Exercise May Mitigate Brain Damage Due to Heavy Drinking

Deborah Brauser

April 16, 2013

Aerobic exercise may help prevent some of the brain damage caused by the effects of heavy alcohol consumption, preliminary research suggests.

A study of adults who drank heavily showed that those who participated in low levels of aerobic exercise had decreases in white matter integrity in the brain's external capsule and superior longitudinal fasciculus (SLF) — areas that are important for cognitive, behavioral, and emotional functioning.

However, the association between alcohol intake and white matter health was not significant for those who reported high levels of exercise involvement.

"The results suggest a first step in better understanding the relationship between the brain, exercise, and alcohol consumption," Hollis C. Karoly, from the Department of Psychology and Neuroscience at the University of Colorado at Boulder, told Medscape Medical News.

She noted in a release that although it is common knowledge that long-term alcohol exposure is linked to white matter damage, "little is known about how this damage could be reversed or prevented."

On the basis of their findings, "aerobic exercise appears to be a promising candidate for decreasing alcohol-related brain damage," said Karoly, adding that clinicians should consider prescribing this type of exercise as adjunct treatment for patients with a history of heavy alcohol use.

"We already know how good exercise is for your heart, your muscles, and your lungs. So the suggestion that it could also lead to positive changes in brain health is not all that surprising. It's something that's important for overall health."

The study was published online April 2 in Alcoholism: Clinical and Experimental Research.

Protective Effect

According to the investigators, aerobic exercise has been shown to decrease cognitive decline and negative neural changes associated with aging and with several neurologic disorders.

"Engaging in regular aerobic exercise has been found to improve learning, memory, and self-control," said Karoly, adding that this appears to be particularly true among older adults who exercise regularly.

She noted that exercise has also been shown to protect white matter from age-associated damage.

"White matter is a crucial part of the nervous system, relaying information between areas of the brain. In general, white matter damage can lead to motor deficits, sensory problems, and cognitive difficulties."

In addition, heavy use of alcohol "is associated with a number of deleterious health outcomes, such as...widespread damage to the brain, including gray and white matter loss," write the researchers.

Given all of this, "it seemed likely that aerobic exercise may work to reverse or prevent some of the damage to the brain caused by chronic alcohol consumption," said Karoly.

Investigators assessed data on 60 adults between the ages of 21 and 55 years who participated in 1 of several previous studies on alcohol and nicotine use.

All had undergone a diffusion tensor imaging scan and had completed the Voluntary Aerobic Exercise Questionnaire; the Alcohol Use Disorders Identification Test (AUDIT); the Time Line Follow Back (TLFB), in which participants recorded the number of drinks consumed in the last 60 days; and the Impaired Control Scale, which is a measure of loss of control over drinking.

Relationships between these factors were assessed by measuring fractional anisotropy in the brain's SLF, external capsule, fornix, and superior and anterior corona radiata.

"These five...tracts were selected based upon their demonstrated association with alcohol consumption in several previous studies," report the investigators.

Results showed a significant association between level of aerobic exercise participation and alcohol consumption on fractional anisotropy in both the external capsule and the SLF (both areas, P < .05).

There was a strong link between low exercise and decreased white matter integrity in both of these brain areas, and this association did not change significantly after adjusting for use of cigarettes or cannabis.

"Both the external capsule and [SLF] connect important brain areas, so damage to these tracts may have a host of more specific implications for negatively impacting cognitive, behavioral, and emotional functioning," said Karoly.

No Causal Claims Yet

No relationship was found between alcohol intake and white matter health for the average or above-average exercisers.

In addition, for the low exercisers, there was a stronger association between alcohol intake and loss of control over drinking than for the high exercisers (P < .01). However, this association was only found in the AUDIT measure and not in the TLFB.

Karoly pointed out that the study did not prove a causal effect or even that aerobic exercise is protective against alcohol-related white matter damage, although the results "are consistent with the notion that exercise may be protective."

"This was more of an associational study, so making a definitive claim like that is a little too strong right now. We don't know the mechanisms by which this effect is happening, and we didn't look at this over time to see if it could repair damage that has already happened," she said.

In addition, future studies "relating neural characteristics to exercise behavior" should consider lifelong exercise patterns as well as more recent participation, note the investigators. They add that a healthier diet and improved sleep that often comes with a heavy exercise lifestyle should also be examined.

Karoly added that the researchers are now planning a new study that will also assess "dose levels" of aerobic exercise (including type, duration, intensity, and frequency) on white matter effects.

Compelling Study

Susan F. Tapert, PhD, professor of psychiatry at the University of California, San Diego, and chief of psychology at the VA San Diego Healthcare System Psychology Service, said in a release that the focus of this study is highly significant because, although heavy drinking has been linked to white matter damage, "it is unclear why the effects are more prominent in some individuals than in others."

"Although we don't know yet if the exercise is protecting against alcohol-related damage, or if it is a sign of factors linked to brain health, this is a very compelling study," said Dr. Tapert, who was not involved with this research.

"This suggests that individuals who have experienced alcohol-related brain problems could possibly use exercise to help recover those effects; studying people over time will tell us if this is in fact the case."

She added that she hoped the findings "drive more research" into this topic area.

"From a neurobiological perspective, it will be very interesting to see how aerobic exercise could potentially mitigate inflammatory, oxidative, and other sources of neural injury produced by heavy alcohol use," concluded Dr. Tapert.

The study was funded by grants from the National Institute on Alcohol Abuse and Alcoholism and the National Institute on Drug Abuse. The study authors have reported no relevant financial relationships.

Alcohol Clin Exp Res. Published online April 2, 2013. Abstract

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