated tobacco smokers when compared to controls. This difference was larger in frontal regions, and was positively correlated with the average number of cigarettes smoked per day. In addition, we found a negative correlation between the number of DTI streamlines in the genual corpus callosum and the number of cigarettes smoked per day. Taken together, our results implicate changes in interhemispheric functional and anatomical connectivity in current cigarette smokers.
Frontiers in Human Neuroscience 03/2015; 9. DOI:10.3389/fnhum.2015.00116 · 3.63 Impact Factor
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