Muscle Strength Up - Alzheimer's Risk Down
Because explicit links exist between the body's motor and cognitive systems, it might be possible to assess brain function by examining how well muscles are functioning. To test this idea, a Japanese study measured handgrip and four other measures of physical strength in 1,552 cognitively healthy men and women over the age of 65. After adjusting for a number of factors that could influence the findings, the researchers found that greater upper and lower body strength was associated with better cognitive functioning and a lower risk of developing cognitive impairment.1 Another study included more than 900 retired, dementia-free people living in Chicago. The researchers tested eleven muscle groups including grip strength. Follow-up 3½ years later found that 138 had developed Alzheimer's. Each one-unit increase in muscle strength at the beginning of the study was linked to a 43% reduced risk of Alzheimer's. Those with the highest muscle strength had a 61% decreased risk of developing Alzheimer's compared to those with the least strength.2 There’s more. In a review of 15 studies published last year, the researchers concluded, "Findings here support the use of handgrip strength as a way to monitor cognitive changes and show that reduced handgrip strength over time may serve as a predictor of cognitive loss with advancing age."3Muscles and Brain - "A Clear Connection"
The most recent study was published in April using data from the UK Biobank of 475,397 individuals. Grip strength was measured against five cognitive tasks covering reaction time, reasoning, ability to remember numbers, recollection of pictures, and prospective memory. The last item in that list tests whether participants can remember to act on an instruction after a delay period. After gender, age, weight, education and geographical location were taken into account, a significant correlation was found between grip strength and each of the cognitive tasks tested.4 The precise nature of the link between muscle and mind is not clear, but higher total brain volume is known to be associated with larger muscles. In addition, older people with stronger grip strength have fewer indications of degradation in the brain's white matter. These bundles of nerve tissue link up different brain regions, carry impulses from one cell to another, and are needed for both physical and mental tasks. Another proposed link between brain and muscles is through inflammation. Higher inflammatory markers predict both age-related cognitive decline and weakened grip. Summing up the findings of the study, lead author Dr. Joseph Firth, an honorary research fellow at the University of Manchester, commented, "We can see there is a clear connection between muscular strength and brain health. But what we need now are more studies to test if we can actually make our brains healthier by doing things which make our muscles stronger – such as weight-training."5- https://www.ncbi.nlm.nih.gov/pubmed/25177186
- https://www.ncbi.nlm.nih.gov/pubmed/19901164
- https://www.ncbi.nlm.nih.gov/pubmed/28189666
- https://academic.oup.com/schizophreniabulletin/advance-article/doi/10.1093/schbul/sby034/4942313
- https://medicalxpress.com/news/2018-04-reveals-stronger-people-healthier-brains.html
