Cerebral Microbleeds and White Matter Hyperintensities in Cognitively Healthy Elderly: A Cross-Sectional Cohort Study Evaluating the Effect of Arterial Stiffness

Associations of cardiac function and arterial stiffness with cerebrovascular disease

BACKGROUND

White matter hyperintensities (WMHs) represent diffuse small vessel disease implicating the cardiac, systemic, and cerebral vasculatures. As the brain may be the end-organ of cumulative vascular disease, and higher education is protective of both cardiovascular and brain health, we aim to clarify their intertwining relationships.

METHODS

We evaluated participants (mean age = 64) from the UK Biobank with neuroimaging measures of WMHs, left ventricular ejection fraction (LVEF) quantified using cardiovascular MRI, and arterial stiffness index (ASI) quantified using finger photoplethysmography. We used multiple regression to evaluate the basic, independent, and interactive relationships of LVEF status (n = 27,512) and ASI (n = 33,584) with WMHs. Moderated mediation analysis was used to determine whether the relationship between LVEF status and WMH was mediated by ASI and moderated by education.

RESULTS

Abnormal LVEF (β = -0.082, p < 0.001) and higher ASI (β = 0.02, p < 0.001) were associated with greater WMHs separately and independently, but not interactively. Moderated mediation analyses revealed that the relationship between abnormal LVEF and WMH was mediated by ASI, for individuals with lower education (β = -0.004, p < 0.001). Abnormal LVEF was associated with lower cortical thickness in 16 predominantly frontotemporal and select parietal regions (FDR, q < 0.05).

CONCLUSIONS

Cardiovascular dysfunction is associated with regional cerebral atrophy and may precipitate cerebrovascular disease via stiffening of systemic vasculatures, particularly for individuals with lower education. Integrative approaches to study biophysiological vascular systems can elucidate the complex interplay between biological and social determinants of brain and cerebrovascular health.

Aortic Characteristic Impedance and Suspected Mild Cognitive Impairment in a Community-Based Healthy Population

BACKGROUND

Aging of the proximal aorta can lead to increased pressure and flow pulsatility in the cerebral microcirculation, which may cause cognitive impairment. This study investigated the association between aortic characteristic impedance (Zc), an indicator of regional stiffness of the proximal aorta, and suspected mild cognitive impairment (MCI), compared with carotid-femoral pulse wave velocity (CFPWV).

METHODS AND RESULTS

A total of 1461 healthy community residents (46.4% men; age range, 35-96 years [mean±SD, 59.9±11.8 years]) without a history of cardiovascular events or stroke were included in the study. Zc was estimated using applanation tonometry and echocardiography. Cognitive function was assessed using the Mini-Mental State Examination. Education-adjusted cut points were used to define suspected MCI. Subjects with suspected MCI (n=493 [33.7%]) had significantly higher Zc and CFPWV than those without. In multivariable analysis, both Zc and CFPWV were inversely associated with Mini-Mental State Examination score. Zc (odds ratio per 1 SD, 1.22 [95% CI, 1.09-1.37] and CFPWV (odds ratio per 1 SD, 1.18 [95% CI, 1.01-1.38]) was also significantly associated with suspected MCI, after adjusting for age, sex, education level, mean arterial pressure, hypertension, diabetes, low-density lipoprotein cholesterol, and smoking status. In joint analysis, Zc was significantly associated with suspected MCI, but CFPWV was not. In the age subgroups of <50 years and 50 to 70 years, only Zc was significantly associated with suspected MCI.

CONCLUSIONS

This study found that Zc was significantly associated with Mini-Mental State Examination score and suspected MCI, especially in younger and middle-aged adults. These findings suggest that Zc may be a useful biomarker for identifying individuals at risk for MCI.

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.

Cerebral small vessel disease burden is associated with decreased abundance of gut Barnesiella intestinihominis bacterium in the Framingham Heart Study

A bidirectional communication exists between the brain and the gut, in which the gut microbiota influences cognitive function and vice-versa. Gut dysbiosis has been linked to several diseases, including Alzheimer's disease and related dementias (ADRD). However, the relationship between gut dysbiosis and markers of cerebral small vessel disease (cSVD), a major contributor to ADRD, is unknown. In this cross-sectional study, we examined the connection between the gut microbiome, cognitive, and neuroimaging markers of cSVD in the Framingham Heart Study (FHS). Markers of cSVD included white matter hyperintensities (WMH), peak width of skeletonized mean diffusivity (PSMD), and executive function (EF), estimated as the difference between the trail-making tests B and A. We included 972 FHS participants with MRI scans, neurocognitive measures, and stool samples and quantified the gut microbiota composition using 16S rRNA sequencing. We used multivariable association and differential abundance analyses adjusting for age, sex, BMI, and education level to estimate the association between gut microbiota and WMH, PSMD, and EF measures. Our results suggest an increased abundance of Pseudobutyrivibrio and Ruminococcus genera was associated with lower WMH and PSMD (p values < 0.001), as well as better executive function (p values < 0.01). In addition, in both differential and multivariable analyses, we found that the gram-negative bacterium Barnesiella intestinihominis was strongly associated with markers indicating a higher cSVD burden. Finally, functional analyses using PICRUSt implicated various KEGG pathways, including microbial quorum sensing, AMP/GMP-activated protein kinase, phenylpyruvate, and β-hydroxybutyrate production previously associated with cognitive performance and dementia. Our study provides important insights into the association between the gut microbiome and cSVD, but further studies are needed to replicate the findings.

Associations of Arterial Stiffness and Bone Mineral Density in Postmenopausal Women

Aim. To study associations  between arterial stiffness and bone mineral density in postmenopausal women.

Material and methods. The intima-media thickness  (IMT), the presence  and  number  of atherosclerotic  plaques  (AP) were studied  using  duplex scanning. Pulse wave velocity (PWV), augmentation index (AI) were measured by applanation. The Bone mineral density (BMD) of the spine, hip neck (HN) and proximal hip (PH) was measured using double energy x-ray absorptiometry.

Results. A significant  correlation  of PWV  with  age,  duration  of menopause was  revealed,  a more pronounced correlation  was  noted  with  blood pressure (BP), maximum IMT thickness.  There was no significant  correlation  between  PWV  and BMD.  AI showed  a statistically  significant but weak negative  correlation  with  the HN  (rs=0.12, p<0.05); a more  pronounced negative  correlation  was  obtained  for BMD  (rs=0.16, p<0.01). For indicators characterizing the degree of bone mass increased,  there is a significant  correlation with age (rs=-0.4, p<0.01), weight (rs=0.4, p<0.01), Quetelet index (rs=0.3, p<0.01) and the presence of AP (rs=-0.12, p<0.05). According to the results of multivariate regression  analysis,  the most significant  predictors of arterial stiffness were indicators  reflecting  obesity and diastolic BP. The relationship  between BMD and age-adjusted vascular stiffness was not statistically significant.

