So we can clearly enhance learning, even if mental gymnastics won’t make us smarter. Don’t worry: there is still more you can do for your brain. It turns out that physical exercise can also improve cognitive function and promote the growth and creation of neurons.

Mice, for example, that are allowed to run on a wheel for just 45 days had more neurons in their hippocampus, a brain region critical for memory formation, than sedentary mice.

In humans, one recent study randomly assigned a group of older people with mild cognitive impairment to three groups: one that engaged in resistance training, one that did aerobic training and a control group that did balance and tone exercises. Random selection ensures that any observed differences between the three groups is a result of the type of exercise, not any other characteristics of the subjects. The researchers found that while both resistance and aerobic training groups improved equally on spatial memory, only the women who did aerobic exercise improved on verbal memory, suggesting that different types of exercise might have specifically different cognitive benefits.

Also, a new study found that women who did weight training twice a week for a year had less brain shrinkage than those who trained once a week or did stretching exercises, though the cognitive significance of this effect is not yet clear.

How might exercise exert these effects? Intriguingly, exercise in humans and animals increases the level of a protein called brain-derived neurotrophic factor, or BDNF, in the blood and brain. BDNF promotes the growth and formation of new neurons, and it may be responsible, in part, for a remarkable effect of exercise on the brain: an increase in size of the hippocampus that is linked with improved memory.

Conversely, adverse experiences like major depression can lower BDNF levels and are associated with hippocampal shrinkage, a phenomenon that helps explain some of the cognitive impairments that are a hallmark of depression. Aside from making people feel better, antidepressants can block the depression-induced drop in BDNF, so these drugs are, in a sense, neuroprotective.

I know, exercise is work, so you undoubtedly want to know if there is a smart pill, like Adderall or Ritalin, that will do the trick. Well, there is little question that these stimulants increase focus and make the world feel more interesting by releasing dopamine in key brain circuits. But when it comes to their effects on memory and learning, the data are mixed.