Brain atrophy, reduced cerebral perfusion, arterial stiffening and wall thickening with ageing coincide with stimulus-specific changes in fMRI-BOLD responses

Am J Physiol Regul Integr Comp Physiol. 2024 Feb 26. doi: 10.1152/ajpregu.00270.2023. Online ahead of print.ABSTRACTThe aim of this study was to investigate how aging affects blood flow and structure of the brain. It was hypothesized older individuals would have lower grey matter volume (GMV), resting cerebral blood flow (CBF0), and depressed responses to iso-metabolic and neuro-metabolic stimuli. Additionally, increased carotid-femoral pulse wave velocity (PWV), carotid intima-media thickness (IMT), and decreased brachial flow-mediated dilation (FMD) would be associated with lower CBF0, cerebrovascular reactivity (CVR) and GMV. Brain scans (magnetic resonance imaging) and cardiovascular examinations were conducted in young (age=24±3 y, range=22-28 y; N=13) and old (age=71±4 y; range=67-82 y, N=14) participants, and CBF0, CVR (iso-metabolic %BOLD in response to a breath-hold (BH)), brain activation patterns during a working memory task (neuro-metabolic %BOLD response to N-back trial), GMV, PWV, IMT and FMD were measured. CBF0 and to a lesser extent CVRBH were lower in the old group (P≤0.050); however, the increase in the %BOLD response to the memory task was not blunted (P≥0.2867). Age-related differential activation patterns during the working memory task were characterized by disinhibition of the default mode network in the old group (P<0.0001). Linear regression analyses revealed PWV, and IMT were negatively correlated with CBF0, CVRBH and GMV across age groups, b...
Source: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology - Category: Physiology Authors: Source Type: research