Brain Tries to Compensate for Damage Caused by Alcohol Abuse

Alcohol-Damaged Brain Tries to Heal Itself

Researchers know that many alcoholics continue to experience cognitive deficits even after long-term abstinence from alcohol. Results from a study in the April issue of Alcoholism: Clinical & Experimental Research confirm that motor deficits also continue to plague abstinent alcoholics.

Furthermore, by using functional magnetic resonance imaging (fMRI) to "watch" brain regions involved in a simple motor task - finger tapping - the study has found that the brain appears to compensate for alcohol-induced damage by "recruiting" other, unexpected brain regions.

Brain Damage in Alcoholics

"We know from neuropathological studies that the two parts of the brain that are most often damaged in chronic alcoholics are the cerebellum and the frontal lobes," said Peter R. Martin, professor of psychiatry and pharmacology, director of the Vanderbilt Addiction Center at the Vanderbilt University School of Medicine, and corresponding author for the study. "Rapid self-paced motor activity such as finger tapping is a function of the motor cortex, the posterior part of the frontal lobe, which initiates a stimulus to the muscles of the hand, that is then coordinated by interplay between the cerebellum and the frontal lobes.

"In other words, I reasoned that there would probably be abnormalities in activation of these regions in alcoholics during finger tapping."

Examining Brain Activity

While undergoing MRI, two groups of participants performed repetitive, self-paced index finger-tapping exercises: eight (7 male, 1 female) alcohol-dependent patients after approximately two weeks of abstinence; and nine (7 females, 2 males) healthy volunteers or "controls." Participants alternated between using their dominant hands (DH) and non-dominant hands (NDH) to perform the index finger-tapping exercises.

Researchers used fMRI analysis to compare DH and NDH performance in each subject group in order to examine whether the groups differed in the patterns of activation they exhibited in the cerebral cortex and cerebellum.

Using More of the Brain

The detoxified alcohol-dependent patients performed the finger-tapping tasks significantly slower than the control group. However, contrary to expectations, the slower tapping was not accompanied by proportionately decreased fMRI brain activation in the cerebral cortex and cerebellum; rather, the alcoholics had a significant increase of activation in the cortical brain region ipsilateral to (on the same side as) the active hand during DH tapping. In other words, the alcoholics had to use more of their brains to do less.

Part 2: Results Explained

Source: Vanderbilt University School of Medicine.