Dementia tends to affect people as they reach old age and symptoms of the condition can include memory loss, mental sharpness and difficulty carrying out day activities. The four main types of dementia are Alzheimer’s disease, lewy body dementia, vascular dementia and frontotemporal dementia. While there’s no cure, some experts believed there are ways the condition can be prevented. Older people who are physically frail are more likely to develop dementia, warns new research.
Frailty increases the effect of the natural brain changes that occur with age, according to the study.
The findings, published in The Lancet Neurology, showed physically weak participants were more likely to have Alzheimer’s like damage in their grey matter – along with symptoms.
On the other hand, those who were physically stronger showed fewer clinical signs – despite having the same neuronal loss.
Study leader Professor Kenneth Rockwood said: “By reducing an individual’s physiological reserve, frailty could trigger the clinical expression of dementia when it might remain asymptomatic in someone who is not frail.
“This indicates a ‘frail brain’ might be more susceptible to neurological problems like dementia as it is less able to cope with the pathological burden.”
The findings, based on 456 Americans aged 59 or over, follow recent British research showing frail older people are three-and-a-half times more at risk of dementia.
Prof Rockwood said: “While frailty is likely to reduce the threshold for Alzheimer’s disease-related brain changes to cause cognitive decline, it probably also contributes to other mechanisms in the body that give rise to dementia, weakening the direct link between Alzheimer’s disease-related brain changes and dementia.
“While more research is needed, given that frailty is potentially reversible, it is possible that helping people to maintain function and independence in later life could reduce both dementia risk and the severity of debilitating symptoms common in this disease.”
Frailty affects around 17 per cent of the elderly in the UK. It’s defined as having an issue with mobility, a physical disability, poor general health, sight loss, problems hearing and having chronic illnesses like cardiovascular diseases or depression.
Most people who develop Alzheimer’s dementia are older than 65 years and have several other health problems.
Prof Rockwood, of Nova Scotia Health Authority and Dalhousie University in Canada, and colleagues used computer modelling to assess the relationships between frailty, Alzheimer’s-related brain changes and dementia.
The participants were members of the Rush Memory and Ageing Project (MAP) who had either no dementia or Alzheimer’s when they died and underwent brain autopsy.
Every year since 1997 they received neuro-psychological and clinical evaluations, which included detailed cognitive testing and neurological examinations.
Just over half had been given a diagnosis of possible or probable Alzheimer’s at their last clinical assessment.
Amyloid brain plaques and tau tangles of rogue proteins were measured after death.
The researchers also developed a frailty index using a combination of 41 components of health status – such as fatigue, joint and heart problems, osteoporosis, mobility, meal preparation – obtained at each clinical evaluation.
Overall, 35 participants (eight per cent) had substantial Alzheimer’s disease-related brain changes without having been diagnosed with dementia, and 50 (11%) had Alzheimer’s dementia but had little disease-related brain changes.
The analysis revealed that frailty and Alzheimer’s disease-related brain changes independently contributed to dementia diagnosis – after adjusting for age, sex and education.
There was also significant association between frailty and Alzheimer’s disease-related brain changes after excluding activities of daily living from the frailty index and adjusting for other risk factors such as stroke, heart failure, high blood pressure and diabetes.
Dr James Pickett, Head of Research at Alzheimer’s Society, said: “What’s fascinating about this research is it suggests physical activity might not slow down dementia related changes in the brain, but could help the brain cope with these changes.
“Exercise might help by strengthening the connections between brain-cells – referred to as cognitive reserve – which makes our brain more resilient to the changes that cause cognitive decline.
“The link between exercising and lowering your risk is becoming more and more established, but the question we need to answer now is how to help people incorporate more activity into their daily lives.
“This is why we have campaigned hard to have NHS mid-life health checks include recommendations on dementia risk reduction.
“For anyone concerned about keeping their brains healthy in later life, we encourage eating a balanced diet, avoiding smoking and excessive drinking, and getting that step count up.”