Exercise and Addiction

I just finished reading an interesting article in the New York Times today entitled How Exercise Can Prime the Brain for Addiction.

In the study they studied two groups of mice – one sedentary and one with access to wheels. They found that those who exercised generated more brain cells than those who didn’t. Good, right?

Then they gave all the mice liquid cocaine. As the article states, “[t]hey liked it.”. After introducing drugs, they also introduced the previous sedentary mice to exercise wheels.

They then attempted to gauge addiction by monitoring the place preference of the mice. Did they keep returning to the bar area where they’d received the drug?

The researchers noted two distinct patterns among the addicted exercisers. The formerly sedentary mice that had begun running only after they became addicted lost their conditioned place preference quickly and with apparent ease. For them, it appeared relatively easy to break the habit.

Those that had been runners when they first tried cocaine, however, lost their preference slowly, if at all. Many, in fact, never stopped hanging out in the drug-associated locale, a rather poignant reminder of the power of addiction.

So… the article seems to indicate that exercisers can be more primed for addiction. I have two thoughts on this:

1. Ok sure, they have more brain cells so there is more brain to “enjoy” the effects of the drug. Is this truly a bad thing? The researchers do claim that these extra brain cells are around the hippocampus, which is the area involved in associative learning. So the mice were able to make stronger associations of place and high, and then had more difficulty “forgetting” this association.

2. This study seems a bit unfair.. the new exercisers were provided an alternative activity, one that stimulates the release of endorphins. They were given something else to help them overcome their addiction. The longtime exercisers only had the sense of loss.

In all, though, it was an interesting study. I’m not entirely sure if I agree with the conclusion that “shedding an addiction acquired when a person has been exercising could be extra challenging”, or if it just means that exercise can’t be used as a substitute activity for addiction to the extent it can for those who didn’t previously exercise.

Thoughts?