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A first-of-its-kind study by researchers from the University of California at Irvine has identified a strong correlation between dementia risk and poor performance on two different physical performance tests: the standing balance test and a 13-foot walking test. Interestingly, poor balance had the strongest association with the incidence of dementia. What is the neuroscientific explanation for this?
Although the researchers don’t jump to any conclusions about causation based on this correlation, they do hypothesize that—because walking and maintaining balance require complex brain activity—testing these functions may help doctors predict those who might be most at risk for developing dementia.
The July 2016 study, "Sound Body Sound Mind? Physical Performance and the Risk of Dementia in the Oldest-Old: The 90+ Study," appears online this week and will be published in an upcoming print edition of the Journal of the American Geriatrics Society. This population-based longitudinal study was conducted on 578 people aged 90 or older.
Previous research on dementia has identified a link between poor physical performance and increased odds for dementia in people younger than 85. However, until now, it was unclear what types of poor physical performance were associated with dementia for people 90 and older.
Why Are Poor Balance and Difficulty Walking Associated with Dementia Risk?
The first thought I had while reading this study earlier today was that finding a link between poor balance or difficulty walking and dementia is a textbook example of reminding oneself that “correlation does not mean causation.” Obviously, simply identifying an association between poor balance and higher dementia risk doesn’t necessarily mean that poor balance causes dementia for people over 90 years old.
That said, identifying a strong correlation between poor balance and higher risk of dementia offers interesting food for thought. For example, based on previous research linking the cerebellum (Latin for “little brain) with both balance, fluidity of coordinated movements, and cognitive functions, I have a hunch the cerebellum is somehow involved in this correlation. There is growing evidence suggesting that (contrary to popular belief) the cerebellum contributes to cognition as well as fine-tuned motor functions, balance, and muscular coordination.
Over a decade ago, researchers at Johns Hopkins University School of Medicine published a study identifying that the cerebellum plays a crucial role in balance and self-produced locomotion. One of the characteristic signs of damage to the cerebellum is walking ataxia marked by a lack of fluidity and jerky movements.
In 2014, the Neuroimaging section of the journal Psychiatry Research, published findings that a reduction in the volume of gray matter and white matter in the cerebellum was associated with certain types of dementia and Alzheimer’s disease.
Lastly, based on his extensive research on ataxia and the cerebellum, Jeremy Schmahmann of Harvard Medical School developed a revolutionary hypothesis that just like the cerebellum fine-tunes our movements it also fine-tunes our thinking processes.
Although it's speculative, by putting the pieces of the puzzle together, one could make an educated guess that the cerebellum might be playing a role in the strong association between poor balance and the risk of dementia. Here is a video of Schmahmann explaining his theory of “Dysmetria of Thought."
Conclusions: Use it or Lose it. Your Cerebellum Atrophies If Not Engaged Regularly
Approximately, 7 percent of adults aged 60 and older suffer from dementia—a decline in memory and other cognitive abilities that can make everyday life difficult. The number of people living well into their 90's is projected to quadruple by 2050. This means that by mid-century, nearly 9 million people will be 90-years-old or older.
The good news is that in many cases there are practical ways to keep the Purkinje neurons of the cerebellum robust and functioning optimally based on lifestyle choices such as avoiding sedentarism, staying physically active, moderate aerobic exercise, yoga, dance, Tai Chi, etc.
Additionally, there are cerebral activities that flex critical thinking, problem-solving, and rational analysis that could be viewed as primarily functions of the "left brain-right brain" in the cerebrum. Using the framework of the "Bergland split-brain model" above, you can structure your day to include activities that improve your cerebral and cerebellar (relating to or located in the cerebellum) functions. Ideally, all four brain hemispheres should work in perfect harmony as a unified whole—without any friction or viscosity—to enhance creative capacity.
By making a conscious effort to engage both hemispheres of the cerebellum and both hemispheres of the cerebrum on a daily basis—at every stage throughout your lifespan—my hypothesis is that everybody increases his or her odds of maintaining a sound mind in a sound body until you're a centenarian.
Again, in many ways, this conclusion is conjecture on my part. However, my educated guess is based on years of extensive empirical research on this topic. Also, anecdotal evidence supports the fact that consistently making daily lifestyle choices to stay active and maintain a sense of balance through practices such as yoga and Tai Chi could help millions of seniors reduce their risk of cognitive impairment past the age of 90.
Stay tuned for future studies that could lead to the development of prevention programs and specific treatment strategies for creating an upward spiral of both physical performance and a reduced risk of developing dementia.
To read more on the link between the cerebellum and cognitive function check out my Psychology Today blog posts,
- "The Cerebellum Deeply Influences Our Thoughts and Emotions"
- "Superfluidity: Fluid Intelligence Goes Beyond Brain Size"
- "7 Habits for a Healthy Mind in a Healthy Body"
- "Fear of Falling Creates a Downward Spiral"
- "Why Is Dancing So Good for Your Brain?"
- "Enhanced Cerebellum Connectivity Boosts Creative Capacity"
- "Why Does Physical Activity Improve Cognitive Flexibility?"
- "Decoding the Enigma of Cognitive Flexibility"
- "Your Eyes Are a Window Into the Inner Workings of Your Brain"
- "What's the Secret to Staying Forever Young?"
© 2016 Christopher Bergland. All rights reserved.
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