Exercise may help ease a craving for drugs, and it also may
make addiction harder to beat.
Institute for Advanced Science and Technology at the
University of Illinois in Urbana Champaign made this paradoxical discovery in
their new study of cocaine- addicted mice. The timing of the exercise, it turns
out, is critical. The findings are
reported in The New York Times blog Tara Parker-Pope on Health.
Male mice that did and did not have running wheels in their
cages were divided into separate groups and allowed to run, or sit, for a
month. Then they were put in
multi-room chambers in the lab, and given liquid cocaine, which they liked. If a rodent returns to a place where it
had a drug or pleasurable experience and stays there, it’s called "conditioned place
preference,” which scientists say shows addiction. All the mice were
hooked. All the mice that had
exercised kept it up, and some of the previously sedentary mice were giving
running wheels. Researchers
watched how all the mice reacted when the cocaine was stopped.
Mice that only began exercising after getting cocaine lost
their place preference behavior easily.
Mice that had been runners before getting cocaine lost their addictive behavior
slowly, and some never did.
All the mice had been injected with a chemical that
identifies new brain cells. The exercised mice had twice as many new brain
cells as the sedentary mice, and those new cells were in the hippocampus, an
important place for the ability to associate a new thought with its context.
The exercised mice had learned—far more efficiently than their sedentary
peers—to crave cocaine.
Psychology professor Justin H. Rhodes, an author of the
study published in the European
Journal of Neuroscience, emphasizes that he and colleagues
looked only at one narrow aspect of exercise and addiction. "Exercise is good for you in almost
every way,” he told Gretchen Reynolds, author of the post. But he added that by
exercising "you do create a greater capacity to learn, and it’s up to each
individual to use that capacity wisely.”
A story in Slate by Daniel Engber
describes earlier experiments at Tufts University showing rats that exercised
were less susceptible to the effects of certain stimulant drugs, and less
inclined to crave drugs. Exercise activates the brain’s pleasure centers, which
can give the exerciser a high, and it’s good. But researchers have found for some, exercise itself can be