A genetic tendency for a strong grip is linked to better cognitive health in older adults. Researchers recently discovered that individuals born with DNA traits favoring muscle strength also tend to experience slower mental decline as they age. This relationship operates independently of how much a person exercises, according to a recent study published in Neurobiology of Aging.
Loss of motor function, which includes basic physical movements and muscle control, often precedes cognitive decline. Medical professionals frequently measure hand grip strength using a simple hand-held device as a quick indicator of a person’s overall vitality. Weaker grip strength is a known risk factor for developing memory problems and Alzheimer’s disease later in life.
The biological reasons behind this connection have remained a subject of debate. One common explanation revolves around general health. People who maintain their strength might simply be more physically active, which supports heart health and brain function over time. In this view, lifestyle choices provide the main bridge between a strong body and a sharp mind.
Another explanation suggests a more direct biological link between muscles and the brain. Generating a forceful physical grip requires coordinated signals from the nervous system. As people age, changes in these neural pathways might cause both muscular weakness and cognitive difficulties.
Some evidence points to physiological interactions between tissue types. Skeletal muscles secrete specific proteins that travel through the bloodstream and influence learning and neural adaptation in the brain. In this scenario, genetic profiles that protect muscle mass or nervous system integrity could directly preserve cognitive function.
To investigate this relationship, Rachel Bercovitch and Daniel Felsky, along with a team of colleagues at the University of Toronto, the Centre for Addiction and Mental Health, and Rush University Medical Center, turned to genetic data. They wanted to see if an innate genetic predisposition for hand grip strength could predict cognitive outcomes. They also wanted to see if this genetic link existed before lifestyle factors like exercise came into play.
A polygenic risk score is a tool that adds up the estimated effects of thousands of tiny genetic variations across a person’s entire DNA sequence. Many physiological traits are not controlled by a single gene, but rather by small contributions from countless scattered genetic markers. By calculating this summary score, researchers can gauge an individual’s genetic likelihood of developing a specific physical trait.
The research team generated a genetic score for hand grip strength for more than 25,000 adults. The participants came from two separate aging studies: the Canadian Longitudinal Study on Aging and the Religious Orders Study and Rush Memory and Aging Project. By using two large groups, the researchers could look for patterns that held true across different demographics and testing methods.
The Canadian study included over 23,000 mostly healthy adults in mid-to-late life, allowing the team to observe early variations in memory and thinking. The Rush project tracked roughly 2,000 older individuals, including Catholic nuns and priests in the United States. These older participants underwent detailed annual cognitive tests and agreed to brain donations after their deaths.
First, the researchers verified that their genetic tool worked as intended. In both study groups, individuals with higher genetic scores for hand grip strength also recorded a stronger physical grip when squeezing a testing device. This confirmed that the genetic summary accurately reflected real-world physical traits.
Next, the team examined cognitive performance. In both the Canadian and the Rush groups, people with higher genetic scores for hand grip strength performed better on overall cognitive tests. This test score association remained intact even after the researchers accounted for age, sex, body mass index, and cardiovascular disease risk.
The researchers also tracked changes in memory and thinking skills over time. In the Rush study, where participants were followed for up to 21 years, those in the top third of the grip strength genetic scores experienced a slower rate of cognitive decline compared to those in the bottom third. The difference equated to a 20 percent improvement in preserved cognitive function over the study timeline.
In the Canadian group, the genetic score did not predict longitudinal changes in cognitive speed or memory. The researchers suggested this discrepancy might stem from the Canadian participants being relatively younger and healthier. The shorter follow-up time for the Canadian group might also have made it harder to detect slow changes in mental acuity.
The team then checked if the cognitive benefit simply came down to physical activity. They used statistical models to test whether the association between the genetic score and cognitive health was primarily driven by reported exercise habits. The analysis showed that physical activity did not act as a mediating factor.
Instead, actual physical strength and lean muscle mass played a larger role in connecting the genetic score to cognitive outcomes. This suggests that the genetic predisposition for muscle strength influences cognitive aging primarily through direct biological pathways related to muscle function, rather than behavioral choices like deciding to exercise.
Because the Rush study included brain autopsies, the team was able to look for physical signs of Alzheimer’s disease. These signs include the buildup of misfolded proteins known as amyloid plaques and tau tangles. They also checked for evidence of microinfarcts, which are tiny strokes that can damage brain tissue over time.
The genetic score for hand grip strength showed no relationship to any of the 12 postmortem brain pathologies measured. The lack of an association with traditional indicators of dementia suggests an entirely different biological mechanism at work. The genetic tendency for muscle strength might reflect a form of overall biological resilience that protects the brain without altering the typical accumulation of plaques and tangles.
The researchers also tested their grip strength score alongside an established genetic score for Alzheimer’s disease risk. Medical professionals are increasingly looking at genetic Alzheimer’s risk to help identify patients who might benefit from early interventions. However, these genetic models are still imperfect and capture only part of a person’s total risk.
Adding the grip strength variable improved the accuracy of the baseline Alzheimer’s prediction models. This combined approach demonstrated a stronger association with cognitive outcomes than the Alzheimer’s score alone. Future clinical models might incorporate physical trait genetics to evaluate cognitive conditions with greater precision.
Despite the large sample sizes, the researchers noted several limitations in their data. The metrics for physical activity relied on self-reported questionnaires covering only recent weeks, which might not accurately capture a person’s lifelong exercise habits. A lifetime history of physical activity would provide an accurate picture of how behavioral factors connect to genetic predispositions over decades.
Additionally, the analysis focused exclusively on individuals of European ancestry. Research involving a wider variety of genetic backgrounds would be required to confirm whether these relationships apply globally across diverse populations.
Future research will need to identify the exact biological networks that link muscular and cognitive health. The team is currently examining other potential biological markers, such as specific brain structures visible on brain scans and circulating immune system proteins. Finding the specific metabolic or neurological pathways that tie muscle function to brain health could eventually inspire new strategies to slow memory loss.
The study, “Genetic Predisposition to Hand Grip Strength Predicts Cognitive Decline,” was authored by Rachel Bercovitch, Earvin S. Tio, Rajith Wickramatunga, Melissa Misztal, Kristina Gicas, Philip L. De Jager, Julie A. Schneider, Aron S. Buchman, David A. Bennett, Tarek Rajji, James L. Kennedy, and Daniel Felsky.