Cerebral/Peripheral Vascular Reactivity and Neurocognition in Middle-Age Athletes.

INTRODUCTION: Midlife vascular disease risk is associated with higher incidence of cognitive impairment in late life. Regular aerobic exercise improves vascular function, which in turn may translate into better cognitive function. The purpose of this study was to determine the associations among cardiorespiratory fitness, cerebral and peripheral vascular reactivity, and cognitive function in sedentary and endurance-trained middle-age adults. METHODS: Thirty-two endurance-trained and 27 healthy sedentary participants ages 43-65 yr underwent measurements of maximal oxygen uptake (VO2max), neurocognitive assessment, cerebrovascular reactivity to CO2 (CVR), and brachial artery flow-mediated dilation (FMD). RESULTS: There were no group differences in age, sex, education level, fasting blood glucose, and blood pressure. Compared with sedentary subjects, endurance-trained athletes demonstrated better cognitive performance on memory (z-score: -0.36 ± 1.11 vs 0.30 ± 0.76, P < 0.01), attention-executive function (z-score: -0.21 ± 0.53 vs 0.18 ± 0.72, P = 0.02), and total cognitive composite scores (z-score: -0.27 ± 0.63 vs 0.23 ± 0.57, P < 0.01). Furthermore, brachial FMD (4.70% ± 2.50% vs 7.13% ± 3.09%, P < 0.01) and CVR (4.19% ± 0.71%·mm Hg⁻¹ vs 4.69% ± 1.06%·mm Hg⁻¹, P = 0.052) were greater in endurance-trained individuals than in the sedentary subjects. Total cognitive composite scores showed a significant positive association with brachial FMD (r = 0.36, P < 0.01) and CVR (r = 0.30, P = 0.03). Finally, when brachial FMD and CVR were entered as covariates, fitness-related group differences in total cognitive composite score were significantly attenuated (all P > 0.05). CONCLUSION: Endurance-trained middle-age adults demonstrated better cognitive performance, which may, at least in part, be mediated by their enhanced vascular function, including cerebral and endothelial-dependent vascular reactivity.

Central artery stiffness, neuropsychological function, and cerebral perfusion in sedentary and endurance-trained middle-aged adults.

BACKGROUND: Midlife vascular disease risk is a strong risk factor for late-life dementia. Central arterial stiffness, a hallmark of vascular aging, is associated with accelerated brain aging and cognitive decline. Habitual aerobic exercise is an effective lifestyle strategy to reduce central arterial stiffness and is related to lower risk of cognitive impairment. OBJECTIVE: To determine the associations among cardiopulmonary fitness, neuropsychological function, central arterial stiffness, and cerebral perfusion in the sedentary and endurance-trained middle-aged adults. METHODS: Twenty-six sedentary and 32 endurance-trained middle-aged adults were measured for maximal oxygen consumption, central arterial stiffness determined by aortic pulse wave velocity and carotid ultrasound, neuropsychological function, and regional cerebral blood flow assessed by MRI. RESULTS: There were no group differences in age, sex, ethnicity, education, blood pressure, and carotid intima-media wall thickness (all P>0.05). Neuropsychological performance and occipitoparietal perfusion were greater, and central arterial stiffness was lower in endurance-trained individuals than in sedentary individuals (all P<0.05). Greater cardiopulmonary fitness was related to better cognitive composite scores, including memory and attention-executive function (r=0.28-0.40, P<0.05). Lower carotid arterial stiffness was associated with better neuropsychological outcome independent of age, sex, and education (r=-0.32 to -0.35, P<0.05), and correlated with greater occipitoparietal blood flow (r= -0.37 to -0.51, P<0.05). CONCLUSION: Lower carotid artery stiffness in endurance-trained adults is associated with better neuropsychological outcome and greater occipitoparietal perfusion.

Aerobic fitness and cognitive function in midlife: an association mediated by plasma insulin.

