Approximately 18 million people in the U.S. have an alcohol use disorder (AUD), according to the National Institute on Alcohol Abuse and Alcoholism (NIAAA). Alcohol consumption can lead to such symptoms as blurred vision, impaired memory and gait, decreased reaction time and slurred speech, which can become evident after just one or two drinks and diminish after drinking has ceased. However, for those who have an AUD or participate in binge episodes, alcohol consumption may lead to long-term brain deficits that linger long after drinking. As a result, methods to help recover from alcohol-induced cognitive insufficiencies are of importance to clinicians. Dr. J. Leigh Leasure, associate professor of developmental psychology and Director of the Behavioral Neuroscience Lab in the Department of Psychology at the University of Houston (UH), received a $407,500 award from the NIAAA to investigate the restorative effects of exercise post binge drinking.
What are your goals for the current research, and how will this grant help?
We want to learn more about how exercise helps the brain’s self-repair efforts after a binge. If we can determine the mechanism(s) by which exercise enhances self-repair, it would help in the development of pharmaceutical aids to enhance brain repair after binge damage and, potentially, after other types of brain injury as well, such as stroke.
This grant will enable us to answer or, at least, investigate many questions. The most important one is – How exactly is exercise helping the brain to recover from binge damage?
What is an alcohol use disorder (AUD)? How is it diagnosed?
An alcohol use disorder is a medical condition in which alcohol intake negatively affects one’s life – relationships, job, school or health.
Symptoms include craving alcohol, loss of control over alcohol intake, physical dependence or withdrawal symptoms, and increased tolerance, meaning needing to drink larger amounts in order to get an effect.
In your previous studies, how has exercise been shown to help the brain recover?
My lab has published two studies on the effects of exercise on binge alcohol intake in a rodent model. In our first study published in 2010, we found that exercise partially protected the brain against subsequent binge-induced damage. We do not yet know how exercise does this, although we do know that it is not speeding up the liver’s metabolism of alcohol. In our recent study, published in 2013, we found that exercise after a binge facilitated recovery by enhancing the brain’s own natural repair efforts.
Is there a certain length of time or amount of alcohol that classifies a binge episode?
Binge drinking is an on/off pattern of intake, and it is highly variable. It involves a person drinking a lot of alcohol in a short period of time. The NIAAA defines a binge episode as one in which blood alcohol levels reach 0.08 grams percent or higher. For the average male, this is about five drinks in two hours and four for the average woman. Of course, many people routinely drink more than that. A recent report by the Centers for Disease Control and Prevention (CDC) indicates that one in six American adults binge four times a month, including eight drinks per binge.
How is cognitive function impaired by repeated binge episodes?
In our rodent model, after a single binge episode, spatial navigation, the ability to find one’s way around one’s environment using landmarks, is impaired. This is because alcohol damages the part of the brain that is important for spatial navigation. We expect that repeated binge episodes will worsen this impairment. Alcohol also damages the frontal lobes of the brain, which are important for planning, decision-making and impulse control. We want to explore how multiple binge episodes affect this latter type of cognition.
Can the impairments become permanent? If so, what are the common characteristics?
The brain actually heals pretty well from AUDs. Specifically, the initial imaging findings of tissue loss do partially normalize. However, long-term AUD-induced cognitive dysfunction includes impairment in planning, reasoning, decision-making, impulse control and other frontal-lobe functions. In extreme cases, Korsakoff’s syndrome can occur, in which people cannot form new memories.
In terms of exercise post-binge, is there a window of time that is optimal to begin exercising?
This is an excellent question and one we would like to investigate. When we published Exercise Enhances Hippocampal Recovery Following Binge Ethanol Exposure (2013) last fall, there was a huge Twitter response that ran along the lines of, “Well, if I binge drink one evening, I can fix it by going to the gym the next day.” That is emphatically NOT the bottom line message of our research!
In that study, we waited a week after the binge before exercise commenced. We did this because my graduate work showed that there is a vulnerable period after brain injury during which physical activity will make the injury worse, not better. In our rodent model, this vulnerable period is seven days after the injury. In humans, the length of the vulnerable period is not known. However, we do know that with concussion, it is very bad to exercise right afterwards. This is why sports leagues like the NFL have begun taking players out of the game if a concussion is suspected. The reason is that the brain is injured, and it needs energy and resources in order to heal. If energy and resources are shunted away from the brain and towards the muscles by exercising, brain self-repair efforts will be hindered.
How could this research be applied to the clinical treatment of AUDs?
Exercise could be used as a component of treatment programs for AUDs. Since it enhances plasticity in the post-binge brain, it could be a means by which to promote the learning of new skills to maintain abstinence. There are also published studies that indicate that a bout of exercise acutely reduces cravings, which would be useful for people trying to maintain abstinence. However, I think we also need to be aware that in a subpopulation of people (those who are most impulsive) exercise may increase alcohol consumption. Several large studies have shown a positive correlation between the amount of time spent exercising and alcohol intake. Recently, in conjunction with my colleague, Dr. Clayton Neighbors, I have published a paper entitled Impulsivity Moderates the Association between Physical Activity and Alcohol Consumption (2014), which found that the relationship between exercise and alcohol consumption is strongest in people who are impulsive.
Eighteen million people in the U.S. have an AUD. According to the World Health Organization, that is approximately 5.48 percent of men and 1.92 percent of females in America. As a result, what is the significance of this study for the University of Houston and the Houston community?
Awareness is most significant. I do not think people realize that “going out drinking” or doing a pub crawl or a keg stand can damage the brain. My suspicion is that binge drinking is like concussion, in that the brain can recover just fine from one binge, but that multiple, repeated episodes have serious ramifications for brain function. To be clear, I do not advocate outlawing alcohol. I want people to be aware of the dangers so that they can make their own informed decisions about whether or not they are going to engage in any of the many socially-sanctioned forms of binge drinking.
Leasure is working with co-author and UH graduate student Mark Maynard, who is a Ph.D. candidate in the Department of Psychology at UH and a researcher in the Behavioral Neuroscience Lab.