Does alcohol kill brain cells? Alcohol, blackouts and memory
The real effects of alcohol on the brain are less dramatic than “killing brain cells”, and more widespread than most people think. Here’s what the research shows.
“Every drink kills brain cells” is one of those facts everyone has heard. It isn’t the best way to describe what happens. Alcohol’s real effects on the brain are about memory recording, brain volume and the brain’s wiring, and recent studies suggest they start at lower levels of drinking than many people assume.
Why blackouts happen
A blackout is a gap in memory for things that happened while you were drinking. According to the US National Institute on Alcohol Abuse and Alcoholism (NIAAA), alcohol interferes with the hippocampus, the brain region that turns experiences into long-term memories. During a blackout you’re awake, talking and making decisions, but the memories are never stored. That’s different from passing out.
- Fragmentary blackouts (“brownouts”) are the most common: patchy memories that sometimes come back with a reminder.
- En bloc blackouts are complete gaps, often lasting hours, and the memories can’t be recovered because they were never made.
Blackouts are more likely when you drink quickly or on an empty stomach, or combine alcohol with sleep or anxiety medications. Among college students, blackouts predict injuries, emergency room visits and lower grades.
What alcohol does to the brain over time
Brain volume. A 2022 study in Nature Communications by Remi Daviet and colleagues looked at brain scans of more than 36,000 UK adults. Lower brain volume was already visible at an average of 1 to 2 UK units a day (a UK unit is 8 grams of alcohol, so that’s roughly one standard North American drink or less). Going from 1 to 2 units a day was associated with brain changes equivalent to about 2 years of aging. The study was a snapshot, not proof of cause, but the pattern was consistent across most of the brain.
The hippocampus. In a 2017 BMJ study, Anya Topiwala and colleagues followed 550 adults for 30 years. People who drank 14 to 21 UK units a week had 3 times the odds of shrinkage in the hippocampus compared with non-drinkers. Light drinking showed no protective effect.
White matter. Long-term heavy drinking damages the brain’s white matter, the bundles of fibres that connect regions. Research summarized by the NIAAA found reduced integrity in frontal tracts in people with a long history of heavy drinking, with possible recovery in those who quit earlier in life.
Wernicke-Korsakoff syndrome. Heavy drinking can lead to severe vitamin B1 (thiamine) deficiency. Cleveland Clinic describes the first stage, Wernicke encephalopathy, as confusion, unsteadiness and eye or vision problems: a medical emergency that needs thiamine fast. Untreated, it can progress to Korsakoff syndrome, with severe memory loss.
Alcohol and sleep
A nightcap may help you fall asleep, but a 2013 review of 20 studies found alcohol disrupts the second half of the night and delays REM sleep. Since sleep is when memories are consolidated, a few drinks in the evening can affect what you remember from the day. See sleep and memory.
How much is “safe”?
In 2023 the World Health Organization stated that no amount of alcohol is safe for health, pointing in particular to cancer risk. Canada’s Guidance on Alcohol and Health (2023) puts it on a scale:
- 0 drinks a week: not drinking has benefits, such as better sleep.
- 2 or fewer: you’re likely to avoid alcohol-related harms.
- 3 to 6: higher risk of several cancers.
- 7 or more: significantly higher risk of heart disease and stroke.
The guidance also advises no more than 2 drinks on any one occasion. Excessive drinking is also one of the 14 modifiable risk factors for dementia identified by the 2024 Lancet Commission (see why am I so forgetful?).
Can the brain recover?
Often, to some degree. Brain volume and white matter can partly recover after people stop drinking heavily. If you drink heavily, though, don’t stop suddenly without medical advice: alcohol withdrawal can cause seizures and other dangerous symptoms, and may need medical supervision.
A quick memory check
Try this short word-recall test. You’ll see 12 words for 30 seconds, then type as many as you remember:
For a fun daily check-in, the Words game tests verbal memory in about two minutes. It isn’t a medical test, but it’s an easy way to notice how you do after a good night’s sleep versus a night out.
Need help? In Canada, Health Canada lists national and provincial services on its Get help with substance use page. In the US, the SAMHSA National Helpline is free, confidential and open 24/7 at 1-800-662-4357. In a crisis in Canada or the US, call or text 988.
This article is general information, not medical advice or a diagnosis. If you’re worried about your memory, thinking or health, talk to a doctor.
Sources
- NIAAA: Interrupted memories, alcohol-induced blackouts
- Topiwala et al. (2017), BMJ: moderate drinking and brain health (University of Oxford)
- Daviet et al. (2022), Nature Communications: alcohol consumption and brain structure in UK Biobank
- NIAAA: brain scans reveal heavy drinking damages white matter
- Cleveland Clinic: Wernicke-Korsakoff syndrome
- Ebrahim et al. (2013), Alcoholism: Clinical and Experimental Research: alcohol and sleep (ScienceDaily)
- WHO Europe (2023): no level of alcohol consumption is safe for our health
- Canadian Centre on Substance Use and Addiction: Canada’s Guidance on Alcohol and Health
- Harvard Health: Alcohol withdrawal
- Health Canada: Get help with substance use
- SAMHSA National Helpline (US)
Frequently asked questions
Does alcohol kill brain cells?
The better-documented harms are different: heavy drinking is linked to brain shrinkage, damage to white matter (the brain’s wiring) and, with vitamin B1 deficiency, a serious memory disorder called Wernicke-Korsakoff syndrome.
Why do people black out when drinking?
Alcohol stops the hippocampus from turning experiences into long-term memories. You’re awake and acting, but the memories are never recorded, which is why they can’t be recovered later.
Is moderate drinking bad for your brain?
Large studies suggest it isn’t harmless. One UK study of more than 36,000 adults found lower brain volume even at an average of 1 to 2 UK units a day (8 to 16 grams of alcohol), and another found no protective effect from light drinking.
Can your brain recover after you stop drinking?
To some extent, yes. Research summarized by the NIAAA suggests some white matter damage may recover after people stop drinking, though recovery may be less likely later in life.
Does alcohol help you sleep?
It may help you fall asleep, but it disrupts the second half of the night and delays REM sleep, which matters for memory.