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There is no doubt that chronic alcohol abuse, whether in the form of repeated binge drinking or daily excessive intake, leads to addiction and innumerable, serious health problems. Among the known complications is neurological injury, associated with cognitive impairment, neurotransmitter imbalances, and brain atrophy involving both white and gray matter. Prolonged, excessive consumption is undeniably linked with an increased risk for the development of dementia.
However, low to moderate alcohol consumption, particularly wine and specifically red wine, has been associated with a reduced risk of cardiovascular disease and a number of other disabilities and diseases. For a full recap, visit my previous series at PsychologyToday.com. Recent evidence suggests that compounds found in beer may reduce insulin resistance, reducing the risk of diabetes. These same compounds may also improve cognitive function and memory, despite many an evening lost, wandering with beer goggles askew.
Among the other conditions for which moderate alcohol consumption may be beneficial are neurodegenerative ones, like Alzheimer’s-type dementia (ATD) and Parkinson’s disease (PD). These pathologies share some similarities in the increased intracerebral accumulation of amyloid beta (Aβ) and tau, or α-synuclein aggregates, respectively. In accordance with many other studies examining BMI and comestibles like salt and fresh red meat, the relationship is not linear. Instead, it follows what is known as a “J-shaped" relation in which below a certain consumptive level (or BMI, in the case of that measure), adverse outcomes increase. Above a certain threshold, adverse outcomes again increase, and these borders define the “sweet spot.”
This suggests that, for low to moderate alcohol consumption, there is an associated reduction in the risk of cardiovascular disease, certain cancers, dementia, and overall early mortality. Such consumption has also been associated with an increase in cerebral blood flow (CBF).
A novel structure that has only been recognized within the last five years suggests an insight into the mechanism by which cerebral function may be preserved. This is a highly organized system of cerebrospinal fluid (CSF)-interstitial fluid exchange which occurs within the brain and has been described as the glymphatic system.
The lymph system is a well-described circulatory system adjunct that works in tandem with the immune system to clear organs and the blood of waste, toxins, and potential pathogens. Until recently, no such mechanism was believed to exist within the brain. However, the newly discovered glymphatic system appears to do just that.
It is a fluid transfer pathway that clears waste products and metabolites from the intercellular space of the brain. It drains these compounds into the lymphatic system of the head and neck, where they are carried to the liver for ultimate degradation. The glymphatic system appears to be a key pathway by which potentially neurotoxic proteins, including Aβ and tau proteins, are removed. Interestingly, the glymphatic pathway appears to exhibit a diurnal rhythm, with maximum activity occurring during certain periods of the sleep cycle.
Acute high exposure and chronic binge levels of alcohol were shown to negatively affect this mechanism by reducing the glymphatic system activity in mice. High alcohol intake in this particular study was the equivalent of approximately eight drinks per day, with a drink being a 12-ounce beer (5 percent alcohol) or a five-ounce pour of wine (12 percent alcohol). The function of the glymphatic system returned to normal 24 hours after the cessation of such activity with consumption at this level. Extremely high levels, the equivalent of approximately 21 drinks per day, were associated with profound and sustained detrimental effects.
What was very intriguing was the effect of low and moderate-dose alcohol consumption. At this level of consumption, there was an increase in the activity of the glymphatic system. These findings correlate with an observed reduction in the risk of dementia seen in those with low to moderate alcohol use. What is remarkable with this study is that for the first time, there is a cellular and physiological mechanism to explain the observed phenomena, mainly through enhanced glymphatic system clearance. By such a pathway, low to moderate alcohol consumption (one to three 12-ounce beers, or one to three five-ounce glasses of wine) may act to reduce neuro-inflammation.
This level of daily alcohol consumption is a cornerstone of many traditional diets throughout the world. Indeed, many other studies have attributed some of the benefit in approaches like the Mediterranean diet in no small part to just such a tipple. As it is so often in the course of nature, balance becomes the key. For as the Buddha observed, enlightenment lies in the Middle Path. And the Food Shaman might add, “In vino veritas!”
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