Cerebrovascular function and its association with systemic artery function and stiffness in older adults with and without mild cognitive impairment

Cerebrovascular Reactivity Following Spinal Cord Injury

Background

Spinal cord injuries (SCI) often result in cardiovascular issues, increasing the risk of stroke and cognitive deficits.

Objectives

This study assessed cerebrovascular reactivity (CVR) using functional magnetic resonance imaging (fMRI) during a hypercapnic challenge in SCI participants compared to noninjured controls.

Methods

Fourteen participants were analyzed (n = 8 with SCI [unless otherwise noted], median age = 44 years; n = 6 controls, median age = 33 years). CVR was calculated through fMRI signal changes.

Results

The results showed a longer CVR component (tau) in the grey matter of SCI participants (n = 7) compared to controls (median difference = 3.0 s; p < .05). Time since injury (TSI) correlated negatively with steady-state CVR in the grey matter and brainstem of SCI participants (RS = -0.81, p = .014; RS = -0.84, p = .009, respectively). Lower steady-state CVR in the brainstem of the SCI group (n = 7) correlated with lower diastolic blood pressure (RS = 0.76, p = .046). Higher frequency of hypotensive episodes (n = 7) was linked to lower CVR outcomes in the grey matter (RS = -0.86, p = .014) and brainstem (RS = -0.89, p = .007).

Conclusion

Preliminary findings suggest a difference in the dynamic CVR component, tau, between the SCI and noninjured control groups, potentially explaining the higher cerebrovascular health burden in SCI individuals. Exploratory associations indicate that longer TSI, lower diastolic blood pressure, and more hypotensive episodes may lead to poorer CVR outcomes. However, further research is necessary to establish causality and support these observations.

Cerebrovascular adaptations to habitual resistance exercise with aging

Resistance training (RT) is associated with improved metabolism, bone density, muscular strength, and lower risk of osteoporosis, sarcopenia, and cardiovascular disease. Although RT imparts many physiological benefits, cerebrovascular adaptations to chronic RT are not well defined. Participation in RT is associated with greater resting peripheral arterial diameters, improved endothelial function, and general cardiovascular health, whereas simultaneously linked to reductions in central arterial compliance. Rapid blood pressure fluctuations during resistance exercise, combined with reduced arterial compliance, could lead to cerebral microvasculature damage and subsequent cerebral hypoperfusion. Reductions in cerebral blood flow (CBF) accompany normal aging, where chronic reductions in CBF are associated with changes in brain structure and function, and increased risk of neurodegeneration. It remains unclear whether reductions in arterial compliance with RT relate to subclinical cerebrovascular pathology, or if such adaptations require interpretation in the context of RT specifically. The purpose of this narrative review is to synthesize literature pertaining to cerebrovascular adaptations to RT at different stages of the life span. This review also aims to identify gaps in the current understanding of the long-term impacts of RT on cerebral hemodynamics and provide a mechanistic rationale for these adaptations as they relate to aging, cerebral vasculature, and overall brain health.

The Clinical Relevance of Autonomic Dysfunction, Cerebral Hemodynamics, and Sleep Interactions in Individuals Living With SCI

A myriad of physiological impairments is seen in individuals after a spinal cord injury (SCI). These include altered autonomic function, cerebral hemodynamics, and sleep. These physiological systems are interconnected and likely insidiously interact leading to secondary complications. These impairments negatively influence quality of life. A comprehensive review of these systems, and their interplay, may improve clinical treatment and the rehabilitation plan of individuals living with SCI. Thus, these physiological measures should receive more clinical consideration. This special communication introduces the under investigated autonomic dysfunction, cerebral hemodynamics, and sleep disorders in people with SCI to stakeholders involved in SCI rehabilitation. We also discuss the linkage between autonomic dysfunction, cerebral hemodynamics, and sleep disorders and some secondary outcomes are discussed. Recent evidence is synthesized to make clinical recommendations on the assessment and potential management of important autonomic, cerebral hemodynamics, and sleep-related dysfunction in people with SCI. Finally, a few recommendations for clinicians and researchers are provided.

Nordic Walking in Water on Cerebrovascular Reactivity and Cognitive Function in Elderly Patients with Type 2 Diabetes

INTRODUCTION

Aquatic Nordic walking (ANW) is a novel whole-body low-impact exercise that can be practiced by a variety of older adults with chronic conditions. However, its efficacy on several aspects of health is largely unknown.

PURPOSE

This study aimed to determine the effects of regular ANW on glycemic control and vascular function in older adults with type 2 diabetes and mild cognitive impairment.

METHODS

Thirty-three older adults with type 2 diabetes age 60-75 yr were randomly allocated to nonexercising control ( n = 17) or ANW ( n = 17) groups. Nordic walking was performed in a pool at water temperature of 34°C-36°C, three times per week for 12 wk.

