Cerebral and Extracerebral Vasoreactivity in Patients With Different Clinical Manifestations of Cerebral Small-Vessel Disease: Data From the Significance of Hemodynamic and Hemostatic Factors in the Course of Different Manifestations of Cerebral Small-Vessel Disease Study

Imaging-validated correlates and implications of the pathophysiologic mechanisms of ageing-related cerebral large artery and small vessel diseases: a systematic review and meta-analysis

BACKGROUND

Cerebral large artery and small vessel diseases are considered substrates of neurological disorders. We explored how the mechanisms of neurovascular uncoupling, dysfunctional blood-brain-barrier (BBB), compromised glymphatic pathway, and impaired cerebrovascular reactivity (CVR) and autoregulation, identified through diverse neuroimaging techniques, impact cerebral large artery and small vessel diseases.

METHODS

Studies (1990-2024) that reported on neuroradiological findings on ageing-related cerebral large artery and small vessel diseases were reviewed. Fifty-two studies involving 23,693 participants explored the disease mechanisms, 9 studies (sample size = 3,729) of which compared metrics of cerebrovascular functions (CF) between participants with cerebral large artery and small vessel diseases (target group) and controls with no vascular disease. Measures of CF included CVR, cerebral blood flow (CBF), blood pressure and arterial stiffness.

RESULTS

The findings from 9 studies (sample size = 3,729, mean age = 60.2 ± 11.5 years), revealed negative effect sizes of CVR [SMD = - 1.86 (95% CI - 2.80, - 0.92)] and CBF [SMD = - 2.26 (95% CI - 4.16, - 0.35)], respectively indicating a reduction in cerebrovascular functions in the target group compared to their controls. Conversely, there were significant increases in the measures of blood pressure [SMD = 0.32 (95% CI 0.18, 0.46)] and arterial stiffness [SMD = 0.87 (95% CI 0.77, 0.98)], which signified poor cerebrovascular functions in the target group. In the combined model the overall average effect size was negative [SMD = - 0.81 (95% CI - 1.53 to - 0.08), p < 0.001]. Comparatively, this suggests that the negative impacts of CVR and CBF reductions significantly outweighed the effects of blood pressure and arterial stiffness, thereby predominantly shaping the overall model. Against their controls, trends of reduction in CF were observed exclusively among participants with cerebral large artery disease (SMD = - 2.09 [95% CI: - 3.57, - 0.62]), as well as those with small vessel diseases (SMD = - 0.85 [95% CI - 1.34, - 0.36]). We further delineated the underlying mechanisms and discussed their interconnectedness with cognitive impairments.

CONCLUSION

In a vicious cycle, dysfunctional mechanisms in the glymphatic system, neurovascular unit, BBB, autoregulation, and reactivity play distinct roles that contribute to reduced CF and cognitive risk among individuals with cerebral large artery and/or small vessel diseases. Reduction in CVR and CBF points to reductions in CF, which is associated with increased risk of cognitive impairment among ageing populations ≥ 60 years.

Peripheral vascular function in stroke: systematic review and meta-analysis

Peripheral vascular dysfunction, measured as flow-mediated dilation (FMD), is present across all phases of stroke recovery and elevates the risk for recurrent cardiovascular events. The objective of this systematic review and meta-analysis was to characterize baseline FMD in individuals' poststroke, with consideration for each phase of stroke recovery. Three databases (PubMed, CINAHL, and Embase) were searched between January 1, 2000 and October 12, 2023 for studies that examined baseline FMD in stroke. Three reviewers conducted abstract and full-text screening, data extraction, and quality assessment. A random effects model was used to estimate FMD across studies. Meta-regression was used to examine the impact of age and time since stroke (acute, subacute, chronic) on FMD. Twenty-eight studies with ischemic and hemorrhagic stroke were included. Descriptive statistics for the demographics and FMD values of each study are presented. For the meta-analysis, average estimate FMD was 3.9% (95% CI: 2.5-5.3%). We report a large amount of heterogeneity (Cochrane's Q P value <0.001, and I2 = 99.6%). Differences in average age and the time poststroke between studies were not significantly associated with differences in FMD values. Despite the large heterogeneity for FMD values across studies, our primary finding suggests that FMD remains impaired across all phases of stroke.NEW & NOTEWORTHY This systematic review and meta-analysis offers invaluable insight into poststroke vascular function. Despite the inherent heterogeneity among the 28 studies analyzed, we report that peripheral vascular dysfunction, as quantified by flow-mediated dilation, exists across all stages of stroke recovery. This finding underscores the importance for interventions that focus on improving vascular health and secondary stroke prevention.

