Regular aerobic workouts could slow down brain deterioration in Alzheimer's disease
Exercising several times a week may delay brain deterioration in people at high risk for Alzheimer's disease, according to results from a clinical trial that included 70 participants, 55 years and older. Researchers from the University of Texas (UT) Southwestern Medical Center found that people who had an accumulation of amyloid-beta in the brain - a hallmark of Alzheimer's disease - experienced slower degeneration in a region of the brain that is crucial for memory if they exercised regularly.
In the brains of Alzheimer's patients, abnormal levels of the amyloid beta-protein clump together to form plaques. The researchers say while exercise did not prevent the eventual spread of toxic amyloid plaques blamed for killing neurons in the brains of dementia patients, the findings suggest an "intriguing possibility that aerobic workouts can at least slow down the effects of the disease" if intervention happens in the early stages.
"What are you supposed to do if you have amyloid clumping together in the brain? Right now doctors cannot prescribe anything. If these findings can be replicated in a larger trial, then maybe one day, doctors will be telling high-risk patients to start an exercise plan. In fact, there's no harm in doing so now," says Dr. Rong Zhang, who led the clinical trial. The findings have been published in the Journal of Alzheimer's Disease.
"I am excited about the results, but only to a certain degree. This is a proof-of-concept study, and we cannot yet draw definitive conclusions," adds Dr. Zhang, a neurologist at UT Southwestern's O'Donnell Brain Institute.
According to the World Health Organization (WHO), dementia is a syndrome in which there is deterioration in memory, thinking, behavior, and the ability to perform everyday activities. Around 50 million people are affected by it globally, and there are almost 10 million new cases every year. Alzheimer's disease is the most common form of dementia and may contribute to 60–70% of cases.
Clinical trial
More than 5 million Americans have Alzheimer's disease, and the number is expected to triple by 2050. Billions of dollars that have been spent on trying to prevent or slow dementia have so far not led to proven treatments that would make an early diagnosis actionable for patients. Dr. Zhang is among a group of scientists across the world who are trying to determine if exercise may be the first such therapy. He is leading a five-year national clinical trial aims to dig deeper into potential associations between exercise and dementia.
The trial includes six medical centers across the country, involving over 600 adults (ages 60-85) at high risk of developing Alzheimer's disease. "It will measure whether aerobic exercise and taking specific medications to reduce high blood pressure and cholesterol can help preserve brain volume and cognitive abilities," says the team.
Stating that while understanding the molecular basis for Alzheimer's disease is important, Dr. Zhang says the critical question is whether it is possible to translate the growing knowledge of molecular biology into an effective treatment. "We need to keep looking for answers," he adds.
The latest research builds upon previous studies that have suggested links between fitness and brain health. "For example, a 2018 study showed that people with lower fitness levels experienced faster deterioration of vital nerve fibers in the brain called white matter. Research in mice has similarly shown exercise correlated with slower deterioration of the hippocampus," says the team. These findings encouraged the researchers to investigate whether the same effects could be found in people.
Current findings
The study compared cognitive function and brain volume between two groups with memory issues. While one group did aerobic exercise - at least a half-hour workout four to five times weekly - another group only did flexibility training.
"Both groups maintained similar cognitive abilities during the trial in areas such as memory and problem-solving. But brain imaging showed that people from the exercise group who had amyloid buildup experienced slightly less volume reduction in their hippocampus - a memory-related brain region that progressively deteriorates as dementia takes hold," says the study. It says that the findings merit further research to establish whether "fitness can affect the progression of dementia."
According to Dr. Zhang, it is interesting that the brains of participants with amyloid responded more to the aerobic exercise than the others. "Although the interventions did not stop the hippocampus from getting smaller, even slowing down the rate of atrophy through exercise could be an exciting revelation," he says, adding that more research is needed to determine "how or if the reduced atrophy rate benefits cognition."