Abstract
Cerebrovascular health is important for maintaining a high level of cognitive performance, not only in old age, but also throughout the lifespan. Recently, it was first demonstrated that diffuse optical imaging measures of pulse amplitude and arterial compliance can provide estimates of cerebral arterial health throughout the cortex, and were associated with age, estimated cardiorespiratory fitness (eCRF), neuroanatomy and cognitive function in older adults (aged 55–87). The current study replicates and extends the original findings using a broader age range (a new adult sample aged 18–75), longer recording periods (360 s), and a more extensive optical montage (1536 channels). These methodological improvements represent a 5-fold increase in recording time and a 4-fold increase in coverage compared to the initial study. Results show that reliability for both pulse amplitude and compliance measures across recording blocks was very high (r(45) = .99 and .75, respectively). Pulse amplitude and pulse pressure were shown to correlate with age across the broader age range. We also found correlations between arterial health and both cortical and subcortical gray matter volumes. Additionally, we replicated the correlations between arterial compliance and age, eCRF, global brain atrophy, and cognitive flexibility. New regional analyses revealed that higher performance on the operation span (OSPAN) working memory task was associated with greater localized arterial compliance in frontoparietal cortex, but not with global arterial compliance. Further, greater arterial compliance in frontoparietal regions was associated with younger age and higher eCRF. These associations were not present in the visual cortex. The current study not only replicates the initial one in a sample including a much wider age range, but also provides new evidence showing that frontoparietal regions may be especially vulnerable to vascular degeneration during brain aging, with potential functional consequences in cognition.
Highlights
Many studies have demonstrated that vascular health plays an important role in both normal aging and in conditions that become more prevalent in aging, such as mild cognitive impairment (MCI) and Alzheimer’s disease (AD)
Other studies have shown that frontal and parietal regions are more prone to age-related volumetric losses than other regions such as the occipital cortex [38,39], that reductions in frontal and parietal lobe perfusion are associated with poorer cognitive performance [40,41] and that higher levels of cardiorespiratory fitness (CRF) are associated with greater oxygenation in prefrontal regions [42] and more preserved prefrontal and parietal gray matter volumes [43,44,45]. Motivated by this fMRI- and sMRI-based evidence and by our initial findings that arterial compliance is associated with pulse transit time [23], here we investigated whether regional measures of arterial compliance in the frontoparietal cortex (Brodmann areas 9 and 7) would be more associated with performance on the operation span (OSPAN) working memory task [31] compared to a global estimate of cerebral arterial compliance
These results are in line with those reported by Fabiani et al [23] and others. These results are in agreement with findings showing that higher estimated cardiorespiratory fitness (eCRF) is associated with reduced atrophy in brain volumetric measures (e.g., [44,45], [74]; see [75] for a discussion of the overlap between the effects of age and fitness on regional brain anatomy)
Summary
Many studies have demonstrated that vascular health plays an important role in both normal (pre-clinical) aging and in conditions that become more prevalent in aging, such as mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Vascular health in younger adults has received more limited attention [14], despite evidence showing that arterial aging begins early in life [15,16] and that the negative consequences of arterial stiffness in relatively young populations are associated with poorer white matter health and reduced gray matter volume [17] These adverse outcomes are compounded by other known cardiovascular risk factors, such as low cardiorespiratory fitness (CRF) and poor dietary intake [18,19,20], emphasizing the need for control and intervention strategies at younger ages [21,22] for the prevention of age-related cognitive decline. Ebihara and colleagues [27] analyzed the pulse power spectrum using NIRS in patients with cerebral ischemia and found that pulse transmission in the ischemic cerebral hemisphere was smaller compared to the contralateral side, reflecting the reduced cerebral blood flow associated with ischemia
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