Associations of Cerebrovascular Regulation and Arterial Stiffness With Cerebral Small Vessel Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Cerebral small vessel disease (cSVD) is a major contributing factor to ischemic stroke and dementia. However, the vascular pathologies of cSVD remain inconclusive. The aim of this systematic review and meta-analysis was to characterize the associations between cSVD and cerebrovascular reactivity (CVR), cerebral autoregulation, and arterial stiffness (AS).

METHODS AND RESULTS

MEDLINE, Web of Science, and Embase were searched from inception to September 2023 for studies reporting CVR, cerebral autoregulation, or AS in relation to radiological markers of cSVD. Data were extracted in predefined tables, reviewed, and meta-analyses performed using inverse-variance random effects models to determine pooled odds ratios (ORs). A total of 1611 studies were identified; 142 were included in the systematic review, of which 60 had data available for meta-analyses. Systematic review revealed that CVR, cerebral autoregulation, and AS were consistently associated with cSVD (80.4%, 78.6%, and 85.4% of studies, respectively). Meta-analysis in 7 studies (536 participants, 32.9% women) revealed a borderline association between impaired CVR and cSVD (OR, 2.26 [95% CI, 0.99-5.14]; P=0.05). In 37 studies (27 952 participants, 53.0% women) increased AS, per SD, was associated with cSVD (OR, 1.24 [95% CI, 1.15-1.33]; P<0.01). Meta-regression adjusted for comorbidities accounted for one-third of the AS model variance (R2=29.4%, Pmoderators=0.02). Subgroup analysis of AS studies demonstrated an association with white matter hyperintensities (OR, 1.42 [95% CI, 1.18-1.70]; P<0.01).

CONCLUSIONS

The collective findings of the present systematic review and meta-analyses suggest an association between cSVD and impaired CVR and elevated AS. However, longitudinal investigations into vascular stiffness and regulatory function as possible risk factors for cSVD remain warranted.

Cocaine use is associated with cerebral white matter hyperintensities in HIV disease

BACKGROUND

White matter hyperintensities (WMH), a marker of cerebral small vessel disease and predictor of cognitive decline, are observed at higher rates in persons with HIV (PWH). The use of cocaine, a potent central nervous system stimulant, is disproportionately common in PWH and may contribute to WMH.

METHODS

The sample included of 110 PWH on antiretroviral therapy. Fluid-attenuated inversion recovery (FLAIR) and T1-weighted anatomical MRI scans were collected, along with neuropsychological testing. FLAIR images were processed using the Lesion Segmentation Toolbox. A hierarchical regression model was run to investigate predictors of WMH burden [block 1: demographics; block 2: cerebrovascular disease (CVD) risk; block 3: lesion burden].

RESULTS

The sample was 20% female and 79% African American with a mean age of 45.37. All participants had persistent HIV viral suppression, and the median CD4+ T-cell count was 750. Nearly a third (29%) currently used cocaine regularly, with an average of 23.75 (SD = 20.95) days in the past 90. In the hierarchical linear regression model, cocaine use was a significant predictor of WMH burden (β = .28). WMH burden was significantly correlated with poorer cognitive function (r = -0.27). Finally, higher WMH burden was significantly associated with increased serum concentrations of interferon-γ-inducible protein 10 (IP-10) but lower concentrations of myeloperoxidase (MPO); however, these markers did not differ by COC status.

CONCLUSIONS

WMH burden is associated with poorer cognitive performance in PWH. Cocaine use and CVD risk independently contribute to WMH, and addressing these conditions as part of HIV care may mitigate brain injury underlying neurocognitive impairment.

Epidemiology and Risk Factors for Stroke in Chronic Kidney Disease: A Narrative Review

Patients with chronic kidney disease (CKD) have a higher risk ofboth ischemic and hemorrhagic stroke. This association appears to be partly independent from the higher prevalence of established risk factors for stroke in patients with CKD, including hypertension and atrial fibrillation. In the present review we aim to discuss the impact of CKD on the risk of stroke and stroke-related consequences, and explore the pathophysiology underpinning the increased risk of stroke in patients with CKD. We cover the clinical association between renal dysfunction and cerebrovascular disease including stroke, silent brain infarct, cerebral small vessel disease, microbleeds, and white matter hyperintensity, and discuss the underlying mechanisms.

