What Are the Effects of Alcohol Consumption on the Brain?

A glass of wine with dinner, a happy-hour beer after work, a cocktail (or three) on vacation: Alcohol is deeply ingrained in American culture, and for many, it's a normal part of their daily lives.

However, a 2018 study published in The Lancet suggests that there is no safe level of alcohol consumption. Even low levels of consumption can harm your health; higher levels of consumption have worse effects. Some of those effects, like slurred speech and diminished memory, can be quite clear; others, like long-term cellular damage, may not be as obvious.

According to the U.S. Department of Agriculture (USDA) and U.S. Department of Health and Human Services (HHS) 2020-2025 Dietary Guidelines for Americans, drinking in moderation is defined as one or fewer drinks a day for women and two or fewer drinks a day for men.

The Centers for Disease Control and Prevention (CDC) defines heavy drinking for women as consuming eight or more drinks per week and for men as consuming 15 or more drinks per week.

Where does binge drinking fit into the equation? According to the CDC, binge drinking is defined as consuming four or more alcoholic drinks for women or five or more alcoholic drinks for men on the same occasion.

If you've ever wondered what's really going on in the brain when a person's had too much to drink, here's a brief primer.

Short-Term Effects of Alcohol

Neurotransmitters

Drinking alcohol alters the levels of neurotransmitters in the brain, said Maria Pagano, PhD, an addiction researcher and associate professor of psychiatry at Case Western Reserve University School of Medicine. These chemical messengers transmit signals throughout the body and play a large role in controlling behavior, emotion, and physical activity.

"For starters, alcohol slows down the neurotransmitter GABA, and that's what drives the sluggish movement, slurred speech, and slower reaction time in someone who's intoxicated," said Pagano. At the same time, Pagano added, alcohol speeds up a neurotransmitter called glutamate, which is responsible for regulating dopamine in the brain's reward center. "It's generating feelings of pleasure and well-being," said Pagano. "That's why you might get that warm, fuzzy feeling when you're drinking."

Judgment

Alcohol also lowers inhibitions and clouds judgment, which could lead a person to engage in risky behaviors like having unprotected sex or driving a car while drunk. And if a person has an underlying mental health disorder, like depression or bipolar disorder, alcohol can exacerbate symptoms and increase mood swings.

Binge drinking also affects the cerebellum (which helps regulate balance) and the cerebral cortex (which is responsible for taking in and processing new information). When these regions of the brain are slowed down, a person might feel dizzy and stagger when walking, have blurred or double vision, and have difficulty paying attention to things going on around them. "Your sensory uptake has been dulled, so you're not going to be taking in new information as well," said Pagano.

Memory

The brain's hippocampus region—which helps create new memories—is also affected by alcohol, which contributes to blackouts and short-term memory lapses while drinking. According to a 2020 review in the journal Alcohol Research, men and women experience alcohol-induced blackouts at equal rates, even though women tend to drink less often and less heavily than men.

In the most extreme cases, drinking too much alcohol too fast can cause a loss of consciousness. "We worry about that for safety reasons, of course, but this is also a sign of cell death," said Lara Ray, PhD, professor of psychology at the University of California Los Angeles Brain Research Institute. "So we also worry about brain damage—and with multiple episodes of heavy drinking, that damage can have long-term consequences for learning and memory."

Most of these effects are caused by a spike in blood-alcohol content over a short period of time, said Ray. Taking breaks between drinks—and being sure not to imbibe on an empty stomach—can help reduce your risk of experiencing them yourself.

Long-Term Effects of Alcohol

Binge drinking can certainly put you at risk for embarrassment, injury, or poor decisions. Unfortunately, if you regularly drink alcohol, you can permanently harm your health.

Shrinks Your Brain

According to a 2021 study in Scientific Reports, heavy drinking could lead to loss of brain volume. The researchers found that people with alcohol use disorder (AUD) had less brain matter than people without AUD. The affected brain regions controlled skills like attention, language, memory, and reasoning. By changing your brain, alcohol can therefore lead to worse memory and impaired judgments, among other changes.

Other studies agree that alcohol can impact memory. Heavy drinking also may speed up memory loss in early old age, at least in men, according to a 2014 study in the journal Neurology. Men in the study who had more than two and a half drinks a day experienced signs of cognitive decline up to six years earlier than those who did not drink, had quit drinking, or were light or moderate drinkers (results for women were not conclusive, the authors said).

