A study performed in mice hints that moderate amounts of alcohol may support brain health by reducing inflammation and flushing away metabolic byproducts, including the protein plaques associated with Alzheimer’s and Parkinson’s diseases.
"Prolonged intake of excessive amounts of ethanol is known to have adverse effects on the central nervous system," said lead author Maiken Nedergaard, MD, DMSc, co-director of the Center for Translational Neuromedicine at the University of Rochester Medical Center. "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."
The research, published in Scientific Reports, unexpectedly demonstrated that alcoholic consumption analogous to about 2.5 drinks a day boosts the productivity of the brain’s glymphatic system, a network of waste-clearing vessels within the organ's tightly controlled fluid environment.
Prior to its discovery by Nedergaard and her colleagues in 2012, scientists did not fully understand how waste molecules that accumulate outside brain cells are transported out of the sealed-off tissue area, called parenchyma. We now know that well-hidden channels surrounding the brain’s blood vessels allow exchange between the parenchyma and the cerebrospinal fluid (CSF) ventricles that ultimately drain into the lymphatic vessels of the head and neck. (Early investigations of the glymphatic system also revealed that it is most active during sleep, thus first identifying the crucial link between neurological health and adequate sleep time.)
Following multiple findings that low-to-moderate drinking is actually associated with an increase in overall health and longevity, the Rochester team sought to examine what goes on in the glymphatic system after indulging in a tipple or two.
Their experiment involved getting mice drunk.
First, conscious mice were injected with low (0.5 g/kg), intermediate (1.5 g/kg), or high doses (4 g/kg) of ethanol – corresponding to about 44 milliliters (1.4 ounces), 133 ml (4.5 oz), or 354 ml (12 oz) of pure alcohol for a 70-kilogram (154-pound) human.
Subsequently, a tracer compound was administered into the brain so that the flow of CSF could be observed.
Roughly 45 minutes after receiving the alcohol, mice in the low-dose group showed an average 40 percent increase in glymphatic flow, when compared to mice given a non-alcoholic control liquid. In contrast, the mice who were sloshed on intermediate and high doses displayed 34 percent and 28 percent reductions in glymphatic function, respectively.