Cerebral Vasomotor Reactivity in COVID-19: A Narrative Review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) primarily affects the respiratory system but can also lead to neurological complications. Among COVID-19 patients, the endothelium is considered the Achilles heel. A variety of endothelial dysfunctions may result from SARS-CoV-2 infection and subsequent endotheliitis, such as altered vascular tone, oxidative stress, and cytokine storms. The cerebral hemodynamic impairment that is caused is associated with a higher probability of severe disease and poor outcomes in patients with COVID-19. This review summarizes the most relevant literature on the role of vasomotor reactivity (VMR) in COVID-19 patients. An overview of the research articles is presented. Most of the studies have supported the hypothesis that endothelial dysfunction and cerebral VMR impairment occur in COVID-19 patients. Researchers believe these alterations may be due to direct viral invasion of the brain or indirect effects, such as inflammation and cytokines. Recently, researchers have concluded that viruses such as the Human Herpes Virus 8 and the Hantavirus predominantly affect endothelial cells and, therefore, affect cerebral hemodynamics. Especially in COVID-19 patients, impaired VMR is associated with a higher risk of severe disease and poor outcomes. Using VMR, one can gain valuable insight into a patient's disease progression and make more informed decisions regarding appropriate treatment options. A new pandemic may develop with the COVID-19 virus or other viruses, making it essential that healthcare providers and researchers remain focused on developing new strategies for improving survival in such patients, particularly those with cerebrovascular risk factors.

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.

Chronic Endothelial Dysfunction after COVID-19 Infection Shown by Transcranial Color-Coded Doppler: A Cross-Sectional Study

In addition to respiratory symptoms, COVID-19 often causes damage to many other organs, especially in severe forms of the disease. Long-term consequences after COVID-19 are common and often have neurological symptoms. Cerebral vasoreactivity may be impaired after acute COVID-19 and in our study, we wanted to show how constant and reversible are the changes in brain vasoreactivity after infection. This cross-sectional observational study included 49 patients diagnosed with COVID-19 and mild neurological symptoms 300 days after the onset of the disease. We used a transcranial color-coded Doppler (TCCD) and a breath-holding test (BHT) to examine cerebral vasoreactivity and brain endothelial function. We analyzed the parameters of the flow rate through the middle cerebral artery (MCA): peak systolic velocity (PSV), end-diastolic velocity (EDV), mean velocity (MV), resistance index (RI) and pulsatility index (PI), and we calculated the breath-holding index (BHI). Subjects after COVID-19 infection had lower measured velocity parameters through MCA at rest period and after BHT, lower relative increases of flow velocities after BHT, and lower BHI. We showed that subjects, 300 days after COVID-19, still have impaired cerebral vasoreactivity measured by TCCD and they have chronic endothelial dysfunction.

Cerebrovascular Function, Vascular Risk, and Lifestyle Patterns in Resistant Hypertension

BACKGROUND

Impaired cerebrovascular reactivity (CVR) and blunted cerebral hemodynamic recruitment are thought to be important mechanisms linking hypertension to cerebrovascular and cognitive outcomes. Few studies have examined cardiovascular or dietary correlates of CVR among hypertensives.

OBJECTIVE

To delineate associations between cardiometabolic risk, diet, and cerebrovascular functioning among individuals with resistant hypertension from the TRIUMPH trial (n = 140).

METHODS

CVR was assessed by examining changes in tissue oxygenation (tissue oxygenation index [TOI] and oxygenated hemoglobin [HBO2]) using functional near-infrared spectroscopy (fNIRS) during a breath holding test, a standardized CVR assessment to elicit a hypercapnic response. Participants also underwent fNIRS during three cognitive challenge tasks. Vascular function was assessed by measurement of brachial artery flow mediated dilation and hyperemic flow response. Cardiometabolic fitness was assessed from peak VO2 on an exercise treadmill test and body mass index. Dietary patterns were quantified using the DASH eating score. Cognitive function was assessed using a 45-minute test battery assessing Executive Function, Processing Speed, and Memory.

RESULTS

Greater levels fitness (B = 0.30, p = 0.011), DASH compliance (B = 0.19, p = 0.045), and lower obesity (B = -0.30, p = 0.004), associated with greater changes in TOI, whereas greater flow-mediated dilation (B = 0.19, p = 0.031) and lower stroke risk (B = -0.19, p = 0.049) associated with greater HBO2. Similar associations were found for cerebral hemodynamic recruitment, and associations between CVR and cognition were moderated by duration of hypertension.

CONCLUSION

Impaired CVR elevated cardiometabolic risk, obesity, vascular function, and fitness among hypertensives.

