This Genetic Variant May Make You More Vulnerable To Alcohol-Related Brain Damage

Most of us know that heavy drinking takes a toll on the brain, but new research suggests the damage may run deeper than we tend to think.

When you drink, your body breaks alcohol down into a compound called acetaldehyde. Acetaldehyde is an organic chemical compound that naturally forms when the liver processes alcohol. It's also found in cigarette smoke and some foods, but the body typically clears it quickly through an enzyme called ALDH2.

However, a problem arises with chronic heavy drinking, when the volume of acetaldehyde produced outpaces the body's ability to clear it, allowing it to accumulate and cause damage. With that buildup comes a cascade of effects, said Nagalakshmi Balasubramanian, the postdoctoral associate behind the research, in a press release.

She describes chronic alcohol consumption as "fanning the flames" of Alzheimer's disease, adding that it can "trigger inflammation, oxidative stress, and metabolic dysfunction while also contributing to depression, anxiety, and social withdrawal, changes that are often early warning signs of Alzheimer's disease. In many cases, the writing may be on the wall long before memory loss appears."

To study how acetaldehyde actually impacts Alzheimer's pathways, Balasubramanian used a mouse model carrying the ALDH2*2 genetic variant. The study was done in mice because the animals actually share over 95% of their genes with humans but are much easier to manipulate and observe.

The research examined how acetaldehyde toxicity from heavy, chronic alcohol use influences three things: tau pathology, inflammation, and metabolic dysfunction. Tau pathology refers to the buildup of a protein called tau, one of the recognized hallmarks of Alzheimer's disease. When that buildup combines with ongoing inflammation and cells that can't use energy well, the result is the kind of brain decline seen in Alzheimer's.

Not everyone clears acetaldehyde at the same speed, and that's where genetics enter the picture. A variant called ALDH2*2 impairs the body's ability to break down acetaldehyde efficiently, which means the compound can linger and do more damage.

You may already know this variant by its most visible sign. ALDH2*2 is best known for the "alcohol flush reaction," the warm, reddened face some people get after drinking. But the cheek flushing is the only easily perceptable effect of this genetic variant, and reveals there might be much more going on inside your body when it comes to processing alcohol.

People who carry the variant "struggle to clear acetaldehyde efficiently, allowing this toxic compound to linger like an unwelcome guest and fuel inflammation and oxidative stress throughout the body, including the brain," Balasubramanian said.

A bit of context helps to ease any panic that arises from the study. In the press release, heavy drinking is described as more than eight drinks per week for women, or more than 15 drinks per week for men, sustained over long periods. Those numbers offer a useful benchmark if you're trying to gauge where your own habits land, because most people don't come close to drinking that much.

Plus, it's important to be clear about the limits of this research. This is rodent research, which means the findings haven't been confirmed in people yet. Animal models are a valuable early step for understanding how alcohol changes the brain at the molecular level, but human studies are still needed before anyone can draw firm conclusions.

This research adds to the case that chronic heavy drinking may do more than dull your thinking in the moment. It may help drive the biological aging of the brain and feed into the pathways behind Alzheimer's disease over time, with people who carry the ALDH2*2 variant potentially more vulnerable.