“But, really, what the study shows,” he continues, “is how profoundly exercise affects learning.

”When the brains of the mice were examined, he points out, the runners had about twice as many new brain cells as the animals that had remained sedentary, a finding confirmed by earlier studies. These cells were centered in each animal’s hippocampus, a portion of the brain critical for associative learning, or the ability to associate a new thought with its context.

So, the researchers propose, the animals that had been running before they were introduced to cocaine had a plentiful supply of new brain cells primed to learn. And what they learned was to crave the drug. Consequently, they had much more difficulty forgetting what they’d learned and moving on from their addiction.

Exercise certainly makes addiction to exercise worse.

I do remember another NYT article two months ago exploring a key mechanism underlying exercise-enhanced cognitive functions, which explains why exercise improves our brains.