Cerebral Vasoreactivity Changes Over Time in Patients With Different Clinical Manifestations of Cerebral Small Vessel Disease

Objectives: Endothelial dysfunction (ED) has been linked to the pathogenesis of cerebral small vessel disease (SVD). We aimed to assess ED and cerebrovascular reactivity (CVR) in the patients with a diverse manifestation of SVD, with similar and extensive white matter lesions (WMLs, modified Fazekas scale grade ≥2), compared with a control group (CG) without the MRI markers of SVD, matched for age, gender, hypertension, diabetes, and to evaluate the change of CVR following 24 months. Methods: We repeatedly measured the vasomotor reactivity reserve (VMRr) and breath-holding index (BHI) of the middle cerebral artery (MCA) by the transcranial Doppler ultrasound (TCD) techniques in 60 subjects above 60 years with a history of lacunar stroke (LS), vascular dementia (VaD), or parkinsonism (VaP) (20 in each group), and in 20 individuals from a CG. Results: The mean age, frequency of the main vascular risk factors, and sex distribution were similar in the patients with the SVD groups and a CG. The VMRr and the BHI were more severely impaired at baseline (respectively, 56.7 ± 18% and 0.82 ± 0.39) and at follow-up (respectively, 52.3 ± 16.7% and 0.71 ± 0.38) in the patients with SVD regardless of the clinical manifestations (ANOVA, p > 0.1) than in the CG (respectively, baseline VMRr 77.2 ± 15.6%, BHI 1.15 ± 0.47, p < 0.001; follow-up VMRr 74.3 ± 17.6%, BHI 1.11 ± 0.4, p < 0.001). All the assessed CVR measures (VMRr and BHI) significantly decreased over time in the subjects with SVD (Wilcoxon's signed-rank test p = 0.01), but this was not observed in the CG (p > 0.1) and the decrease of CVR measures was not related to the SVD radiological progression (p > 0.1). Conclusions: This study provided evidence that the change in CVR measures is detectable over a 24-month period in patients with different clinical manifestations of SVD. Compared with the patients in CG with similar atherothrombotic risk factors, all the CVR measures (BMRr and BHI) significantly declined over time in the subjects with SVD. The reduction in CVR was not related to the SVD radiological progression.

Neuroimaging Markers of Cerebral Small Vessel Disease on Hemorrhagic Transformation and Functional Outcome After Intravenous Thrombolysis in Patients With Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

Objective: The aim of this study was to perform a systematic review and meta-analysis to assess whether cerebral small vessel disease (CSVD) on neuroimaging of patients with acute ischemic stroke (AIS) treated with intravenous thrombolysis (IVT) is associated with an increased risk of hemorrhagic transformation (HT), symptomatic intracranial hemorrhage (sICH), and poor functional outcome (PFO). Methods: A thorough search of several databases was carried out to identify relevant studies up to December 2020. We included studies of patients with AIS and neuroimaging markers of CSVD treated with IVT. The primary outcome was HT, and the secondary outcomes were sICH and 3-month PFO. The quality of the studies involved was evaluated using the Newcastle-Ottawa Scale (NOS). The meta-analysis with the fixed effects model was performed. Results: Twenty-four eligible studies (n = 9,419) were pooled in the meta-analysis. All included studies were regarded as high quality with the NOS scores of at least 6 points. The meta-analysis revealed associations between the presence of CSVD and HT, sICH, and the 3-month PFO after IVT. Compared with no CSVD, the presence of CSVD was associated with an increased risk of HT (OR: 1.81, 95% CI: 1.52-2.16), sICH (OR: 2.42, 95% CI: 1.76-3.33), and 3-month PFO (OR: 2.15, 95% CI: 1.89-2.44). For patients with AIS complicated with CSVD, compared with a CSVD score of 0-1, a CSVD score of 2-4 was associated with an increased risk of HT (OR: 3.10, 95% CI: 1.67-5.77), sICH (OR: 2.86, 95% CI: 1.26-6.49), and 3-month PFO (OR: 4.58, 95% CI: 2.97-7.06). Conclusion: Patients with AIS complicated with neuroimaging markers of CSVD are at increased risk of HT and 3-month PFO after IVT. However, it is still necessary to clarify the exact role of CSVD in the occurrence, development, and prognosis of AIS. Systematic Review Registration: www.ClinicalTrials.gov, identifier CRD4202123 3900.

Biomarkers Related to Endothelial Dysfunction and Vascular Cognitive Impairment: A Systematic Review

INTRODUCTION

The damage in the endothelium and the neurovascular unit appears to play a key role in the pathogenesis of vascular cognitive impairment (VCI). Although there have been many advances in understanding the physiopathology of this disease, several questions remain unanswered. The association with other degenerative diseases and the heterogeneity of its clinical spectrum establish a diagnostic problem, compromising a better comprehension of the pathology and halting the development of effective treatments. The investigation of biomarkers is an important movement to the development of novel explicative models and treatment targets involved in VCI.

