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Losing muscle strength could be an early sign of dementia. Victoria Phipps/Getty Images
  • As we age, we lose muscle mass.
  • By the age of 50, humans lose about 10% of their body’s muscle.
  • Researchers from Edith Cowan University believe a loss of muscle strength may herald the start of dementia in older people.
  • Two ways to measure this is through grip strength and how quick and balanced people are when they get up from a chair.

It is a well-known fact that as we get older, we lose muscle mass.

Researchers estimate humans begin to lose muscle mass in their 30s or 40s and lose about 10% of their muscle by the age of 50. Then from age 50 to 70, we lose another 30% of muscle strength.

Now, researchers from Edith Cowan University in Australia have found evidence suggesting a loss of muscle strength may also be a signal for older people developing dementia — an umbrella term for diseases impacting a person’s cognitive ability.

The researchers used grip strength and Timed Up and Go (TUG) as measures of muscle strength.

The study was published in the Journal of Cachexia Sarcopenia and Muscle.

When doctors want to measure the muscle health of a person’s hands and forearms, they may administer a grip strength test.

This simple test uses a tool called a dynamometer. The person simply holds the dynamometer in their hand and squeezes it with all their strength, and the tool measures the amount of force used.

Grip strength has long been considered a biomarker of a person’s overall health. Previous research has associated reduced grip strength with an increased risk of all-cause and cardiovascular mortality.

And past studies found grip strength to be an indicator of a person’s health-related quality of life as they age.

The Timed Up and Go (TUG) test is used as a way for doctors to check a person’s mobility and balance.

During the TUG test, a person is asked to sit in a normal chair. As a medical professional times them with a stopwatch, the person is asked to stand up, walk to a line about 10 feet away from the chair, turn around, walk back to the chair, and sit back down in the chair.

This allows the doctor to see how the person is walking and check their movement for postural or balance issues.

The majority of healthy older adults can finish the TUG test in 10 seconds or less. A time of greater than 13.5 seconds may indicate a person is at a greater risk of falling.

Previous studies have found the TUG test helps predict frailty in older adults, and evaluates their fall risk.

According to Dr. Marc Sim, senior research fellow in the Nutrition & Health Innovation Research Institute at Edith Cowan University in Joondalup, Australia and lead author of this study, they decided to investigate a relationship between muscle function and dementia because current evidence suggests strong links between physical capacity, including muscle mass (e.g. sarcopenia) and cognitive health.

“When taken into the context of dementia, at a community level, the use of fast, inexpensive, and simple tests such as grip strength and TUG are extremely appealing,” he told Medical News Today.

“This could serve as a screening tool to help clinicians identify those most at risk and enable the promotion of primary prevention strategies, (such as) exercise (and) nutrition. Screening for dementia risk at the community level is rarely performed,” he said.

Dr. Sim said they selected grip strength and TUG tests as their methods to analyze study participants’ muscle function because they are both simple and easy to perform and are currently recommended as functional tests as part of sarcopenia criteria in Australia.

“There is very strong evidence for these tests to predict a range of adverse outcomes in older populations — falls/ fracture/CVD/mortality — and take [around] 3 [minutes] to perform by clinicians,” he added.

For this study, Dr. Sim and his team used data from the Perth Longitudinal Study of Ageing in Women to examine more than 1,000 women with an average age of 75.

Researchers administered grip strength and TUG tests to each woman. The tests were then repeated five years later.

The scientists found over the next 15 years, about 17% of study participants either had a dementia event that was either a dementia-related hospitalization or death.

Additionally, the research team found lower grip strength and slower TUG were significant risk factors for a study participant experiencing dementia. And the women with the weakest grip strength and slowest TUG tests were more than twice as likely to have a late-life dementia event.

This was independent of other risk factors such as smoking, alcohol use, and physical activity levels.

“Because these functional tests are likely to provide a snapshot of current health status, I would not say the results are surprising. Especially since we know that people who struggle with daily activities of living due to physical limitations are less likely to engage in exercise-a major risk factor for dementia,” Dr. Sim commented.

“What was of interest to me was the high dementia risk associated with declining function over five years, where those with the greatest decline were at the highest risk. This is also an important point for clinicians to consider,” he added.

After reviewing this study, Dr. Raphi Wald, a board-certified neuropsychologist at Marcus Neuroscience Institute, established at Boca Raton Regional Hospital part of Baptist Health South Florida, who was not involved in the study, told MNT that this study is helpful in confirming what we knew and strongly suspected about declining strength and cognitive functioning.

“There are a number of often subclinical signs and symptoms of dementia that pop up before serious deterioration begins. This is another hint for doctors that a process may be beginning and needs to be addressed,” he said.

“I think it would be helpful to have more information about those patients that successfully address their muscle weakness and how much it decreases their risk for dementia once they do so,” Dr. Wald added when asked what he would like to see as next steps for this research.

Ryan Glatt, senior brain health coach and director of the FitBrain Program at Pacific Neuroscience Institute in Santa Monica, California, also not involved with this study, told MNT these findings are consistent with prior studies showing that grip strength and mobility are correlated with aspects of cognitive decline in older adults.

“Collecting mobility, gait, and strength data in clinical settings can be helpful in comprising a comprehensive set of data that could be helpful in predicting the risk of dementia. It would be interesting to correlate these mobility and strength measures with other aspects of brain health,” he added.

Medical News Today also spoke with Dr. William Buxton, a board-certified neurologist and director of Neuromuscular and Neurodiagnostic Medicine and of Fall Prevention at Pacific Neuroscience Institute at Providence Saint John’s Health Center in Santa Monica, about this study.

“[This study] tells us that the extra few minutes to do some really basic simple testing in the office, even just routine visits, like the Time Up and Go test and testing grip strength, can give us good, scientifically grounded reason to encourage physical activity not only for cardiac benefit but also for cognitive fitness.”
— Dr. William Buxton

“And for those individuals to pay a little bit closer attention to watching for cognitive decline that we may be able to slow down as a result of paying that extra attention,” Dr. Buxton, who was also not involved in the study, added.

Dr. Buxton said he would like to see a similar study done in men and also research to see if there’s an added benefit to exercising in groups.

“We know that people who stay socially active also are less prone to develop and/or experience worsening of cognitive problems. So I’d be eager to see if group exercise that’s linked to social engagement would have added benefit above and beyond individual exercise,” he added.