Author: John Carter

Alcohol-induced blackouts: A review of recent clinical research with practical implications and recommendations for future studies PMC

Most reports suggest middle-age males with alcoholism are more likely to black out. Considerable evidence suggests that chronic alcohol use damages the frontal lobes and leads to impaired performance of tasks that rely on frontal lobe functioning (Kril and Halliday 1999; Moselhy et al. 2001). In a typical LTP experiment, two electrodes (A and B) are lowered into a slice of hippocampal tissue kept alive by bathing it in oxygenated artificial cerebral spinal fluid (ACSF).

By fine-tuning our approach to studying blackouts, we will improve our understanding of alcohol-induced blackouts, and consequently, be better situated to improve prevention strategies. Overall, these findings suggest that alcohol-induced blackouts can have profound effects on an individual’s overall health and well-being, above and beyond the effects of heavy alcohol consumption. Modern neuroimaging techniques, such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), provide incredible opportunities for investigating the impact of drugs like alcohol on brain function during the performance of cognitive tasks. The use of these techniques will no doubt yield important information regarding the mechanisms underlying alcohol-induced memory impairments in the coming years. Memory formation and retrieval are highly influenced by factors such as attention and motivation (e.g., Kensinger et al. 2003). With the aid of neuroimaging techniques, researchers may be able to examine the impact of alcohol on brain activity related to these factors, and then determine how alcohol contributes to memory impairments.

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

Alcohol and Hippocampal Long-Term Potentiation

But you could probably remember everything you did, with a little effort and reminders. You’re out celebrating with your pals, throwing back shots and maybe a pint or two from your local brewery. But next thing you know, you wake up feeling groggy, your phone is missing, you can’t find your shoes and you don’t remember how the evening ended.

If you start the night by taking shots, chugging beer or playing drinking games, the odds of remembering everything the next day drop drastically. Alcohol is dehydrating by nature, so making sure you’re drinking plenty of water and staying hydrated is important. Being aware of potential signs of intoxication can also be helpful in understanding your limitations. How much alcohol or substance use is needed to cause a blackout varies based on a person’s height, weight, sensitivity and assigned sex at birth. “Anything that causes damage to the brain, whether temporary or permanent, can cause memory loss if the damage is in the right spot,” states Dr. Streem. THC, the psychoactive compound found in marijuana, may also increase blackouts when combined with alcohol.

There are two possible interpretations for these data, both of which support the hypothesis that some people are more susceptible to blackouts than others. One plausible interpretation is that subjects in the fragmentary blackout group always have been more vulnerable to alcohol-induced memory impairments, which is why they performed poorly during testing under alcohol, and why they are members of the blackout group in the first place. A second interpretation is that subjects in the blackout group performed poorly during testing as a result of drinking enough in the past to experience alcohol-induced memory impairments.

Types of Blackouts

Using longitudinal methods, Schuckit and colleagues (2015) and Wilhite and Fromme (2015) focused specifically on prospective analyses of alcohol-induced blackouts. Schuckit and colleagues (2015) used latent class growth analysis to evaluate the pattern of occurrence of alcohol-induced blackouts across 4 time points in 1,402 drinking adolescents between the ages of 15–19. Surprisingly, 30% of the adolescents reported experiencing an alcohol-induced blackout at the age of 15, which increased to 74% at age 19. A host of other brain structures also are involved in memory formation, storage, and retrieval (Eichenbaum 2002).

1. Wetherill and colleagues (2012) conducted a follow-up study that used a within subject alcohol challenge followed by two functional magnetic resonance imaging (fMRI) sessions under no alcohol and alcohol (target BrAC of .08 g/dl) conditions.
2. In a typical LTP experiment, two electrodes (A and B) are lowered into a slice of hippocampal tissue kept alive by bathing it in oxygenated artificial cerebral spinal fluid (ACSF).
3. More than 50 percent of adults have blacked out at least once in their lives.
4. The fact that subjects could remember aspects of the events 2 minutes after they occurred but not 30 minutes or 24 hours afterward provides compelling evidence that the blackouts stemmed from an inability to transfer information from short-term to long-term storage.
5. Researchers link that risk to the heavy drinking habits common among many college students.

Based on his observations, Ryback concluded that a key predictor of blackouts was the rate at which subjects consumed their drinks. He stated, “It is important to note that all the blackout periods occurred after a rapid rise in blood alcohol level” (p. 622). The two subjects who did not black out, despite becoming extremely intoxicated, experienced slow increases in blood alcohol levels. In a subsequent study, White and colleagues (2004) interviewed 50 undergraduate students, all of whom had experienced at least one blackout, to gather more information about the factors related to blackouts. As in the previous study, students reported engaging in a range of risky behaviors during blackouts, including sexual activity with both acquaintances and strangers, vandalism, getting into arguments and fights, and others.

Indeed, elements of this model still can be seen in virtually all models of memory formation. Drinking to the point of a blackout has gained pop culture notoriety in recent years. Alcohol-induced blackouts can lead to impaired memory of events that transpired while intoxicated, and a drastically increased risk of injuries and other harms. They can occur in anyone who drinks alcohol, no matter their age or level of experience with drinking.

So-called blackouts and brownouts can lead to temporary and even permanent memory loss. Not to mention, they can put you in danger of serious harm in the moment when you’re not quite sure of your surroundings or what’s happening. A blackout ends when your body finally absorbs the alcohol and your brain can make memories again. Sleep helps end blackouts because rest gives the body time to process the alcohol.

Preventing an Alcohol Blackout

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. However, long-term effects of chronic alcohol abuse — such as liver damage, nerve damage and increased cancer risk — do not always go away. For example, people with minor liver problems can recover from heavy drinking if they stop drinking. Alcohol-related blackouts are gaps in memory, when you can’t recall what happened while you were intoxicated. Blackouts can happen to anyone who drinks alcohol, regardless of their age or experience with drinking.

They’re evidence of a possible genetic vulnerability to alcohol.

If sufficient alcohol is present in the ACSF bathing the slice of hippocampal tissue when the patterned stimulation is given, the response recorded later at position B will not be larger than it was at baseline (that is, it will not be potentiated). And, just as alcohol tends not to impair recall of memories established before alcohol exposure, alcohol does not disrupt the expression of LTP established before alcohol exposure. During the first half of the 20th century, two theoretical hurdles hampered progress toward an understanding of the mechanisms underlying the effects of alcohol on memory.

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. Excessive alcohol use isn’t the only thing that can cause blackouts or brownouts. Substance misuse on its own or with alcohol can increase your likelihood of experiencing a blackout. Hypnotics or sedatives and benzodiazepines like flunitrazepam (also known as Rohypnol or roofies) can also lead to blackouts or brownouts. Psychiatrist and addiction specialist David Streem, MD, discusses how alcohol and substance use aren’t the only pathways to memory loss and shares what’s really happening when you’re blacked out.

As Fleming stated nearly 70 years ago, “the striking and inescapable impression one gets from a review of acute alcoholic intoxication is of the almost infinite diversity of symptoms that may ensue from the action of this single toxic agent” (1935) (pp. 94–95). In addition to impairing balance, motor coordination, decisionmaking, and a litany of other functions, alcohol produces detectable memory impairments beginning after just one or two drinks. Under certain circumstances, alcohol can disrupt or completely block the ability to form memories for events that transpire while a person is intoxicated, a type of impairment known as a blackout. This article reviews what is currently known regarding the specific features of acute alcohol-induced memory dysfunction, particularly alcohol-induced blackouts, and the pharmacological mechanisms underlying them.