Effect of intensive blood pressure control on the prevention of white matter hyperintensity: Systematic review and meta‐analysis of randomized trials

Effect of high-fat diet on cerebral pathological changes of cerebral small vessel disease in SHR/SP rats

Cerebral small vessel diseases (CSVD) are neurological disorders associated with microvessels, manifested pathologically as white matter (WM) changes and cortical microbleeds, with hypertension as a risk factor. Additionally, a high-fat diet (HFD) can affect peripheral vessel health. Our study explored how HFD affects cerebral small vessels in normotensive WKY, hypertensive SHR, and SHR/SP rats. The MRI results revealed that HFD specifically increased WM hyperintensity in SHR/SP rats. Pathologically, it increased WM pallor and vacuolation in SHR and SHR/SP rats. Levels of blood-brain barrier (BBB) protein claudin 5 were decreased in SHR and SHR/SP compared to WKY, with HFD having minimal impact on these levels. Conversely, collagen IV levels remained consistent among the rat strains, which were increased by HFD. Consequently, HFD caused vessel leakage in all rat strains, particularly within the corpus callosum of SHR/SP rats. To understand the underlying mechanisms, we assessed the levels of hypoxia-inducible factor-1α (HIF-1α), Gp91-phox, and neuroinflammatory markers astrocytes, and microglia were increased in SHR and SHR/SP compared to WKY and were further elevated by HFD in all rat strains. Gp91-phox was also increased in SHR and SHR/SP compared to WKY, with HFD causing an increase in WKY but little effect in SHR and SHR/SP. In conclusion, our study demonstrates that HFD, in combined with hypertension, intensifies cerebral pathological alterations in CSVD rats. This exacerbation involves increased oxidative stress and HIF-1α in cerebral vessels, triggering neuroinflammation, vascular basement membrane remodeling, IgG leakage, and ultimately WM damage.

Pulse pressure is associated with decline in physical function in older adults

OBJECTIVES

This study examined the associations between pulse pressure, hypertension, and the decline in physical function in a prospective framework.

STUDY DESIGN

The Healthy Aging Longitudinal Study tracked a group of Taiwanese adults aged 55 or more over an average of 6.19 years to assess pulse pressure and decline in physical function, including in handgrip strength, gait speed, and 6-min walking distance, at baseline (2009-2013) and in the second phase of assessments (2013-2020).

MAIN OUTCOME MEASURES

Pulse pressure was calculated as the difference between systolic and diastolic blood pressure values. Weakness, slowness, and low endurance were defined as decreases of ≥0.23 m/s (one standard deviation) in gait speed, ≥5.08 kg in handgrip strength, and ≥ 57.73 m in a 6-min walk, as determined from baseline to the second phase of assessment. Linear and logistic regressions were employed to evaluate the associations between pulse pressure, hypertension, and decline in physical function.

RESULTS

Baseline pulse pressure was associated with future handgrip strength (beta = -0.017, p = 0.0362), gait speed (beta = -0.001, p < 0.0001), and 6-min walking distance (beta = -0.470, p < 0001). In multivariable models, only handgrip strength (beta = -0.016, p = 0.0135) and walking speed (beta = -0.001, p = 0.0042) remained significantly associated with future pulse pressure. Older adults with high systolic blood pressure (≥140 mmHg) and elevated pulse pressure (≥60 mmHg) exhibited a significantly increased risk of weakness (odds ratio: 1.30, 95 % confidence interval: 1.08-1.58), slowness (1.29, 1.04-1.59), and diminished endurance (1.25, 1.04-1.50) compared with the reference group, who exhibited systolic blood pressure of <140 mmHg and pulse pressure of <60 mmHg.

CONCLUSIONS

Among older adults, pulse pressure is associated with a decline in physical function, especially in terms of strength and locomotion.

Clinical Predictors of Postmortem Amyloid and Nonamyloid Cerebral Small Vessel Disease in Middle-Aged to Older Adults

Background and Objectives

Sporadic cerebral small vessel disease (CSVD) is a class of important pathologic processes known to affect the aging brain and to contribute to cognitive impairment. We aimed to identify clinical risk factors associated with postmortem CSVD in middle-aged to older adults.

Methods

We developed and tested risk models for their predictive accuracy of a pathologic diagnosis of nonamyloid CSVD and cerebral amyloid angiopathy (CAA) in a retrospective sample of 160 autopsied cases from the Edinburgh Brain Bank. Individuals aged 40 years and older covering the spectrum of healthy aging and common forms of dementia (i.e., highly-prevalent etiologies such as Alzheimer disease (AD), vascular cognitive impairment (VCI), and mixed dementia) were included. We performed binomial logistic regression models using sample splitting and cross-validation methods. Demographics, lifestyle habits, traditional vascular risk factors, chronic medical conditions, APOE4, and cognitive status were assessed as potential predictors.

