WASHINGTON — Tantalizing clues indicated that exercise might spur changes in the brain to help prevent addiction to drugs or alcohol. Now the government is beginning a push for hard research to prove it.
The question is just how regular physical activity of varying intensity — dancing, bicycling, swimming, tae kwan do — might affect mood, academic performance, even the very reward systems in the brain that can get hijacked by substance abuse.
What first caught the attention of National Institute on Drug Abuse chief Dr. Nora Volkow: A study found tweens and teens who reported exercising daily were half as likely to smoke as their sedentary counterparts, and 40 percent less likely to experiment with marijuana.
Volkow knows — from her own 6-mile daily runs and from her scientific experiments — that the brain literally likes physical activity. Exercise seems to invigorate neurochemicals that sense and reinforce pleasure.
But the nation’s children are becoming more sedentary, as illustrated by the obesity epidemic, “screen time” replacing outdoor play and a drop in school P.E. And as youngsters approach adolescence, the run around the yard that used to be fun too often becomes a chore. The sedentary teen turns into the sedentary adult.
Last week she brought more than 100 specialists in exercise and neurobiology to a two-day conference to explore physical activity’s potential in fighting substance abuse, and announced $4 million in new research grants to help.
Drug treatment programs often include exercise, partly to keep people distracted from their cravings, but there’s been little formal research on the effects.
In the best evidence, Brown University took smokers to the gym three times a week and found adding the exercise to a smoking cessation program doubled women’s chances of successfully kicking the habit. The quitters who worked out got an extra benefit: They gained half as much weight as women who managed to quit without exercising, says lead researcher Dr. Bess Marcus.
Other clues:
Rats were less likely to ingest amphetamines if their cages had running wheels, suggesting exercise stimulated a reward pathway in the brain to leave them less vulnerable to the drug’s rush.
In people, exercise acts as a mild antidepressant and relieves stress. Depression, anxiety and stress increase the risk of alcoholism, smoking or drug abuse.
Baby monkeys who don’t play enough in childhood have problems controlling aggression when they’re older. The most aggressive tend to have defects involving the feel-good brain chemical serotonin — and binge-drink when researchers offer them alcohol.
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