Physical fitness relates to dementia risk

We look forward with great anticipation to publication of the results from the MID-Frail study. We know from experience that it is possible to engage elderly (+70 years) people in exercise programs and we expect to see positive benefits on their metabolic health. Previous studies from the literature have demonstrated similar clinical benefits.

But what happens in terms of mental health in the elderly? We have long suspected that elderly subjects who are physically active have better mental health. Scientists have now collected evidence that exercise improves brain health and could be a lifesaving ingredient that prevents Alzheimer's disease. In particular, a study from UT Southwestern's O'Donnell Brain Institute indicated that lower physical fitness is related to a more rapid rate of deterioration in vital brain nerve fibres. This deterioration results in cognitive decline, including loss of memory issues that are characteristic of dementia. The findings support the hypothesis that improving people's fitness may improve their brain health and attenuate the effect of ageing.

The study published in the Journal of Alzheimer's Disease focused on a type of brain tissue called white matter, which is composed of millions of bundles of nerve fibres used by neurons to communicate across the brain. It enrolled older patients at high risk to develop Alzheimer's disease - displaying early signs of memory loss and/or mild cognitive impairment. The researchers determined that poorer white matter and impaired brain functions were demonstrated in patients with lower levels of fitness. Brain imaging techniques were used to measure the functionality of each patient's white matter and objectively measured cardiorespiratory fitness using a scientific formula called maximal oxygen uptake. This differentiates the work from earlier studies, which have relied on more subjective assessments.

Patients underwent memory and other cognitive testing to measure brain function, allowing scientists to establish correlations between exercise, brain health, and cognition. Adding to the growing body of evidence, the findings of the study appear to underline one simple message for the elderly - exercise regularly. Further tests are being designed for the early detection of patients who will go on to develop dementia, and seeking methods to slow or stop the spread of toxic proteins associated with the disease such as beta-amyloid and tau, which are blamed for destroying certain groups of neurons in the brain.

The study leaves several questions still unanswered - like exactly how fitness and Alzheimer's disease are intertwined, what fitness level is needed to notably reduce the risk of dementia and is it too late to intervene when patients begin showing symptoms of mental decline? Some of these topics are already being researched in a 5-year national clinical trial led by the O'Donnell Brain Institute. In a fashion similar to that being used in MID-Frail, the study aims to determine whether regular aerobic exercise and taking specific medications to reduce high blood pressure and cholesterol levels can help preserve brain function. It involves more than 600 older adults at high risk to develop Alzheimer's disease. The message seems to be that exercise promotes healthy ageing.