A study conducted by researchers at the Beckman Institute for Advanced Science and Technology at the University of Illinois in Urbana-Champaign has put into question the long-held belief that exercise can help addicts overcome their desire for drugs and alcohol.
The results of the study, performed on mice, indicate that people who follow regular exercise regimens may find it harder to overcome their addictions, depending on when they begin exercising and when they begin using substances. While, statistically, people who exercise are much less likely to abuse alcohol and drugs than inactive people, exercise may hinder a person’s ability to overcome his or her addictions if the addiction coincides with the start of the exercise regimen.
The mice were divided into two groups—one given running wheels in their cages and the other put in cages without running wheels—for 30 days during the study. After being injected with a chemical that marks newly formed brain cells, the mice were placed in multi-room chambers and introduced to liquid cocaine. The mice quickly developed a fondness for the cocaine and kept coming back to the place where they were first given the liquid, having come to associate that particular chamber with the pleasures a cocaine-induced high.
Having developed a fondness for stimulants, the mice were returned to their cages, with some of the sedentary mice and were given running wheels. The mice that had been given running wheels when the study commenced continued to use the wheels as well. The researchers then cut off the animals’ drug supply, put them back into the chambers, and watched to see how long it took before they stopped returning to the place where they had received their daily fixes.
The researchers found that the mice that had been sedentary during the initial stage of the study were able to overcome their preferences quickly once given the option of exercising on running wheels, while those that were introduced to cocaine while using the running wheels took much longer to overcome theirs. Many of the mice were unable to overcome their preferences at all, continuing to inhabit the location where they were fed the drug.
One possible reason for the difference: the mice that were given running wheels produced about twice the number of new brain cells as those that had remained sedentary. These brain cells were centered in the hippocampus, which plays a key role in the creation of new memories and connecting sensory stimuli—sights, sounds, smells, touch, and tastes—with those memories. When they began producing these new brain cells proved critical to the recovery process.
The researchers propose that the first set of mice exposed to exercise had produced a large quantity of new brain cells that came to associate cocaine with pleasure. Meanwhile, the sedentary mice produced fewer brain cells that associated cocaine use with pleasure and were, in effect, less intensely addicted to the drug.
Better still, the mice that were exposed to exercise after becoming addicted to cocaine produced large quantities of brain cells that were blank slates, aiding the recovery process by helping the mice to disassociate the drug from both their exercise regimen and the place they received it. Their ability to make the transition from regular use to sobriety was significantly greater.
According to Justin S. Rhodes, a professor of psychology at the University of Illinois and one of the co-authors of the 2011 study, published in the European Journal of Neuroscience, previous studies by other researchers have shown that exercise stimulates reward centers in the brain, producing a sensation that can serve as a substitute for addiction-based cravings. The high produced by exercise lessens the need for the high produced by stimulants, facilitating the recovery process.
The implication is that taking up exercise in sobriety may aid people with substance abuse problems in order to overcome their addictions more quickly and successfully. “What this study shows,” says Dr. Rhodes, “is how profoundly exercise affects learning.”
- Reynolds, Gretchen. “How Exercise May Make Addictions Better, or Worse.” The New York Times. 11 April 2012. Web. 10 July 2012.
- Mustroph ML, Stobaugh DJ, Miller DS, DeYoung EK, Rhodes JS. “Wheel running can accelerate or delay extinction of conditioned place preference for cocaine in male C57BL/6J mice, depending on timing of wheel access.” National Center for Biotechnology Information. 22 August 2011. Web. 10 July 2012.
- Bailey, Regina. “Hippocampus.” About.com. Web. 10 July 2012.
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