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Monday, May 7, 2012

Callosal White Matter Microstructural Recovery in Abstinent Alcoholics: A Longitudinal Diffusion Tensor Imaging Study

Previous neuroimaging studies of recently detoxified alcohol-dependent patients (RDA) have found significant loss of white matter integrity associated with the shrinkage of the frontal lobes and thinning of the corpus callosum, especially the genu. The current study hypothesized that, in addition to exhibiting the most microstructural white matter disruption in RDA, the genu will also evidence the most recovery after abstinence. This microstructural recovery will be associated with improvements in executive functioning measures.

Fifteen RDA were examined approximately 2 weeks after abstinence and again after 1 year of abstinence and compared to 15 age- and education-matched nonalcoholic controls using diffusion tensor imaging (DTI). The effects of group, time, and their interactions on fractional anisotropy, radial diffusivity, and axial diffusivity were evaluated with repeated measures MANOVA; in addition, 2 × 2 ANOVA was used to test changes in measures of executive functioning in the 2 groups.

At 2 weeks of abstinence, DTI of RDA showed significantly lower fractional anisotropy and greater radial diffusivity compared to controls in the genu and body of the corpus callosum. Reexamination after 1 year showed significant time by group interaction with fractional anisotropy increasing and radial diffusivity decreasing in RDA but not controls in these 2 regions. A smaller relapsed group did not show 0improvements between the 2 time points. Abstinent RDA also showed improvement on Digit Span Backward, a measure of working memory, but did not benefit from practice effects on the Halstead Category Test compared to controls.

The results suggest susceptibility of the genu and body of the corpus callosum to the effects of alcohol, and the potential for recovery of both these regions after abstinence, perhaps via mechanisms involving myelin reconstitution.

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