Conclusion. In our study, postmenopausal women have increased arterial stiffness,  suggesting a higher risk of cardiovascular disease. The relationship between  bone mineral density and vascular  wall stiffness  was insignificant. To a greater extent,  arterial stiffness  depended  on age,  increased  blood pressure, and the presence of atherosclerotic  changes.

Discriminative accuracy of the A/T/N scheme to identify cognitive impairment due to Alzheimer's disease

Introduction

The optimal combination of amyloid-β/tau/neurodegeneration (A/T/N) biomarker profiles for the diagnosis of Alzheimer's disease (AD) dementia is unclear.

Methods

We examined the discriminative accuracy of A/T/N combinations assessed with neuroimaging biomarkers for the differentiation of AD from cognitively unimpaired (CU) elderly and non-AD neurodegenerative diseases in the TRIAD, BioFINDER-1 and BioFINDER-2 cohorts (total n = 832) using area under the receiver operating characteristic curves (AUC).

Results

For the diagnosis of AD dementia (vs. CU elderly), T biomarkers performed as well as the complete A/T/N system (AUC range: 0.90-0.99). A and T biomarkers in isolation performed as well as the complete A/T/N system in differentiating AD dementia from non-AD neurodegenerative diseases (AUC range; A biomarker: 0.84-1; T biomarker: 0.83-1).

Discussion

In diagnostic settings, the use of A or T neuroimaging biomarkers alone can reduce patient burden and medical costs compared with using their combination, without significantly compromising accuracy.

Development of cerebral microbleeds and its impact on cognitive function in adult patients receiving medical management alone for ischemic moyamoya disease: supplementary analysis of a 5-year prospective cohort

OBJECTIVE

De novo cerebral microbleeds (CMBs) on T2*-weighted magnetic resonance imaging (MRI) develop over time in adult moyamoya disease (MMD) and are generally associated with a decline in global cognitive function. The present supplementary analysis of a 5-year prospective cohort aimed to elucidate the incidence of an interval increase in CMBs in adult patients receiving medical management alone for ischemic MMD and its impact on cognitive function.

METHODS

Sixty-four patients without misery perfusion in the symptomatic cerebral hemispheres at inclusion who did not experience any further ischemic symptoms or new hemorrhagic events during a 5-year follow-up period underwent T2*-weighted MRI and five kinds of neuropsychologic tests at inclusion and the end of the 5-year follow-up.

RESULTS

When T2*-weighted MRI was compared between inclusion and the end of the 5-year follow-up, 10 patients (15%) had an interval increase in CMBs in the symptomatic cerebral hemisphere at inclusion. The scores from two kinds of neuropsychologic tests significantly deteriorated at the end of the 5-year follow-up compared with those at inclusion in patients with an interval increase in CMBs, whereas the scores of four kinds of neuropsychologic tests significantly improved at the end of the 5-year follow-up compared with those at inclusion in patients without interval increases in CMBs, asymptomatic ischemic lesions, or angiographic disease progression.

CONCLUSIONS

The incidence of an interval increase in CMBs was 15% per 5 years in adult patients receiving medical management alone for ischemic MMD, and this increase was associated with a decline in cognitive decline.

Excess pressure but not pulse wave velocity is associated with cognitive function impairment: a community-based study

BACKGROUND

Carotid-femoral pulse wave velocity (cf-PWV), an index of mainly distal aortic stiffness, has been inconsistently associated with cognitive function. Excess pressure, derived from the arterial reservoir-excess pressure analysis, may integrate the pulsatile load of the proximal aorta. The present study examined whether increased excess pressure is associated with cognitive function impairment in community adults.

METHODS

A total of 992 community participants (69.5% females; mean age: 67.3 years; education 13.6 years) without cerebrovascular disease or dementia received the Montreal Cognitive Assessment (MoCA) to evaluate global cognition. Arterial reservoir and excess pressure, arterial stiffness, and wave reflections were assessed, using carotid tonometry and aortic Doppler flowmetry.

RESULTS

Excess pressure integral (XSPI), percentage XSPI, cf-PWV, characteristic impedance (Zc), and forward and backward pressure amplitude (Pf, Pb, respectively) were significantly higher in 197 participants (19.9%) with a low MoCA score (<26 or <25, depending on level of education). In multivariable analyses, XSPI (standardized odds ratio, 95% confidence interval, 1.30, 1.06-1.59), and percentage XSPI (1.27, 1.06-1.52) but not cf-PWV (1.04, 0.85-1.26) were significantly associated with a low MoCA. Further analysis revealed that Pf and Zc were the major determinants of XSPI (partial R2: Pf = 0.656, Zc = 0.467) and percentage XSPI (Pf = 0.459, Zc = 0.371). In contrast, age, instead of Pf and Zc, was the major determinant of cf-PWV (partial R2: age = 0.187).

CONCLUSIONS

Excess pressure (XSPI/percentage XSPI), mainly determined by the pulsatile hemodynamics of the proximal aorta, was significantly associated with cognitive function impairment in middle-aged and elderly community adults.

Interaction between arteriosclerosis and the APOE4 gene in cognitive decline in older adults: a cross-sectional study in rural minority areas in western China

BACKGROUND

Numerous studies have confirmed that the apolipoprotein E4 allele (APOE4) gene and arteriosclerosis (AS) have a combined effect on the occurrence of cognitive function impairment, and dyslipidaemia levels are significantly correlated with APOE4 levels and AS. Few studies have focused on the combined effect of the APOE4 gene and AS on cognitive function. Therefore, this study aimed to investigate the effect of APOE4 gene and AS acting together on cognitive function through dyslipidaemia levels, which could provide certain scientific research value for future studies.

METHODS

A multi-stage cluster sampling method was used to investigate older adults aged 60 years and above in rural areas of Guizhou, China. The demographic sociological characteristics were collected, and laboratory tests, blood lipid measurements, and physical examinations were performed. Mini-Mental State Examination (MMSE) was used to determine cognitive function. Analysis of variance with two-factor factorial design was used to analyse the interaction between the APOE4 gene and AS on cognitive function and its domains.

