How Does Alcohol Cause Blackouts?

Sometimes people who have never experienced an alcoholic blackout wonder “is it real, or is it just a convenient excuse to avoid responsibility/embarrassment with regard to things done while drunk?”

In 1969 (so, still in the era of incredibly unethical psychological experiments that ranged from the 50s into the 70s), Dr. Donald Goodwin conducted a study in which intoxicated participants were asked to recall an object they had just seen. Most succeeded initially, but half were unable to remember the object just 30 minutes later, demonstrating alcohol-induced memory blackouts.

But, is it any different from regular forgetting? And the answer is: yes, it is indeed different.

The memories that never got stored

Ethanol, the active compound in alcohol, is lipophilic, enabling it to cross the blood-brain barrier and disrupt brain function. It impairs all kinds of things, including decision-making, impulse control, motor skills, and, notably, memory networks—which is what we’re looking at today.

Memory formation (beyond “working memory”, which is the kind that enables you to have an idea of what you were just doing, and carry out simple plans like “pick up this cup, raise it to my mouth, and take a sip”, without forgetting partway through) relies on a process called long-term potentiation (LTP), which strengthens neural connections to store information. Ethanol disrupts this process, preventing memory storage and causing blackouts.

In effect, this means you didn’t just forget a memory; you never stored it in the first place. For this reason, experiences from during an alcoholic blackout cannot be retrieved in the same ways we might retrieve other memories (e.g. in regular forgetting, it’s possible that a context clue jogs our memory and then we remember the experience—because in regular forgetting, the memory was in there; we just didn’t recall it until we were reminded).

Blackouts (in which the memory is never stored in the first place) typically occur when blood alcohol concentration (BAC) exceeds 0.16, while lower levels can result in partial memory loss (brownouts) in which some things may be recalled, but not others. Factors such as dehydration, genetics, medications, food consumption, and age influence the likelihood of complete blackouts.

While alcohol’s residual effects typically subside within a day, repeated over-drinking can cause permanent neuron damage, as well as of course plenty of damage to other organs in the body (especially the liver and gut).

For more on all of this, enjoy:

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Want to learn more?

You might also like to read:

What Happens To Your Body When You Stop Drinking Alcohol

Take care!