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A new study looked at how exercise could benefit the brain. Getty Images
  • A new study finds that aerobic exercise may help combat changes in the brain associated with dementia.
  • But any kind of exercise is associated with a decreased risk of developing Alzheimer’s disease or dementia.
  • Other research is being done to see if cholesterol levels are associated with risk of developing dementia.

Physical activity can help prevent Alzheimer’s disease, but new research finds aerobic exercise in particular 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.

“We wanted to know if exercise prevents or improves neurocognitive function in older adults who have memory problems, thus, at high risk of Alzheimer’s disease,” said Dr. Rong Zhang, neurologist with UT Southwestern’s O’Donnell Brain Institute who led the clinical trial.

“We also wanted to know if exercise would reduce brain atrophy and amyloid buildup, which are both neuroimaging biomarkers of Alzheimer’s,” he said.

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.

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 amyloid in the brain.”

He speculated that aerobics may be unique to other forms of exercise because it increases vascular function or certain factors that encourage neuron growth and survival, which may reduce 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, PhD, ABPP-CN, assistant professor of neuropsychology at Columbia University Medical Center.

Recent studies have shown how overall cardiovascular health can affect risk of Alzheimer’s and other dementia.

Research shows that high cholesterol levels are associated with a significantly increased risk of Alzheimer’s disease in late-life.

Meanwhile, another recent study found that high blood pressure may be linked with dementia.

Zhang is leading a 5-year clinical trial that’s 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, PhD, 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.”

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, lead author of the study and associate professor in the department of neurological sciences at Rush in a statement.

Dementia isn’t a natural or inevitable part of aging, said Fargo, although age is the largest risk factor and the greatest predictor of whether someone will have Alzheimer’s.

He said that although 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 10 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.”

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 it was specifically aerobic exercise that appeared to slow 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, healthy diet, and managing blood pressure, we can significantly reduce the risk.