Teens and young adults who binge drink often have genetic and structural changes in the brain as a result of the overuse of alcohol. The brain is still developing in the teen years, and damage from drinking is a serious risk.
New research from Duke Health could provide a way for that damage to be released. A study completed recently showed that the drug donepezil, which is used for patients who have Alzheimer's disease (AD) could reverse that damage.
In teens who drink, especially bouts of binge drinking where large amounts are consumed in a short time, the damage done is mostly to the hippocampus of the brain, which is responsible for learning and memory. Since teens are still developing and still learning, any injury that impacts memory or the ability to learn new information can be devastating. Not a lot is known about this damage, including whether or not it is permanent. It's difficult to study the effects of drinking on the teenage brain since it's not ethical to expose teens to alcohol in clinical trials and studies that use self-reported data are not as reliable. The team at Duke used lab rats since the brains of rats are similar to human brains.
Senior author of the study Dr. Scott Swartzwelder is a professor of psychiatry at Duke. He explained what researchers already know about drinking in adolescence, "Clinical studies are starting to show that adolescents who drink early and consistently across the college years have some deficits in learning and memory. It's not a sledgehammer -- it's not knocking their memory out completely -- but there are demonstrable if subtle, effects on their cognitive function."
In the study, the researchers exposed rats who were still developing to "intermittent" alcohol use. They were given enough alcohol to raise their blood alcohol content (BAC) to .08 which is the legal limit for driving while intoxicated. The rats ingested this amount of alcohol three to four times a week. In adulthood, those same rats were examined, and in the brain, it was found that they had far fewer dendritic spines coming off the neurons. Dendritic spines carry signals and neurotransmitters around the brain. In rats not exposed to alcohol, these spines reach out and resemble a heavily treed forest of branches and connections. In the rats who had been exposed to booze, the spines were far fewer in number and were stubby and not as firmly connected.
Swartzwelder explained how necessary it is for these spines to be healthy and strong, stating, "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. They need to be just right. 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."
When the alcohol-exposed rats were given the drug donepezil, the damage to the neural networks of spines seems to reverse itself. There was more density, and the spines grew longer. The team also discovered that the gene Fmr1, when mutated, results in the same kind of damage to the dendritic spines in the brain. The use of alcohol changed the way the Fmr1 gene is expressed. The donepezil not only reversed the structural damage to the brain by improving the number and quality of the spines but was able to correct the regulation of Fmr1 as well. The video below has more information on what this could mean for research into conditions like Alzheimer's, Parkinson's and alcoholism.