The first study I'll discuss today showed that older adults with mild to moderate AD who had at least 80% adherence to an aerobic exercise program and maintained at least 70% of their maximum heart rate (the "high exercise" group, which was prescribed 1 hour of aerobic exercise three times a week for 16 weeks) had a statistically significant advantage on the Symbol Digit Modalities Test (SDMT) over a control group.
The analysis also found that neuropsychiatric symptoms improved in the 66 patients in the "high exercise" group; there was a 3.4-point difference on the Neuropsychiatric Inventory (NI) compared with controls. The NI is a 12-item questionnaire that rates, among other things, depression, apathy, agitation, hallucinations, irritability, weight loss, and sleep.
"We saw that the control group got worse; there was a small decline in this group, which you would expect because this is progressive disease," said the reseachers. "But the intervention group remained at the same level and even got a little better, so at end of the intervention there was a significant difference."
The question arises of whether exercise could not just delay worsening of symptoms but actually change brain pathology. The answer, suggests other research, is yes. In a separate study presented at the same conference, researchers found decreased phosphorylated tau (P tau) in older, previously sedentary persons completing a 6-month regimen of moderate- to high-intensity aerobic exercise.
The study enrolled 70 patients aged 55 to 89 years with prediabetes as well as amnestic mild cognitive impairment (MCI). "They had both prediabetes and MCI. We think they are at high, high risk for developing dementia of the Alzheimer's type," stated the researchers.
These patients were randomly assigned to the aerobic exercise group or to the stretching group. Those in the aerobic group started slowly (about 10 minutes of exercise a week) and gradually built the time and intensity up over 6 weeks to the point where they were exercising 45 minutes a day, 4 days a week, at 75% to 85% of their maximum heart rate.
"Starting slowly is the key," said the lead researcher. "For the average 70-year-old, we were getting the heart rate above 130 or 132 beats per minute for at least 30 of those 45 minutes, with the rest of the exercise period being a warm-up and cool-down."
This group had a choice of exercises: treadmill, stationary cycling, elliptical trainer, or preapproved group classes. The stretching group, whose members could do balance exercises, gentle yoga, and other approved classes in addition to stretching, maintained a maximum heart rate of below 35%.
All exercises were adapted to the needs and limitations of individual patients and were done at a local YMCA.
Unlike other studies that compare exercise with usual care, in this study the control group "had all the same demands: they had to come out of their house, they had to go to the YMCA, they got the same contact with staff and a trainer." The only difference was that they did only stretching and balance exercises and their heart rate was not significantly and consistently elevated.
The analysis showed a statistically significant reduction of 14% in P tau levels among those older than age 70 years in the exercise group. Most intervention trials don't show such changes in P tau. "But we saw it with exercise and no medications," said the authors. "Exercise was enough to move a biomarker that indicates the severity of the disease."
The study also showed that the aerobic activity increased blood flow to the brain and that the increased blood flow was in regions characteristically affected by aging and AD (ie, memory and processing).
Cognitive benefits were particularly noteworthy for executive function, where there was a 15% increase from baseline in the exercise group for all tests. The improvement relative to the stretching group, which includes expected further decline in cognition, was 80%, she said.
AD may not be the only dementia potentially treatable through exercise. Another study discussed at the meeting showed that this intervention may help those with vascular cognitive impairment (VCI).
It's the first intervention trial to suggest that exercise can improve cognition in patients with confirmed VCI, said the lead researcher behind this study.
The 6-month study included 71 patients aged 56 to 96 years with mild VCI of varying physical capacities. They were assigned to usual care that included a nutrition component or to an intervention of moderate-intensity walking, 3 times a week for an hour. Patients walked outside in small groups, starting in short time blocks, with an option to rest. Over time, they increased the walking period to 40 minutes without rest, in addition to a warm-up and cool-down.
These studies add more convincing evidence that humans, through 1000s of years of evolution, are designed to be physically active.When in doubt, go back to our roots.
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Source: Alzheimer's Association International Conference (AAIC) 2015. Oral presentations 05-0406, 0504-05, and 05-04-04. Presented July 23, 2015.
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