Curious Facts About Dementia and Handgrip Strength
At Anatomical Concepts, we are getting to grips with the Carbonhand again, so we have been delving into the research literature and sorting through the significant, curious and sometimes serious, facts to do with grip strength and human function. We don’t often write about Dementia but it is one of the conditions that shortens lives and seriously affects healthspan so we certainly don’t doubt it’s importance as a topic.
In Dr Peter Attia's excellent book, "Outlive", he mentions a recent study (by Irene Esteban-Cornejo et al, 2022) looking at nearly half a million patients in the UK which found that grip strength, which is strongly correlated with overall strength and indeed lifespan, was inversely associated with the incidence of dementia. These are findings are from the UK Biobank prospective cohort study.
People with the weakest grip had a 72% higher incidence of dementia compared to those in the top quartile for grip strength (the strongest).
What do we make of this?
Of course, correlation is not the same as causation. In other words, a weak grip does not cause dementia.
But even when the authors adjusted for the usual confounding factors such as age, sex, socio-economic status, pre-existing disease and various lifestyle factors, the message was consistent - The greater someone's grip strength, the lower their risk of dementia.
What is dementia?
Dementia is a generic term used to describe an umbrella of symptoms that are associated with impairments in memory, thinking, language and behaviour. Alzheimer's disease is the most common type of dementia. The number of people living with Alzheimer's in the UK is increasing. According to figures from 2017, more than 850,000 people had dementia and the prevalence rose to more than 1 million by 2021. Alzheimer's disease accounts for 60-80% of all cases of dementia and is by far the most common form of it.
In other articles on anatomicalconcepts.com, I have been a bit sceptical of the value of epidemiology for the individual because the data can so easily be misused or misinterpreted so it becomes of little value when we try to interpret how we, as individuals, fit into the overall picture. Prevalence data are important of course to influence healthcare policies and also for ensuring resources are allocated effectively for research.
In this particular 2022 study and others that focus on cardiorespiratory disease too, the message is consistent that strength and cardiorespiratory fitness are linked with neurodegeneration.
if you are in your thirties and forties, good advice would be to head to the gym - which is by far the best guidance we have at the moment to protect against neurodegeneration in later years. Frankly, there is not much else that seems to work in this regard. If you are in your fifties and beyond then best head for the gym too but nothing beats starting early when prevention is the aim.
Neurodegeneration
Several conditions result in neurodegeneration including Alzheimer's disease, other forms of dementia and Parkinson's disease. None of these are curable at the moment and the best we can hope for is to do what we can to prevent them which is not especially easy either.
Dr Alois Alzheimer was a German psychiatrist and neuropathologist who is best known for his description of what became known as Alzheimer’s disease.
In 1906, Dr Alzheimer identified the first documented case of this brain disorder by performing an autopsy on a person who had earlier presented with memory loss, hallucinations and other cognitive and behavioural issues. The autopsy revealed strange deposits on the subject's brain. It took decades before science accepted that dementia wasn't a natural consequence of ageing but a true disease state.
By the 1980's the brain deposits sometimes found in these cases were identified as amyloid-beta and not surprisingly, these deposits were suspected to be a primary cause of Alzheimer's. Since the 1980's a great deal of effort, time and money has been directed at trying to deal with amyloid-beta deposits in the expectation that if these could be prevented or cleared from the brain then "success" would be achieved - Alzheimer's treated and cognition restored.
Unfortunately, although drugs have been successful in clearing away amyloid this has not achieved the hoped-for benefits in improving cognitive function.
It does seem that amyloid is not the clear culprit it was once believed it was. It seems that lots of people have amyloid deposits at death but never showed any symptoms of cognitive decline. Similarly, people with cognitive decline do not always have amyloid deposits. Research suggests that amyloid is a pathological product of neurodegeneration but not the primary cause as was once thought.
At the moment we are far away from having a cure for Alzheimer's, but we do know several factors are important
Sleep - sleep disruptions and poor sleep increase the risk of dementia
Hearing loss seems to be associated with Alzheimer's even if it is not a cause
Oral health - bacteria that commonly cause gum disease have shown up in the brains of people with Alzheimer's although it is not certain that this is a causative factor. This suspected link and the stronger influence of oral health on cardiovascular condition is enough to encourage some of us to pay attention to frequent teeth brushing and flossing.
Plato, the Greek philosopher, was one of the first to suggest that ageing could lead to diminished cognitive abilities and reduce a person's capacity for leadership. He famously wrote in The Republic that "No man over forty should be allowed near the helm of a state". Plato believed that, by this age, people have lost their ability for discernment, reasoning and wisdom and can no longer be trusted to make sound decisions. In Plato's time, senility was a recognised phenomenon and associated with old age. At least we know now that these are diseases and not a simple consequence of ageing.
Conclusion
The problem with Alzheimer's and the family of neurodegenerative diseases is that once they are established, medicine, as it is practised today, can offer very little help. Likely, these diseases progress slowly over many years and the best situation is to act early and whilst young to prevent their onset. So, although grip strength is not a cause of dementia we might be seeing weak grip alongside dementia as both are symptoms of lower levels of fitness and general health.
Clinicians now recognise that there are early clinical signs of dementia referred to as stage 1 preclinical and mild cognitive impairment. At stage 1, the subtler signs of Alzheimer's may be missed; with mild cognitive impairment, symptoms will be obvious and generally recognised by friends and loved ones. It is estimated that over 46 million people in the United States are at stage 1 preclinical, although of course it is not known how many might go on to develop Alzheimer's.
The best medicine we know of so far is exercise as this can act on our metabolism and vascular systems to preserve brain health. Many articles on this site discuss the importance of exercise whether we are disabled or not. Exercise is truly medicine. Of course, it is not just one "thing" and we all typically need to do more aerobic and strength training throughout life.
References
Attia, P (2023) Outlive: The science and art of longevity. Penguin random House
Esteban-Cornejo, Irene & Ho, Frederick & Petermann-Rocha, Fanny & Lyall, Donald & Martinez-Gomez, David & Cabanas-Sánchez, Verónica & Ortega, Francisco & Hillman, Charles & Gill, Jason & Quinn, Terence & Sattar, Naveed & Pell, Jill & Gray, Stuart & Celis-Morales, Carlos. (2022). Handgrip strength and all‐cause dementia incidence and mortality: findings from the UK Biobank prospective cohort study. Journal of Cachexia, Sarcopenia and Muscle. 13. 10.1002/jcsm.12857.
Carson, RG (2018) Get a grip: Individual variations in grip strength are a marker of brain health, August 2018, Neurobiology of Aging 71, DOI:10.1016/j.neurobiolaging.2018.07.023
McGrath, Ryan & Robinson-Lane, Sheria & Klawitter, Lukus & Rhee, Yeong & Hamm, Jeremy & McCourt, Mark & Parker, Kelly & Hackney, Kyle. (2022). Undiagnosed Dementia Is Associated with Poor Physical Function in Older Adults. Journal of Alzheimer's Disease. 89. 1-10. 10.3233/JAD-220257.
What's a Prospective cohort study?
A prospective cohort study is a type of observational research study in which participants are identified and then followed over time to determine the impact of factors such as lifestyle, environment, and genetics on an outcome or disease. During the study, risk factors for diseases are collected by researchers to identify potential causes or predictors of the outcomes.