Increased Tolerance and Dependence

People who drink regularly may also notice that booze doesn't have the same effect on them as it used to. "With chronic drinking, the wiring element to your brain's reward system can get worn out and lose some of its normal functioning," said Pagano. "You build up a tolerance, and after a while, you don't feel as good as you once did with the same amounts of alcohol."

These changes in the brain also cause people to change their behaviors around alcohol. "They become much more likely to seek alcohol and to rely on it to cope with negative feelings," said Ray. "Often when people start drinking, they drink to feel good—but as they drink more chronically, they have to drink to avoid feeling bad."

Cell Death and Brain Damage

Drinking to avoid feeling bad leads to higher and higher levels of consumption, which can cause greater damage to the brain and the rest of the body. Alcohol kills cells and damages cellular networks in the brain, for example, and it's not entirely clear to what extent they can grow back.

"You might hear the classic term 'wet brain,' and that's a real thing," said Pagano. According to the National Institute of Neurological Disorders and Stroke (NINDS), "wet brain" is technically known as Wernicke-Korsakoff syndrome, and it's a type of dementia caused by a deficiency of thiamine, or vitamin B1, in the brain. Alcohol hinders a person's absorption of thiamine and interferes with the enzyme that converts it into a usable form in the body.

"Chronic drinking can really alter a person's personality," said Pagano. "I've seen cases where I wouldn't recognize a patient based on how they're acting." Brain damage (and symptoms like brain fog) can also be caused by cirrhosis of the liver, another common complication of long-term, heavy drinking.

After cutting back on alcohol, Pagano said, damaged regions of the brain can start to "light up" again on brain scans. "But there are certainly limits," said Pagano, "and we often see improvement only after months of complete abstinence and giving the brain time to heal."

Alcohol-related damage to the brain (and the body) can even be deadly: In a 2018 study published in The Lancet, people who regularly had 10 or more drinks a week had one to two years shorter life expectancies than those who had fewer than five drinks a week.

That number jumped to four or five years for those who had 18 drinks or more per week. The researchers observed that alcohol consumption was linked to various types of cardiovascular problems, including stroke—a potentially fatal blockage of blood flow to the brain.

How Much Is Too Much?

Whether or not a person engages in drinking should be a decision they make on their own, or with the help of a doctor or mental health professional. For many people without a history of dependence or addiction, Pagano said, drinking at low or moderate levels—no more than seven drinks a week for women, and no more than 14 a week for men—can be a healthy part of life.

But if you have a response to alcohol that's noticeably different from other people's, it may be time to reexamine your relationship with drinking, advised Pagano. "If you can drink other people under the table, or you see your friends leaving alcohol in their glasses and you know you could never do that yourself, those are signals you've got a genetic setup for developing an addiction," said Pagano.

Ray agreed that while some people can safely stay within the 2020-2025 Dietary Guidelines for Americans recommendations for low-risk drinking—one or fewer drinks a day for women and two or fewer drinks a day for men—others may have a hard time sticking to those limits due to genetics, stressful life situations, or other risk factors. That's important to keep in mind, said Ray, as researchers have observed an increased prevalence of alcohol-use disorders and heavy drinking in recent years, primarily among women.

It's important to note that the 2020-2025 Dietary Guidelines for Americans also state that some people should avoid alcohol altogether, including people who are:

• pregnant or think they might be pregnant
• going to drive a vehicle or operate machinery
• participating in activities that require skill, coordination, or alertness
• taking medications that interact with alcohol
• managing a medical condition that could be made worse by drinking alcohol
• recovering from alcohol use disorder (AUD)
• under the U.S. legal drinking age of 21

While alcohol can act as a social lubricant and may provide "liquid courage" for people who are otherwise anxious or shy, Pagano warned against relying on it too much. "If drinking allows you to engage in behavior you wouldn't engage in otherwise, maybe you shouldn't be doing it," said Pagano. "And if you always use it to have a good time, you won't learn how to be okay in social situations without it."

For people who do decide to stop drinking, Pagano says there are many reasons to be optimistic. "A lot of people fear giving it up and not being able to drink," said Pagano. "But in reality, life can get better when you're making better choices and you're able to fully savor your experiences, rather than seeing them through a haze."

Let's face it—alcohol can be tricky. It's legal (if you're over 21), it's often used in social situations, and it can have some health benefits when used in moderation. But when used in excess or in certain situations, it can have some pretty negative consequences. If you feel alcohol is interfering with your life or health and want help stopping or regaining control, contact your healthcare provider or call the Substance Abuse and Mental Health Services Administration (SAMHSA) national helpline at 1-800-662-HELP (4357).