RESULTS

A total of 549 elderly subjects were eligible for this study. The result of the factorial design analysis revealed there was a significant interaction between the APOE4 gene and AS in terms of attention and numeracy (F = 6.878, P = 0.009).

CONCLUSIONS

The combination of the APOE4 gene and AS leads to a decrease in the level of attention and numeracy domains, and certain attention should be focused on such populations in the future.

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.

De Novo Cerebral Microbleeds and Cognitive Decline in Cerebral Hyperperfusion After Direct Revascularization for Adult Moyamoya Disease

OBJECTIVES

Adult patients with moyamoya disease (MMD) occasionally develop cognitive decline due to cerebral hyperperfusion following direct revascularization surgery. However, how the hyperperfusion phenomenon contributes to declines in cognitive function remains unclear. The present supplementary analysis of a prospective study aimed to determine whether cerebral hyperperfusion following direct revascularization surgery for adult MMD with ischemic presentation and misery perfusion leads to development of de novo cerebral microbleeds (CMBs) and whether postoperative cognitive decline is related to these CMBs.

MATERIALS AND METHODS

In total, 32 patients who underwent direct revascularization surgery also underwent T2*-weighted magnetic resonance imaging (T2*WI) and neuropsychological testing before and 2 months after surgery. Development of cerebral hyperperfusion and hyperperfusion syndrome following surgery was defined based on brain perfusion single-photon emission computed tomography (SPECT) findings and clinical symptoms.

RESULTS

Cerebral hyperperfusion on brain perfusion SPECT (95% confidence interval [CI], 1.1-10.8; p = 0.0175) or cerebral hyperperfusion syndrome (95%CI, 1.3-15.3; p = 0.0029) was significantly associated with postoperatively increased CMBs on T2*WI. Postoperatively increased CMBs were significantly associated with postoperative cognitive decline (95%CI, 1.8-20.4, p = 0.0041). For patients with cerebral hyperperfusion on brain perfusion SPECT, the incidence of postoperative cognitive decline was significantly greater in patients with than in those without postoperatively increased CMBs (p = 0.0294).

CONCLUSIONS

Cerebral hyperperfusion following direct revascularization surgery for adult MMD with ischemic presentation and misery perfusion contributes to the development of de novo CMBs and postoperative cognitive decline is related to these CMBs.

Development of cerebral microbleeds in patients with cerebral hyperperfusion following carotid endarterectomy and its relation to postoperative cognitive decline

OBJECTIVE

A primary cause of cognitive decline after carotid endarterectomy (CEA) is cerebral injury due to cerebral hyperperfusion. However, the mechanisms of how cerebral hyperperfusion induces cerebral cortex and white matter injury are not known. The presence of cerebral microbleeds (CMBs) on susceptibility-weighted imaging (SWI) is independently associated with a decline in global cognitive function. The purpose of this prospective observational study was to determine whether cerebral hyperperfusion following CEA leads to the development of CMBs and if postoperative cognitive decline is related to these developed CMBs.

METHODS

During the 27-month study period, patients who underwent CEA for ipsilateral internal carotid artery stenosis (≥ 70%) also underwent SWI and neuropsychological testing before and 2 months after surgery, as well as quantitative brain perfusion SPECT prior to and immediately after surgery.

RESULTS

According to quantitative brain perfusion SPECT and SWI before and after surgery, 12 (16%) and 7 (9%) of 75 patients exhibited postoperative cerebral hyperperfusion and increased CMBs in the cerebral hemisphere ipsilateral to surgery, respectively. Cerebral hyperperfusion was associated with an increase in CMBs after surgery (logistic regression analysis, 95% CI 5.08-31.25, p < 0.0001). According to neuropsychological assessments before and after surgery, 10 patients (13%) showed postoperative cognitive decline. Increased CMBs were associated with cognitive decline after surgery (logistic regression analysis, 95% CI 6.80-66.67, p < 0.0001). Among the patients with cerebral hyperperfusion after surgery, the incidence of postoperative cognitive decline was higher in those with increased CMBs (100%) than in those without (20%; p = 0.0101).

CONCLUSIONS

Cerebral hyperperfusion following CEA leads to the development of CMBs, and postoperative cognitive decline is related to these developed CMBs.

Aortic Stiffness and White Matter Microstructural Integrity Assessed by Diffusion Tensor Imaging: The ARIC-NCS

Background

Changes in white matter microstructural integrity are detectable before appearance of white matter lesions on magnetic resonance imaging as a manifestation of cerebral small‐vessel disease. The information relating poor white matter microstructural integrity to aortic stiffness, a hallmark of aging, is limited. We aimed to examine the association between aortic stiffness and white matter microstructural integrity among older adults.

Methods and Results

We conducted a cross‐sectional study to examine the association between aortic stiffness and white matter microstructural integrity among 1484 men and women (mean age, 76 years) at the 2011 to 2013 examination of the ARIC‐NCS (Atherosclerosis Risk in Communities Neurocognitive Study). Aortic stiffness was measured as carotid‐femoral pulse wave velocity. Cerebral white matter microstructural integrity was measured as fractional anisotropy and mean diffusivity using diffusion tensor imaging. Multivariable linear regression was used to examine the associations of carotid‐femoral pulse wave velocity with fractional anisotropy and mean diffusivity of the overall cerebrum and at regions of interest. Each 1‐m/s higher carotid‐femoral pulse wave velocity was associated with lower overall fractional anisotropy (β=−0.03; 95% CI, −0.05 to −0.02) and higher overall mean diffusivity (β=0.03; 95% CI, 0.02–0.04). High carotid‐femoral pulse wave velocity (upper 25th percentile) was associated with lower fractional anisotropy (β=−0.40; 95% CI, −0.61 to −0.20) and higher overall mean diffusivity (β=0.27; 95% CI, 0.10–0.43). Similar associations were observed at individual regions of interest.

Conclusions

High aortic stiffness is associated with low cerebral white matter microstructural integrity among older adults. Aortic stiffness may serve as a target for the prevention of poor cerebral white matter microstructural integrity.

