Armed with exercise in the fight against dementia

People are always asking what they can do to protect themselves against Alzheimer’s disease and related dementias.  Concern over the risk of these ailments is evident in the tremendous success of super foods, super supplements, and mind games, all claiming to preserve mental acuity into old age.  Persuasive findings from several recent studies add to a growing body of literature suggesting that physical activity may be especially effective in the fight against dementia.

Brain imaging from a new study in Neurology revealed that seniors who are physically active have less atrophy (shrinkage) than their more sedentary peers. The integrity of their white matter was also superior, meaning that the “wiring” that connects brain regions was healthier.  These folks were in their 70s, so the grueling activities associated with these benefits were things like walking several times a week.  Interestingly, none of these same benefits were seen with mental exercises. While there may certainly be benefit to some of the mind games currently flooding the market, the promising advertising claims appear way ahead of the scientific evidence.

Just days ago, the journal Stroke published evidence that a physically active lifestyle significantly reduces the risk for cognitive impairments and vascular dementia. Vascular dementia is caused by reduced or obstructed blood flow in the brain, and limits the oxygen and nutrients reaching brain cells.  Depending on where blood flow is reduced, symptoms may include confusion, disorientation, and problems with memory or attention.  The relationship between physical activity and reduced dementia risk in this study was robust, even after accounting for education level, age, and other risk factors for dementia.

The strength of these two studies lies in their numbers (both had over 600 participants), but they are limited in that they can only demonstrate associations.  It could simply be that people with healthier brains are more likely to remain active, rather than that activity causes these benefits to the brain. Herein lies the power of intervention studies.

In a 2011 study, Erickson et al. recruited 120 older adults and randomly assigned half of them to a stretching and toning program and half to an aerobic exercise program that consisted of moderate-intensity walking of up to 40 min. at a time.  Six and 12-month follow-ups showed that aerobic exercise physically increased the size of the hippocampus.  This region shrinks in late adulthood, even in those without dementia.  This volume loss impairs memory and increases the likelihood of developing dementia. The people in this study who walked effectively reversed the age-related loss of hippocampal volume by 1 to 2 years.

I think the most powerful message here is that it is never too late.  Some of these participants started walking in their late 70s and early 80s, and their brains physically changed as a result of moving their bodies.  Never mind the reduced cholesterol and blood pressure that undoubtedly came with this exercise…regions of their brain actually grew because they were walking!  Now, there is always a need for more large-scale, controlled interventions, but the science is consistently exposing exercise as a neuroprotective factor—helping to defend against deterioration in the brain.

People are always asking what they can do to protect themselves against Alzheimer’s disease and related dementias.  It seems to me that at least one answer is pretty clear.