A drug used to slow the relentless cognitive decline in Alzheimer’s patients appears to repair brain damage following binge drinking — at least in rats.
Researchers at Duke University found that a short course of the drug donepezil can reverse both structural and genetic damage that bouts of alcohol use causes in neurons, or nerve cells, in young brains.
Few studies have examined the extent to which alcohol effects the developing brain in teens and adolescents, but it’s evident that drinking during adolescence causes changes. Much of the existing research has looked specifically at the hippocampus, which is linked to learning and memory. It is unknown whether or not the changes are permanent.
“Clinical studies are starting to show that adolescents who drink early and consistently across the college years have some deficits in learning and memory,” said senior author Scott Swartzwelder, Ph.D., professor in psychiatry at Duke.
“It’s not a sledgehammer — it’s not knocking their memory out completely,” he continued, “but there are demonstrable, if subtle, effects on their cognitive function.”
Since ethics preclude adolescents being exposed to alcohol to study its effects, researchers use the developing brains of rats to understand the effects of “intermittent alcohol exposure” — the equivalent of drinking to a blood-alcohol level of .08 (the legal limit for driving while impaired) three or four nights a week.
When researchers examined neurons in the brains of adult rats that had been exposed to alcohol when they were adolescents, they found far fewer dendritic spines, which resemble leggy mushrooms that stem from neurons and receive information. What looked like a dense forest of dendritic spines in healthy rats was reduced to sparse, stubby structures in those previously exposed to alcohol.
“Any change in the density of spines on dendrites tells you those cells are processing information differently than they should be, and whether that processing goes up or down can be a problem,” Swartzwelder said.
“Downstream, these changes can throw a monkey wrench into how cells function. You can imagine how quickly that could multiply in a region of the brain where you’ve got millions of cells interacting.”
But a short course of treatment with donepezil reversed these changes by affecting the activity of a gene called Fmr1, which is linked to Parkinson’s disease and autism. Alcohol appears to affect the density of dendritic spines, and the drug restored their density, making changes on a genetic level.
The study was published in the journal Alcoholism: Clinical and Experimental Research.
Although binge drinking harms the brain, moderate drinking can help adult brains help clear away toxins, including those associated with Alzheimer’s disease. A study at the University of Rochester found that when mice were exposed to the equivalent of two-and-a-half drinks a day, their brains showed less inflammation and were more efficient at clearing out toxic Alzheimer’s-related beta amyloid and tau proteins from the brain compared to control animals.
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