It has been said that you can tell a lot about a person’s character from his handshake, but can it also reveal whether that person is at higher risk for dementia? Weak handgrip strength is often used as one of the correlates for frailty, a risk factor for dementia.
Frailty can be classified in several ways, with no single standardized clinical definition, but is most commonly defined by a set of physical characteristics that includes unintentional weight loss, slow walking, weak grip strength, exhaustion, and low physical activity [1]. There isn’t a single definition because frailty occurs on a spectrum where people can range from very fit to severely frail, such that there is progressive loss of independence as one moves through the various stages [2]. From a physiological perspective, frailty refers to a loss of resiliency, or a condition where the body loses the capacity to adapt to stress [3]. In this way, frailty can be most easily thought of as a state of vulnerability. Being frail makes one more vulnerable to, and less likely to recover from, accidents, infections, and age-related diseases, including dementia.
A meta-analysis found that the odds of developing dementia were 1.8 times higher for frail older adults relative to their non-frail peers [4]. This stems from the finding that although frailty is commonly characterized by its physical manifestations, it involves decline across multiple organ systems, including the brain [5]. Many frail individuals score lower on tests of cognitive function, indicative of mild cognitive impairment, or the early stages of cognitive decline [3; 5; 6; 7]. The cognitive functions most affected by frailty include attention, executive function, and processing speed [5]. These cognitive deficits are closely associated with vascular pathology and cardiovascular disease [4; 8; 9].
Frail individuals have a lower capacity to withstand damage to the brain, so they will start showing signs of cognitive impairment early in the disease course when only a modest amount of brain pathology is present [6]. Frailty, then, can be considered the opposite of cognitive reserve, as both are measures of resiliency. While the brains of those with more reserve are highly resistant to stress, the brains of the frail are unable to cope with stress, such that mild impairments are more likely to progress to dementia [7]. At this time, there is insufficient evidence to indicate that frailty is a cause of dementia; rather, it is thought to lower the threshold for disease-associated pathology to induce clinical signs of dementia, and to accelerate the progression of cognitive decline.
Just as there isn’t a single definition of frailty, there isn’t a single cause. Frailty most often occurs in the context of aging, but it can also occur in the context of disease, especially cardiovascular disease, metabolic disease, and arthritis [9]. A common feature to these is the loss of physical activity. The onset of frailty frequently follows periods of immobility due to hospitalization, especially due to falls [9]. Frailty, in turn, increases the risk for future falls. Joint stiffness and pain often restrict movement in those with arthritis, while those with cardiovascular disease and obesity also exhibit lower levels of physical activity [9; 10]. Decreased mobility can lead to a loss of independence and accelerate functional decline [8]. All of this suggests that physical activity is the stone that can tip the balance toward or away from frailty, likely due to the ability of exercise to generate protective substances in the body that enhance resilience.
The good news is that evidence supports the idea that frailty is both preventable and at least partially reversible, with physical activity as the key player [3; 7]. Diet and management of chronic disease also play a role. As previously indicated, frailty can be categorized along a spectrum of different types and stages [1; 3]. Targeted intervention is expected to have the greatest impact on those in the middle of the spectrum, classified as apparently vulnerable, also called pre-frail, or mildly frail. Individuals in these categories may start showing a subset of the physical hallmarks of frailty, or early signs of dependency on others for daily activities. Pre-frail individuals may also start showing some cognitive signs of frailty, such as reduced attention [5]. These individuals are best positioned to stop the progression toward frailty through lifestyle interventions.
While it is important for an exercise program to be tailored to the capabilities of an individual, multicomponent exercise programs have been shown to provide benefit for both physical and cognitive function [11]. Multicomponent exercise includes aerobic, resistance, and balance training. The balance training, in particular, impacts cognition, while the other components are important for improving cardiovascular fitness and strength. Because frail individuals are at a higher risk for injury, supervision may be necessary to ensure that exercise is conducted safely [12]. Overall, a healthy diet and regular exercise are the best ways to stave off frailty.
Betsy Mills, PhD, is a member of the ADDF's Aging and Alzheimer's Prevention program. She critically evaluates the scientific evidence regarding prospective therapies to promote brain health and/or prevent Alzheimer's disease, and contributes to CognitiveVitality.org. Dr. Mills came to the ADDF from the University of Michigan, where she served as the grant writing manager for a clinical laboratory specializing in neuroautoimmune diseases. She also completed a Postdoctoral fellowship at the University of Michigan, where she worked to uncover genes that could promote retina regeneration. She earned her doctorate in neuroscience at Johns Hopkins University School of Medicine, where she studied the role of glial cells in the optic nerve, and their contribution to neurodegeneration in glaucoma. She obtained her bachelor's degree in biology from the College of the Holy Cross. Dr. Mills has a strong passion for community outreach, and has served as program presenter with the Michigan Great Lakes Chapter of the Alzheimer's Association to promote dementia awareness.
Get the latest brain health news:
Exercise – It’s Not Just Good For The Heart
Cognitive and Physical Activity Reduce Your Risk for Dementia
The Dash Diet With Exercise Improved Cognitive Functions in Older Adults
Want Better Brain Health? Study Says to Start Exercising Now
Is Yoga Good for Your Brain Health?
Fit Body, Fit Mind
Which Diets Are Best for Cognitive Health?
Three Promising Diets to Improve Cognitive Vitality
Better Diet Is Associated With Larger Brain Volumes
How Does the Brain Protect Itself Against Cognitive Decline?
Building Cognitive Reserve: Do Computer Games Really Work?
Brain Training Can Reduce Dementia Risk
Nine Lifestyle Factors May Lower Your Alzheimer’s Risk
Diabetes & Dementia: Is High Blood Sugar Damaging Your Brain?
Manage Hypertension, Prevent Dementia?
Does Obesity Accelerate Brain Aging?
Does Stress Worsen Cognitive Functions?
It Is Never Too Early to Protect Your Heart
Does Chronic Pain Increase Dementia Risk?