Cholinergic white matter pathways make a stronger contribution to attention and memory in normal aging than cerebrovascular health and nucleus basalis of Meynert

The integrity of the cholinergic system plays a central role in cognitive decline both in normal aging and neurological disorders including Alzheimer's disease and vascular cognitive impairment. Most of the previous neuroimaging research has focused on the integrity of the cholinergic basal forebrain, or its sub-region the nucleus basalis of Meynert (NBM). Tractography using diffusion tensor imaging data may enable modelling of the NBM white matter projections. We investigated the contribution of NBM volume, NBM white matter projections, small vessel disease (SVD), and age to performance in attention and memory in 262 cognitively normal individuals (39-77 years of age, 53% female). We developed a multimodal MRI pipeline for NBM segmentation and diffusion-based tracking of NBM white matter projections, and computed white matter hypointensities (WM-hypo) as a marker of SVD. We successfully tracked pathways that closely resemble the spatial layout of the cholinergic system as seen in previous post-mortem and DTI tractography studies. We found that high WM-hypo load was associated with older age, male sex, and lower performance in attention and memory. A high WM-hypo load was also associated with lower integrity of the cholinergic system above and beyond the effect of age. In a multivariate model, age and integrity of NBM white matter projections were stronger contributors than WM-hypo load and NBM volume to performance in attention and memory. We conclude that the integrity of NBM white matter projections plays a fundamental role in cognitive aging. This and other modern neuroimaging methods offer new opportunities to re-evaluate the cholinergic hypothesis of cognitive aging.

Association of aortic stiffness with cognitive decline: Whitehall II longitudinal cohort study

Aortic stiffness is associated with an increased risk of cardio- and cerebrovascular disease and mortality and may increase risk of dementia. The aim of the present study is to examine the association between arterial stiffness and cognitive decline in a large prospective cohort study with three repeated cognitive assessment over 7 years of follow-up. Aortic pulse wave velocity (PWV) was measured among 4300 participants (mean ± standard deviation age 65.1 ± 5.2 years) in 2007-2009 and categorized based on the tertiles: (lowest third: < 7.41 m/s), (middle third: 7.41-8.91 m/s), and (highest third: > 8.91 m/s). A global cognitive score was calculated in 2007-2009, 2012-2013, and 2015-2016 based on responses to memory, reasoning and fluency tests. Standardized global cognitive score (mean = 0, SD = 1) in highest third versus lowest third of PWV category was lower at baseline (- 0.12, 95% CI - 0.18, - 0.06). Accelerated 7-year cognitive decline was observed among individuals with the highest PWV [difference in 7-year cognitive change for highest third versus lowest third PWV: - 0.06, 95% CI - 0.11, - 0.01, P < 0.01]. Higher aortic stiffness was associated with faster cognitive decline. Clinicians may be able to use arterial stiffness severity as an indicator to administer prompt treatments to prevent or delay the onset of cognitive decline or dementia. Future studies need to determine whether early intervention of vascular stiffness is effective in delaying these outcomes.

Use of anticoagulant therapy and cerebral microbleeds: a systematic review and meta-analysis

BACKGROUND

Anticoagulant therapy increases the risk that cerebral microbleeds (CMBs) progress to intracerebral hemorrhage, but whether the therapy increases risk of CMB occurrence is unclear. We performed a systematic review and meta-analysis to investigate the potential association between anticoagulant use and CMB occurrence in stroke and stroke-free individuals.

METHODS

We searched observational studies in PubMed, Ovid EMBASE, and Cochrane Library from their inception until September 2019. We calculated the pooled odds ratio (OR) and 95% confidence interval (CI) for the prevalence and incidence of CMBs in anticoagulant users relative to non-anticoagulant users.

RESULTS

Forty-seven studies with 25,245 participants were included. The pooled analysis showed that anticoagulant use was associated with CMB prevalence (OR 1.54, 95% CI 1.26-1.88). The association was observed in subgroups stratified by type of participants: stroke-free, OR 1.86, 95% CI 1.25-2.77; ischemic stroke/transient ischemic attack, OR 1.33, 95% CI 1.06-1.67; and intracerebral hemorrhage, OR 2.26, 95% CI 1.06-4.83. Anticoagulant use was associated with increased prevalence of strictly lobar CMBs (OR 1.68, 95% CI 1.22-2.32) but not deep/infratentorial CMBs. Warfarin was associated with increased CMB prevalence (OR 1.64, 95% CI 1.23-2.18), but novel oral anticoagulants were not. Anticoagulant users showed higher incidence of CMBs during long-term follow-up (OR 1.72, 95% CI 1.22-2.44).

CONCLUSION

Anticoagulant use is associated with higher prevalence and incidence of CMBs. This association appears to depend on location of CMBs and type of anticoagulants. More longitudinal investigations with adjustment for confounders are required to establish the causality.

Physical activity mitigates adverse effect of metabolic syndrome on vessels and brain

Metabolic syndrome (MetS) adversely affects the vasculature and cerebral white matter (CWM) integrity. Arterial stiffening has been associated with diminished CWM integrity. Physical activity (PA) can ameliorate components of MetS and subsequently affect arterial stiffening and CWM integrity. Our aim was to determine the role of PA on mitigating the adverse influence of MetS on arterial stiffness and CWM integrity. In a cross-sectional study design, sixty-six middle-aged adults (40-62 years) composed of 18 sedentary MetS (Sed MetS), 21 physically active MetS (Active MetS), and 27 healthy individuals absent of MetS risk factors were studied. Carotid artery stiffness was assessed via simultaneous ultrasound and tonometry. CWM integrity was measured using diffusion tensor imaging (DTI) through metrics of fractional anisotropy (FA) and mean diffusivity (MD). Carotid β-stiffness index in Active MetS was lower than Sed MetS but was not different from Healthy controls (6.6 ± 1.5, 7.7 ± 2.1, and 5.6 ± 1.6 au, p = 0.001). CWM integrity was significantly greater in Active MetS subjects compared to Sed MetS subjects but statistically equal to Healthy controls in the anterior limb of the internal capsule, and splenium of the corpus callosum, uncinate fasciculus, and superior corona radiata (all p < 0.05). Middle-aged individuals with MetS who habitually perform PA demonstrated lower arterial stiffness and more favorable CWM integrity than their sedentary peers, indicating that PA may be effective in mitigating the adverse effects of MetS on the vasculature and brain at midlife.

Cerebral microbleeds: hearing through the silence-a narrative review

OBJECTIVE

The term cerebral microbleed (CMB) refers to lesions documented as unexpected findings during computed tomography or magnetic resonance imaging examination of the brain. Initially, a CMB was thought to represent hemosiderin-laden macrophages marking an area of a tiny hemorrhage. Recently, histopathologic studies have shown that the structure of a CMB can be variable. To aid in dealing with this finding and judging its clinical significance, this review addresses important aspects of a CMB, including the definition, prevalence, and incidence in various populations, end-organ damage, associated conditions, and whether any action or treatment by the clinician might be indicated.

