Blood pressure variability and microvascular dysfunction: the Maastricht Study

Leukoaraiosis: Epidemiology, Imaging, Risk Factors, and Management of Age-Related Cerebral White Matter Hyperintensities

Leukoaraiosis (LA) manifests as cerebral white matter hyperintensities on T2-weighted magnetic resonance imaging scans and corresponds to white matter lesions or abnormalities in brain tissue. Clinically, it is generally detected in the early 40s and is highly prevalent globally in individuals aged >60 years. From the imaging perspective, LA can present as several heterogeneous forms, including punctate and patchy lesions in deep or subcortical white matter; lesions with periventricular caps, a pencil-thin lining, and smooth halo; as well as irregular lesions, which are not always benign. Given its potential of having deleterious effects on normal brain function and the resulting increase in public health burden, considerable effort has been focused on investigating the associations between various risk factors and LA risk, and developing its associated clinical interventions. However, study results have been inconsistent, most likely due to potential differences in study designs, neuroimaging methods, and sample sizes as well as the inherent neuroimaging heterogeneity and multi-factorial nature of LA. In this article, we provided an overview of LA and summarized the current knowledge regarding its epidemiology, neuroimaging classification, pathological characteristics, risk factors, and potential intervention strategies.

Microvascular Dysfunction and Whole-Brain White Matter Connectivity: The Maastricht Study

BACKGROUND

Microvascular dysfunction is involved in the development of various cerebral disorders. It may contribute to these disorders by disrupting white matter tracts and altering brain connectivity, but evidence is scarce. We investigated the association between multiple biomarkers of microvascular function and whole-brain white matter connectivity.

METHODS AND RESULTS

Cross-sectional data from The Maastricht Study, a Dutch population-based cohort (n=4326; age, 59.4±8.6 years; 49.7% women). Measures of microvascular function included urinary albumin excretion, central retinal arteriolar and venular calibers, composite scores of flicker light-induced retinal arteriolar and venular dilation, and plasma biomarkers of endothelial dysfunction (intercellular adhesion molecule-1, vascular cell adhesion molecule-1, E-selectin, and von Willebrand factor). White matter connectivity was calculated from 3T diffusion magnetic resonance imaging to quantify the number (average node degree) and organization (characteristic path length, global efficiency, clustering coefficient, and local efficiency) of white matter connections. A higher plasma biomarkers of endothelial dysfunction composite score was associated with a longer characteristic path length (β per SD, 0.066 [95% CI, 0.017-0.114]) after adjustment for sociodemographic, lifestyle, and cardiovascular factors but not with any of the other white matter connectivity measures. After multiple comparison correction, this association was nonsignificant. None of the other microvascular function measures were associated with any of the connectivity measures.

CONCLUSIONS

These findings suggest that microvascular dysfunction as measured by indirect markers is not associated with whole-brain white matter connectivity.

Associations of plasma NfL, GFAP, and t-tau with cerebral small vessel disease and incident dementia: longitudinal data of the AGES-Reykjavik Study

We investigated the associations of plasma neurofilament light (NfL), glial fibrillary acidic protein (GFAP), and total tau (t-tau) with markers of cerebral small vessel disease (SVD) and with incident dementia. We also investigated whether associations of NfL, GFAP, and t-tau with incident dementia were explained by SVD. Data are from a random subsample (n = 1069) of the population-based AGES-Reykjavik Study who underwent brain MRI and in whom plasma NfL, GFAP, and t-tau were measured at baseline (76.1 ± 5.4 years/55.9% women/baseline 2002-2006/follow-up until 2015). A composite SVD burden score was calculated using white matter hyperintensity volume (WMHV), subcortical infarcts, cerebral microbleeds, and large perivascular spaces. Dementia was assessed in a 3-step process and adjudicated by specialists. Higher NfL was associated with a higher SVD burden score. Dementia occurred in 225 (21.0%) individuals. The SVD burden score significantly explained part of the association between NfL and incident dementia. WMHV mostly strongly contributed to the explained effect. GFAP was not associated with the SVD burden score, but was associated with WMHV, and WMHV significantly explained part of the association between GFAP and incident dementia. T-tau was associated with WMHV, but not with incident dementia. In conclusion, the marker most strongly related to SVD is plasma NfL, for which the association with WMHV appeared to explain part of its association with incident dementia. This study suggests that plasma NfL may reflect the contribution of co-morbid vascular disease to dementia. However, the magnitude of the explained effect was relatively small, and further research is required to investigate the clinical implications of this finding.

