Degradation of Association and Projection White Matter Systems in Alcoholism Detected with Quantitative Fiber Tracking

Abstract

Background Excessive alcohol use can cause macrostructural tissue shrinkage with regional preference for frontal systems. The extent and locus of alcoholism’s effect on white matter microstructure is less known. Methods Quantitative fiber tracking derived from diffusion tensor imaging (DTI) assessed the integrity of samples of 11 major white matter bundles in 87 alcoholics (59 men, 28 women) and 88 healthy control subjects (42 men, 46 women). Fiber integrity was expressed as fractional anisotropy (FA) and apparent diffusion coefficient (ADC), quantified separately for longitudinal diffusivity (λL), a putative index of axonal integrity, and transverse diffusivity (λT), a putative index of myelin integrity. Results Alcoholism affected FA and diffusivity, particularly λT, of several fiber bundles. Frontal and superior sites (frontal forceps, internal and external capsules, fornix, and superior cingulate and longitudinal fasciculi) showed greatest abnormalities in alcoholics relative to control subjects. More posterior and inferior bundles were relatively spared. Lifetime alcohol consumption correlated with regional DTI measures in alcoholic men but not women. When matched for alcohol exposure, alcoholic women showed more DTI signs of white matter degradation than alcoholic men in several fiber bundles. Among all alcoholics, poorer performance on speeded tests correlated with DTI signs of regional white matter degradation. Conclusions This survey of multiple brain fiber systems revealed a differential pattern of alcoholism’s effect on regional FA and diffusivity with functional consequences attributable in part to compromised fiber microstructure with prominence in signs of myelin degradation. Sex-based differences suggest that women are at enhanced risk for alcoholism-related degradation in selective white matter systems.

An MRI study of white matter tract integrity in regular cannabis users: effects of cannabis use and age

“…Lastly, DTI measures were correlated with cannabis use measures in the cannabis user group only. All white matter integrity analyses included covariates of age, gender, education, IQ, alcohol and cigarette consumption since these variables have known associations with white matter integrity (Szeszko et al 2003;Lebel et al 2008;Pfefferbaum et al 2009;Hudkins et al 2012). Given the unequal tobacco use between groups, we conducted additional partial analysis of models to assess for confounding of tobacco use which is presented in the supplemental information.…”

Alcohol-induced changes in the brain as assessed by MRI and CT

“…Quantitative diffusion tensor imaging has shown that excessive alcohol abuse not only causes macrostructural tissue shrinkage, but also fibre microstructure compromise with white matter degradation in multiple different fibre systems including the corpus callosum [10,11].…”

Acute Effects of Alcohol on the Human Brain: Diffusion Tensor Imaging Study

“…11 In connection with chronic alcohol consumption, many previous DTI studies have reported reduced FA in certain brain regions: for example, in the genu of the corpus callosum; the centrum semiovale 12 ; and the frontal and superior sites, such as frontal forceps, internal and external capsules, and fornix. 13 DTI has revealed evidence for microstructral disruption of white matter in alcoholic men and women, even in regions appearing normal on conventional volume imaging.…”