METHODS

PubMed Medline, EMBASE, BIOSIS, Current Contents, and Derwent Drug Files databases were searched for the keywords "microbleeds-detection-damage", "silent bleeds", "microbleeds", or "silent bleeds AND hemophilia" from 2011-2016. References of retrieved articles were also reviewed and included if applicable.

RESULTS

The published data are found primarily in the imaging literature and focus on diagnostic techniques. Some publications address relationships with diverse, co-existing clinical conditions and implications for treatment, especially in stroke, intracranial hemorrhage, and antithrombotic therapy.

CONCLUSIONS

It is critical for non-radiologist clinicians (primary care, internists, neurologists, hematologists) to be aware of the potential importance of the finding of a CMB, and the fact that these lesions are not always truly silent or without important clinical consequences. As additional studies appear, clinicians may be able to "hear" more clearly through the silence of the CMB and understand potential clinical implications in patients.

Discriminative Accuracy of [18F]flortaucipir Positron Emission Tomography for Alzheimer Disease vs Other Neurodegenerative Disorders

IMPORTANCE

The positron emission tomography (PET) tracer [18F]flortaucipir allows in vivo quantification of paired helical filament tau, a core neuropathological feature of Alzheimer disease (AD), but its diagnostic utility is unclear.

OBJECTIVE

To examine the discriminative accuracy of [18F]flortaucipir for AD vs non-AD neurodegenerative disorders.

DESIGN, SETTING, AND PARTICIPANTS

In this cross-sectional study, 719 participants were recruited from 3 dementia centers in South Korea, Sweden, and the United States between June 2014 and November 2017 (160 cognitively normal controls, 126 patients with mild cognitive impairment [MCI], of whom 65.9% were amyloid-β [Aβ] positive [ie, MCI due to AD], 179 patients with AD dementia, and 254 patients with various non-AD neurodegenerative disorders).

EXPOSURES

The index test was the [18F]flortaucipir PET standardized uptake value ratio (SUVR) in 5 predefined regions of interest (ROIs). Cut points for tau positivity were determined using the mean +2 SDs observed in controls and Youden Index for the contrast AD dementia vs controls.

MAIN OUTCOMES AND MEASURES

The reference standard was the clinical diagnosis determined at the specialized memory centers. In the primary analysis, the discriminative accuracy (ie, sensitivity and specificity) of [18F]flortaucipir was examined for AD dementia vs all non-AD neurodegenerative disorders. In secondary analyses, the area under the curve (AUC) of [18F]flortaucipir SUVR was compared with 3 established magnetic resonance imaging measures (hippocampal volumes and AD signature and whole-brain cortical thickness), and sensitivity and specificity of [18F]flortaucipir in MCI due to AD vs non-AD neurodegenerative disorders were determined.

RESULTS

Among 719 participants, the overall mean (SD) age was 68.8 (9.2) years and 48.4% were male. The proportions of patients who were amyloid-β positive were 26.3%, 65.9%, 100%, and 23.8% among cognitively normal controls, patients with MCI, patients with AD dementia, and patients with non-AD neurodegenerative disorders, respectively. [18F]flortaucipir uptake in the medial-basal and lateral temporal cortex showed 89.9% (95% CI, 84.6%-93.9%) sensitivity and 90.6% (95% CI, 86.3%-93.9%) specificity using the threshold based on controls (SUVR, 1.34), and 96.8% (95% CI, 92.0%-99.1%) sensitivity and 87.9% (95% CI, 81.9%-92.4%) specificity using the Youden Index-derived cutoff (SUVR, 1.27) for distinguishing AD dementia from all non-AD neurodegenerative disorders. The AUCs for all 5 [18F]flortaucipir ROIs were higher (AUC range, 0.92-0.95) compared with the 3 volumetric MRI measures (AUC range, 0.63-0.75; all ROIs P < .001). Diagnostic performance of the 5 [18F]flortaucipir ROIs were lower in MCI due to AD (AUC range, 0.75-0.84).

CONCLUSIONS AND RELEVANCE

Among patients with established diagnoses at a memory disorder clinic, [18F]flortaucipir PET was able to discriminate AD from other neurodegenerative diseases. The accuracy and potential utility of this test in patient care require further research in clinically more representative populations.

18F-AV-1451 and CSF T-tau and P-tau as biomarkers in Alzheimer's disease

To elucidate the relationship between cerebrospinal fluid (CSF) total-tau (T-tau) and phosphorylated tau (P-tau) with the tau PET ligand ¹⁸F-AV-1451 in Alzheimer's disease (AD), we examined 30 cognitively healthy elderly (15 with preclinical AD), 14 prodromal AD, and 39 AD dementia patients. CSF T-tau and P-tau were highly correlated (R = 0.92, P < 0.001), but they were only moderately associated with retention of ¹⁸F-AV-1451, and mainly in demented AD patients. ¹⁸F-AV-1451, but not CSF T-tau or P-tau, was strongly associated with atrophy and cognitive impairment. CSF tau was increased in preclinical AD, despite normal ¹⁸F-AV-1451 retention. However, not all dementia AD patients exhibited increased CSF tau, even though ¹⁸F-AV-1451 retention was always increased at this disease stage. We conclude that CSF T-tau and P-tau mainly behave as biomarkers of "disease state", since they appear to be increased in many cases of AD at all disease stages, already before the emergence of tau aggregates. In contrast, ¹⁸F-AV-1451 is a biomarker of "disease stage", since it is increased in clinical stages of the disease, and is associated with brain atrophy and cognitive decline.

Prevalence of and risk factors for cerebral microbleeds in a general Japanese elderly community

Background

We investigated the prevalence of and risk factors for cerebral microbleeds (CMBs) in a cross-sectional study of a general population of Japanese elderly.

Methods

In 2012, brain MRI scanning at 1.5T and comprehensive health examination were conducted for 1281 residents aged 65 years or older. CMBs were defined as ovoid hypointensity lesions less than 10 mm in diameter on T2*-weighted images and classified into deep/infratentorial or lobar CMBs. Age- and sex-specific and overall prevalence of CMBs were estimated, and the associations of traditional cardiovascular risk factors and APOE polymorphism with the presence of CMBs were examined using a logistic regression analysis.

Results

The crude prevalences of total, deep/infratentorial, and lobar CMBs were 18.7% (n = 240), 13.5% (n = 173), and 9.6% (n = 123), respectively. The prevalence of total CMBs was 23.0% in men and 15.5% in women and increased with aging in both sexes (both p for trend <0.01). Hypertension was significantly associated with the presence of both deep/infratentorial and lobar CMBs. Lower serum total cholesterol was a significant risk factor for deep/infratentorial CMBs, but not for lobar CMBs, while APOE ε4 carriers had a significantly higher likelihood only of lobar CMBs compared with noncarriers.