RESULTS

Measures of functional physical fitness including chair stand, timed up and go, chair sit and reach, reach and back scratch, and 6-min walk test scores were all improved after ANW (all P < 0.05). Plasma glucose, glycosylated hemoglobin, and homeostasis model assessment of insulin resistance decreased (all P < 0.05) in ANW. Vascular reactivity as assessed by brachial flow-mediated dilation increased, and arterial stiffness as assessed by brachial-ankle pulse wave velocity decreased in ANW (all P < 0.05). No significant changes were observed in the control group. Middle cerebral artery pulsatility index decreased with ANW under normocapnia condition ( P < 0.05). Cerebrovascular conductance increased with ANW under hypercapnia condition. Montreal Cognitive Assessment score increased in the ANW group ( P < 0.001). Changes in Montreal Cognitive Assessment scores were positively associated with corresponding changes in brain-derived neurotrophic factor ( r = 0.540, P = 0.031).

CONCLUSIONS

Nordic walking in water was a safe and effective innovative exercise modality to improve glycemic control, vascular function, physical fitness, cerebrovascular reactivity, and cognitive function in older adults with type 2 diabetes.

Cerebral oxygenation during exercise deteriorates with advancing chronic kidney disease

BACKGROUND

Cognitive impairment and exercise intolerance are common in chronic kidney disease (CKD). Cerebral perfusion and oxygenation play a major role in both cognitive function and exercise execution. This study aimed to examine cerebral oxygenation during a mild physical stress in patients at different CKD stages and controls without CKD.

METHODS

Ninety participants (18 per CKD stage 2, 3a, 3b and 4 and 18 controls) underwent a 3-min intermittent handgrip exercise at 35% of their maximal voluntary contraction. During exercise, cerebral oxygenation [oxyhaemoglobin (O2Hb), deoxyhaemoglobin (HHb) and total haemoglobin (tHb)] was assessed by near-infrared spectroscopy. Indices of microvascular (muscle hyperaemic response) and macrovascular function (carotid intima-media thickness and pulse wave velocity (PWV)) and cognitive and physical activity status were also evaluated.

RESULTS

No differences in age, sex and body mass index were detected among groups. The mini-mental state examination score was significantly reduced with advancing CKD stages (controls: 29.2 ± 1.2, stage 2: 28.7 ± 1.0, stage 3a: 27.8 ± 1.9, stage 3b: 28.0 ± 1.8, stage 4: 27.6 ± 1.5; P = .019). Similar trends were observed for physical activity levels and handgrip strength. The average response in cerebral oxygenation (O2Hb) during exercise was lower with advancing CKD stages (controls: 2.50 ± 1.54, stage 2: 1.30 ± 1.05, stage 3a: 1.24 ± 0.93, stage 3b: 1.11 ± 0.89, stage 4: 0.97 ± 0.80 μmol/l; P < .001). The average tHb response (index of regional blood volume) showed a similar decreasing trend (P = .003); no differences in HHb among groups were detected. In univariate linear analysis, older age, lower estimated glomerular filtration rate (eGFR), Hb, microvascular hyperaemic response and increased PWV were associated with poor O2Hb response during exercise. In the multiple model, eGFR was the only parameter independently associated with the O2Hb response.

CONCLUSIONS

Brain activation during a mild physical task appears to decrease with advancing CKD as suggested by the smaller increase in cerebral oxygenation. This may contribute to impaired cognitive function and reduced exercise tolerance with advancing CKD.

Anthracycline chemotherapy, vascular dysfunction and cognitive impairment: burgeoning topics and future directions

Anthracyclines, chemotherapeutic agents used to treat common forms of cancer, increase cardiovascular (CV) complications, thereby necessitating research regarding interventions to improve the health of cancer survivors. Vascular dysfunction, which is induced by anthracycline chemotherapy, is an established antecedent to overt CV diseases. Potential treatment options for ameliorating vascular dysfunction have largely been understudied. Furthermore, patients treated with anthracyclines have impaired cognitive function and vascular dysfunction is an independent risk factor for the development of mild cognitive impairment. Here, we will focus on: anthracycline chemotherapy associated CV diseases risk; how targeting mechanisms underlying vascular dysfunction may be a means to improve both CV and cognitive health; and research gaps and potential future directions for the field of cardio-oncology.

The effect of levodopa treatment on vascular endothelial function in Parkinson's disease

OBJECTIVE

There has been increasing awareness that micro-vascular alteration or vascular inflammation has been associated with levodopa-induced dyskinesia in PD. Vascular endothelial function assessed by flow mediated dilation (FMD) is known to reflect early microvascular change. We compare the impact of levodopa or dopamine agonist treatment on the change of FMD in de novo PD patients.

METHODS

This retrospective study used a selected sample from registry. We identified de-novo PD patients who underwent FMD at baseline, and follow-up FMD after 1 year (± 2 month) of levodopa (n = 18) or dopamine agonist (n = 18) treatment.

