Cerebral Vasomotor Reactivity during Hypo- and Hypercapnia in Sedentary Elderly and Masters Athletes

Abstract

Physical activity may influence cerebrovascular function. The objective of this study was to determine the impact of life-long aerobic exercise training on cerebral vasomotor reactivity (CVMR) to changes in end-tidal CO2 (EtCO2) in older adults. Eleven sedentary young (SY, 27 ± 5 years), 10 sedentary elderly (SE, 72 ± 4 years), and 11 Masters athletes (MA, 72 ± 6 years) underwent the measurements of cerebral blood flow velocity (CBFV), arterial blood pressure, and EtCO2 during hypocapnic hyperventilation and hypercapnic rebreathing. Baseline CBFV was lower in SE and MA than in SY while no difference was observed between SE and MA. During hypocapnia, CVMR was lower in SE and MA compared with SY (1.87 ± 0.42 and 1.47 ± 0.21 vs. 2.18 ± 0.28 CBFV%/mm Hg, Po0.05) while being lowest in MA among all groups (Po0.05). In response to hypercapnia, SE and MA exhibited greater CVMR than SY (6.00 ± 0.94 and 6.67 ± 1.09 vs. 3.70 ± 1.08 CBFV1%/mm Hg, Po0.05) while no difference was observed between SE and MA. A negative linear correlation between hypo-and hypercapnic CVMR (R 2 ¼ 0.37, Po0.001) was observed across all groups. Advanced age was associated with lower resting CBFV and lower hypocapnic but greater hypercapnic CVMR. However, life-long aerobic exercise training appears to have minimal effects on these age-related differences in cerebral hemodynamics.

Association of Cardiorespiratory Fitness and Vascular Risk on Cognitive Function in Young Adults

“…Consistent with previous research, this study found that the potential beneficial effects of regular physical activity participation and a healthy body weight on the vascular and cognitive health of young adults have been previously highlighted (Zhu et al, 2014;Zhu et al, 2013). Evidence suggests that physical inactivity, pooper cardiorespiratory fitness, or obesity increases CRP levels and impairs cognitive dysfunction.…”

“…Although the data from the adjusted regression analysis highlight the potential pathways of health indices on CRP and cognitive function, our findings do not establish a causal relationship. Therefore, having higher cardiorespiratory fitness level and lower BMI may result in lowered CRP level, thus mediating cognitive function (Ge et al, 2013;Zhu et al, 2013).…”

“…C-reactive protein (CRP), known as a biomarker of systemic inflammation and an independent predictor of future cardiovascular events, is emerging as an indicator of cognitive dysfunction among older adults (Ge et al, 2013;Zhu et al, 2013). Higher levels of CRP are correlated with reduced performance on tasks involving executive function (Wersching et al, 2010).…”

Phosphodiesterase‐5 inhibition potentiates cerebrovascular reactivity in chronic traumatic brain injury

“…End‐tidal CO 2 (EtCO 2 ) was measured continuously using a capnograph (Smith Medical, Model 9004). These conditions (5% CO 2 for no longer than one minute at a time) did not result in significant changes in mean arterial blood pressure, heart rate, or oxygen saturation 37. The sequence's parameters were TR/TE = 2000/25 msec, flip angle=80°, field of view=220 × 220 mm 2 , matrix= 64 × 64, 36 slices, thickness=3.6 mm, no gap between slices, 210 volumes.…”

Impact of age on cerebrovascular dilation versus reactivity to hypercapnia

“…2,3 Aging reduces absolute CBFV, as measured at the middle cerebral artery (MCA) with transcranial Doppler ultrasound. [4][5][6] However, the evidence regarding the effect of age on CVR remains unclear with some studies reporting a decreased CVR, 4,[7][8][9] while others reported no difference. 6,[10][11][12] Different vasodilatory stimuli, ranging from 5 to 7% CO 2 in room air 4,[6][7][8][9][10][11][12] or 5% CO 2 in 95% oxygen, 7 or measures of CBFV versus CBF (transcranial Doppler ultrasound, 4,[6][7][8]10,11 positron emission tomography, 12 xenon inhalation 9 ) represent potential sources of variation amongst studies.…”