Conclusions

Our study suggests that approximately 1 of 5 Japanese elderly people have CMBs, and that risk factors for deep/infratentorial and lobar CMBs are different, indicating the distinct pathologic backgrounds of these lesions.

Associations of carotid arterial compliance and white matter diffusion metrics during midlife: modulation by sex

Sex differences in cerebral white matter (WM) aging have been debated extensively over the past 2 decades without unequivocal resolution. We aimed to determine if the effects of age and arterial stiffness on WM microstructure differ between sexes. Artery elasticity via carotid artery compliance (CAC) and WM diffusion metrics via diffusion tensor image-derived fractional anisotropy (FA) and mean diffusivity (MD) were measured in 155 (87 females) middle-aged (40-62 years) adults. Males demonstrated poorer water diffusion metrics in WM than women in the corpus callosum body, cingulum, and cingulum (hippocampal). Age and CAC had greater effects on WM water diffusion in males than females in midlife independent of education and cardiovascular risk factors. Sex-moderated age (cingulum FA, cingulum [hippocampal] MD, and uncinate MD, all p < 0.05) and CAC (cingulum FA, p < 0.05) related reductions in regional WM diffusion metrics. CAC mediated age-related associations in regional WM diffusion metrics (cingulum FA, cingulum MD, superior corona radiata MD, and uncinate MD, all p < 0.05) in males but not in females. Age and CAC were associated with WM diffusion metrics independent of cardiovascular risk factors. These associations appear to be stronger in males than in females.

Impacts of Metabolic Syndrome Scores on Cerebrovascular Conductance Are Mediated by Arterial Stiffening

BACKGROUND

Individuals with metabolic syndrome (MetS) exhibit reduced cerebral blood flow. The mechanisms of this reduction remain unknown but arterial stiffening has been implicated as a contributor. We determined if MetS was associated with reduced cerebral blood flow at midlife, and if so, whether arterial stiffness was responsible for mediating their relation.

METHODS

Middle-aged (40-60 years) community dwelling adults (n = 83) were studied. MetS score was calculated for each subject. Middle cerebral artery hemodynamics was measured using transcranial Doppler ultrasound. Indices of aortic, systemic, and carotid artery stiffness were derived.

RESULTS

Subjects had subclinical MetS pathology (MetS score = 19.8 ± 10.4) that was inversely associated with cerebrovascular conductance (CVC: r = -0.261, P = 0.02). Carotid-femoral pulse wave velocity (cfPWV) (r = -0.188, P = 0.09), brachial-ankle pulse wave velocity (baPWV) (r = -0.161, P = 0.15), and carotid artery distensibility (r = -0.10, P = 0.37) abrogated the direct association of MetS score and CVC, demonstrating full mediation. Nonparametric bootstrapping further indicated significant indirect effects of cfPWV, baPWV, and carotid artery distensibility, fully mediating reductions of CVC exerted from sublcinical MetS. Carotid artery distensibility demonstrated the greatest effect on CVC (B = -0.0019, SE = 0.0012, -0.0050 to -0.0002 95% confidence interval).

CONCLUSIONS

Arterial stiffness, particularly the stiffness of the carotid artery, mediated reductions in CVC related to MetS.

Increased midlife triglycerides predict brain β-amyloid and tau pathology 20 years later

OBJECTIVE

To evaluate the effect of midlife lipid levels on Alzheimer brain pathology 20 years later in cognitively normal elderly individuals.

METHODS

This is a longitudinal cohort study of 318 cognitively normal individuals with data on fasting lipid levels at midlife (mean age 54 years). Presence of β-amyloid (Aβ) and tau pathologies 20 years later (mean age 73 years) were detected by quantifying Alzheimer disease (AD) biomarkers in CSF. In a subset (n = 134), Aβ (¹⁸F-flutemetamol) PET was also performed.

RESULTS

CSF Aβ₄₂ and Aβ PET revealed Aβ pathology in approximately 20% of the cognitively healthy population and CSF Aβ₄₂/phosphorylated tau (p-tau) ratio indicated both Aβ and tau pathology in 16%. Higher levels of triglycerides in midlife were independently associated with abnormal CSF Aβ₄₂ (odds ratio [OR] 1.34, 95% confidence interval [CI] 1.03-1.75, p = 0.029) and abnormal Aβ₄₂/p-tau ratio (OR 1.46, 95% CI 1.10-1.93; p = 0.009) adjusting for age, sex, APOE ε4, education, and multiple vascular risk factors. Triglycerides were also associated with abnormal Aβ PET in multivariable regression models, but the association was attenuated in the fully adjusted model. Increased levels of medium and large low-density lipoprotein subfractions were significantly associated with abnormal Aβ PET and large high-density lipoprotein particles were associated with decreased risk of abnormal Aβ PET.

CONCLUSIONS

Increased levels of triglycerides at midlife predict brain Aβ and tau pathology 20 years later in cognitively healthy individuals. Certain lipoprotein subfractions may also be risk factors for Aβ pathology. These findings further support an involvement of lipids in the very early stages of AD development.

Location of Cerebral Microbleeds And Their Association with Carotid Intima-media Thickness: A Community-based Study

To assess whether high cerebral microbleeds (CMBs) are associated with carotid intima-media thickness (CIMT), a marker of systemic atherosclerosis, we cross-sectionally evaluated participants from a community-based study, the I-Lan Longitudinal Aging Study. The participants' demographics and cardiovascular risk factors were determined by questionnaire and/or laboratory measurements. CIMT was measured by ultrasonography. CMBs were assessed by susceptibility-weighted-imaging on 3 T MRI. Of the 962 subjects [62.5(8.6) years, 44.2% men] included, CMBs were found in 134(14.0%) subjects. Among the subjects with identified CMB's, 85(63.4%) had deep or infratentorial (DI) and 49(36.6%) had strictly lobar(SL) CMBs. After the results were adjusted for age and sex, the analysis revealed that hypertension, hyperlipidemia, obesity, and higher triglyceride levels correlated with DI but not SL CMBs. The subjects with DI CMBs also had a higher mean CIMT and higher prevalence of top quartile CIMT. The multivariate analysis demonstrated that high CIMT (top quartile) significantly predicted the presence of DI CMBs (odds ratio = 2.1; 95% confidence interval = 1.3-3.4; P = 0.004), independent of age, sex, cardiovascular risk factors, and other cerebral small vessel diseases, lacune, and white matter hyperintensity. There was no association between CIMT and SL CMBs. Our results support that there are distinct pathogenesis in DI and SL CMBs.

