Alcohol and Cognitive Function
Mark Scheutzow, M.D., Ph.D., MHA, MPH
In a previous article that appeared in February, we considered alcohol and cardiovascular health, showing that abstainers actually have the best cardiovascular risk profile. This article will consider moderate alcohol consumption as a risk factor for adverse brain outcomes and cognitive decline.
It is obvious that chronic dependent drinking is associated with Korsakoff syndrome and alcoholic dementia, but the long-term effects of light or moderate alcohol consumption are poorly understood.
There are conflicting results in the research of the effects of moderate alcohol use on the brain. Some studies show no effect, others are associated with reduced total brain volume, increased ventricular size, grey matter atrophy, and reduced density of frontal and parietal grey matter. Part of the problem lies in study design. It is difficult to randomize alcohol consumption over a long period of time; most studies have been cross-sectional or with limited prospectively gathered data; and, people typically underestimate their alcohol intake, which is more inherent in a retrospective study.
A recently published study used data on alcohol consumption gathered prospectively over 30 years to investigate the associations between brain structural content and functional outcomes in 527 non-dependent alcohol using participants in the United Kingdom. The hypothesis was that light drinking of less than seven drinks per week was protective.
The study found a previously uncharacterized dose dependent association between alcohol consumption over 30 years of follow-up and neurological changes. Higher alcohol consumption was associated with increased odds of hippocampal atrophy in a dose dependent fashion (OR 5.8). Individuals with moderate drinking (14-21 drinks/week) had three times the odds of right sided hippocampal atrophy. Higher alcohol use was associated with reduced grey matter density, hippocampal atrophy, and reduced white matter microstructural integrity. There was no protective effect of light drinking over abstinence on brain structure.
Hippocampal atrophy is a very sensitive and relatively specific marker of Alzheimer’s disease although it has also been reported in chronic alcoholics. Previously, the brain regions most vulnerable to alcohol abuse were thought to be the frontal lobes. In this study even higher alcohol use was not associated with significant frontal brain atrophy.
Higher alcohol consumption predicted faster decline on vocabular fluency but not on sentence fluency or word recall. Any amount of drinking, including one drink daily, had a decline in vocabular fluency compared to abstainers. People drinking seven to less than 14 drinks weekly had a 14% reduction in vocabular fluency over 30 years. There was no evidence to support light drinkers being relatively protected from cognitive decline compared with abstainers. Vocabular fluency has been associated with frontal executive function. Sentence fluency depends more on the temporal lobe.
There is no agreed upon mechanism for the biological mechanisms underlying these findings. Ethanol and its metabolite acetaldehyde are neurotoxic and cause both morphological changes and a reduction in hippocampal neurons. The right side of the brain may be more susceptible for hippocampal damage. Individuals with a higher risk of Alzheimer’s disease (ApoE4 homozygotes) have more severe hippocampal atrophy on the right side. There is also an association between increased alcohol consumption and reduced grey matter density in the amygdala. Alzheimer’s disease also presents with amygdala atrophy.
The strengths of the study were the 30-year longitudinal data on alcohol consumption and the detailed available data on confounders. The additional strengths included the advanced MRI techniques used and the large volume of imaging data collected. The limitations were that the participants were mostly educated and middle-class men in the civil service in the United Kingdom. Some people may have been alcohol dependent during a point in the study.
If you remember, the previous article showed there were no cardiac benefits to alcohol use, even light drinking. This study has the same findings – no cognitive benefits to even light alcohol use. Abstinence is the best policy for maximizing cardiac and cognitive function as individuals age.
Mark H. Scheutzow, M.D., Ph.D., MHA, MPH, of Asheboro, NC, received his Doctorate of Medicine and of Philosophy from Ohio State University College of Medicine, Columbus, OH, and his Master of Health Administration/Master in Public Health from UNC Gillings School of Global Public Health, Chapel Hill, NC. Over the last five years he has completed over 1700 continuing medical education hours in pain, addiction, and psychiatric medicine, as well as training in Age Management Medicine. He is certified by, and a Diplomat of the American Board of Addiction Medicine, certified by, and a Diplomat of the American Academy of Pain Management, was a Founding Diplomat of the American Board of Holistic Medicine, and is a Fellow and Board Member of the American Association of Integrative Medicine. He practices Interventional and Chronic Pain Medicine, Addiction Medicine, Addiction Psychiatry and Regenerative Pain Medicine, in Winston-Salem and Greensboro, NC. Dr. Scheutzow can be reached at firstname.lastname@example.org.