METHODS

We searched MEDLINE considering the original research based on VCI biomarkers in the past 20 years, following prespecified selection criteria, data extraction, and qualitative synthesis.

RESULTS

We reviewed 42 articles: 16 investigated plasma markers, 17 analyzed neuropathological markers, 4 studied CSF markers, 4 evaluated neuroimaging markers (ultrasound and MRI), and 1 used peripheral Doppler perfusion imaging.

CONCLUSIONS

The biomarkers in these studies suggest an intrinsic relationship between endothelial dysfunction and VCI. Nonetheless, there is still a need for identification of a distinctive set of markers that can integrate the clinical approach of VCI, improve diagnostic accuracy, and support the discovery of alternative therapies.

Cerebral Vasoreactivity Evaluated by Transcranial Color Doppler and Breath-Holding Test in Patients after SARS-CoV-2 Infection

From the beginning of the SARS-CoV-2 virus pandemic, it was clear that the virus is highly neurotrophic. Neurological manifestations can range from nonspecific symptoms such as dizziness, headaches and olfactory disturbances to severe forms of neurological dysfunction. Some neurological complication can occur even after mild forms of respiratory disease. This study’s aims were to assess cerebrovascular reactivity in patients with nonspecific neurological symptoms after SARS-CoV-2 infection. A total of 25 patients, aged 33–62 years, who had nonspecific neurological symptoms after SARS-CoV-2 infection, as well as 25 healthy participants in the control group, were assessed for cerebrovascular reactivity according to transcranial color Doppler (TCCD) which we combined with a breath-holding test (BHT). In subjects after SARS-CoV-2 infection, there were statistically significantly lower flow velocities through the middle cerebral artery at rest period, lower maximum velocities at the end of the breath-holding period and lower breath holding index (BHI) in relation to the control group. Changes in cerebral artery flow rate velocities indicate poor cerebral vasoreactivity in the group after SARS-CoV-2 infection in regard to the control group and suggest vascular endothelial damage by the SARS-CoV-2 virus.

Preseason Cerebrovascular Function in Adolescent Athletes

The purpose of this study was to investigate the effects of sport participation, concussion history, and age of first exposure to football on preseason cerebrovascular function in adolescent athletes. Athletes (n = 53, age = 15.8 ± 1.2 years) were examined based on three exposure groupings: (1) sport participation (football vs. non-collision), (2) concussion history (none vs. ≥ 1), and (3) age of first exposure (football participants only). Transcranial Doppler assessed cerebrovascular reactivity (CVR) and neurovascular coupling (NVC), and separate independent samples t-tests evaluated group differences in CVR and NVC outcomes. Separate univariate linear regressions determined how age of first exposure related to CVR and NVC outcomes. Linear mixed effects models assessed group differences in CVR and NVC relative response curves. Differential response to NVC visual task response was significantly greater in non-collision sport athletes (F_1,2946 = 38.69, p < 0.0001) and athletes without a concussion history (F_1,2946 = 25.23, p < 0.0001). Older age of first exposure significantly predicted reduced breath-holding CVR response (F_1,1560 = 2.92, p = 0.03). Healthy adolescent athletes have similar pre-season cerebrovascular function despite different sport participation and concussion history. However, age of first exposure may predict CVR in adolescent football athletes. Developmental literature identifies cerebrovascular function as dynamically changing throughout adolescence. Our study provides fundamental data informing the clinical meaningfulness of short- and long-term physiological function changes.

Blood markers of endothelial dysfunction and their correlation to cerebrovascular reactivity in patients with chronic hepatitis C infection

Although liver cirrhosis and hepatocellular carcinoma are major consequences of hepatitis C (HCV), there has been an increasing number of studies examining extrahepatic manifestations, especially those caused by systemic chronic inflammation and metabolic complications that might predispose HCV patients to atherosclerosis and ischemic cerebrovascular disease (CVD). The aim of our study was to assess E-selectin, VCAM-1, ICAM-1 and VEGF-A serum levels in patients with chronic HCV infection and to correlate them with cerebrovascular reactivity. A blood sample was taken from eighteen patients with chronic hepatitis C infection and from the same number of healthy blood donors in the control group. The aim was to analyse markers of endothelial dysfunction and to correlate them with cerebrovascular reactivity expressed as breath-holding index (BHI) determined using transcranial color Doppler. The obtained results revealed significant differences between the groups in all endothelial markers except for the E selectin. While the ICAM-1 and sVCAM-1 were significantly increased in the hepatitis group, VEGF-A was significantly decreased. A significant reduction of 0.5 (95% CI 0.2, 0.8) in the mean BHI was found in the hepatitis group (mean BHI 0.64) compared to controls (mean BHI 1.10). No significant association between the BHI and any of the endothelial markers was found in the control group, while in the hepatitis group, the scatter plot of ICAM-1 vs BHI suggested that the association might be present. In conclusion, the results of this study confirm an association between a chronic HCV infection and altered cerebrovascular reactivity as well as higher levels of markers of endothelial activation (ICAM-1, VCAM-1) as possible indicators of an increased CVD risk.

