Watch someone after they’ve had a few drinks, and you’ll find clear evidence that alcohol does something to their brain. They stumble, slur their words, lose control of their emotions, and forget things.
Some people have tried to explain this behavior as the aftermath of cell death caused by alcohol. Often, it’s packaged as a neat factoid like “Three beers kill 10,000 brain cells.”
But is this true? No. But alcohol does damage some of your 86 billion brain cells, or neurons, which send electrical and chemical messages within the brain and between it and other parts of the body.
Ethyl alcohol (the kind found in boozy beverages, also known as ethanol) can kill cells and microorganisms. That’s what makes it an effective antiseptic. Fortunately, when you drink alcoholic beverages, your body tries not to let all of that ethanol roam around unchecked. Enzymes in your liver convert it first info acetaldehyde (which is highly toxic) and then into acetate, which is broken down into water and carbon dioxide and eliminated by your body.
The liver can only work so fast, though, processing about 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of distilled spirits per hour. If you’re knocking drinks back fast enough that your liver can’t keep up, the excess alcohol hangs out in the blood and travels through the body until it can be processed.
When this alcohol reaches the brain, it doesn’t kill the cells. What it does is inhibit the communication between dendrites, or branching connections at the ends of neurons that send and receive information between neurons, in the cerebellum, a part of the brain involved in motor coordination. This poor communication results in some of the typical impairments of intoxication.
Researchers at Washington University in St. Louis found that alcohol, even when applied directly to neurons, didn’t kill them. It just interfered with the way they transmit information. Specifically, the researchers showed that alcohol causes certain receptors on neurons to manufacture steroids that inhibit memory formation.
Some alcoholics can experience neuron death as part of a brain disorder called Wernicke-Korsakoff syndrome. In these cases, the evidence again suggests that the disease and cell death aren’t caused by the alcohol itself, but a B1 (or thiamine) deficiency and general malnutrition that often go hand in hand with alcoholism.
For moderate drinkers, a number of studies from the last 15 years suggest that, far from killing brain cells, a little tipple is actually associated with a reduced risk of cognitive decline and dementia.