Lifestyle Factors That Affect Brain Health: Exercise

The impact of lifestyle factors on brain health is significant. Such factors include diet, exercise, social activity, environmental enrichment, educational attainment, occupation, psychosocial stress, and exposure to adverse life circumstances.

Recent evidence has emerged that Alzheimer’s disease may a exist on a continuum with normal brain aging.

The Brain Health Spectrum

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This model suggests that that path to full blown neurodegenerative disease may be incremental and progressive. Alterations in brain structure like cortical thinning, sleep and circadian dysregulation, and behavioral disturbances, often precede the onset of Alzheimer’s.

The point of no return exists somewhere between mild cognitive impairment (MCI) and frank neurodegeneration.  The good news is that the course of neurodegenerative disease can be slowed or even reversed by positive lifestyle changes.

During the natural course of aging, cognitive reserve (the brain’s ability to compensate after neurological insults like a mild concussion) is gradually depleted. This cognitive reserve may be understood as extra brain tissue or residual efficiency of neural networks that can be later deployed to compensate for insults to brain down the road.

Loss of cognitive reserve capacity is particularly insidious because by the time it is recognized, it may be too late for preventive measures to have a meaningful effect. Hence, the aftereffects of events that adversely affect brain health like a major depressive episode or concussion may be “masked” by cognitive reserve.

This information tells us that cognitive reserve can be maintained through positive lifestyle choices, including regular exercise, a rich and engaging social life and a diet comprised of brain healthy foods. One’s “dose” of education (i.e., educational attainment), is also likely a protective factor, though the causal directionality of this observation remains to be seen.  (One possibility  is that people with more resilient brains from the outset are more likely to attain terminal degrees, such as a PhD.)

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What is a Brain-Healthy Lifestyle?

In this section we’ll consider modifiable risk factors for accelerated brain aging, excluding diet and nutrition, which is discussed elsewhere.

Exercise

If exercise came in the form of a pill, it would be the most sought-after drug in the world.

Mounting evidence suggests that “exercise has profound benefits for brain function” [ref]http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2680508/[/ref], and regular exercise may be the single most important modifiable risk factor for cognitive decline.

Exercise confers the following benefits to brain health:

  • Increased neurogenesis (birth of new brain cells) in animal models
  • Increased brain-derived neurotrophic factor (BDNF), which promotes the formation of new brain connections (synaptogenesis) and is vital to higher-order thinking, learning and memory (neuroplasticity)
  • Increased expression of synapsin 1 and synaptophysin; these proteins regulate neurotransmitter release (neurotransmitters that activate brain cells)
  • In a 1-year randomized controlled trial with 120 older adults, exercise increased hippocampal volume (a brain structure implicated in learning/memory)[ref]http://www.ncbi.nlm.nih.gov/pubmed/21282661/[/ref], leading to improvements in spatial memory
  • Reduced symptoms of depression, improved affect and cognitive processing, faster retention time on working memory tasks [ref]http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768113/[/ref], [ref]http://www.ncbi.nlm.nih.gov/pubmed/19588354[/ref]
  • Corresponds with greater amplitude of P3, a measure of the allocation of cognitive resources, indicating that exercises improves executive function [ref]http://www.ncbi.nlm.nih.gov/pubmed/12798990[/ref]
  • Cognitive ability declines globally and linearly with age, and exercise protects against this age-related loss of cognitive function
  • Body mass index, fasting plasma insulin, and type 2 diabetes were strongly associated with brain atrophy; and exercise prevents the development of diabetes
  • Exercise in young adults is correlated to intelligence and learning in children [ref]http://www.researchgate.net/publication/235913924TherelationshipbetweenphysicalactivityandcognitioninchildrenA_meta-analysis[/ref] and confers immediate benefits to reaction time and vocabulary learning in young adults[ref]http://www.ncbi.nlm.nih.gov/pubmed/12798990[/ref], [ref]http://www.ncbi.nlm.nih.gov/pubmed/17185007[/ref], suggesting that there is no ceiling effect of exercise in the youth
  • The cognitive benefits of exercise are reflects in neurophysiological parameters such as event related potential (ERP), electroencephalogram, and magnetic resonance imaging (MRI) studies [ref]http://www.ncbi.nlm.nih.gov/pubmed/18094706/[/ref]
  • A subpopulation of carriers of ApoeE-e4 (a genetic risk factor for the development of Alzheimer’s disease), may benefit even more from exercise than non-carriers [ref]http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2680508/#R27[/ref]
  • Reduced beta-amyloid load (a hallmarker of Alzheimer’s) in a transgenic rodent model of Alzheimer’s disease [ref]http://www.ncbi.nlm.nih.gov/pubmed/15858047/[/ref]

Resistance Training vs Aerobic Exercise

Exercise is a promising strategy for combating cognitive decline, but what kind of exercise is best? It turns out that any physical beneficial. A single-blinded, randomized controlled trial comparing the efficacy of resistance training verses aerobic exercise was recently conducted [ref]http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3514552/[/ref]. Both types of physical activity improved measures of cognitive function.

Getting Motivated to Exercise

When you haven’t been in a good exercise routine, it can be very difficult to start. It is a cruel paradoxic that regular, high-intensity exercise is one of the best things to alleviate depression, yet depressed subjects will have the most difficulty getting motivated to exercise.

How to Trick Yourself Into Exercise When You Really, Really Don’t Want To

Mental framing and imagination can have a big effect on exercise motivation. If you imagine a grueling 1.5hour workout ahead of you, it’s easy to tell yourself “forget it” and never leave the couch.

You can deceive yourself by instead saying that you’ll go to the gym to do something low-key like walk slowly on the treadmill. If even that sounds daunting, you can say that you’ll just put on your exercise clothing without committing to going to the gym. If you focus all of your attention on the next simple step ahead of you, it can make it psychologically easier to follow through with an exercise routine.

Remember that no one has ever regretted getting a workout, and there is rarely ever something better that you can be doing with your time than exercising.

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