The relationship between resilience and neurophysiological stress in Special Operations Forces combat service members

Military resilience research is increasing due to the growing literature associating resilience with stress adaptation. This study aimed to investigate which physiological stress adaptation components were associated with resilience in Special Operations Forces combat service members. Special Operations Forces combat service members (n = 117) self-reported resilience (ER89) and lifetime clinician-confirmed mild traumatic brain injury history. Participants also underwent transcranial Doppler ultrasonography to measure middle cerebral artery velocity during rest and a breath-holding task. Neither resilience nor mild traumatic brain injury history was significantly associated with middle cerebral artery velocity percent increase following breath-holding; younger Special Operations Forces combat service members had a higher percent increase in middle cerebral artery velocity following a breath-holding task. Resilience was negatively associated with time to return to baseline middle cerebral artery velocity following peak velocity; whereas, mild traumatic brain injury history did not have a significant association. The Special Operations Forces combat service members that scored higher in resilience tended to return to baseline middle cerebral artery velocity following peak velocity faster than their less resilient counterparts. More resilient Special Operations Forces combat service members recovered faster from physiological stress (breath-holding) than less resilient counterparts. This is the first study to investigate resilience and cerebrovascular stress response and recovery in this population. Our initial findings indicated that the Ego Resiliency Scale may be an optimal resilience psychometric and should be used to evaluate effective military resilience trainings, which aim to improve performance and mental health.

Repetitive Head Impact Exposure and Cerebrovascular Function in Adolescent Athletes

The purpose of this study was to determine how subconcussive head impact exposure in high school collision sport student-athletes influenced cerebrovascular function. Transcranial Doppler was used to assess pre- to post-season changes in: (1) resting middle (MCA) and posterior cerebral arteries (PCA), (2) cerebrovascular reactivity (CVR) via breath-holding index (BHI), vasomotor reactivity response (VMRr) and overall MCA response curve, and (3) neurovascular coupling (NVC) via NVC response magnitude and overall PCA response curve. Fifty-three high school-aged athletes (age = 15.8 ± 1.2years, height = 175.8 ± 8.1cm, mass = 69.4 ± 13.5kg) were recruited into two groups (collision vs. non-collision sport). All participants completed a pre-season cerebrovascular function assessment. Following a 4- to 5-month window (118.6 ± 12.2 days), 48 athletes from the original sample (age = 16.0 ± 1.2 years, height = 175.5 ± 8.1 cm, mass = 68.6 ± 4.0 kg) repeated the cerebrovascular assessment. There were no group differences in any cerebrovascular measures at pre-season testing (p > 0.05). At post-season testing, collision sport athletes demonstrated greater positive change in BHI (t₄₄ = -2.21, p = 0.03) while non-collision sport athletes demonstrated greater negative change in the NVC response magnitude to the reading task (t₄₄ = 1.98, p = 0.048), and lower overall PCA response curve to the reading task (F_1,2710 = 101.54, p < 0.001). All other pre- to post-season change values were non-significant (p > 0.05). Our data indicate that single-season changes in cerebrovascular outcomes may differ between collision and non-collision sport athletes. Although the clinical interpretation is still unclear, our study demonstrates that CVR and NVC assessments may be sensitive to the dynamic cerebrovascular changes occurring in adolescent athletes. Future research should continue to assess these outcomes following both subconcussive head impact exposure and throughout the recovery trajectory following concussion.