Results

Forty percent of our sample had a clinical diagnosis of dementia (AD = 33, VCI = 26 and mixed = 5) while others were cognitively healthy (n = 96). The mean age at death was 73.8 (SD 14.1) years, and 40% were female. The presence of none-to-mild vs moderate-to-severe nonamyloid CSVD was predicted by our model with good accuracy (area under the curve [AUC] = 0.84, sensitivity [SEN] = 72%, specificity [SPE] = 95%), with the most significant clinical predictors being age, history of cerebrovascular events, and cognitive impairment. The presence of CAA pathology was also predicted with high accuracy (AUC = 0.86, SEN = 93%, SPE = 79%). Significant predictors included alcohol intake, history of cerebrovascular events, and cognitive impairment. In a subset of atypical dementias (n = 24), our models provided poor predictive performance for both nonamyloid CSVD (AUC = 0.50) and CAA (AUC = 0.43).

Discussion

CSVD pathology can be predicted with high accuracy based on clinical factors in patients within the spectrum of AD, VCI, and normal aging. Whether this prediction can be enhanced by the addition of fluid and neuroimaging biomarkers warrants additional study. Improving our understanding of clinical determinants of vascular brain health may lead to novel strategies in the prevention and treatment of vascular etiologies contributing to cognitive decline.

Classification of Evidence

This study provides Class II evidence that selected clinical factors accurately distinguish between middle-aged to older adults with and without cerebrovascular small vessel disease (amyloid and nonamyloid) pathology.

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.

Orthostatic blood pressure changes do not influence cognitive outcomes following intensive blood pressure control

BACKGROUND

Effects of intensive blood pressure (BP) control on cognitive outcomes in patients with excess orthostatic BP changes are unclear. We aimed to evaluate whether orthostatic BP changes modified the effects of BP intervention on cognitive impairment.

METHODS

We analyzed 8547 participants from the Systolic Blood Pressure Intervention Trial Memory and cognition IN Decreased Hypertension. Associations between orthostatic BP changes and incident cognitive outcomes were evaluated by restricted cubic spline curves based on Cox models. The interactions between orthostatic BP changes and intensive BP intervention were assessed.

RESULTS

The U-shaped associations were observed between baseline orthostatic systolic BP changes and cognitive outcomes. However, there were insignificant interactions between either change in orthostatic systolic BP (P for interaction = 0.81) or diastolic BP (P for interaction = 0.32) and intensive BP intervention for the composite outcome of probable dementia or mild cognitive impairment (MCI). The hazard ratio of intensive versus standard target for the composite cognitive outcome was 0.82 (95% CI 0.50-1.35) in those with an orthostatic systolic BP reduction of >20 mmHg and 0.41 (95% CI 0.21-0.80) in those with an orthostatic systolic BP increase of >20 mmHg. Results were similar for probable dementia and MCI. The annual changes in global cerebral blood flow (P for interaction = 0.86) consistently favored intensive BP treatment across orthostatic systolic BP changes.

CONCLUSION

Intensive BP control did not have a deteriorating effect on cognitive outcomes among hypertensive patients experiencing significant postural BP changes.

Physical and brain frailty in ischaemic stroke or TIA: Shared occurrence and outcomes. A cohort study

BACKGROUND

There is increasing interest in the concept of frailty in stroke, including both physical frailty and imaging-evidence of brain frailty. We aimed to establish the prevalence of brain frailty in stroke survivors as well as the concurrent and predictive validity of various frailty measures against long-term cognitive outcomes.

METHODS

We included consecutively admitted stroke or transient ischaemic attack (TIA) survivors from participating stroke centres. Baseline CT scans were used to generate an overall brain frailty score for each participant. We measured frailty via the Rockwood frailty index, and a Fried frailty screening tool. Presence of major or minor neurocognitive disorder at 18-months following stroke or TIA was established via a multicomponent assessment. Prevalence of brain frailty was established based upon observed percentages within groups defined by frailty status (robust, pre-frail, frail). We assessed the concurrent validity of brain frailty and frailty scales via Spearman's rank correlation. We conducted multivariable logistic regression analyses, controlling for age, sex, baseline education and stroke severity, to evaluate association between each frailty measure and 18-month cognitive impairment.

RESULTS

Three-hundred-forty-one stroke survivors participated. Three-quarters of people who were frail had moderate-severe brain frailty and prevalence increased according to frailty status. Brain frailty was weakly correlated with Rockwood frailty (Rho: 0.336; p < 0.001) and with Fried frailty (Rho: 0.230; p < 0.001). Brain frailty (OR: 1.64, 95% CI = 1.17-2.32), Rockwood frailty (OR: 1.05, 95% CI = 1.02-1.08) and Fried frailty (OR: 1.93, 95% CI = 1.39-2.67) were each independently associated with cognitive impairment at 18 months following stroke.

