Effects of aerobic exercise on brain metabolism and grey matter volume in older adults: results of the randomised controlled SMART trial

Abstract

There is mounting evidence that aerobic exercise has a positive effect on cognitive functions in older adults. To date, little is known about the neurometabolic and molecular mechanisms underlying this positive effect. The present study used magnetic resonance spectroscopy and quantitative MRI to systematically explore the effects of physical activity on human brain metabolism and grey matter (GM) volume in healthy aging. This is a randomised controlled assessor-blinded two-armed trial (n=53) to explore exercise-induced neuroprotective and metabolic effects on the brain in cognitively healthy older adults. Participants (age >65) were allocated to a 12-week individualised aerobic exercise programme intervention (n=29) or a 12-week waiting control group (n=24). The main outcomes were the change in cerebral metabolism and its association to brain-derived neurotrophic factor (BDNF) levels as well as changes in GM volume. We found that cerebral choline concentrations remained stable after 12 weeks of aerobic exercise in the intervention group, whereas they increased in the waiting control group. No effect of training was seen on cerebral N-acetyl-aspartate concentrations, nor on markers of neuronal energy reserve or BDNF levels. Further, we observed no change in cortical GM volume in response to aerobic exercise. The finding of stable choline concentrations in the intervention group over the 3 month period might indicate a neuroprotective effect of aerobic exercise. Choline might constitute a valid marker for an effect of aerobic exercise on cerebral metabolism in healthy aging.

Exercise and microstructural changes in the motor cortex of older adults

“…This hypothesis is substantiated by other findings involving aerobic exercise in older adults. A previous study using magnetic resonance spectroscopy in this cohort found no change in N‐acetylaspartate/choline levels in the exercise group, but decreased levels in the control group that were driven by increases in total choline levels (Matura et al, ), a finding that is commonly found in dementia patients. These findings pair with a previous cross‐sectional study which is found that brain tissue density losses found with normal aging were mitigated by aerobic fitness scores (Colcombe et al, ).…”

“…A previous voxel‐based morphometry (VBM) analysis of the data used in this study did not uncover any volumetric changes in GM (Matura et al, ). This may suggest that VBM has reduced sensitivity for detecting changes in brain microstructure compared to measures of MRI signal, such as R 1 .…”

“…To examine the correlation of microstructural changes with functional changes, we assessed the effect exercise on Δ R 1 in the dorsal medial precentral gyrus using a linear model: Δ R 1 ~ Age + ΔVT1 O 2 /kg. The original study by Matura et al () found brain correlates with VT1 and not with VO 2 max, so we chose to correlate with functional changes as measured by ΔVT1 O 2 /kg. ΔVT1 O 2 /kg is the change in VT1 over the study period that accounts for the subject's size.…”

“…The original study found no changes in GM volume in the exercise group but did highlight that exercise stabilized age‐related increases in cortical choline levels, which was hypothesized to have a neuroprotective effect. Additionally, the study found that changes in fitness as scored by the first ventilator threshold (VT1) were positively correlated with N‐acetylaspartate/choline ratios in the training group (Matura et al, ). The current study examines R 1 maps collected before and after the intervention period to investigate whether changes in physical fitness promote changes in cortical microstructure.…”

Early Changes in Memory, Motor Coordination and Strength in the Transgenic Rat Model of Alzheimer’s Disease, TgF344-AD

“…Exercise can slow the rate of cognitive decline among individuals suffering from AD; even general physical activity and higher fitness levels decrease risk of AD (Best, Chiu, Hsu, Nagumatsu, & Liu-Ambrose, 2015;Maass et. al, 2015;Matura et al, 2017;Nagumatsu et al, 2013;Voss et al, 2013). Nouchi et al (2014) studied the effects of shortterm exercise on cognitive functions among 64 healthy subjects over the age of 62.…”