Hemodynamic and structural brain measures in high and low sedentary older adults

Abstract

Due to its cardiovascular effects sedentary behaviour might impact cerebrovascular function in the long term, affecting cerebrovascular regulatory mechanisms and perfusion levels. Consequently this could underly potential structural brain abnormalities associated with cognitive decline. We therefore assessed the association between sedentary behaviour and brain measures of cerebrovascular perfusion and structural abnormalities in community-dwelling older adults. Using accelerometery (GENEActiv) data from The Irish Longitudinal Study on Ageing (TILDA) we categorised individuals by low- and high-sedentary behaviour (≤8 vs >8 hours/day). We examined prefrontal haemoglobin oxygenation levels using Near-Infrared Spectroscopy during rest and after an orthostatic challenge in 718 individuals (66 ± 8 years, 52% female). Global grey matter cerebral blood flow, total grey and white matter volume, total and subfield hippocampal volumes, cortical thickness, and white matter hyperintensities were measured using arterial spin labelling, T1, and FLAIR MRI in 86 individuals (72 ± 6 years, 55% female). While no differences in prefrontal or global cerebral hemodynamics were found between groups, high-sedentary individuals showed lower hippocampal volumes and increased white matter hyperintensities compared to their low-sedentary counterparts. Since these structural cerebral abnormalities are associated with cognitive decline and Alzheimer’s disease, future work exploring the causal pathways underlying these differences is needed.

Active Life for Brain Health: A Narrative Review of the Mechanism Underlying the Protective Effects of Physical Activity on the Brain

“…One of the mechanisms underlying the brain-protective effects of PA is the preservation of brain volume, or even an increase in brain volume. Observational studies have found that brain volume, particularly that of the hippocampus, is preserved in more active people ( Erickson et al, 2010 ; Flöel et al, 2010 ; Maasakkers et al, 2021 ). PA is also associated with preservation of cortical thickness ( Walhovd et al, 2014 ; Lee et al, 2016 ).…”

Cross‐sectional associations between sedentary time with cognitive engagement and brain volume among community‐dwelling vulnerable older adults

“…[6][7][8] Although physical activity (PA) is a protective factor for brain volume and is associated with increased brain volume in older adults, 9,10 older adults are inclined to decrease PA and increase sedentary time (ST). [11][12][13] Vulnerable older adults, including those who have physical frailty and cognitive impairment, find it difficult to engage in PA and are prone to more ST. [14][15][16][17] A recent systematic review reported a negative association between ST and brain structure: 18 ST is negatively associated with total brain volume, 19 cortical thickness, 20 and white matter volume. 21 Therefore, especially in vulnerable older adults, protective factors against brain atrophy should be identified.…”

“…Vulnerable older adults, including those who have physical frailty and cognitive impairment, find it difficult to engage in PA and are prone to more ST 14–17 . A recent systematic review reported a negative association between ST and brain structure: 18 ST is negatively associated with total brain volume, 19 cortical thickness, 20 and white matter volume 21 . Therefore, especially in vulnerable older adults, protective factors against brain atrophy should be identified.…”

The Sedentary Lifestyle and Masticatory Dysfunction: Time to Review the Contribution to Age-Associated Cognitive Decline and Astrocyte Morphotypes in the Dentate Gyrus

“…Unhealthy brain aging and cognitive decline associate with a sedentary lifestyle and, at a cellular level, this is accompanied by astrocyte hypertrophy, myelin dysregulation, neurovascular dysfunction [ 1 ] and the impairment of neurogenesis [ 2 ]. Highly sedentary humans (≥8 h/day) display reduced hippocampal volumes and increased white matter (WM) hyperintensities [ 3 , 4 ] that are associated with accelerated cognitive, neuropsychiatric and functional decline [ 5 ]. In addition to the changes associated with a sedentary life, it has become clear that oral dysfunction is present in the same individuals and that this group feature is also associated with dementia or mild cognitive decline [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ].…”