- Most of the research on brain damage related to alcohol has been gathered from abstinent alcoholics during or after treatment.
- New research uses magnetic resonance technology to examine brain damage in heavy drinkers.
- The metabolite changes that were found in heavy drinkers are associated with lower brain function and are likely of behavioral significance.
Almost all knowledge about brain damage due to chronic alcohol consumption has been gathered from alcoholics, who have generally been studied toward the end of their institutionalized treatment program (several weeks after their last drink) or many months into abstinence. Abstinent alcoholics during or following treatment, however, may represent a different population than heavy drinkers recruited from the community. A study in the April issue of Alcoholism: Clinical & Experimental Research has found that community-based heavy drinkers have clear brain metabolite changes that are associated with lower brain function and are likely of behavioral significance.
"This research is fundamentally different from previous stages of research on the effects of chronic alcohol consumption on the brain," said Dieter J. Meyerhoff, associate professor of radiology at the University of California San Francisco, associate researcher at the Veterans' Affairs Medical Center San Francisco, and lead author of the study. "It moves away from describing the endpoints of a disease that has devastating effects on individuals and affects their families and society as a whole, and moves toward a better understanding of the disease process. What our findings indicate is that brain damage is detectable in heavy drinkers who are not in treatment and function relatively well in the community."
"There are real benefits to this study," added Peter R. Martin, professor of psychiatry and pharmacology, and director of the Vanderbilt Addiction Center at the Vanderbilt University School of Medicine, "in that they're looking at changes that may occur prior to patients being sick enough to be hospitalized. If you take this to mean that these are people who are earlier in the course of their alcoholism, then it becomes very valuable, as they have studied a population that has not yet been studied, and it complements what's already in the literature."
Meyerhoff and his colleagues examined 46 chronic, heavy drinkers (38 males, 8 females) and 52 light drinkers (32 males, 20 females) recruited from the general community via newspaper advertisements and flyers. Researchers compared measures of regional brain structure using magnetic resonance imaging (MRI), as well as measures of common brain metabolites in both gray and white matter of the major cerebral lobes, subcortical nuclei, brainstem, and cerebellum using short-echo time MR spectroscopic imaging. Regional levels of N-acetylaspartate (NAA), myo-inositol (mI), and creatine- and choline-containing metabolites were also compared as a function of the groups' drinking practices, including binge drinking, and family history of alcoholism.
Meyerhoff said that the cumulative lifetime alcohol consumption among the heavy drinkers was about 60 percent of that typically found among treatment populations. Nonetheless, they found that frontal white matter NAA - generally considered to be a marker of neuronal damage - was lower in heavy drinkers than light drinkers, and was associated with lower executive and working memory functions.
"Although the men and women who drank heavily for many years demonstrated fewer changes in brain metabolites than do alcoholics in treatment," he said, "the abnormalities that we found are nonetheless associated with lower brain function." Lower cognitive functioning, he said, can affect daily living routines in not-so-obvious ways - the changes may be too gradual or too weak to be noticeable - but they may still interfere with basic cognitive processes such as decision making, planning, regulation of emotion and motivation, memory, and motor control. "These deficits may have an affect on the heavy drinkers' ability to judge his/her drinking as adversely affecting his/her life," he added, "and can also interfere with the drinker's decision to seek treatment or reduce drinking, thus perpetuating drinking behavior."
Meyerhoff said some of the behaviors that could be associated with the metabolite changes include the inability to apply consequences from past actions, difficulties with abstract concepts of time and money, difficulties with storing and retrieving information, and frequently needing external motivators.
"Ultimately we have to reconcile these two types of findings that have been found among abstinent alcoholics and people who are drinking too much but haven't sought out treatment," said Martin. "We don't know why the results are different. It could be that we're partially studying withdrawal, it could be that we're partially studying the metabolic effects of alcohol being in the brain at the time, it could be that we're studying neuronal damage ... there are a whole variety of explanations. I think that ultimately this study suggests to me that we need to look at people over time to see what happens as the degree of drinking and the duration of abstinence increase."
Both Martin and Meyerhoff said the study's findings of chemical abnormalities in the brains of heavy social drinkers provide evidence of brain impairment, even if the drinkers cannot see it themselves.
"Our major aim was to detect early adverse effects of alcohol drinking on brain function and to provide useful information to the heavy alcohol drinker, family practitioners, and society," said Meyerhoff. "Our message is: 'Drink in moderation! Heavy drinking damages your brain ever so slightly, reducing your cognitive functioning in ways that may not be readily noticeable. To be safe, don't overdue it.'" He added that for most adults, moderate alcohol use - up to two drinks per day for men, and one drink per day for women and older people - causes few if any problems.
Alcoholism: Clinical & Experimental Research (ACER) is the official journal of the Research Society on Alcoholism and the International Society for Biomedical Research on Alcoholism. Co-authors of the ACER paper, "Effects of heavy drinking, binge drinking, and family history of alcoholism on regional brain metabolites," were: R. Blumenfeld, D. Truran, J. Lindgren, D. Flenniken, V. Cardenas, L.L. Chao, J. Rothlin, C. Studholme, and M.W. Weiner of the Departments of Radiology, Medicine, Psychiatry, and Neurology at the University of California San Francisco and the MR Unit at the Department of Veterans' Affairs Medical Center in San Francisco. The manuscript is dedicated to the memory of Linda Rogers, Ph.D. (1946-2003). The study was funded by the National Institute on Alcohol Abuse and Alcoholism.