February 22, 2023
How strong your grip is, and how quickly you can walk, may be indicators of how likely you are to suffer from the ravages of Alzheimer’s disease, according to a new report. The small study, in the Journal of Alzheimer’s Disease, found that in people showing early signs of Alzheimer’s disease, hand strength and walking speed were correlated with brain volume. The weaker their muscle strength, and the slower they walked, the smaller the size of key areas of the brain, including the hippocampus, a brain region critical for memory that is one of the first areas affected by Alzheimer’s disease. The findings add to growing evidence that physical fitness is a good indicator of overall health, including the health of the brain.
For the study, researchers at Washington University in St. Louis and other institutions looked at 38 older men and women who were attending an outpatient memory clinic. All had problems with memory and thinking skills and showed evidence of amyloid plaque buildup in the brain, a hallmark of Alzheimer’s disease.
The researchers assessed their grip strength in both hands using a hand dynamometer, a medical instrument that measures the force with which someone is able to squeeze the hand against resistance. They also had participants complete the two-minute walk test, which measures how far someone can walk during that time. Both tests are a general measure of “frailty”: a weak handgrip strength and a slow gait speed are both signs that an elderly person is in a frail state of health.
In addition, the researchers measured the volumes of key brain areas using an MRI brain scan. They found that the greater a person’s handgrip strength, the larger the volume of the hippocampus and other brain areas critical for cognitive functions. Higher scores on the two-minute walk test were also associated with larger volume of several key brain areas. Conversely, the more physically “frail” a person was, the lower the volume of critical brain areas.
The findings were a correlation and cannot prove cause and effect, and they were assessed only in several dozen people. But other, larger studies have likewise shown a strong correlation between handgrip strength and overall health and longevity. One recent study of 1,275 men and women found that those with weaker grip strength had evidence of premature aging in their DNA. Other studies have shown that increased handgrip strength in midlife is associated with lower levels of brain abnormalities known as white matter hyperintensities, which may presage serious cognitive problems and even the onset of dementia.
Other studies have shown that slow walking speed, as a marker of frailty, has likewise been tied to an increased risk of Alzheimer’s disease, even in people whose brains show few signs of damage from the illness. And in those who have brain changes typical of Alzheimer’s disease, good overall health seems to help protect against the development of memory loss and other symptoms of dementia.
“It is possible that interventions specifically focused on improving ambulatory mobility and handgrip strength could be beneficial in improving dementia trajectories,” the authors note. “Such work will continue to be important for optimizing cognitive health in those at risk for and suffering from Alzheimer’s disease.”
The researchers say that training the muscles has indirect consequences that also helps to sustain the brain, and that exercise is among the best strategies for maintaining a healthy body and mind with age. While other studies have shown that aerobic training aids the brain, these findings add to the importance of strength training in supporting successful aging, they added.
Many doctors’ offices and gyms have hand dynanometers where you can test your grip strength. A healthy 40-year-old man, for example might have a grip strength of just over 100 pounds, compared to 66 pounds for a women. Those numbers gradually decrease over the decades, and scales are available to see where you fall.
General exercises to increase muscle strength, such as pushups or lifting light hand weights, can all help to improve grip strength. Squats and leg lifts can strengthen the leg muscles and improve walking speed. Regardless of age, what’s good for the body can be good for the brain, a growing body of research shows.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Meysami, Somayeh; Raji, Cyrus A.; Glatt, Ryan M.; et al: “Handgrip Strength Is Related to Hippocampal and Lobar Brain Volumes in a Cohort of Cognitively Impaired Older Adults with Confirmed Amyloid Burden.” Journal of Alzheimer’s Disease, December 14, 2022