Insulin resistance in midlife increases the risk of dementia in late-life. In contrast, habitual aerobic exercise is an established strategy to ameliorate insulin resistance which may translate into better cognitive outcome. To determine the role of plasma insulin in mediating the relation between cardiorespiratory fitness and cognitive function, fifty-eight adults completed assessments of plasma insulin levels, maximal oxygen consumption (VO2max), and neuropsychological test performance. Endurance-trained subjects demonstrated better cognitive outcome (total composite z-score: 0.21 ± 0.08 versus -0.26 ± 0.10, P = 0.001) and lower concentrations of plasma insulin (12.6 ± 0.6 versus 21.3 ± 1.5 ulU/mL, P < 0.001) than sedentary subjects. Greater VO2max was significantly associated with higher memory performance (ß = 0.37, P = 0.01) and lower plasma insulin levels (ß = -0.68, P < 0.001). The significant association between VO2max and memory performance was abolished when the indirect effect of plasma insulin was statistically removed (ß = 0.24, P = 0.19). Fitness-related cognitive enhancement may be mediated, at least in part, by plasma insulin levels.

Influence of skin type and wavelength on light wave reflectance.

PURPOSE: A new application of photoplethysmography (PPG) has emerged recently to provide the possibility of heart rate monitoring without a telemetric chest strap. The aim of this study was to determine if a new device could detect pulsation over a broad range of skin types, and what light wavelength would be most suitable for detecting the signals. A light emitting diode-based PPG system was used to detect changes in pulsatile blood flow on 23 apparently healthy individuals (11 male and 12 female, 20-59 years old) of varying skin types classified according to a questionnaire in combination with digital photographs with a skin type chart. Four different light wavelengths (470, 520, 630, and 880 nm) were tested. Normalized modulation level is calculated as the AC/DC component ratio and represents the change in flow over the underlying constant state of flow or perfusion. RESULTS: In the resting condition, green light wavelength (520 nm) displayed greater modulation (p < 0.001) than all the other wavelengths analyzed regardless of skin types. Type V (dark brown) skin type was significantly lower in modulation than all other skin types. In the exercise condition, both blue (470 nm) and green (520 nm) light wavelengths displayed greater signal-to-noise ratios than red (630 nm) or infrared (880 nm) light wavelengths (p < 0.001). CONCLUSIONS: We concluded that a PPG-based device can detect pulsation across all skin types and that a greater resolution was obtained using a green light wavelength at rest and a green or blue light wavelength during exercise.

Aerobic fitness and the brain: increased N-acetyl-aspartate and choline concentrations in endurance-trained middle-aged adults.

Engagement in regular aerobic exercise is associated with cognitive benefits, but information on the mechanisms governing these changes in humans is limited. The goal of the current study was to compare neurometabolite concentrations relating to cellular metabolism, structure, and viability in endurance-trained and sedentary middle-aged adults. Twenty-eight endurance-trained and 27 sedentary adults, aged 40-65 years, underwent general health assessment, cardiorespiratory fitness measurement, neuropsychological testing, and proton magnetic resonance spectroscopy ((1)H MRS). (1)H MRS was used to examine N-acetyl-aspartate (NAA), creatine (Cr), myo-inositol (mI), choline (Cho), and glutamate (Glu) concentrations in frontal and occipitoparietal grey matter. Group differences in concentrations of NAA, Cho, mI, and Glu, calculated as ratios over Cr, were explored using ANOVA. There were no significant differences in global cognitive function, memory, and executive function performance between the groups. In comparison to sedentary adults, the endurance-trained group displayed significantly higher NAA/Cr in the frontal grey matter (F(1, 53) = 5.367, p = 0.024) and higher Cho/Cr in the occipitoparietal grey matter (F(1, 53) = 5.138, p = 0.028). Within our middle-aged sample, endurance-trained adults demonstrated higher levels of NAA/Cr in the frontal grey matter and higher Cho/Cr in the occipitoparietal grey matter. Higher levels of NAA may indicate greater neuronal integrity and higher cerebral metabolic efficiency in association with cardiorespiratory fitness, whereas increased Cho may represent increased phospholipid levels secondary to neural plasticity.