Low levels of alcohol consumption may reduce inflammation and help the brain clear away toxins, including those associated with Alzheimer’s disease, new research suggests.
“Prolonged intake of excessive amounts of ethanol is known to have adverse effects on the central nervous system. However, in this study we have shown for the first time that low doses of alcohol are potentially beneficial to brain health, namely it improves the brain’s ability to remove waste,”
said Maiken Nedergaard, co-director of the Center for Translational Neuromedicine at the University of Rochester Medical Center (URMC) and lead author of the study.
Glymphatic System
The finding adds to a growing body of research that point to the health benefits of alcohol in small doses. While excessive consumption of alcohol is a well-documented health hazard, many studies have linked lower levels of drinking with a reduced risk of cardiovascular diseases as well as a number of cancers.
The research focuses on the glymphatic system, the brain’s unique cleaning process that was first described by Nedergaard and her colleagues in 2012.
They showed how cerebral spinal fluid (CSF) is pumped into brain tissue and flushes away waste, including the proteins beta amyloid and tau that are associated with Alzheimer’s disease and other forms of dementia. Subsequent research has shown that the glymphatic system is more active while we sleep, can be damaged by stroke and trauma, and improves with exercise.
Astrocytes in normal physiological conditions facilitate the influx of CSF to perivascular pathways.Chronic exposure to 0.5 g/kg (low dose) of alcohol per day downregulates GFAP expression and leads to increased glymphatic function.
Chronic exposure to 1.5 g/kg alcohol (binge drinking level) increases AQP4 expression in the non-end-foot processes, increases GFAP expression, and impairs glymphatic function.
Credit: Iben Lundgaard, et al CC-BY
Conducted in mice, the new study looked at the impact of both acute and chronic alcohol exposure.
When the researchers studied the brains of animals exposed to high levels of alcohol over a long period of time, they observed high levels of a molecular marker for inflammation, particularly in cells called astrocytes which are key regulators of the glymphatic system. They also noted impairment of the animal’s cognitive abilities and motor skills.
2 ½ Drinks A Day
Animals exposed to low levels of alcohol consumption, analogous to approximately 2 ½ drinks per day, actually showed less inflammation in the brain and their glymphatic system was more efficient in moving CSF through the brain and removing waste, compared to control mice who were not exposed to alcohol.
The low dose animals’ performance in the cognitive and motor tests was identical to the controls.
“The data on the effects of alcohol on the glymphatic system seemingly matches the J-shaped model relating to the dose effects of alcohol on general health and mortality, whereby low doses of alcohol are beneficial, while excessive consumption is detrimental to overall health.
Studies have shown that low-to-moderate alcohol intake is associated with a lesser risk of dementia, while heavy drinking for many years confers an increased risk of cognitive decline. This study may help explain why this occurs. Specifically, low doses of alcohol appear to improve overall brain health,”
said Nedergaard.
Funding for the work was provided by the Department of Navy’s Office of Naval Research, the National Institute of Neurological Disorders and Stroke, and the National Institute on Aging.
Iben Lundgaard, Wei Wang, Allison Eberhardt, Hanna Sophia Vinitsky, Benjamin Cameron Reeves, Sisi Peng, Nanhong Lou, Rashad Hussain & Maiken Nedergaard
Beneficial effects of low alcohol exposure, but adverse effects of high alcohol intake on glymphatic function
Scientific Reportsvolume 8, Article number: 2246 (2018) doi:10.1038/s41598-018-20424-y