The significant effects of cerebral microbleeds on cognitive dysfunction: An updated meta-analysis

Objective

Accumulated data suggests that cerebral microbleeds (CMBs) play an important role in the decline of cognitive function, but the results remain inconsistent. In the current study, we aimed to investigate the association between CMBs and cognitive function, as well as the various effects of CMBs on different domains of cognition.

Methods

We searched through the databases of PubMed, Embase, Cochrane Library, and ScienceDirect. After a consistency test, the publication bias was evaluated and a sensitivity analysis was performed with combined odds ratios (OR) and standardized mean difference (SMD) of CMBs.

Results

A meta-analysis of 25 studies with 9343 participants total was conducted. Patients with CMBs had higher incidence of cognitive impairment (OR:3.5410; 95% confidence interval [CI] [2.2979, 5.4567], p<0.05) and lower scores of cognitive functions (SMD: -0.2700 [-0.4267, -0.1133], p<0.05 in Mini-Mental State Examination [MMSE] group and -0.4869 [-0.8902, -0.0818], p<0.05 in Montreal Cognitive Assessment [MoCA] group). Our results also indicated that patients with CMBs had obvious decline in cognitive functions, for instance, orientation (SMD: -0.9565 [-1.7260, -0.1869], p<0.05), attention and calculation (SMD: -1.1518 [-1.9553, -0.3484], p<0.05) and delayed recall (SMD: -0.5527 [-1.1043, -0.0011], p = 0.05).

Conclusions

Our data suggested that CMBs might be an important risk factor for cognitive dysfunction, especially in the domains of orientation, attention and calculation and delayed recall functions. Prospective cohort studies with further investigations will be needed in larger samples.

The effect of white matter hyperintensities on statistical analysis of diffusion tensor imaging in cognitively healthy elderly and prodromal Alzheimer's disease

Diffusion tensor imaging (DTI) has been used to study microstructural white matter alterations in a variety of conditions including normal aging and Alzheimer's disease (AD). White matter hyperintensities (WMH) are common in cognitively healthy elderly as well as in AD and exhibit elevated mean diffusivity (MD) and reduced fractional anisotropy (FA). However, the effect of WMH on statistical analysis of DTI estimates has not been thoroughly studied. In the present study we address this in two ways. First, we investigate the effect of WMH on MD and FA in the dorsal and ventral cingulum, the superior longitudinal fasciculus, and the corticospinal tract, by comparing two matched groups of cognitively healthy elderly (n = 21 + 21) with unequal WMH load. Second, we assess the effects of adjusting for WMH load when comparing MD and FA in prodromal AD subjects (n = 83) to cognitively healthy elderly (n = 132) in the abovementioned white matter tracts. Results showed the WMH in cognitively healthy elderly to have a generally large effect on DTI estimates (Cohen’s d = 0.63 to 1.27 for significant differences in MD and −1.06 to −0.69 for FA). These effect sizes were comparable to those of various neurological and psychiatric diseases (Cohen’s d = 0.57 to 2.20 for differences in MD and −1.76 to −0.61 for FA). Adjusting for WMH when comparing DTI estimates in prodromal AD subjects to cognitively healthy elderly improved the explanatory power as well as the outcome of the analysis, indicating that some of the differences in MD and FA were largely driven by unequal WMH load between the groups rather than alterations in normal-appearing white matter (NAWM). Thus, our findings suggest that if the purpose of a study is to compare alterations in NAWM between two groups using DTI it may be necessary to adjust the statistical analysis for WMH.

Arterial stiffness and cognitive impairment

BACKGROUND

Arterial stiffness is one of the earliest indicators of changes in vascular wall structure and function and may be assessed using various indicators, such as pulse-wave velocity (PWV), the cardio-ankle vascular index (CAVI), the ankle-brachial index (ABI), pulse pressure (PP), the augmentation index (AI), flow-mediated dilation (FMD), carotid intima media thickness (IMT) and arterial stiffness index-β. Arterial stiffness is generally considered an independent predictor of cardiovascular and cerebrovascular diseases. To date, a significant number of studies have focused on the relationship between arterial stiffness and cognitive impairment.

OBJECTIVES AND METHODS

To investigate the relationships between specific arterial stiffness parameters and cognitive impairment, elucidate the pathophysiological mechanisms underlying the relationship between arterial stiffness and cognitive impairment and determine how to interfere with arterial stiffness to prevent cognitive impairment, we searched PUBMED for studies regarding the relationship between arterial stiffness and cognitive impairment that were published from 2000 to 2017. We used the following key words in our search: "arterial stiffness and cognitive impairment" and "arterial stiffness and cognitive impairment mechanism". Studies involving human subjects older than 30years were included in the review, while irrelevant studies (i.e., studies involving subjects with comorbid kidney disease, diabetes and cardiac disease) were excluded from the review.

RESULTS

We determined that arterial stiffness severity was positively correlated with cognitive impairment. Of the markers used to assess arterial stiffness, a higher PWV, CAVI, AI, IMT and index-β and a lower ABI and FMD were related to cognitive impairment. However, the relationship between PP and cognitive impairment remained controversial. The potential mechanisms linking arterial stiffness and cognitive impairment may be associated with arterial pulsatility, as greater arterial pulsatility damages the cerebral microcirculation, which causes various phenomena associated with cerebral small vessel diseases (CSVDs), such as white matter hyperintensities (WMHs), cerebral microbleeds (CMBs), and lacunar infarctions (LIs). The mechanisms underlying the relationship between arterial stiffness and cognitive impairment may also be associated with reductions in white matter and gray matter integrity, medial temporal lobe atrophy and Aβ protein deposition. Engaging in more frequent physical exercise; increasing flavonoid and long-chain n-3 polyunsaturated fatty acid consumption; increasing tea, nitrite, dietary calcium and vitamin D intake; losing weight and taking medications intended to improve insulin sensitivity; quitting smoking; and using antihypertensive drugs and statins are early interventions and lifestyle changes that may be effective in preventing arterial stiffness and thus preventing cognitive impairment.

CONCLUSION

Arterial stiffness is a sensitive predictor of cognitive impairment, and arterial stiffness severity has the potential to serve as an indicator used to facilitate treatments designed to prevent or delay the onset and progression of dementia in elderly individuals. Early treatment of arterial stiffness is beneficial and recommended.