RESULTS

FMD decreased after levodopa (8.60 ± 0.46 to 7.21 ± 0.4, p = 0.002) but there were no significant changes after DA treatment (8.33 ± 0.38 to 8.22 ± 0.33, p = 0.26). Homocysteine rose (11.52 ± 0.45 to 14.33 ± 0.68, p < 0.05) during levodopa treatment, but dopamine agonist had no effect (10.59 ± 0.38 to 11.38 ± 0.67, p = 0.184). Correlation analysis revealed that the changes in homocysteine level had non-significant correlation with FMD change (r =  - 0.30, p = 0.06). FMD change was not associated with age (p = 0.47), disease duration (p = 0.81), baseline motor UPDRS (p = 0.43), motor UPDRS change (p = 0.64), levodopa equivalent dose change (p = 0.65).

CONCLUSIONS

We found that 1-year levodopa treatment may adversely affect vascular endothelial function in de novo PD. Further studies are needed to clarify the exact pathogenesis and clinical implication of levodopa-induced endothelial dysfunction in PD.

Aerobic exercise training reduces cerebrovascular impedance in older adults: a 1-year randomized controlled trial

Older adults have higher cerebrovascular impedance than young individuals which may contribute to chronic brain hypoperfusion. Besides, middle-aged athletes exhibit lower cerebrovascular impedance than their sedentary peers. We examined whether aerobic exercise training (AET) reduces cerebrovascular impedance in sedentary older adults. We conducted a proof-of-concept trial that randomized 73 older adults to 1 yr of AET (n = 36) or stretching and toning (SAT, n = 37) interventions. Cerebrovascular impedance was estimated from simultaneous recordings of carotid artery pressure (CAP) via applanation tonometry and cerebral blood flow velocity (CBFV) in the middle cerebral artery via transcranial Doppler using transfer function analysis. Fifty-six participants completed 1-yr interventions, and 41 of those completed cerebrovascular impedance measurements. AET group showed a significant increase in V̇o2peak after the intervention [estimated marginal mean (95% confidence interval); from 22.8 (21.6 to 24.1) to 24.9 (23.6 to 26.2) mL·kg-1·cm-1, P < 0.001], but not SAT [from 21.7 (20.5 to 22.9) to 22.3 (21.1 to 23.7) mL·kg-1·cm-1, P = 0.114]. Coherence between changes in CBFV and CAP was >0.90 in the frequency range of 0.78-3.12 Hz. The averaged cerebrovascular impedance modulus (Z) in this frequency range decreased after 1-yr AET [from 1.05 (0.96 to 1.14) to 0.95 (0.92 to 1.06) mmHg·s·cm-1, P = 0.023], but not SAT [from 0.96 (0.87 to 1.04) to 1.01 (0.92 to 1.10) mmHg·s·cm-1, P = 0.138]. Reductions in Z were correlated positively with reductions in carotid pulse pressure (r = 0.628, P = 0.004) and inversely with mean CBFV (r = -0.563, P = 0.012) in the AET group. One-year AET reduces cerebrovascular impedance in older adults, which may benefit brain perfusion.NEW & NOTEWORTHY Estimation of cerebrovascular impedance is essential for understanding dynamic cerebral blood flow regulation. This randomized controlled trial demonstrated that aerobic exercise training reduced cerebrovascular impedance in older adults, which may benefit brain perfusion.

An examination of the relationship among plasma brain derived neurotropic factor, peripheral vascular function, and body composition with cognition in midlife African Americans/Black individuals

African American/Black individuals have been excluded from several lines of prominent neuroscience research, despite exhibiting disproportionately higher risk factors associated with the onset and magnitude of neurodegeneration. Therefore, the objective of the current investigation was to examine potential relationships among brain derived neurotropic factor (BDNF), peripheral vascular function, and body composition with cognition in a sample of midlife, African American/Black individuals. Midlife adults (men: n = 3, 60 ± 4 years; women: n = 9, 58 ± 5 years) were invited to complete two baseline visits separated by 4 weeks. Peripheral vascular function was determined by venous occlusion plethysmography, a dual-energy X-ray absorptiometry was used to determine body composition, and plasma was collected to quantify BDNF levels. The CNS Vital Signs computer-based test was used to provide scores on numerous cognitive domains. The principal results included that complex attention (r = 0.629) and processing speed (r = 0.734) were significantly (p < 0.05) related to the plasma BDNF values. However, there was no significant (p > 0.05) relationship between any vascular measure and any cognitive domain or BDNF value. Secondary findings included the relationship between lean mass and peak hyperemia (r = 0.758) as well as total hyperemia (r = 0.855). The major conclusion derived from these results was that there is rationale for future clinical trials to use interventions targeting increasing BDNF to potentially improve cognition. Additionally, these results strongly suggest that clinicians aiming to improve cognitive health via improvements in the known risk factor of vascular function should consider interventions capable of promoting the size and function of skeletal muscle, especially in the African American/Black population.