Self-reported physical activity and objective aerobic fitness: differential associations with gray matter density in healthy aging

Abstract

Aerobic fitness (AF) and self-reported physical activity (srPA) do not represent the same construct. However, many exercise and brain aging studies interchangeably use AF and srPA measures, which may be problematic with regards to how these metrics are associated with brain outcomes, such as morphology. If AF and PA measures captured the same phenomena, regional brain volumes associated with these measures should directly overlap. This study employed the general linear model to examine the differential association between objectively-measured AF (treadmill assessment) and srPA (questionnaire) with gray matter density (GMd) in 29 cognitively unimpaired community-dwelling older adults using voxel based morphometry. The results show significant regional variance in terms of GMd when comparing AF and srPA as predictors. Higher AF was associated with greater GMd in the cerebellum only, while srPA displayed positive associations with GMd in occipito-temporal, left perisylvian, and frontal regions after correcting for age. Importantly, only AF level, and not srPA, modified the relationship between age and GMd, such that higher levels of AF were associated with increased GMd in older age, while decreased GMd was seen in those with lower AF as a function of age. These results support existing literature suggesting that both AF and PA exert beneficial effects on GMd, but only AF served as a buffer against age-related GMd loss. Furthermore, these results highlight the need for use of objective PA measurement and comparability of tools across studies, since results vary dependent upon the measures used and whether these are objective or subjective in nature.

Hippocampal gene expression patterns linked to late-life physical activity oppose age and AD-related transcriptional decline

“…Lifestyle factors have a striking ability to empower the adult brain -strengthening plasticity, building cognitive reserve, and preventing functional decline. Physical activity in particular has emerged as a powerful life-style factor that can improve cognitive function Buchman et al, 2008;Erickson et al, 2010;Erickson et al, 2011;Kramer and Erickson, 2007a, b;Smith et al, 2010;Stubbs et al, 2017;Suwabe et al, 2018), reduce the risk of age-associated cognitive decline and AD (Buchman et al, 2012;Erickson et al, 2012;Hillman et al, 2008;Kirk-Sanchez and McGough, 2014;Korol et al, 2013;Prakash et al, 2015;Weuve et al, 2004;Yaffe et al, 2001), counteract age-and AD-related losses of grey and white matter (Baker et al, 2010;Best et al, 2017;Bherer et al, 2013;Erickson et al, 2014;Lautenschlager et al, 2008;Okonkwo et al, 2014;Suzuki et al, 2012;Voss et al, 2013;Zlatar et al, 2015) and counteract age-and AD-related declines in cognitive neural network function (Colcombe et al, 2004;Huang et al, 2016;Voss et al, 2010). While the benefits of physical activity are evident, the underlying mechanisms by which physical activity supports brain function and health and slows Aging-and AD-related declines in the human brain are poorly understood.…”

Changes in Cortical Activation Patterns in Language Areas following an Aerobic Exercise Intervention in Older Adults

“…Aerobic exercise has been increasingly associated with improvements in memory, executive function, and patterns of neural activity as assessed by fMRI [ 2 – 4 , 7 – 11 ]. Recent fMRI evidence has also indicated that increased levels of aerobic capacity in older adults are also associated with improvements in language function and a more efficient neural recruitment array during a semantic verbal fluency task.…”

“…For example, in a cross-sectional study, Zlatar et al, 2013, demonstrated that the neural recruitment array during a semantic verbal fluency task in physically active older adults resembled that of younger adults, while sedentary older adults showed decrements in suppression of areas that should be inhibited during the task. They went on to demonstrate that longer interhemispheric inhibition, as measured by transcranial stimulation, was associated with more negative task-related activity in the right and left posterior perisylvian cortex, suggesting that sedentary aging may result in losses in task facilitatory cortical motor inhibition [ 11 ]. As such, based on these findings, the losses of negative task-related activity may be mitigated by regular engagement in physical exercise [ 12 , 13 ].…”

Advances in neurocognitive rehabilitation research from 1992 to 2017: The ascension of neural plasticity.

“…The advent of voxel-based morphometry (VBM) on structural MRI data has shown increased volume in overall brain mass as well as white and gray matter, specifically areas of the frontal cortex and hippocampus in physically active vs. sedentary older adults (Colcombe et al, 2003; Zlatar et al, 2015). Importantly, exercise interventions have also shown morphometric differences in these areas from pre-to post-exercise intervention (Colcombe et al, 2006; Erickson et al, 2011) with corresponding increases in cognitive function.…”