Researchers Laura Baker, PhD and colleagues from Wake Forest Baptist Medical Center, Winston Salem NC, USA had previously shown that in older adults with mild cognitive impairment (MCI), regular moderate-to-high intensity aerobic exercise has benefits for cognition and plasma levels of amyloid protein, the primary component of the other Alzheimer's hallmark lesion, known as plaques. At AAIC 2015, they reported results of a 6-month randomized controlled trial of moderate-to-high intensity aerobic exercise in 65 sedentary adults 55-89 years old with MCI to test whether aerobic exercise might also lower tau levels in the brain.

Participants in the study were randomly assigned to either supervised aerobic training or a stretching group for 45-60 minutes four times per week for six months, using community facilities. The aerobic group exercised at 70-80% of their maximum heart rate, while the stretching group exercised at below 35 percent. The researchers tested participant's cognitive skills (verbal recall, tests of executive function) and examined blood and cerebrospinal fluid (CSF) samples at the beginning and end of the study. Forty participants also received MRI brain scans. Participants completed their assigned exercise activities 92 percent of the time.


The researchers found that:

Participants who completed aerobic exercise (most commonly using a treadmill) saw a statistically significant (p<0.05) reduction in tau levels in CSF. The effect was most pronounced in adults over the age of 70.
Aerobic exercise significantly (p<0.05) increased blood flow in the memory and processing centers of participant's brains, with a corresponding improvement in attention, planning, and organizing abilities referred to as "executive function" (p<0.05).
"These findings are important because they strongly suggest a potent lifestyle intervention such as aerobic exercise can impact Alzheimer's-related changes in the brain," Baker said. "No currently approved medication can rival these effects."

Aerobic Exercise Improves Cognition in Vascular Cognitive Impairment in a 6-Month Trial
Cerebrovascular disease is the second most common cause of dementia in older adults, behind Alzheimer's. Research suggests that reducing heart health risk factors, such as high blood pressure and high cholesterol, may reduce dementia risk, and possibly even slow down the progression of cognitive decline due to mini-strokes – known as vascular cognitive impairment (VCI).

"This made us believe that aerobic exercise, such as running and brisk walking, may be a very promising strategy against vascular cognitive impairment," said Teresa Liu-Ambrose, Canada Research Chair, PhD, PT, University of British Columbia and researcher at the Djavad Mowafaghian Centre for Brain Health, which is part of the Vancouver Coastal Health Research Institute, Vancouver, BC, Canada. "Research shows that aerobic exercise not only decreases heart health risk factors but may also improve brain structure and function."

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