Association of White Matter Hyperintensities and Cardiovascular Disease: The Importance of Microcirculatory Disease

Cardiac and cerebrovascular diseases are currently the leading causes of mortality and disability worldwide. Both the heart and brain display similar vascular anatomy, with large conduit arteries running on the surface of the organ providing tissue perfusion through an intricate network of penetrating small vessels. Both organs rely on fine tuning of local blood flow to match metabolic demand. Blood flow regulation requires adequate functioning of the microcirculation in both organs, with loss of microvascular function, termed small vessel disease (SVD) underlying different potential clinical manifestations. SVD in the heart, known as coronary microvascular dysfunction, can cause chronic or acute myocardial ischemia and may lead to development of heart failure. In the brain, cerebral SVD can cause an acute stroke syndrome known as lacunar stroke or more subtle pathological alterations of the brain parenchyma, which may eventually lead to neurological deficits or cognitive decline in the long term. Coronary microcirculation cannot be visualized in vivo in humans, and functional information can be deduced by measuring the coronary flow reserve. The diagnosis of cerebral SVD is largely based on brain magnetic resonance imaging, with white matter hyperintensities, microbleeds, and brain atrophy reflecting key structural changes. There is evidence that such structural changes reflect underlying cerebral SVD. Here, we review interactions between SVD and cardiovascular risk factors, and we discuss the evidence linking cerebral SVD with large vessel atheroma, atrial fibrillation, heart failure, and heart valve disease.

Association between Intracranial Arterial Dolichoectasia and Cerebral Small Vessel Disease and Its Underlying Mechanisms

Intracranial arterial dolichoectasia (IADE), also known as dilatative arteriopathy of the brain vessels, refers to an increase in the length and diameter of at least one intracranial artery, and accounts for approximately 12% of all patients with stroke. However, the association of IADE with stroke is usually unclear. Cerebral small vessel disease (CSVD) is characterized by pathological changes in the small vessels. Clinically, patients with CSVD can be asymptomatic or present with stroke or cognitive decline. In the past 20 years, a series of studies have strongly promoted an understanding of the association between IADE and CSVD from clinical and pathological perspectives. It has been proposed that IADE and CSVD may be attributed to abnormal vascular remodeling driven by an abnormal matrix metalloproteinase/tissue inhibitor of metalloproteinase pathway. Also, IAD-Erelated hemodynamic changes may result in initiation or progression of CSVD. Additionally, genetic factors are implicated in the pathogenesis of IADE and CSVD. Patients with Fabry’s disease and late-onset Pompe’s disease are prone to developing concomitant IADE and CSVD, and patients with collagen IV alpha 1 or 2 gene (COL4A1/COL4A2) and forkhead box C1 (FOXC1) variants present with IADE and CSVD. Race, strain, familial status, and vascular risk factors may be involved in the pathogenesis of IADE and CSVD. As well, experiments in mice have pointed to genetic strain as a predisposing factor for IADE and CSVD. However, there have been few direct genetic studies aimed towards determining the association between IADE and CSVD. In the future, more clinical and basic research studies are needed to elucidate the causal relationship between IADE and CSVD and the related molecular and genetic mechanisms.

Total small vessel disease score and cerebro-cardiovascular events in healthy adults: The Kashima scan study

BACKGROUND AND AIMS

We explored the association between the total small vessel disease score obtained from baseline magnetic resonance imaging and subsequent cerebro-cardiovascular events in neurologically healthy Japanese adults.

METHODS

The presence of small vessel disease features, including lacunae, cerebral microbleeds, white matter changes, and basal ganglia perivascular spaces on magnetic resonance imaging, was summed to obtain a "total small vessel disease score" (range, 0-4). After excluding participants with previous stroke or ischemic heart disease, intracranial artery stenosis (≥50%), or cerebral aneurysm (≥4 mm), a total of 1349 participants (mean age, 57.7 years; range, 22.8-85.0 years; 46.9% male) were classified into three groups by total small vessel disease score: 0 (n = 984), 1 (n = 269), and ≥2 (n = 96). Cerebro-cardiovascular events (i.e., any stroke, transient ischemic attack, ischemic heart disease, acute heart failure, and aortic dissection) were defined as the primary end point. The hazard ratio (HR) of events during follow-up was calculated using Cox proportional hazards modeling with adjustments for age, sex, hypertension, diabetes mellitus, and smoking. Cumulative event-free rates were estimated using the Kaplan-Meier method.

RESULTS

During follow-up (mean, 6.7 years), 35 cerebro-cardiovascular (16 cerebrovascular) events were identified. Higher small vessel disease score was associated with increased risk of cerebro-cardiovascular events (HR per unit increase, 2.17; 95% confidence interval, 1.36-3.46; P = 0.001). Events were more frequent among participants with higher score (P < 0.001, log-rank test).

CONCLUSIONS

This study offered additional evidence for the clinical relevance of total small vessel disease score, suggesting the score as a promising tool to predict the risk of subsequent vascular events even in healthy populations.

