Older adults with mild cognitive impairment (MCI) who engaged in moderate physical activity had greater hippocampal volume. Atrophy of the hippocampus is a hallmark of Alzheimer’s, therefore these results suggest that exercise can help to stave off Alzheimer’s.
Over 300 participants aged 65 or older whose scores on the MMSE were around 24/30, indicating mild cognitive impairment (MCI), were chosen for the study. Each was given an MRI scan to determine hippocampal size.
Memory performance was established using three different tests. Two subtests (Logical and Visual) from the Wechsler Memory Scale- Revised (WMS-R) and the Rey Auditory Verbal Learning Test (RAVLT) for verbal memory.
Participants were given a triaxial accelerometer (like a fitbit) to wear for continuous measurement of daily physical activity (PA) patterns. “Slow-pace walking with light effort (1.0–2.0 mph) would be classified as light PA and brisk walking with moderate effort (3.0–4.0 mph) would be considered moderate PA.” The number of steps and the speed were used to calculate intensity and the output was expressed in the more scientifically pleasing metric of metabolic equivalents (METs; multiples of resting metabolic rate).
After measuring PA for two weeks they went back to look for correlations between PA level and the size of a participant’s hippocampus. They found a strong association between moderate PA and a larger hippocampus.
They also looked for an association between PA level and memory, but could not make a direct connection. However, using the indirect effects model they clearly showed that moderate PA leads to a larger hippocampus and that loss of hippocampal volume was significantly and directly associated with poor memory performance.
These findings are very similar to those in the University of Maryland study published a few months before this one. The Maryland study used older adults at risk for Alzheimer’s (but without cognitive impairment) and relied on self reporting of PA. This study used older adults with mild cognitive impairment and tracked them objectively with an accelerometer. Both studies show that moderate PA protects the hippocampus from atrophy.
As previously noted in At Risk for Alzheimer’s? Don’t Just Sit There! Moderate Exercise Protects the Brain, here’s what other studies (Erickson, et al. 2001 and Trejo and Torres-Aleman 2001) have shown are some of the brain benefits of physical activity:
- promotes the release of neurotrophins that increase neurogenesis:
- BDNF (brain derived neurotrophic factor)
- insulin-like growth factor-1 (IGF1)
- increases cerebral blood flow
- enhances neural activation
- possibly relieves amyloid burden
- produces neurogenesis in the young and old
- increases the size of the anterior hippocampus, leading to improvements in spatial memory
- increases hippocampal volume by 2%, effectively reversing age-related loss in volume
- improves neurotransmitter function in the hippocampus and cerebral cortex
- increase production of anti-inflammatory cytokines
Two 2014 studies on different groups of older individuals show that moderate physical activity protects the hippocampus from atrophy.