Differential age effects on cerebral blood flow and BOLD response to encoding: Associations with cognition and stroke risk

Abstract

Changes in the cerebrovascular system due to age or disease can significantly alter the bloodoxygenation-level-dependent (BOLD) signal and complicate its interpretation. The simultaneous acquisition of arterial spin labeling (ASL) and BOLD data represents a useful technique to more fully characterize the neurovascular underpinnings of functional brain response to cognition. We conducted a functional magnetic resonance imaging (FMRI) study of episodic memory encoding to investigate whether age is related to cerebral blood flow (CBF) and BOLD response in the medial temporal lobe (MTL). Results demonstrated a significant reduction in resting state CBF in older compared to young adults. Conversely, older adults showed significantly increased CBF but not BOLD response in the MTL during picture encoding relative to young adults. Correlations between CBF response and cognition were demonstrated whereas associations with BOLD were not observed. Stroke risk was associated with both CBF and BOLD response. Results suggest that aging effects on CBF and BOLD responses to encoding are dissociable and that cerebrovascular alterations contribute to findings of age-related differences.

Aging and large-scale functional networks: White matter integrity, gray matter volume, and functional connectivity in the resting state

“…In a similar vein, these results provide evidence against the notion that the observed reduction in BOLD activation in older adults during the resting state is due to age-related differences in cerebral vasculature alone (Bangen et al, 2009;D'Esposito, Deouell & Gazzaley, 2003;Kannurpatti et al, 2010 (Balsters et al, 2013).…”

Neuropsychological Contributions to the Early Identification of Alzheimer’s Disease

“…Similarly, this association has been detected in normally aging older adults who later converted to MCI (de Leon et al 2001). Bangen et al (2007) have also shown robust associations between resting cerebral blood flow in the medial temporal lobe and CVD risk in cognitively intact healthy older adults. Silvestrini et al (2006) have also demonstrated that altered cerebrovascular hemodynamics (i.e., elevated cerebral vasomotor reactivity to hypercapnia) was associated with hastened cognitive decline in AD patients over 1 year.…”

Cardiovascular risk in cognitively preserved elderlies is associated with glucose hypometabolism in the posterior cingulate cortex and precuneus regardless of brain atrophy and apolipoprotein gene variations

“…Previous results from clinical imaging and molecular studies have suggested a link between CVRF, structural deformities of brain microvessels (including arterial stiffness and microvascular damage), and the risk of dementia (Bell et al 2009;Grammas 2011a). Chronic cerebral blood flow deficits secondary to conditions such as diabetes, hypertension, and atherosclerosis, as well as heart failure-related microembolism, may all lead to decreased oxygen and glucose supply to the brain, as well as local toxic or metabolic disturbances (KumarSingh 2008;Bangen et al 2009;Menon and Kelley 2009). It has been suggested that microvascular changes secondary to chronic cerebral blood flow reductions might trigger the characteristic neuropathological changes of AD, such as aggregates of amyloid β-peptide (de la Torre 1999; de la Torre et al 2003).…”