What Happens When You Drink Too Much?

Alcohol’s effects are worse than you think.

Many of us drink, whether it’s a beer or two … or sometimes more. 

In fact, 90 percent of the population has had a drink during the past month, says Olivier George, an assistant professor at The Scripps Research Institute, who studies the neurobiology of addiction. 

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Some of alcohol’s initial effects are positive — undoubtedly a reason for its wide appeal. After the first drink, you’ll feel better, more relaxed, less anxious or stressed. By the second drink, your blood alcohol level is about 0.05 to 0.08 — “right below the DUI,” George says. 

It’s what he calls the “sweet spot.” “You’re more talkative, more receptive, more eloquent,” he says. “Disinhibition makes alcohol a social lubricant, so people start talking to each other. It’s fun — that’s why people go to happy hour, so they can de-stress from the day.”

Those positive effects are the work of endorphins, George explains, which act like natural opiates in the brain. Alcohol releases the same pleasurable compounds in the brain that exercise does — so the euphoria you feel when drinking is similar to how you feel after a good workout or run.

And that sociability, even for the shy or socially awkward? "People don't seem to feel any social anxiety after they've had a couple of drinks,” he says. It’s likely the result of GABA, a neurotransmitter released by alcohol. GABA inhibits negative feelings like shyness.

Alcohol also releases serotonin, a neurotransmitter that George describes as, “in a sense, like a light Prozac" — meaning, initially anyway, alcohol has an effect similar to an antidepressant. 

Another drink or two, however, and you’ll start to run into trouble.

Alcohol also blocks another neurotransmitter, called glutamate, which is the primary way your prefrontal cortex controls the rest of your brain. Think of it as a kind of “central command” with power over everything else, such as your emotions, actions, and stress levels. When alcohol blocks glutamate transmission, it impairs decision making and other “command” functions.

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By the third or fourth drink, you’re forgetting to count how many drinks you’ve had. You might think you’re the life of the party, but here’s where the fun stops. With glutamate blocked in the brain, "the cortex isn't in control anymore," George says. You could have dramatic mood swings, and that initial euphoria may turn into depression, anger, or a crying jag. You’ll likely lose motor coordination and awareness of your actions. 

Glutamate also controls memory and new memory formation. It’s believed to be responsible for why some people black out, George says. “When you wake up in the morning, you don't remember what happened, because the system was completely shut down." Continue to drink heavily over time, and you’ll permanently damage your ability to form new memories.

Past four or five drinks, you enter a true danger zone. A blood alcohol level of 0.3 is “close to the level of general anesthesia,” George notes, and could send you into a coma. At a 0.4 blood alcohol level, you have a 50 percent chance of death. (Check estimates of blood alcohol levels here.)

Alcohol’s initial feel-good effects might keep people drinking. We may go from “I'm drinking because I want to have a little bit of fun, to I'm drinking because I don't want to be depressed,” George says. At that point, you’re veering into alcohol dependence. “This is one of the reasons we think people go from acute drinking to regular and compulsive alcoholism.” “People use alcohol to self-medicate for depression or anxiety.”

Binge drinking is usually defined as more than four drinks for women or five drinks for men within two hours. If that’s you, you may have more to worry about than you think. George studies animal models of binge drinkers in his lab (with — that’s right — alcoholic rats). Three times a week — “party days,” he calls them — the rats have unlimited access to alcohol. After just three or four weeks, they start showing the same neuroadaptations in the brain seen in chronic alcoholism.

George thinks we need to reconsider official definitions of alcoholism. A chronic weekend binge drinker is already harming the brain, he says: “Excessive drinking is a problem already."

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