Physical activity can help prevent Alzheimer’s disease. Still, new research finds aerobic exercise may help slow shrinkage in the hippocampus, the part of the brain that deals with memory.
Published in the Journal of Alzheimer’s Disease, this study compared cognitive function and brain size between 2 groups of sedentary older adults with memory issues.
It’s the first randomized and controlled trial to investigate the effect of exercise on brain structure, function, and amyloid plaque in older people with memory problems.
Aerobic Exercise is Key
The study was a small proof-of-concept trial of people ages 55 and older with mild cognitive impairment (MCI). One group performed aerobic exercise for about a half-hour, 4 to 5 times weekly, while another group only did flexibility training. Although both groups preserved their cognitive abilities for memory and problem solving, brain imaging showed people from the exercise group with amyloid buildup lost slightly less volume in the hippocampus — a brain region that deteriorates as dementia progresses.
“The finding that both aerobic and stretching exercise prevented cognitive decline is similar to previous studies in cognitively normal older adults,” said Zhang. “What’s surprising is that it was aerobic, not stretching exercise, that reduced hippocampus atrophy in those who already have a lot of amyloids in the brain.”
He speculated that aerobics might be unique to other forms of exercise because it increases vascular function or individual factors that encourage neuron growth and survival, reducing the harmful effects of amyloid plaques on neurons in the hippocampus.
“We don’t yet fully understand how exercise lowers dementia risk, but we know that heart-healthy behaviors like exercise lead to better vascular health and therefore better brain health. Unfortunately, exercise can’t completely prevent or cure dementia,” said Jason Krellman, Ph.D., ABPP-CN, assistant professor of neuropsychology at Columbia University Medical Center.
The rrAD Study
Recent studies have shown how overall cardiovascular health can affect the risk of Alzheimer’s and other dementia. Zhang is leading a 5-year clinical trial digging deeper into these factors, exercise, and how they relate to this memory-destroying illness. The Risk Reduction for Alzheimer’s Disease (rrAD) trial is a study testing several strategies that could reduce Alzheimer’s risk in people at risk of this disease.
These strategies include the effects of aerobic exercise, intensive medical management of blood pressure and cholesterol, and a combination of these two approaches. While experts aren’t sure about the effectiveness of reducing cholesterol, Keith N. Fargo, Ph.D., director of scientific programs and outreach at the Alzheimer’s Association, emphasized the importance of controlling blood pressure. “There is mixed evidence on cholesterol. At this point, most people don’t consider cholesterol control to be of major importance for reducing risk for Alzheimer’s disease but controlling blood pressure is a whole different story,” Fargo said. “Blood pressure control is considered [a] very important modifiable risk factor for Alzheimer’s.”
Be Active for Better Memory
A recent study conducted at Rush University Medical Center found that active older adults may keep more of their cognitive abilities than those less active, even if they have brain lesions or biomarkers linked to dementia. The association between activity and scores on cognitive tests remained even when researchers adjusted for how severe a participant’s brain lesions were. The relationship was also consistent in people who had dementia and those who didn’t.
Researchers also found that participants who showed better movement and coordination had sharper memory and cognition. “People who moved more had better thinking and memory skills compared to those who were more sedentary and did not move much at all,” said Dr. Aron S. Buchman, of neurological sciences at Rush.
Dementia isn’t a Normal Part of Aging
Dementia isn’t a natural or inevitable part of aging, said Fargo, although age is the largest risk factor and the most significant predictor of whether someone will have Alzheimer’s. He said that although the risk increases with age, even in those 85 and older, only 1 in 3 have Alzheimer’s.
“It’s a specific brain disease that the risk for happens to increase as you age,” he said. But even those at higher genetic risk of the disease can take steps to lessen their risk. Fargo added that there’s strong evidence that making better lifestyle choices can reduce our risk of dementia. “Randomized controlled clinical trial evidence, such as this paper on exercise, show that if you change a risk factor, you’re reducing risk.”
He pointed out, “There are ten that we believe are supported by the evidence, and we list those on our website. However, the most important of those 10 is exercise, diet, and controlling blood pressure.”
The Bottom Line
A recent study finds exercise doesn’t just help Alzheimer’s symptoms but may also slow brain degeneration associated with the disease. Researchers found that aerobic exercise appeared to slow the shrinkage of a part of the brain involved in memory. Experts say dementia isn’t a normal part of aging, and by following recommendations like exercise, a healthy diet, and managing blood pressure, we can significantly reduce the risk.