Heavy drinking impairs next-day cognitive functioning in college students

Young adults who engage in high-intensity drinking or drink to the point of blacking out tend to experience significant cognitive issues the following day. These next-day effects include noticeable memory lapses and difficulties with basic mental tasks, which suggests that the impacts of heavy alcohol consumption linger well after intoxication wears off. The findings were published in the journal Alcohol: Clinical and Experimental Research.

Young adults between the ages of 18 and 25 report the highest rates of heavy alcohol use among all age groups. It is estimated that more than five million young adults in the United States met the criteria for an alcohol use disorder in 2023. About half of young adults who consume alcohol report experiencing at least one blackout, which involves alcohol-induced memory loss.

High-intensity drinking is a particularly extreme behavior defined as consuming eight or more drinks in a single sitting for women, or ten or more drinks for men. Blackout drinking happens when alcohol blocks the brain from forming new memories, meaning the person is still awake and acting but will have no recollection of those events later. Both behaviors are common among college populations and carry significant risks for physical injury and poor decision-making.

Prior experimental laboratory studies provide evidence that a single heavy drinking episode can cause short-term changes in brain structure. Heavy alcohol use tends to alter structures like the corpus callosum, which helps the two hemispheres of the brain communicate. These structural changes suggest that young adults might experience functional consequences in their daily lives after a night of extreme drinking.

The authors wanted to see if young people actually experience and notice cognitive consequences the morning after intense drinking or blacking out. They recognized a gap in the existing scientific literature, as most past studies only looked at very short time frames or focused solely on either self-reported feelings or objective laboratory tests. A more comprehensive approach in a natural setting was necessary to capture the real-world impact of alcohol on the brain.

To explore this topic, the researchers recruited 304 college-attending young adults for a 21-day diary study. The participants were between 18 and 25 years old, and 79 percent of the group was female. To be eligible, the students had to report engaging in heavy drinking at least twice in a typical month and having experienced at least one blackout in the past year.

Across the three-week study period, participants received survey links on their mobile phones four times a day. These prompts arrived at 11 a.m., 1 p.m., 3 p.m., and 5 p.m., and the participants had one hour to complete each set of questions. The surveys asked them to detail any alcohol they had consumed the day before, including the exact number of drinks and whether they had blacked out.

In addition to logging their drinking behavior, the students reported on their own cognitive lapses over the past two hours. The researchers measured prospective memory lapses, which involve forgetting something you planned to do in the future, like taking a medication on time. They also measured retrospective memory lapses, which involve forgetting previously learned information, such as someone’s name or where you placed your keys.

The daily surveys also asked about general cognitive lapses. These included non-memory issues like having trouble paying attention or struggling to make a basic decision. After finishing the survey questions, the participants were directed to complete quick, objective “brain games” designed to measure their actual cognitive performance.

One of these performance tasks tested working memory with updating, asking users to recognize if a current visual prompt matched one shown a few steps earlier. Another task tested executive functioning and inhibitory control by measuring how quickly participants could react to a target while ignoring distracting visual information around it. A third task measured working memory with manipulation by asking participants to recall a sequence of numbers in the reverse order they had appeared.

When the researchers analyzed the daily responses, they found that any amount of drinking the previous day was linked to a 14 percent higher likelihood of general cognitive lapses the next day. This was in comparison to days that followed no alcohol consumption. Each additional drink an individual consumed increased the likelihood of a next-day cognitive lapse by 5 percent.

The effects became much more severe following high-intensity drinking episodes. Participants were 66 percent more likely to report a prospective memory lapse on the day following a high-intensity drinking event. They were also 75 percent more likely to experience a retrospective memory lapse.

High-intensity drinking was associated with twice the likelihood of reporting general cognitive lapses the next day. Blackout drinking also showed strong associations with self-reported mental struggles. Days following a blackout drinking episode were linked to a 61 percent greater likelihood of a retrospective memory lapse and a 40 percent greater likelihood of general cognitive lapses.

While the self-reported data showed wide-ranging impacts, the objective performance-based tasks told a slightly different story. Most of the objective brain games were unassociated with the various drinking indicators on a daily basis. The one exception was blackout drinking, which was linked to poorer performance on the backward number recall task the following day.

The researchers note that self-reported measures and objective tasks evaluate different spheres of human cognition. Self-reports tend to capture global functioning and a person’s overall ability to meet daily mental demands. The objective tasks evaluate very specific underlying mechanisms, which might not show obvious deficits on a day-to-day basis in young, adaptable brains.

High-intensity drinking affects the prefrontal cortex, a brain region responsible for planning and attention. Blackout drinking disrupts the hippocampus, which is responsible for turning short-term experiences into long-term memories. Because these behaviors impact different brain regions, they likely alter day-to-day cognitive functioning in slightly different ways.

A potential misinterpretation of this study is the assumption that young adults who drink heavily are experiencing permanent or universally measurable cognitive decline. The lack of significant findings on most of the performance-based tasks suggests that young adults possess a degree of cognitive resilience. They might be able to rally and perform well on a focused, two-minute computer task despite feeling mentally foggy in their broader daily lives.

The study features some limitations that provide context for the findings. The sample consisted mostly of white, female college students, which means the results might not apply to young adults who do not attend college or to individuals from minoritized backgrounds. Relying on self-reported drinking data also introduces the possibility of recall bias, especially on days when participants experienced a blackout and could not remember their actions.

The specific cognitive tasks chosen for the study might have missed other mental processes that alcohol disrupts, such as sustained attention or associative memory. The timing of the surveys only captured lapses that happened between 11 a.m. and 5 p.m., leaving evening cognitive struggles unrecorded. Exploring how cognitive lapses accumulate over multiple consecutive days of drinking represents a needed next step.

Future research could incorporate wearable alcohol sensors to gather objective data on intoxication levels, removing the reliance on memory. Scientists also hope to investigate how sleep might protect the brain after a night of heavy drinking. Other upcoming projects will look at the effects of combining alcohol and cannabis, as well as tracking cognitive outcomes as young adults age into midlife.

Recognizing these next-day memory lapses could serve as an effective intervention tool. Because young people are actively noticing their mental struggles the morning after heavy drinking, health professionals could deliver personalized messages to their mobile phones at these specific moments. Helping young adults connect their immediate mental fog to yesterday’s extreme drinking might encourage healthier behaviors moving forward.

The study, “High-intensity and blackout drinking impact on next-day cognitive functioning among college-attending young adults,” was authored by Ashley N. Linden-Carmichael, Jacqueline Mogle, Sara E. Miller, Jennifer L. Shipley, and Stephen J. Wilson.