Day to Day Blood Pressure Variability Associated With Cerebral Arterial Dilation and White Matter Hyperintensity

Previous studies suggested blood pressure variability (BPV) might help reveal interactions between blood pressure fluctuation and white matter lesions, and the impact of elevated BPV on white matter hyperintensity (WMH) or cerebral arterial dilation is unclear.

Blood pressure variability and structural brain changes: a systematic review

BACKGROUND

Blood pressure variability (BPV) has been linked with cognitive impairment and dementia. However, the pathophysiological mechanisms by which BPV affects cognition are unclear. This systematic review aims to assess the links between different BPV measures and white and grey matter structures.

METHODS AND RESULTS

The following databases were searched from inception through to January 2021; EMBASE, MEDLINE, EMCARE and SCOPUS. Studies that reported on the relationship between within-individual BPV (short, medium or long-term variability) or a circadian blood pressure (BP) measurement and MRI assessed brain structures were included. Overall, 20 studies met the criteria and were included, of which 11 studies looked at short-term BPV, eight articles investigated visit-to-visit BPV and one study looked at a compositional BPV measurement. Due to heterogeneity in study samples, meta-analysis was not possible. Across the included studies, associations between MRI indices and BP dipping patterns were mixed; higher long-term BPV and higher sleep systolic BPV was found to be associated with lower whole brain volume and hippocampal volume.

CONCLUSION

Increased BPV, in particular systolic long-term and systolic night-time BPV, appears to be associated with lower brain volume and hippocampal volume. This highlights the adverse effect that increased BPV has upon the brain, potentially contributing to cognitive decline, including dementia, in late-life.

E-Selectin Is Associated with Daytime and 24-Hour Diastolic Blood Pressure Variability in Type 2 Diabetes

E-selectin is an endothelial cell adhesion molecule involved in vascular inflammation. Elevated E-selectin has been reported in patients with high blood pressure and diabetes. Given the increasing clinical relevance of parameters derived from ambulatory blood pressure monitoring, further investigation of their relationships with E-selectin is of interest. In this study, we aimed to investigate the association between serum E-selectin, office blood pressure and 24 h ambulatory blood pressure parameters in patients with type 2 diabetes. Blood pressure variability was assessed by computing the standard deviation of mean systolic and diastolic blood pressure separately for daytime and nighttime during 24 h ambulatory blood pressure monitoring in a cohort of patients with type 2 diabetes (n = 132). Additionally, were assessed nighttime systolic dipping and pulse pressure separately for daytime, nighttime, and 24 h. Serum E-selectin was measured using the enzyme-linked immunosorbent assay technique. We found that E-selectin was consistently associated with 24 h diastolic blood pressure variability (r = 0.238; p = 0.019) and daytime diastolic blood pressure variability (r = 0.258; p = 0.012), after adjustment for confounding factors. No association of E-selectin with office blood pressure and other 24 h ambulatory blood pressure parameters was observed. In conclusion, endothelial activation indicated by elevated serum E-selectin is associated with increased ambulatory diastolic blood pressure variability in patients with type 2 diabetes.

