What Happens During an Alcohol Induced Blackout

If you’ve ever woken up from a night of drinking, realizing you have very little memory of the events that took place, you know how scary a blackout can be. But even more worrisome is what goes on in your body and brain during that period. According to George Koob, the director of the National Institute on Alcohol Abuse and Alcoholism, blackouts are “a gap in the tape” of your memory, so to speak. “At roughly twice the legal limit, a blood alcohol content of .16, you become vulnerable for a blackout ― although this varies,” Koob said. “In a blackout, alcohol shuts down the ability of the brain to consolidate memories.”

Experts describe exactly how alcohol works in your system when you’re drinking heavily ― and how to tell when you’re getting to the point where you’re at risk of blacking out. The primary ingredient driving your alcohol-related symptoms is ethanol, a compound found in the alcoholic beverages you drink. As you drink one to four drinks or more in a short span of time, the effects of the substance become more pronounced. This is especially true if you have not eaten much. “Absorption of ethanol occurs in the gastrointestinal system,” primarily in the parts of the small intestine and stomach, said Benjamin M. Kaplan, an internal medicine physician from Orlando Health Internal Medicine Faculty Practice.

“When the stomach is empty, peak blood ethanol levels are reached between 30 and 90 minutes after ingestion.” In other words, as you drink, your blood ethanol level, which is what helps determine what most people know as their blood alcohol concentration, or BAC, will inch higher and higher for around an hour. This also means you may not realize how drunk you’re getting until you’ve already tipped back one too many. A couple of hours into drinking, the ethanol “can freely diffuse across the blood-brain barrier,” Kaplan said. The alcohol can then target receptors in the brain’s hippocampus (the part of the mind that controls functions like emotions and recollection), including one receptor known as the gamma-aminobutyric acid, or GABA, receptor. When GABA receptors are affected by alcohol, the transmission of signals in the brain stops ― including signals that will solidify memory ― which then results in a blackout, Koob said.

Additionally, alcohol inhibits a neurotransmitter in the brain called glutamate, which results in you feeling calmer. Drinking also “releases other inhibitors, such as dopamine and serotonin,” Kaplan said, which are chemicals that prompt those happy emotions. The GABA and glutamate receptors can be found in reward centers of the brain, which may create a system of positive reinforcement, Kaplan explained. This is why you may start to feel great while drinking ― so you keep doing it ― while also getting a bit wobbly. The reward system in your brain also regulates garden-variety actions like walking, speaking and reaction time.

Koob added that as the alcohol in your blood is increasing, you may also be compelled to act out of character, thanks to the chemical changes in your brain. “In the blackout zone, you could be dancing on a table in front of your boss, but the next day you’re not going to remember a thing,” he explained. But, and this is important to know, he said a blackout is “not permanent damage to the brain, but rather a gap in time” where the brain is not producing any memory. As alcohol is cascading through the brain, the person drinking may not seem like themselves, but Kaplan said specific symptoms will likely vary.

“It is not always obvious when someone is close to blackout,” he said. “There may even be delayed effects between symptoms of ‘coherence’ and what they do and don’t remember. And remember, different parts of the brain may be reacting differently, causing these different effects.” There will be signs of heavy intoxication, though. Common symptoms of someone in danger of blackout might be appearing uncoordinated, vomiting or needing help to get home. “Slurred speech is also common, and people are sensitive to that; it’s why police use it as a test,” Koob added. “Also, same with motor coordination. They might be bumping into things. It’s hard to walk in a straight line when you’re that intoxicated.”

Koob stressed that the key to drinking is moderation. If you’re interested in finding out how alcohol affects you personally based on your height, weight and number of drinks you consume, there are calculators that can estimate these factors and give you more information. But, bottom line, drinking to the point of blackout ― especially repeatedly ― is always an issue for your long-term health.

Reference: https://www.huffingtonpost.com/entry/alcohol-blackout-brain_us_5ba941dfe4b0375f8f9fa658
  • 2 Commentsby Likes|Date
  • I think blackouts are one of the scariest parts about drinking in excess. I can't imagine going through that experience on a regular basis.
  • Agreed, deffinetly a good post as it's something I really haven't had thoughts about in quite a long time. Just thinking about blackouts brings me a wave of anxiety and embarrassment even though I am only aware of the smallest fraction of those events. Fortunately I have been able to- and hopefully will continue to keep that checked off on my long list of things I no longer have to worry about or burden myself with as long as I can stay on track.
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