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Exercise May Help Reverse Neurodegeneration in Early Stage Alzheimer’s

Older adults that improved their fitness through a moderate intensity exercise program increased the thickness of their brain’s cortex, the outer layer of the brain that typically atrophies with Alzheimer’s disease, according to a new study from the University of Maryland School of Public Health. These effects were found in both healthy older adults and those diagnosed with mild cognitive impairment (MCI), an early stage of Alzheimer’s disease.

“Exercise may help to reverse neurodegeneration and the trend of brain shrinkage that we see in those with MCI and Alzheimer’s,” says Dr. J. Carson Smith, associate professor of kinesiology and senior author of the study, published in the Journal of the International Neuropsychological Society on Nov. 19, 2015. “Many people think it is too late to intervene with exercise once a person shows symptoms of memory loss, but our data suggest that exercise may have a benefit in this early stage of cognitive decline.”

The previously physically inactive participants (ages 61-88) were put on an exercise regimen that included moderate intensity walking on a treadmill four times a week over a twelve-week period. On average, cardiorespiratory fitness improved by about 8% as a result of the training in both the healthy and MCI participants.

Photo of running shoes.

The previously physically inactive participants (ages 61-88) were put on an exercise regimen that included moderate intensity walking on a treadmill four times a week over a twelve-week period. On average, cardiorespiratory fitness improved by about 8% as a result of the training in both the healthy and MCI participants. Image is for illustrative purposes only.

The atrophy of the brain’s cortical layer is a marker of Alzheimer’s disease progression and correlates with symptoms including cognitive impairment. Dr. Smith and colleagues found that the study participants who showed the greatest improvements in fitness had the most growth in the cortical layer, including both the group diagnosed with MCI and the healthy elders. While both groups showed strong associations between increased fitness and increased cortical thickness after the intervention, the MCI participants showed greater improvements compared to healthy group in the left insula and superior temporal gyrus, two brain regions that have been shown to exhibit accelerated neurodegeneration in Alzheimer’s disease.

Dr. Smith previously reported that the participants in this exercise intervention showed improvements in neural efficiency during memory recall, and these new data add to the evidence for the positive impact of exercise on cognitive function. Other research he has published has also shown that moderate intensity physical activity, such as walking for 30 minutes 3-4 days per week, may protect brain health by staving off shrinkage of the hippocampus in older adults.

This is the first study to show that exercise and improved fitness can impact cortical thickness in older adults diagnosed with mild cognitive impairment. Dr. Smith plans future studies that include more participants engaging in a longer-term exercise intervention to see if greater improvements can be seen over time, and if the effects persist over the long term. The key unanswered question is if regular moderate intensity physical activity could reverse or delay cognitive decline and help keep people out of nursing homes and enable them to maintain their independence as they age.

About this Alzheimer’s disease research

Source: Kelly Blake – University of Maryland
Image Source: The image is in the public domain
Original Research: Abstract for “Improved Cardiorespiratory Fitness Is Associated with Increased Cortical Thickness in Mild Cognitive Impairment” by Katherine Reiter, Kristy A. Nielson, Theresa J. Smith, Lauren R. Weiss, Alfonso J. Alfini and J. Carson Smith in Journal of the International Neuropsychological Society. Published online November 2015 doi:10.1017/S135561771500079X


Abstract

Improved Cardiorespiratory Fitness Is Associated with Increased Cortical Thickness in Mild Cognitive Impairment

Cortical atrophy is a biomarker of Alzheimer’s disease (AD) that correlates with clinical symptoms. This study examined changes in cortical thickness from before to after an exercise intervention in mild cognitive impairment (MCI) and healthy elders. Thirty physically inactive older adults (14 MCI, 16 healthy controls) underwent MRI before and after participating in a 12-week moderate intensity walking intervention. Participants were between the ages of 61 and 88. Change in cardiorespiratory fitness was assessed using residualized scores of the peak rate of oxygen consumption (V̇O2peak) from pre- to post-intervention. Structural magnetic resonance images were processed using FreeSurfer v5.1.0. V̇O2peak increased an average of 8.49%, which was comparable between MCI and healthy elders. Overall, cortical thickness was stable except for a significant decrease in the right fusiform gyrus in both groups. However, improvement in cardiorespiratory fitness due to the intervention (V̇O2peak) was positively correlated with cortical thickness change in the bilateral insula, precentral gyri, precuneus, posterior cingulate, and inferior and superior frontal cortices. Moreover, MCI participants exhibited stronger positive correlations compared to healthy elders in the left insula and superior temporal gyrus. A 12-week moderate intensity walking intervention led to significantly improved fitness in both MCI and healthy elders. Improved V̇O2peak was associated with widespread increased cortical thickness, which was similar between MCI and healthy elders. Thus, regular exercise may be an especially beneficial intervention to counteract cortical atrophy in all risk groups, and may provide protection against future cognitive decline in both healthy elders and MCI.

“Improved Cardiorespiratory Fitness Is Associated with Increased Cortical Thickness in Mild Cognitive Impairment” by Katherine Reiter, Kristy A. Nielson, Theresa J. Smith, Lauren R. Weiss, Alfonso J. Alfini and J. Carson Smith in Journal of the International Neuropsychological Society. Published online November 2015 doi:10.1017/S135561771500079X

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