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Alcoholic drinks are meant as an integral part of social gatherings in many cultures around the world. Drinking such beverages are advised to be enjoyed responsibly because too much can affect decision-making and inhibitions. Responsible drinking of one to two glasses of alcohol may be helpful to the brain, according to a new study published in Scientific Reports.
The new study showed that drinking low doses of alcohol can help the brain clear out accumulated toxins and wastes in the nervous system. Also, the effects can be helpful to reduce the causative agent behind Alzheimer’s disease, a chronic neurodegenerative disease with dementia as its hallmark symptom.
“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 Dr. Maiken Nedergaard, the lead author of the study and co-director of the Center for Translocational Neuromedicine at the University of Rochester Medical Center.
In a report in 2013, Dr. Nedergaard and her colleagues discovered that a dedicated system helps the brain remove harmful compounds in the central nervous system. It is called the glymphatic system that acts a functional waste clearance pathway for the central nervous system. The glymphatic system is responsible for the removal of beta-amyloid, a toxic protein that can build up in the brain. High concentration of the toxic protein can affect the communications between neurons that can lead to Alzheimer’s disease. It seems that drinking a small amount of alcohol may help both the central nervous and glymphatic systems remove wastes and toxic proteins more efficiently.
To determine the benefits of alcohol drinks to the brain, the researchers conducted their study in mice and analyzed the impact of alcohol exposure. Mice exposed to small doses of alcohol, equivalent to about two and a half drinks a day, expressed less inflammation in the brain with a more efficient glymphatic system in moving the cerebrospinal fluid through the brain and removing waste products, including beta-amyloid and tau proteins, compared to mice without alcohol exposure. The mice exposed to small amounts of alcohol also retained similar cognitive functions with the controls.
However, the mice models exposed to high doses of alcohol over a period of time expressed significant inflammation in the brain. The cells called astrocytes that regulate the glymphatic system were also inflamed, affecting their capability to move the CSF and waste products out of the central nervous system. Moreover, the cognitive functions and motor skills of the mice were found to be impaired as well.
“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,” said Dr. Nedergaard.
Ethyl alcohol or ethanol is the active ingredient in beer, liquor, and wine products. Ethanol is produced during the fermentation process of alcohol beverages. While the chemical can help people socialize in gatherings, it mainly serves as a depressant in the brain. It acts on the receptor sites of neurotransmitters, such as GABA, glutamate, and dopamine. Signs that ethanol has acted with GABA and glutamate receptors include slurred speech, poor coordination, and impaired memory. When it acts on the dopamine receptors, the people receive pleasurable feelings that cause them to drink more.
The effects of alcohol vary from person to person depending on their age, gender, genetics, overall health condition, and how long they have been drinking. Of course, the alcoholic drink matters as well, depending on its composition.
Occasional drinkers usually suffer from blackout after drinking high doses of alcohol, while moderate drinkers can receive both positive and negative health associations. Potential positive effects of moderate drinking equivalent to one or two drinks per day may reduce risks of cardiovascular diseases and certain types of cancers. Potential negative effects include severe behavioral changes, such as violence, becoming more prone to accidents including drowning and falls, and physical health consequences, including the risk of breast cancer. Heavy drinkers commonly suffer from brain damage that leads to cognitive issues and thiamine deficiency, a deficiency of vitamin B1 which often results in the Wernicke-Korsakoff syndrome.
“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 Dr. Nedergaard.
The study suggests that responsible drinking of low doses of alcohol may help promote a healthy central nervous system. This may be combined with the habit of getting adequate sleep every day to further improve the glymphatic system. Dr. Nedergaard and colleagues discovered in a study that sleeping speeds up the removal of toxic proteins in the brain.
[메디컬리포트=Ralph Chen 기자]