Academic journal article Alcohol Research

Magnetic Resonance Imaging of the Living Brain: Evidence for Brain Degeneration among Alcoholics and Recovery with Abstinence

Academic journal article Alcohol Research

Magnetic Resonance Imaging of the Living Brain: Evidence for Brain Degeneration among Alcoholics and Recovery with Abstinence

Article excerpt

Magnetic resonance imaging (MRI) provides a safe, noninvasive method to examine the brain's macrostructure, microstructure, and some aspects of how the living brain functions. MRI is capable of detecting abnormalities that can occur with alcoholism as well as changes that can occur with sobriety and relapse. The brain pathology associated with chronic excessive alcohol consumption is well documented with imaging of the living body (i.e., in vivo imaging). Consistent findings include shrinkage of the frontal cortex,1 underlying white matter, and cerebellum and expansion of the ventricles. Some of these changes are reversible with abstinence, but some appear to be enduring. Research showing correlations between brain structure and quantitative neuropsychological testing demonstrates the functional consequences of the pathology. In addition, functional imaging studies provide evidence that the brain compensates for cognitive deficits. The myriad concomitants of alcoholism, the antecedents, and the consumption patterns each may influence the observed brain changes associated with alcoholism, which tend to be more deleterious with increasing age. The multifaceted nature of alcoholism presents unique challenges and opportunities to understand the mechanisms underlying alcoholism-induced neuropathology and its recovery. Longitudinal MRI studies of animal models of alcoholism, however, can address questions about the development and course of alcohol dependence and the scope and limits of in vivo degeneration and recovery of brain structure and concomitant function that may not be readily addressed in clinical studies. KEY WORDS: Alcoholism; brain; brain function; brain structure; neuropathology; cognitive impairment; brain imaging; neuroimaging; magnetic resonance imaging (MRI); functional magnetic resonance imaging (fMRI); diffusion tensor imaging (DTI); in vivo imaging studies; frontal cortex; white matter; human studies; animal models; longitudinal studies

Alcohol use disorders are characterized by the excessive consumption of alcohol despite its interference with an individual's physical, mental, interpersonal, and social wellbeing. These harmful behavioral effects are mediated through the brain, which can undergo changes in structure, function, and basic physiology. Some studies (e.g., Cardenas et al. 2007; Gazdzinski et al. 2005a; Pfefferbaum et al. 1995) have shown evidence for recovery with extended sobriety, but some of the brain changes may persist even after extended sobriety, reflecting diminished ability to maintain function when confronted by degenerative processes (i.e., functional reserve) and decreased ability of the brain to change (i.e., plasticity). These persistent alcoholinduced brain changes themselves then may contribute to the selfsustaining nature of alcoholism.

This article reviews studies using three different types of magnetic resonance imaging (MRI)2 brain scanning to measure the effects of excessive chronic alcohol consumption on brain size or shape (i.e., macrostructure), tissue quality (i.e., microstructure), and function (i.e., localized blood flow in support of cognitive or motor tasks). To assess the immediate effects of chronic excessive drinking on the brain and cognitive and motor performance, investigators most commonly test alcoholics shortly after they enter treatment and compare them with lowalcohol- consuming study participants (i.e., control subjects) of similar age, sex, and socioeconomic level.

To test whether the effects of excessive alcohol consumption persist after sobriety is maintained, investigators may compare alcoholics with different lengths of sobriety or preferably follow the same people over time and retest them after varying periods of sobriety. Importantly, these longitudinal studies also require retesting a comparison group of lowalcohol drinkers to control for normal changes in aging and distortion inherent to MRI (i.e., scanner drift) over time. …

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