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Alcohol-Induced Blackouts, Amnesia and Memory Loss

Memory loss and amnesia are common side effects of binge drinking. When people black out, they are conscious but unable to create long-term memories. They are often awake, alert and able to hold conversations. However, they’ll forget the conversations within minutes and won’t remember anything the next day.

Drinking can make us feel excited, spontaneous and euphoric. But we all know that as blood alcohol content goes up, our judgment and coordination go down. Alcohol also affects a person’s ability to make memories but not in the same way that it affects other cognitive functions.

Ever drink slowly throughout a day or night? The next day, you probably woke up dehydrated with a headache and a hangover. But you could probably remember everything you did, with a little effort and reminders.

If you start the night by taking shots, chugging beer or playing drinking games, the odds of remembering everything the next day drop drastically.

More than 50 percent of adults have blacked out at least once in their lives.

That’s because the brain’s ability to create long-term memories isn’t affected as much by blood alcohol content as it is by rapid rises in that level. Binge drinking — consuming numerous drinks in a short period— is more likely to cause blackouts, amnesia and memory loss than slow, heavy drinking, according to numerous studies.

Blacking out is different from passing out. A blackout is a loss of the ability to make memories, but people are still conscious when blacked out. They can still walk and talk, although they may do so drunkenly.

It happens quite often, too. Despite advice from experts and beer commercials, most people do not drink responsibly. More than 50 percent of adults have blacked out at least once in their lives. The number isn’t surprising considering almost 25 percent of adults binge-drink every month, according to the National Institute on Alcohol Abuse and Alcoholism.

How Alcohol Affects Memory

Scientists debate the exact way a memory is formed, but most agree that memories are made in three stages.

Several factors affect the likelihood that information will be transferred into long-term memory. For decades, researchers have known that alcohol disrupts the brain’s ability to transfer memories from short-term to long-term memory, but they didn’t know how. The common consensus was that alcohol killed brain cells, causing memory loss and other cognitive impairments.

Alcohol isn’t damaging the cells in any way that we can detect. As a matter of fact, even at the high levels we used here, we don’t see any changes in how the brain cells communicate. You still process information. You’re not anesthetized. You haven’t passed out. But you’re not forming new memories.

Dr. Charles F. Zorumski

However, scientists at the Washington University School of Medicine found in a 2011 study that alcohol didn’t kill brain cells. Instead, they found that alcohol interfered with receptors in the brain, making them produce steroids that interrupted the learning and memory-building process.

“Alcohol isn’t damaging the cells in any way that we can detect,” lead author Dr. Charles F. Zorumski said in a news release. “As a matter of fact, even at the high levels we used here, we don’t see any changes in how the brain cells communicate. You still process information. You’re not anesthetized. You haven’t passed out. But you’re not forming new memories.”

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That is why people experience a range of memory loss symptoms when they binge-drink. Alcohol can cause minor memory loss, such as being unable to remember details of a conversation after a few drinks, or major memory loss, such as forgetting hours of time after taking shots.

Experts place blackouts in two categories:

During en bloc blackouts, what most people refer to as being blacked out, someone can’t remember anything after a specific period of time. The brain’s ability to create long-term memories is completely blocked. However, sensory and short-term memories continue to function. The person can have conversations, continue ordering drinks at a bar, dance and so on.

People who experience a fragmentary blackout may think they can’t remember what happened the night before, but their memory comes back when someone or something reminds them. Researchers believe a person may be unable to access the memory unless a reminder triggers it.

What Causes a Person to Black Out

For most people, binge-drinking large amounts of alcohol causes them to black out. Studies seem to agree that heavy drinking alone doesn’t cause blackouts. A person has to drink a lot in a short period of time. Thus, the main cause of a blackout is a rapid rise in blood alcohol, which can be propelled by drinking on an empty stomach or while dehydrated.

The 86-Proof Bourbon Experiment

In a 1970 experiment, researchers in the Washington University School of Medicine’s psychiatry department gave 10 men with a history of alcoholism 16 to 18 ounces of 86-proof bourbon in a four-hour period.

The researchers tested their memories after the first hour by showing them images and asking them to recall the details two minutes, 30 minutes and 24 hours later. Most men were able to remember the images two minutes after seeing them, but half of the men could not remember them 30 minutes or 24 hours later.

The authors concluded that the blackouts were caused by an inability to transfer information from short-term to long-term memory when blood alcohol levels were rising. Studies with similar designs have produced similar results.

Predisposition

Alcohol affects people differently. Research suggests that some people’s brains are more apt to blacking out than others. The reverse is also true: Some brains may be resistant to blacking out.

Doctor viewing output of CT scan

In a study of 100 alcoholics published in the American Journal of Psychiatry, 36 participants said they had never experienced a blackout despite a history of heavy alcohol use.

Research also indicates that a person who has experienced one blackout is more likely to have blackouts in the future. The long-term effects of a blackout are unknown, but they may cause the brain to be more susceptible to memory losses in the future.

