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

The 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 gray matter volume (GMV), resting cerebral blood flow (CBF0), and depressed responses to isometabolic and neurometabolic stimuli. In addition, 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 yr, range = 22-28 yr; n = 13) and old (age = 71 ± 4 yr; range = 67-82 yr, n = 14) participants, and CBF0, CVR [isometabolic % blood oxygen level-dependent (BOLD) in response to a breath hold (BH)], brain activation patterns during a working memory task (neurometabolic %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, but within the old group alone only the relationships between PWV-CVRBH and IMT-GMV remained significant (P ≤ 0.0183). These findings suggest the impacts of age on cerebral %BOLD responses are stimulus specific, brain aging involves alterations in cerebrovascular and possibly neurocognitive control, and arterial stiffening and wall thickening may serve a role in cerebrovascular aging.NEW & NOTEWORTHY Cerebral perfusion was lower in old versus young adults. %Blood oxygen level-dependent (BOLD) responses to an isometabolic stimulus and gray matter volume were decreased in old versus young adults and associated with arterial stiffening and wall thickening. The increased %BOLD response to a neurometabolic stimulus appeared unaffected by age; however, the old group displayed disinhibition of the default mode network during the stimulus. Thus, age-related alterations in cerebral %BOLD responses were stimulus specific and related to arterial remodeling.

The impact of exercise training on endothelial function in postmenopausal women: a systematic review.

NEW FINDINGS: What is the topic of this review? The aim of this systematic review was to evaluate and summarize all published literature examining the impact of various exercise training interventions on endothelial function in postmenopausal women. What advances does it highlight? There was a moderate effect of training on macrovascular and microvascular endothelial function and just under two-thirds of studies demonstrated a significant increase in at least one measure of endothelial function in postmenopausal women. Factors including exercise intensity and duration, vessel type, clinical status, hormone therapy, and menopausal status may influence the effects of training on endothelial function in postmenopausal women. ABSTRACT: Women experience a rapid decline in endothelial function during menopause. Therefore, it is important to explore interventions, such as exercise training, that may prevent endothelial dysfunction in postmenopausal women. The aim of this systematic review was to evaluate and summarize all published literature examining the impact of various exercise training interventions on endothelial function in postmenopausal women. Three electronic databases (MEDLINE, EMBASE and Web of Science) were used to systematically select studies related to exercise training, endothelial function and postmenopausal women. The major initial and secondary update systematic searches yielded 502 unique articles that were screened for eligibility. Thirty-five studies were included in the systematic review. Two-thirds of all studies demonstrated a group-level increase in at least one measure of endothelial function with training. Most studies investigating biomarkers of endothelial function showed improvement in at least one measured biomarker post-training. There was a moderate effect of training on both macrovascular and microvascular endothelial function in observational and randomized intervention studies. Variability in study designs, training protocols and participant characteristics make it difficult to directly compare studies. Factors including exercise intensity and duration, vessel type, clinical status, hormone therapy, and menopausal status may contribute to the inconsistent effects of training on endothelial function in postmenopausal women. Future research is needed in this population to understand the mechanisms driving inter-study and inter-individual differences in training-induced changes in endothelial function.