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Background Age‐related impairments in cerebrovascular function likely contribute to cognitive decline with aging. In particular, cerebral artery stiffening with aging leads to transmission of damaging, pulsatile blood flow to the microcirculation, causing suboptimal tissue perfusion and cerebrovascular dysfunction. Conversely, physically active older adults with higher cardiorespiratory fitness (CRF) often have greater cerebrovascular function, as evidenced by greater cerebrovascular reactivity, than sedentary peers. This suggests that either regular physical activity, higher CRF, or both has beneficial effects on the cerebrovasculature and may contribute to preserved cognitive function with aging. However, little is known about the relations between physical activity, as assessed by leisure time physical activity (LTPA), or CRF and cerebrovascular stiffness. Purpose To determine if cerebrovascular stiffness is related to LTPA, CRF or both among healthy mid‐life and older adults, and if individuals with higher levels of LTPA and/or CRF have greater cerebrovascular stiffness reactivity in response to a vasodilatory stimulus and/or better cognitive function. Methods Cerebrovascular stiffness (pulsatility index, PI), LTPA, CRF and cognitive function were assessed in 27 mid‐life/older adults (12F/15M; 67±1 years) free from chronic diseases and dementia. Middle cerebral artery velocity (MCAv) was measured with a 2‐MHz Doppler probe during 5 minutes of normocapnia and hypercapnia (breathing 5% CO2). PI was defined as (MCAvsystolic‐MCAvdiastolic)/MCAvmean measured over the final 60 seconds of each phase. LTPA was calculated using the Modifiable Activity Questionnaire. CRF was determined by assessing maximal oxygen consumption (VO2max) during incremental treadmill exercise to exhaustion. The cognitive domains of executive function, processing speed, working memory, and language were assessed with the NIH Toolbox Cognition Domain and composite scores for fluid, crystallized, and total cognition were calculated. Results PI was inversely related to CRF under both normocapnic (r=0.41, p=0.04) and hypercapnic (r=0.46, p=0.02) conditions, indicating lower cerebrovascular stiffness in those with greater CRF. However, there was no relation between LTPA and PI under normocapnic (r=0.04, p=0.86) or hypercapnic (r=0.12, p=0.55) conditions. There were no relations between the change in PI from normocapnia (baseline) to hypercapnia and CRF (r=0.06, p=0.23) or LTPA (r=0.041, p=0.84). Finally, there were no relations between any measures of cognitive function and PI under either normocapnic or hypercapnic conditions (all p>0.05). Conclusions These preliminary results suggest cerebrovascular stiffness is inversely related to CRF, but unrelated to LTPA, among healthy mid‐life/older adults. However, the change in cerebrovascular stiffness in response to a vasodilatory stimulus was not related to CRF, suggesting that absolute cerebrovascular stiffness may be more strongly associated with CRF than functional reactivity. Cognitive performanc...

Background Age is the primary risk factor for cardiovascular diseases (CVD), cognitive decline, Alzheimer's disease and related dementias. Young women are at a lower risk for the above‐mentioned diseases compared to age‐matched men; however, their risk becomes greater than men after menopause. Age‐related declines in peripheral and cerebral vascular function are thought to play a role in the increased risk for CVD and related chronic conditions. It is often assumed that changes in peripheral vascular function are directly indicative of changes in cerebrovascular function. However, in young, healthy adults, there does not appear to be an association between peripheral and cerebral vascular function. There is still limited evidence for whether peripheral vascular function is indicative of cerebrovascular function in postmenopausal (PM) women and midlife and older (ML/O) men. Purpose To determine the relation between cerebrovascular reactivity (CVR; an index of cerebrovascular function) and vascular endothelial function (brachial artery flow‐mediated dilation [FMDBA]) in PM women and ML/O men and to determine if cerebrovascular function is associated with cognitive function in these groups. Methods CVR, FMDBA, and cognitive function were assessed in 17 PM women (67±6 years) and 26 men (66±7 years). Middle cerebral artery velocity (MCAv; cm/s) using a 2‐MHz transcranial Doppler probe and end‐tidal CO2 (etCO2; mmHg) were measured during 5 minutes of normocapnia and 5 minutes of hypercapnia (5% CO2). CVR was calculated as ΔMCAv/ΔetCO2. FMDBA was determined with the forearm cuff method and data expressed as Δ% from baseline diameter. The NIH Toolbox Cognition Battery of tests was used to assess global cognitive function, as well as specific cognitive domains. Results CVR was correlated with FMDBA (r=0.33, p=0.02) in PM women but was not correlated with FMDBA in ML/O men (r<0.01, p=0.85). There was a significant difference in this relation between sexes (p=0.04). Stepwise linear regression identified CVR and body mass index (BMI), but not age, blood pressures, LDL and HDL cholesterol, triglycerides or glucose, as significantly related to FMD­BA in PM women; correcting for BMI strengthened the relation between CVR and FMDBA in PM women (r=0.62, p<0.01). In contrast, only plasma LDL cholesterol and triglycerides were significantly related to FMD­BA in ML/O men. There were no relations between CVR and cognitive function in PM women (all p>0.05). In men there was a significant positive relation between CVR and the picture vocabulary test measure of language (r=0.56, p<0.01), but no other measures of cognitive function (all p>0.05). Conclusions These findings suggest cerebrovascular function is associated with peripheral vascular endothelial function in PM women, but not ML/O men, while cerebrovascular function has no to minimal relation to cognitive function in these groups. Controlling for BMI increased the strength of the relation between CVR and FMD­BA in PM women, indicating that body composition may be an important fact...