Why does brain size matter? Gradual brain shrinkage is part of the normal aging process, but Burns says that the rate of shrinkage doubles in those with Alzheimer's disease. According to The Alzheimer's Action Plan, having more brain matter means having more intact connections between brain cells, which suggests better cognitive functioning.
Burns hopes that his study's results indicate that physical exercise could slow the progression of Alzheimer's disease. Still, he cautions that more research is needed to further clarify the relationship between exercise and brain fitness.
A Cochrane Library review on the subject agrees, stating that even though other research suggests that exercise can improve cognition and mental health in older adults -- and perhaps reduce one's risk for dementia or delay its onset by 3 to 6 years -- there's not enough evidence to say that exercise should be prescribed to address Alzheimer's symptoms.
Still, if a person is medically cleared to engage in regular exercise, regardless of whether the person has dementia, it certainly can't hurt.
Sources:
Doraiswamy, P. M., Gwyther, L. P., & Adler, T. (2008). The Alzheimer's action plan: The experts' guide to the best diagnosis and treatment for memory problems. New York: St. Martin's Press.
Exercise may prevent brain shrinkage in early Alzheimer's disease. American Academy of Neurology. July 14, 2008. http://www.aan.com/press/index.cfm?fuseaction=release.view&release=641
Forbes D, Forbes S, Morgan DG, Markle-Reid M, Wood J, Culum I. Physical activity programs for persons with dementia. Cochrane Database of Systematic Reviews 2008, Issue 3. Art. No.: CD006489. DOI: 10.1002/14651858.CD006489.pub2
