The Effects of Alcohol on Memory & Cognition

Almost everyone who comes into my office asks me about alcohol. We receive mixed messages all the time, from how dangerous it can be, to it even being beneficial to our health (in moderation, of course). We hear the message, a “daily glass of wine increases risk of early death by 20%”; but then, “having a drink may help you live longer.” It is nearly impossible to keep up with the changing messages, and the truth about alcohol most likely lies somewhere in between harmful and beneficial. Harvard University’s Chan School of Public Health said it well: “alcohol is both a tonic and a poison. The difference lies mostly in the dose.”

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One drink is considered to be 0.5 ounces or 15 grams of alcohol, equivalent to 5 oz wine (12% alcohol), 12 oz of beer (5% alcohol), or 1.5 oz of 80-proof distilled spirits (~40% alcohol), according to the US National Institutes of Health. The USDA defines “moderate” alcohol consumption as up to 1 drink per day for women and up to 2 drinks per day for men. “Heavy” drinking is consuming more than 3 drinks on any day or more than 7 per week for women, and more than 4 drinks on any day or more than 14 per week for men.

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In the United States, roughly 50 percent of adults were regular drinkers, and 14 percent were infrequent drinkers, according to the USDA’s Dietary Guidelines from 2010. Approximately 9 percent of men consumed an average of more than two drinks per day, and 4 percent of women consumed an average of more than one drink per day. In the US, there are about 1.5 billion episodes of binge drinking every year. Binge drinking is defined as consuming 5 or more drinks within 2 hours for men, and 4 or more drinks within 2 hours for women. Oregon State University’s Linus Pauling Institute lists the health benefits of heavy alcohol consumption as: none.

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It is widely understood that alcohol consumption affects the pharmacodynamics of medications. Whis issue is important across all adult age groups, it may be particularly relevant to older adults, who may be taking several medications while not being as forthcoming about their alcohol consumption. Another negative effect of alcohol consumption is impairment of prospective memory, which one paper describes as “the cognitive ability of remembering to carry out an intended action at some future point in time.” Prospective memory (PM) is a crucial component of everyday functioning, because it is involved in activities such as remembering to keep appointments or to take medications on time.

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A recent study showed that subjects (college students) who were hung over had significantly impaired PM compared to those who were not hung over. Anyone who’s ever tossed back one too many knows that cognitive impairment occurs during acute intoxication, but it may be news for some that the decline in memory and cognition can be as great or greater during a hangover, when the blood alcohol level is zero.

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While it may not seem like a big deal to meet coworkers for a few drinks after work one night, many may not realize that if they drink a bit more than they should, the negative effects can persist well into the next day, and they go far beyond nausea and a headache. Divided attention, delayed recognition and reaction time can be a hazardous factor for anyone driving or operating machinery. For people in more cerebral professions, it can affect overall cognitive performance. A 2018 systematic review examining the next‐day effects of heavy alcohol consumption on cognitive performance found that “sustained attention and driving abilities were impaired during hangover.” Maybe it is time to bring awareness not only to driving under the influence, but also to driving while hungover, or driving “after” the influence.

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Excessive drinking also affects nutrient status. Heavy drinkers may have poor absorption of B-vitamins, and the conversion of B-vitamins to their active forms is impaired by alcohol. Most heavy drinkers are often lacking in a host of B-vitamins. Another deficiency also common among heavy drinkers is magnesium. Adequate zinc status is essential for liver processing of alcohol. Alcohol intake increases urinary losses of zinc, calcium and magnesium. People who drink large amounts of alcohol should try to consume a nutrient-rich diet and supplement under the care of a medical or nutrition professional while working to decrease their habitual alcohol consumption.

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Alcohol can be enjoyed responsibly and in moderation, and a designated driver should always be used. Having a drink or two with loved ones may be a reasonable means of relaxation after a stressful day, but all should remember that there is potential for negative lingering effects, even after the alcohol has been metabolized.