Studies also suggest that prenatal exposure to alcohol increases a person’s chance of experiencing blackouts in the future, and certain genes may increase a person’s likelihood to black out.

Do Women Black Out More Easily?

Similar numbers of men and women report blacking out, but men drink much more often and more heavily than women. The logical conclusion is that women are at a greater risk for blacking out than men. Researchers theorize that women may black out more easily because of differences in the ways men and women metabolize drinks, but more research is needed to be sure.

We do know that women are more likely to experience other side effects of heavy alcohol use, such as liver cirrhosis, heart damage and nerve damage. Research on brain damage isn’t as conclusive.

A pair of studies — one published in Psychological Medicine and the other in Alcoholism, Clinical and Experimental Research — found that men and women both experienced brain shrinkage and memory problems after heavy alcohol consumption. The latter study found that women experienced the side effects after drinking only half as much as men.

Drug Use

People who are drunk or blacked out are more likely to try illicit drugs than they would be sober. In a 2004 study published in the American Journal of Alcohol and Drug Abuse, only one out of 50 college students who had experienced a blackout said they blacked out after drinking beer alone.

Intoxicated college student with a marijuana joint

Other studies have found using benzodiazepines such as Valium and Rohypnol alongside alcohol greatly increase the chances of a blackout. Abusing these drugs without alcohol can cause memory loss, but alcohol enhances the effects of the drugs. Research also indicates that smoking marijuana while drinking increases the likelihood of blacking out.

Symptoms of a Blackout

Popular media and Hollywood glamorize blacking out, and not being able to remember what happened the night before is the topic of many fun-filled tales. But blackouts are no laughing matter, according to expert researcher Dr. Marc Schuckit.

“Some people think that blackouts, very bad hangovers, and outrageous behaviour at parties are very funny,” Schuckit said in a press release for a study on college students who blacked out. “This does not represent ‘fun.’ People don’t understand how dangerous blackouts are. In fact, people have oodles of misconceptions about drinking.”

Some people think that blackouts, very bad hangovers, and outrageous behaviour at parties are very funny. This does not represent ‘fun.’ People don’t understand how dangerous blackouts are. In fact, people have oodles of misconceptions about drinking.

Dr. Marc Schuckit

People experiencing a blackout often feel similar symptoms to being drunk. They feel carefree, are overly friendly or overly aggressive, have slurred speech and can’t walk straight. Signs that they may be blacking out or are blacked out include losing their train of thought, not understanding normal speech and getting confused about recent events.

Schuckit’s study and several others have found that people who black out from drinking risk a number of negative consequences.

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Risky Behavior

Alcohol poisoning and death from alcohol overdose are direct consequences of drinking too much alcohol.

People who are blacked out are likely to continue drinking because the substance jeopardizes their judgment. They may not remember how much they have consumed, so they continue drinking excessively.

Man drinking beer while driving

They’re also more likely to engage in other risky behavior. People report driving cars, having unprotected sex, vandalizing property, getting into fights and abusing illicit drugs when blacked out.

Long-Term Effects

The long-term effects of a blackout are unknown. Short-term effects of alcohol abuse — such as coordination problems, slurred speech and blurry vision — fade when alcohol is metabolized, which can take hours or days.

Heavy alcohol use contributes to a shrinkage of the brain similar to Alzheimer’s disease, which is characterized by memory loss.

However, long-term effects of chronic alcohol abuse — such as liver damage, nerve damage and increased cancer risk — do not go away. Heavy alcohol use contributes to a shrinkage of the brain similar to Alzheimer’s disease, which is characterized by memory loss. However, studies do not support alcohol as a cause of Alzheimer’s disease.

Still, several studies link heavy alcohol use to learning and memory problems. It’s unclear whether blacking out causes serious long-term damage, but heavy alcohol use and risky behaviors while blacked out can have serious long-term health effects.

How to Stop Blacking Out from Alcohol

The easiest way to avoid blacking out is to limit how much you drink. If you’re committed to drinking heavily or for long periods of time, then pacing yourself throughout the day or night will prevent your blood alcohol from rising too quickly.

A good rule of thumb is to only consume one drink per hour and to have a glass of water for every drink you consume. Also avoid drinking on an empty stomach.

Be aware of warning signs. If you’re having difficulty concentrating, remembering recent events or keeping track of a conversation, you may be close to blacking out. If you’re in that situation, find someone you trust and find a safe ride home.

If you’re worried about how much a friend has had to drink, ask him about something that occurred 10 to 15 minutes ago. If he can’t remember, he might be blacked out. The best option is get the friend home safely. If you see warning signs for alcohol poisoning or overdose — such as vomiting, difficulty breathing, or cold or blue skin — then get emergency medical help immediately.

You don’t have to drink heavily or quickly to have fun. If you’re unable to control how much you drink, avoid drinking altogether. If you have experienced a blackout before, you’re likely at a higher risk for blacking out in the future and should exercise caution.

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