Aerobic Exercise Intervention, Cognitive Performance, and Brain Structure: Results from the Physical Influences on Brain in Aging (PHIBRA) Study

Abstract

Studies have shown that aerobic exercise has the potential to improve cognition and reduce brain atrophy in older adults. However, the literature is equivocal with regards to the specificity or generality of these effects. To this end, we report results on cognitive function and brain structure from a 6-month training intervention with 60 sedentary adults (64–78 years) randomized to either aerobic training or stretching and toning control training. Cognitive functions were assessed with a neuropsychological test battery in which cognitive constructs were measured using several different tests. Freesurfer was used to estimate cortical thickness in frontal regions and hippocampus volume. Results showed that aerobic exercisers, compared to controls, exhibited a broad, rather than specific, improvement in cognition as indexed by a higher “Cognitive score,” a composite including episodic memory, processing speed, updating, and executive function tasks (p = 0.01). There were no group differences in cortical thickness, but additional analyses revealed that aerobic fitness at baseline was specifically related to larger thickness in dorsolateral prefrontal cortex (dlPFC), and hippocampus volume was positively associated with increased aerobic fitness over time. Moreover, “Cognitive score” was related to dlPFC thickness at baseline, but changes in “Cognitive score” and dlPFC thickness were associated over time in the aerobic group only. However, aerobic fitness did not predict dlPFC change, despite the improvement in “Cognitive score” in aerobic exercisers. Our interpretation of these observations is that potential exercise-induced changes in thickness are slow, and may be undetectable within 6-months, in contrast to change in hippocampus volume which in fact was predicted by the change in aerobic fitness. To conclude, our results add to a growing literature suggesting that aerobic exercise has a broad influence on cognitive functioning, which may aid in explaining why studies focusing on a narrower range of functions have sometimes reported mixed results.

Cardiorespiratory fitness predicts effective connectivity between the hippocampus and default mode network nodes in young adults

“…More specifically, our results demonstrate that greater CRF is associated with greater causal influence from the bilateral HC to the vmPFC and lLTC, from the rHC to the PCC, and from the dmPFC to the bilateral HC. These findings are illuminating when considered among the rodent (Creer et al, ; Marlatt et al, ; Nokia et al, ; van Praag, Christie, et al, ; van Praag, Kempermann, & Gage, ) and human (Erickson et al, ; Jonasson et al, ; Maass et al, ; Pereira et al, ; Rosano et al, ; Thomas et al, ) literature, which demonstrate associations between both aerobic exercise and CRF and hippocampal plasticity. Our results extend this literature by suggesting that the relationship between CRF and hippocampal plasticity may influence large‐scale brain networks, a hypothesis which can be further examined in exercise intervention studies.…”

“…In humans, the relationship between aerobic exercise and brain health at the cellular level cannot be observed directly in vivo; however, neuroimaging studies in older and young adults further evidence a relationship between aerobic exercise and hippocampal structure and function. Clinical trials in healthy older adults demonstrate that participation in aerobic exercise training is positively associated with hippocampal volume (Erickson et al, ; Jonasson et al, ; Rosano et al, ; reviewed in Firth et al ()) and cerebral blood flow (Maass et al, ). Furthermore, similar relationships have been evidenced earlier in the adult lifespan: Clinical trials in healthy young to middle‐aged adults demonstrate that aerobic exercise increases the volume of the anterior HC (Thomas et al, ) and cerebral blood volume of the dentate gyrus subfield of the HC (Pereira et al, ).…”

Physical activity as a model for health neuroscience

“…Several recent studies examined this question. In secondary analyses, Jonassen et al 55 observed that participants in a 6-month aerobic PA (walking) intervention who had larger hippocampal volumes at baseline showed greater changes in cardiorespiratory fitness in response to the intervention. Similarly, using preexisting data from two clinical trials of PA, Best et al 56 found that gray matter volume of the LPFC, a region supporting executive control, could predict exercise class attendance in 122 older women.…”

Exercise and cognitive function in patients with end‐stage kidney disease

“…82,83 ET has a stronger impact on cognitive function and cortical thickness than it does on aerobic fitness. 63 Cognitive training (CT) 62,85,86 is another promising nonpharmacological intervention used to slow decline in executive function in otherwise healthy older adults. CT prevents age-related declines in key areas of cognitive function, particularly in executive function, including abstraction, working memory, verbal reasoning, and inhibition 33,34,87,88 by improving the neural structures that mediate executive function.…”

“…Even a single ET session changes neurophysiology and executive function . ET has a stronger impact on cognitive function and cortical thickness than it does on aerobic fitness …”