How Alcohol Affects Our Genes

A Few Beers Deep: How Alcohol Affects Our Genes In Different Ways

By: Rohan Sachdeva

It's Friday night, and you’re out at the bar with some friends. You’re a few drinks deep and start to feel a buzz coming on. The music sounds better, and your words flow easier. Everything starts to loosen up. It feels effortless, but a lot is going on beneath the surface. 

Every sip you take sets off a chain reaction in your body. In your liver, enzymes break down ethanol into acetaldehyde, a toxic intermediate, before turning it into harmless compounds your body can process.

You glance over and notice one of your friends is noticeably tipsy, even though you’ve had the same number of drinks. How can that be? Turns out, it’s not dependent on just body size. Part of the answer lies in genes.

Everyone carries ADH and ALDH2 enzymes that metabolize alcohol into harmless compounds, but not everyone’s enzymes work at the same speed. Your lightweight friend has a genetic variant that slows the breakdown, allowing toxic acetaldehyde to build up in their system. The result? The few drinks they’ve had have hit them a lot harder than everyone else.

A few drinks later, you really start to let loose. Your thoughts slow down, and your confidence rises. The edges of the room start to blur into a foggy haze.

In your brain, alcohol is changing the levels of neurotransmitters being produced, slowing your reflexes and making coordination more difficult. At the same time, your dopamine system is flooded, amplifying that feel-good buzz.

Your friend comes up to you, swaying slightly, and says they want to head home soon. While they feel overwhelmed and ready to call it a night, you’re still fired up by the music and want to leave it all on the dance floor. You decide to be a good friend and go with them anyway. 

Not everyone’s brain experiences alcohol in the same way. Changes in your neurotransmitter receptors, like GABA and glutamate, play a big role in how sensitive your brain is to alcohol. At the same time, variations in dopamine receptors influence how rewarding and pleasurable the buzz feels. These genetic differences are why your friend feels calm and sleepy after a drink, while you feel euphoric and energized.

When you get home, your friend passes out on the couch, while you feel hungry. You fire up the stovetop and start making some pasta. Alcohol stimulates appetite by boosting ghrelin, the “hungry” hormone, and dampening leptin, the “full” hormone. At the same time, your brain’s dopamine system, already buzzing from the night’s drinks, makes the idea of a warm plate of pasta feel especially rewarding.

Your experience of the late-night munchies isn’t the same for everyone. Your genes help shape it. Variants in genes that control appetite hormones, taste receptors, and dopamine signalling influence how hungry you get after a night out. 

You climb into bed with a full belly and fall into a deep sleep. Morning comes, and you stir awake feeling surprisingly refreshed. The pasta, the deep sleep, and your metabolism all seem to have worked in your favour. Your friend, on the other hand, groans from the couch, clutching their head and nursing a queasy stomach.

Once again, genes are at play. In addition to differences in ADH and ALDH2 genes, which regulate alcohol metabolism, genes that regulate inflammation, sleep cycles, and neurotransmitter activity help determine who wakes up with a pounding headache and who barely feels the effects.

While your friend struggles through a miserable morning, your body seems to shrug off the night’s excesses. However, repeated alcohol use can leave more than just temporary effects. Alcohol can actually rewrite how your genes are expressed through epigenetic changes. 

Epigenetics involves chemical tags that attach to your DNA, turning genes on or off without changing the underlying genetic code. Alcohol can add or remove these tags in genes that control stress response, liver metabolism, dopamine pathways, and neurotransmitter activity. 

These changes slowly rewire how your brain and body respond to alcohol. It can make alcohol feel less rewarding, alter your tolerance, and increase your long-term risk for addiction. It can also impede liver metabolism and make it harder for your brain to feel pleasure without alcohol.

So next Friday night, remember that your genetic makeup shapes how you experience alcohol. Keep in mind that drinking can leave lasting epigenetic marks on your brain and liver. And most importantly, no matter your genotype, your choices still matter, as they influence your long-term health.