Influence of Multiple Cardiovascular Risk Factors on Task-Switching in Older Adults: An fMRI Study

Abstract

Not only are the effects of cardiovascular risk factors such as high blood pressure and low fitness on executive functions and brain activations in older adults scarcely investigated, no fMRI study has investigated the combined effects of multiple risk factors on brain activations in older adults. This fMRI study examined the independent and combined effects of two cardiovascular risk factors, arterial plasticity, and physical fitness, on brain activations during task-switching in older adults. The effects of these two risk factors on age-related differences in activation between older and younger adults were also examined. Independently, low physical fitness and low arterial plasticity were related to reduced suppressions of occipital brain regions. The combined effects of these two risks on occipital regions were greater than the independent effects of either risk factor. Age-related overactivations in frontal cortex were observed in low fitness older adults. Brain-behavior correlation indicates that these frontal overactivations are maladaptive to older adults' task performance. It is possible that the resulting effects of cardiovascular risks on the aging brain, especially the maladaptive overactivations of frontal brain regions by high risk older adults, contribute to often found posterior-anterior shift in aging (PASA) brain activations. Furthermore, observed age-related differences in brain activations during task-switching can be partially attributed to individual differences in cardiovascular risks among older adults.

Functional activation features of memory in successful agers across the adult lifespan

“…Another caveat is that non-neural differences could be a confounding factor, such as neurovascular coupling and vascular dynamics which have been found to affect BOLD signal in older adults ( Andrews-Hanna et al, 2007 ; D’Esposito et al, 2003 ). This potential influence is a common issue in most studies examining age-related effects on fMRI activation ( Grady and Garrett, 2014 ; Qin and Basak, 2020 ). Future studies may consider incorporating measures, such as cerebrovascular reactivity ( Liu et al, 2013 ) or the resting-state fluctuation amplitude ( Tsvetanov et al, 2015 ), that correct for its effect on BOLD signal ( Liu et al, 2019 ).…”

The neural–vascular basis of age‐related processing speed decline

“…These results, along with others suggesting, for instance, age‐related decreases in occipital oxy‐ and de‐oxyhemoglobin coupling, with increasing flicker‐frequency (Fabiani, Gordon, et al., 2014), underscore the point that age‐related changes in the physiological factors underlying BOLD signal complicate straightforward interpretation of BOLD as an index of age‐related neural change. Other factors such as participants' fitness level also complicate interpretation (Fabiani, Gordon, et al., 2014; Kramer et al., 1999; Qin & Basak, 2020; Zimmerman et al., 2014). Indeed, these results suggest that fundamentally different functions characterize the neural activity‐BOLD relationship in younger and older adults.…”