Aortic Stiffness, Increased White Matter Free Water, and Altered Microstructural Integrity: A Continuum of Injury

BACKGROUND AND PURPOSE

Previous reports from the Framingham Heart Study have identified cross-sectional associations of arterial stiffness, as reflected by carotid-femoral pulse wave velocity (CFPWV) and systolic blood pressure with vascular brain injury. The purpose of this study is to examine free water (FW), fractional anisotropy (FA), and white matter hyperintensities (WMH) in relation to arterial stiffness among subjects of the Framingham Offspring and Third-Generation cohorts.

METHODS

In 2422 participants aged 51.3±11.6 years, FA, FW, and WMH were related to CFPWV using voxel-based linear and generalized linear regressions, adjusting for relevant covariables. Mean FW, mean FA, and WMH burden (log transformed) were computed within white matter (WM) region and related to systolic blood pressure and CFPWV using multiple mediation analyses.

RESULTS

CFPWV was found to be associated with higher FW, lower FA, and higher WMH incidence in WM areas covering, respectively, 356.1, 211.8, and 10.9 mL of the WM mask. Mediation analyses revealed that the effect of systolic blood pressure on FW was mediated by CFPWV (direct and indirect effects: a=0.040; P<0.001, and a'=0.020; P>0.05). Moreover, the effect of CFPWV on FA was mediated by FW (direct and indirect effects: b=-0.092; P<0.001, and b'=0.012; P>0.05), whose effect on WMH was, in turn, mediated by FA (direct and indirect effects: c=0.246; P<0.001, and c'=0.116; P>0.05).

CONCLUSIONS

From these data, we propose a biomechanical hypothesis designed for future research experiments to explain how hemodynamic alteration may lead to WM injury by impacting cerebral water content and more subtly WM integrity, to finally lead to WMH development.

White matter hyperintensities and geriatric syndrome: An important role of arterial stiffness

White matter hyperintensities (WMH) are defined as cerebral white matter changes presumed to be of vascular origin, bilateral and mostly symmetrical. They can appear as hyperintense on T2-weighted and fluid-attenuated inversion recovery sequences, and as isointense or hypointense on T1-weighted magnetic resonance imaging of the brain. WMH have been focused on because of their clinical importance as a risk factor for cerebrovascular diseases and cognitive impairment. WMH are associated with geriatric syndrome, which is defined by clinical symptoms characteristic of older adults, including cognitive and functional impairment and falls. Cerebral small vessel diseases, such as WMH, might play an important role as risk factors for cerebrovascular diseases, cognitive impairment and geriatric syndrome through the mechanism of arterial stiffness. However, the vascular, physiological and metabolic roles of arterial stiffness remain unclear. Basically, arterial stiffness indicates microvessel arteriosclerosis presenting with vascular endothelial dysfunction. These changes might arise from hemodynamic stress as a result of a "tsunami effect" on cerebral parenchyma. In the present article, we review the clinical characteristics of WMH, focusing particularly on two associations: (i) those between cerebral small vessel diseases including WMH and arterial stiffness; and (ii) those between WMH and geriatric syndrome.

Intracranial atherosclerosis and cerebral small vessel disease in intracerebral hemorrhage patients

BACKGROUND

The association between cerebral small vessel diseases (cSVD) and intracranial atherosclerosis is debated and conflicting results have been reported. We sought to investigate this association in patients with intracerebral hemorrhage (ICH), due to severe cSVD.

METHODS

Consecutive ICH patients were divided into those meeting criteria for cerebral amyloid angiopathy (CAA) and those with deep hypertensive ICH consistent with hypertensive cSVD (HTN-SVD). White matter hyperintensity volumes (WMH) and microbleed counts (MB) were measured on MRI. CTA was rated for severity of intracranial carotid calcifications and for presence of >50% intracranial stenosis (ICS). Associations of intracranial atherosclerosis severity with type of SVD (CAA vs HTN-cSVD) and with imaging and clinical markers of cSVD burden were analyzed.

RESULTS

The cohort included 253 CAA and 90 HTN-SVD patients. In multivariable models, the type of cSVD (CAA vs. HTN-cSVD) was not associated with calcification severity (OR=1.04, 95% CI [0.62-3.5], p=0.37) or presence of ICS (OR=0.84, 95% CI [0.21-2.74], p=0.78). We found no association between intracranial atherosclerosis (calcifications and stenoses) and parenchymal markers of cSVD severity (WMH and MB, adjusted p≥0.2 for all comparisons) and no association with presence of dementia before ICH (adjusted p≥0.2 for both comparisons).

CONCLUSIONS

We found no association between intracranial atherosclerosis and parenchymal or clinical consequences of cSVD, suggesting that cSVDs while sharing some risk factors are not influenced by upstream larger vessel pathologies.

Carotid stiffness is associated with impairment of cognitive performance in individuals with and without type 2 diabetes. The Maastricht Study

BACKGROUND AND AIMS

There is increasing evidence linking arterial (mainly aortic) stiffness and type 2 diabetes, a risk factor for arterial stiffness, to cognitive impairment and dementia. However, data on carotid stiffness, which may be especially relevant for cognitive performance, are scarce, and few studies have addressed the interplay between arterial stiffness, type 2 diabetes, and cognitive performance.

METHODS

We studied individuals with (n = 197) and without (n = 528) type 2 diabetes, who completed a neuropsychological test battery and underwent applanation tonometry and vascular ultrasound to evaluate aortic (i.e. carotid-to-femoral pulse wave velocity) and carotid stiffness (i.e. distensibility, compliance and Young's elastic modulus). Linear regression analyses were performed and adjusted for demographics, vascular risk factors, and depression.

RESULTS

Overall, our results showed that carotid, but not aortic, stiffness was associated with worse cognitive performance, primarily in the domains of processing speed (standardized regression coefficient for distensibility -0.083, p = 0.040; compliance -0.077, p = 0.032) and executive function and attention (distensibility -0.133, p = 0.001; compliance -0.090, p = 0.015; Young's elastic modulus -0.081, p = 0.027). These associations did not differ by diabetes status. The differences in cognitive performance between individuals with and without type 2 diabetes (mean difference in domain scores relative to those without diabetes for free recall memory -0.23, processing speed -0.19, executive function and attention -0.23; all p ≤ 0.009 and adjusted for demographics, traditional vascular risk factors, and depression) were not substantially altered after additional adjustment for carotid stiffness.

CONCLUSIONS

Our findings suggest that carotid stiffness is associated with cognitive performance in both individuals with and without diabetes, but does not mediate the relationship between type 2 diabetes and cognitive dysfunction.