Monday, August 1, 2016

This is your brain on wine: an update on cognition, Alzheimer’s, and wine

Even as the silent epidemic of Alzheimer’s disease grows, wine’s positive if seemingly unlikely effects on brain health continue to offer a map toward a solution. It’s long been known from lifestyle surveys that wine drinking is a defining characteristic of the lowest risk group for Alzheimer’s (AD).* In fact, without exception regular wine consumption is the only factor that features in every study across the board. But given that alcohol is neurotoxic, it just didn’t seem to make sense.

The resveratrol promise tested

Resveratrol, the anti-aging miracle molecule in wine, offered a plausible explanation. Laboratory and animal studies showed that resveratrol works in several specific ways to counteract the noxious effects on brain cells of protein plaques called ß-amyloid, a marker for AD. While the role of ß-amyloid in the pathogenesis of AD is still not completely clear, it is evident that with enough resveratrol the formation of the plaques can be suppressed, and health of the neurons enhanced, at least in lab studies. No other product, whether a drug, vitamin, or nutraceutical, has shown such promise.
These findings led to several clinical trials of resveratrol as a supplement. Most are still are underway, with only one having published results (1); however this study produced more questions than answers. For example, after one year levels of one type of ß-amyloid in the fluid around the brain (CSF) declined more in the placebo group, and brain volume shrunk more in the resveratrol cohort. The authors pointed out that the “etiology and interpretation of brain volume loss observed here and in other studies are unclear, but they are not associated with cognitive or functional decline.” One take-away message was that only tiny levels of resveratrol in the brain were required to have an effect.

More to wine’s benefits than just resveratrol

So there must be something more to wine’s unique association with brain health than resveratrol and AD. It is likely that there is synergy between resveratrol and other polyphenols in red wine, for example, and alcohol may help absorption of these compounds making them more bioavailable. And we cannot discount the fact that moderate daily consumption of wine is a lifestyle marker for other healthy behaviors. Maybe wine drinkers are just smarter to begin with!
*Studies on lifestyle factors and cognition/dementia

  • Canadian Study on Health and Aging: Cohort study of >6000 subjects; wine, coffee, NSAID use, regular exercise (Am J Epidemiol 2002)
  • Copenhagen City Heart Study: 15-year case-control study of >1700 subjects; wine consumption but not beer or spirits correlated with lowest risk (Am Acad Neurol 2002)
  • Bordeaux Study: Cohort of ~4000 subjects age >65; 80% lower incidence in wine drinkers (European J Epidemiol 2000)
  • Catholic University of Rome multicenter study: cognitive testing of >15,000 subjects; highest scores in men drinking up to 1 liter/day, women 0.5 liters/day (Alcoholism Clin Exp Res 2001)

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