In a major breakthrough, Rong Zhang, a neurologist at the University of Texas Southwestern (UTSW) Medical Center, and his colleagues found that regular aerobic exercise training can stall brain deterioration and reduce brain plaques in older adults at risk of Alzheimer's disease.
The results of the RCT, published online in the Journal of Alzheimer's Disease, also demonstrated that regular stretching or toning exercises can confer the same beneficial effects, albeit to a smaller degree.
This is the first RCT to examine the effects of aerobic exercise on brain structure, brain function and brain plaque in older adults at risk of dementia, noted Zhang.
Regular aerobic exercise can delay brain deterioration
The idea that fitness could be related to dementia risk is no recent concept. Past studies on fitness and brain health had long since suggested that exercise could slash dementia risk among older adults, but the effects of exercise on plaques and hippocampus deterioration, in particular, are less studied.
In this recent trial, Zhang and his colleagues randomized 70 participants aged 55 and older to 12 months of either aerobic exercise training or stretching exercises. The participants had been diagnosed with mild cognitive impairment (MCI), a degenerative disorder that could later on progress to Alzheimer's disease.
Brain imaging showed that participants in the aerobic exercise group lost less volume in their hippocampus. Degenerative brain conditions tend to affect the hippocampus the most, so much so that neurologists use the size of the hippocampus to diagnose the progression of brain deterioration in dementia patients.
Furthermore, participants in the aerobic exercise group who had more amyloid plaque in their brains experienced less volume reduction in their hippocampus compared to the others in the same group, despite showing no improvements in their cognitive abilities.
Amyloid plaques are proteins that have clumped together in the spaces between nerve cells. Because the plaques are often found in the brains of patients with Alzheimer's disease, neurologists agree that the plaques are integral to the onset and progression of the disease.
It is interesting that patients with more plaque responded better to the aerobic exercise intervention than the others, said Zhang. Moreover, although neither intervention can stop the hippocampus from getting smaller, these findings reveal that regular exercise can slow the rate of its deterioration, added Zhang.
He also speculated that aerobic exercise training has the most beneficial effects on brain plaque and hippocampus deterioration because of its influence over cardiovascular health. Proper blood circulation is integral to brain health as it encourages neuron growth and survival, said Zhang.
Regular aerobic exercises, such as walking and jogging, are known to boost blood circulation and improve overall cardiovascular fitness. Therefore, aerobic exercises could promote better blood flow in the brain that, in turn, helps in reducing the damaging effects of plaque and stalling brain deterioration, added Zhang.
Zhang is now leading a national clinical trial that aims to further explore the connection between exercise or fitness and dementia. The trial is set to involve more than 600 older adults aged 60 to 85 at a high risk of Alzheimer's disease. (Related: The link between sleep deprivation and Alzheimer's.)
Zhang and his colleagues hope to determine whether aerobic exercise can reduce high blood pressure and cholesterol and, in so doing, preserve brain volume and cognitive abilities. The findings of this trial could help scientists better understand the molecular mechanisms behind the progression of dementia, said Zhang.
Poor fitness heightens the risk of dementia
This latest research had built upon numerous studies suggesting similar links between exercise or fitness and brain health. In 2018, for instance, another team of scientists from UTSW's O'Donnell Brain Institute found a link between poor fitness and higher dementia risk.
Neurologist Kan Ding and her colleagues studied the brains of older patients that had MCI. Brain imaging revealed that those who had lower fitness levels had weaker white matter and lower brain function. White matter, one of the two major kinds of brain tissues, is comprised of millions of nerve fibers that neurons use to communicate across different regions of the brain.
Ding and her team had built their research on past studies, too, including a 2013 investigation that Zhang had led. In that trial, Zhang and his team found that neural communication was more efficient in the brains of older adults who have engaged in life-long aerobic exercise training.
Taken together, these studies offer empirical evidence that exercise habits and fitness levels hold some influence over brain health and dementia risk in later life. Given further research, these studies might just persuade people to exercise more for better brain health, said Ding.
Read more articles about dementia and brain health at Brain.news.
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