Association between Blood Pressure, Blood Pressure Variability, and Post-Stroke Cognitive Impairment

After stroke, dynamic changes take place from necrotic-apoptotic continuum, inflammatory response to poststroke neurogenesis, and remodeling of the network. These changes and baseline brain pathology such as small vessel disease (SVD) and amyloid burden may be associated with the occurrence of early or late poststroke cognitive impairment (PSCI) or dementia (PSD), which affect not only stroke victims but also their families and even society. We reviewed the current concepts and understanding of the pathophysiology for PSCI/PSD and identified useful tools for the diagnosis and the prediction of PSCI in serological, CSF, and image characteristics. Then, we untangled their relationships with blood pressure (BP) and blood pressure variability (BPV), important but often overlooked risk factors for PSCI/PSD. Finally, we provided evidence for the modifying effects of BP and BPV on PSCI as well as pharmacological and non-pharmacological interventions and life style modification for PSCI/PSD prevention and treatment.

Prognostic impact of short-term ambulatory blood pressure variability for microvascular and macrovascular outcomes in patients with type 2 diabetes: the Rio de Janeiro Type 2 Diabetes Cohort Study

OBJECTIVE

To evaluate the prognostic importance of short-term blood pressure variability (BPV) for the occurrence of macrovascular and microvascular complications in individuals with type 2 diabetes.

METHODS

Six hundred and forty patients had 24-h ambulatory BP monitoring performed at baseline and were followed-up over a median of 11.2 years. Daytime, night-time and 24-h SBP and DBPV parameters (standard deviations and variation coefficients) were calculated. Multivariate Cox analysis, adjusted for risk factors and mean BPs, examined the associations between BPV and the occurrence of microvascular (retinopathy, microalbuminuria, renal function deterioration, peripheral neuropathy) and macrovascular complications [total cardiovascular events (CVEs), major adverse CVEs [MACEs]), and cardiovascular and all-cause mortalities. Improvements in risk discrimination were assessed by the C-statistic and Integrated Discrimination Improvement (IDI) index.

RESULTS

During follow-up, 186 patients had a CVE (150 MACEs), and 237 patients died (107 from cardiovascular diseases); 155 newly developed or worsened diabetic retinopathy, 200 achieved the renal composite outcome (124 newly developed microalbuminuria and 102 deteriorated renal function), and 170 newly developed or worsened peripheral neuropathy. Daytime DBPV was the best predictor for all cardiovascular outcomes and mortality, with hazard ratios (for increments of 1SD) ranging from 1.27 (95% CI 1.09-1.48) for all-cause mortality to 1.55 (1.29-1.85) for MACEs, and it improved cardiovascular risk discrimination (with increases in C-statistic of up to 0.026, and IDIs of up to 22.8%). No BPV parameter predicted any microvascular outcome.

CONCLUSION

Short-term BPV, particularly daytime DBPV, predicts future development of macrovascular complications and mortality and improves cardiovascular risk discrimination in patients with diabetes.

Contribution of Predictive and Prognostic Biomarkers to Clinical Research on Chronic Kidney Disease

Chronic kidney disease (CKD), defined as the presence of albuminuria and/or reduction in estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2, is considered a growing public health problem, with its prevalence and incidence having almost doubled in the past three decades. The implementation of novel biomarkers in clinical practice is crucial, since it could allow earlier diagnosis and lead to an improvement in CKD outcomes. Nevertheless, a clear guidance on how to develop biomarkers in the setting of CKD is not yet available. The aim of this review is to report the framework for implementing biomarkers in observational and intervention studies. Biomarkers are classified as either prognostic or predictive; the first type is used to identify the likelihood of a patient to develop an endpoint regardless of treatment, whereas the second type is used to determine whether the patient is likely to benefit from a specific treatment. Many single assays and complex biomarkers were shown to improve the prediction of cardiovascular and kidney outcomes in CKD patients on top of the traditional risk factors. Biomarkers were also shown to improve clinical trial designs. Understanding the correct ways to validate and implement novel biomarkers in CKD will help to mitigate the global burden of CKD and to improve the individual prognosis of these high-risk patients.