Researchers found that older adults who engaged in either moderate/high-intensity aerobic training or low-intensity stretching, balance, and range-of-motion exercises for 12 months showed no decline from their baseline in terms of cognitive function. That’s according to lead study author Laura Baker, PhD, professor of gerontology and geriatric medicine at Wake Forest University School of Medicine in Winston-Salem, North Carolina, who spoke at the AAIC conference. “There is increasing evidence that our health overall greatly impacts our brain,” said Maria Carrillo, PhD, chief scientific officer of the Alzheimer’s Association, who was not involved in the study. Previous research has found that regular physical activity of any kind may reduce damaging inflammation and increase blood flow to the brain, she said.
About 12 to 18 Percent of People Over 60 Have Mild Cognitive Impairment
The EXERT trial was designed to be the definitive study addressing the question of whether exercise could slow cognitive decline in adults with mild cognitive impairment (MCI), said Dr. Baker in a press conference following her presentation. It’s the largest and longest study to look at the impact of exercise on cognitive decline, she added. MCI is an early stage of memory loss or cognitive decline. Common signs include losing things often, forgetting appointments, and having trouble finding the right words, according to the National Institute on Aging. About 12 to 18 percent of people age 60 or older have MCI, and about 1 in 8 of those people will develop dementia over a one-year period, according to the Alzheimer’s Association.
Year-Long Trial Allowed the ‘Brain Benefits’ of Physical Activity to Accumulate
To explore the impact of regular exercise on the brain, a total of 296 people between the ages of 65 and 89 (average age of 75) with MCI were recruited and randomized into two groups. Participants had their cognitive function measured using a validated standardized tool known as the ADAS-Cog-Exec test, which combines elements of the Alzheimer’s Disease Assessment Scale. Because the researchers wanted to measure the effects of the exercise intervention, participants had to be sedentary or underactive (as determined by a telephone assessment) to be included in the trial. All the participants went to their local YMCA four times a week for 52 weeks to exercise for 30 minutes, plus a 10-minute warm-up and a 5-minute cooldown. For the first two weeks, all of the sessions were supervised by a trained professional, and after that, two of the four weekly sessions were supervised. One group performed aerobic exercise at a moderate to high intensity — 70 to 80 percent of their maximum heart rate. The the second group did stretching/balance/range of motion exercises at a much lower intensity — at or below 35 percent of their max heart rate. At the end of the year, the participants were given the ADAS-Cog-Exec test to see how they performed in comparison with when the trial began. Researchers found no differences between the groups — both the moderate/hard exercisers and the low-intensity exercisers showed no decline from the previous year. Researchers then compared the results to those found in a different study, known as the ADNI trial, a large “usual care” observational study of people with MCI in which there was no intervention — but in which data on Alzheimer’s progression and cognitive decline were collected. After matching up participants of similar age, sex, education, and baseline cognitive status, the investigators found that the non-exercising participants in the ADNI group had a “significant cognitive decline” over the 12 months.
Exercise of Any Intensity Had a Protective Effect on Cognition
Although the study authors weren’t surprised that the moderate-intensity exercisers were able to stave off cognitive decline, they were surprised that the low-intensity group achieved the same protection. However, it may be a function of the very long intervention involving an entire year of exercise, said Baker. “A lot of our conclusions in the past were based on trials of shorter duration, and so it’s possible that longer-duration trials that allow the buildup of more exercise over time could have impact,” she said. Each participant in the EXERT trial went from being sedentary to completing more than 100 hours of exercise over a year, she noted. “We believe it’s a volume issue — for lower-intensity exercise, it may take longer to see benefits,” said Baker.
Regular Supported Exercise Should Be Part of Preventing Dementia
“Our findings suggest that regular supported exercise should be part of the prevention strategies for dementia,” said Baker. These results are encouraging, in part because this amount of low-intensity exercise is quite doable, she said, adding that guidance and supervision by a trained professional are key components in order for an exercise intervention to be successful for people with MCI.
