You may or may not remember last year's landmark four-year study related to Alzheimer's disease sponsored by the Italians. The study appeared in December's issue of Neurology. I found a link to an article about it below.
In summary it showed that elderly people (over 65) who regularly walk significantly lower risk of vascular dementia.(1) Thus there is a lot of talk about physical activity, like walking, as having a potential effect for reducing risk of Alzheimer's disease.(1) Because walking and other activity increases oxygen in the brain, it may be directly improve memory.(1)
Suggestion: Walk a mile or two before taking Anatomy and Physiology tests!
Reference
1. American Academy of Neurology. Walking and moderate exercise help prevent dementia. ScienceDaily. Available at: http://www.sciencedaily.com/releases/2007/12/071219202948.htm. Accessed on Oct. 18, 2008.