An IL-18-centered inflammatory network as a biomarker for cerebral white matter injury

Chronic systemic sterile inflammation is implicated in the pathogenesis of cerebrovascular disease and white matter injury. Non-invasive blood markers for risk stratification and dissection of inflammatory molecular substrates in vivo are lacking. We sought to identify whether an interconnected network of inflammatory biomarkers centered on IL-18 and all previously associated with white matter lesions could detect overt and antecedent white matter changes in two populations at risk for cerebral small vessel disease. In a cohort of 167 older adults (mean age: 76, SD 7.1, 83 females) that completed a cognitive battery, physical examination, and blood draw in parallel with MR imaging including DTI, we measured cerebral white matter hyperintensities (WMH) and free water (FW). Concurrently, serum levels of a biologic network of inflammation molecules including MPO, GDF-15, RAGE, ST2, IL-18, and MCP-1 were measured. The ability of a log-transformed population mean-adjusted inflammatory composite score (ICS) to associate with MR variables was demonstrated in an age and total intracranial volume adjusted model. In this cohort, ICS was significantly associated with WMH (β = 0.222, p = 0.013), FW (β = 0.3, p = 0.01), and with the number of vascular risk factor diagnoses (r = 0.36, p<0.001). In a second cohort of 131 subjects presenting for the evaluation of acute neurologic deficits concerning for stroke, we used serum levels of 11 inflammatory biomarkers in an unbiased principal component analysis which identified a single factor significantly associated with WMH. This single factor was strongly correlated with the six component ICS identified in the first cohort and was associated with WMH in a generalized linear regression model adjusted for age and gender (p = 0.027) but not acute stroke. A network of inflammatory molecules driven by IL-18 is associated with overt and antecedent white matter injury resulting from cerebrovascular disease and may be a promising peripheral biomarker for vascular white matter injury.

Impaired cerebrovascular reactivity in chronic obstructive pulmonary disease

Impaired cerebrovascular reactivity (CVR) is associated with stroke. Cerebrovascular diseases are common comorbidity in chronic obstructive pulmonary disease (COPD) patients. The aim of our study was to quantify CVR in the anterior and posterior cerebral circulation during voluntary breath-holding in COPD patients according to airflow limitation severity. In this cross-sectional study, we compared 90 COPD patients without previous cerebrovascular disease and 30 age- and sex-matched healthy volunteers (mean age 67 ± 7.9, 87 males). Using transcranial Doppler ultrasound and breath-holding index (BHI), we analysed baseline mean flow velocities (MFV) and CVR of middle cerebral artery (MCA) and basilar artery (BA). Our results demonstrated that COPD patients had lower baseline MFV of both MCA and BA than controls. COPD patients had significantly lower BHI_mMCA and BHI_mBA than controls (0.8 and 0.7 versus 1.24 and 1.07, respectively; p < 0.001). With the severity of airflow obstruction, there were significant declines of BHI_mMCA and BHI_mBA in mild (0.94 and 0.83), moderate (0.8 and 0.7) and severe to very severe COPD (0.7 and 0.6), respectively (p < 0.001). For all participants, we found a significant and positive correlation between forced expiratory volume in one second (FEV₁) and BHI_mMCA (Rho = 0.761, p < 0.001) and between FEV₁ and BHI_mBA (Rho = 0.409, p < 0.001). COPD patients have impaired CVR in anterior and posterior cerebral circulation. Impairment of CVR increase with the airflow limitation severity. CVR is an appropriate marker to identify vulnerable COPD subjects at high risk to develop cerebrovascular disease. Prospective studies are needed for further evaluation.

The role of endothelial dysfunction and oxidative stress in cerebrovascular diseases

Cerebrovascular diseases (CBD) are one of the most dangerous complications of atherosclerosis. The clinical consequences of CBD deeply impact quality of life and the prognosis of patients. Atherosclerosis is the main cause of CBD development. Hypertension, dyslipidemia, diabetes, smoking, obesity, and other risk factors explain the higher CBD incidence in the general population, as they are able to anticipate the clinical expression of atherosclerosis. These risk factors are effectively able to promote endothelial dysfunction which is the premise for the early, clinical expression of atherosclerosis. The mechanisms by which risk factors can influence the occurrence of CBD are different and not fully understood. The inflammatory background of atherosclerosis can explain a great part of it. In particular, the oxidative stress may promote the development of vascular lesions by negatively influencing biochemical cellular processes of the endothelium, thus predisposing the vascular tree to morphological and functional damages. The aim of this narrative review is to evaluate the role of endothelial dysfunction and oxidative stress in CBD development.