CONCLUSIONS

There appears to be value in the assessment of both physical and brain frailty in patients with ischaemic stroke and TIA. Both are associated with adverse cognitive outcomes and physical frailty remains important when assessing cognitive outcomes.

Hypertension and small vessel disease: do the drugs work?

Associations of hypertension with ischaemic stroke and intracerebral haemorrhage, particularly when attributed to cerebral small vessel disease, are well established. While it seems plausible that treating hypertension should prevent small vessel disease from developing or progressing, there is limited evidence demonstrating this. This article critically appraises the evidence answering this clinical question. Hypertension is also closely associated with chronic kidney disease, with anatomical and functional similarities between the vasculature of the brain and kidneys leading to the hypothesis that shared multi-system pathophysiological processes may be involved. Therefore, the article also summarises data on prevention of progression of chronic kidney disease. Evidence supports a target blood pressure of <130/80 mmHg to optimally prevent progression of both small vessel disease and chronic kidney disease. However, future studies are needed to determine long-term effects of more intensive blood pressure treatment targets on small vessel disease progression and incident dementia.

Effects of intensive blood pressure control on cognitive function in patients with cerebral small vessel disease

OBJECTIVE

This study aimed to investigate the effects of intensive blood pressure control on cognitive function in elderly patients with cerebral small vessel disease (CSVD).

METHODS

From May 2020 to June 2022, 140 outpatients and inpatients with CSVD and hypertension in the Department of Neurology of Beijing Shijingshan Hospital were selected. They were randomly divided into the standard and intensive blood pressure control groups, and the dosage of antihypertensive drugs was adjusted to reduce the blood pressure to the target level. The patients were followed up for 2 years. The medical records or data at "enrollment" and "2-year follow-up" were analyzed and evaluated. The Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were used to evaluate cognitive function. Cranial magnetic resonance imaging was performed to evaluate lacunar infarctions (LIs) and white matter hyperintensity (WMH). Multiple linear regression was used to analyze the correlation between MMSE scores and blood pressure, WMH, and LIs.

RESULTS

(1) The MMSE and MoCA scores in the standard group were significantly lower than those at enrollment. The WMH score in the standard group was significantly higher than that at enrollment. (2) After the 2-year follow-up, the 24-h systolic blood pressure (SBP), 24-h diastolic blood pressure (DBP), daytime mean SBP, daytime mean DBP, and nighttime mean SBP in the two groups significantly decreased, which had significant statistical significance (P < 0.05). (3) The correlation between blood pressure and MMSE score was analyzed using multiple linear regression analysis. The WMH score, LIs, 24-h SBP, and 24-h DBP were independently correlated with MMSE scores.

CONCLUSION

In elderly patients with hypertension, a decrease in SBP to 126 mmHg, compared with 134 mmHg, can delay cognitive impairment as well as reduce LIs and cerebral WMH lesions in patients with CSVD.

Past antihypertensive medication use is associated with lower levels of small vessel disease and lower Aβ plaque stage in the brains of older individuals

AIMS

This study assesses the association of antihypertensive medication use on the severities of neuropathological cerebrovascular disease (CVD excluding lobar infarction) in older individuals.

METHODS

Clinical and neuropathological data were retrieved for 149 autopsy cases >75 years old with or without CVD or Alzheimer's disease and no other neuropathological diagnoses. Clinical data included hypertension status, hypertension diagnosis, antihypertensive medication use, antihypertensive medication dose (where available) and clinical dementia rating (CDR). Neuropathological CVD severity was evaluated for differences with anti-hypertensive medication usage.

RESULTS

Antihypertensive medication use was associated with less severe white matter small vessel disease (SVD, mainly perivascular dilatation and rarefaction), with a 5.6-14.4 times greater likelihood of less severe SVD if medicated. No significant relationship was detected between infarction (presence, type, number and size), lacunes or cerebral amyloid angiopathy and antihypertensive medication use. Only increased white matter rarefaction/oedema and not perivascular dilation was associated with Alzheimer's pathology, with a 4.3 times greater likelihood of reduced Aβ progression through the brain if white matter rarefaction severity was none or mild. Antihypertensive medication use was associated with reduced Aβ progression but only in those with moderate to severe white matter SVD.

CONCLUSIONS

This histopathological study provides further evidence that antihypertensive medication use in older individuals is associated with white matter SVD and not with other CVD pathologies. This is mainly due to a reduction in white matter perivascular dilation and rarefaction/oedema. Even in those with moderate to severe white matter SVD, antihypertensive medication use reduced rarefaction and Aβ propagation through the brain.

Resistance Training Maintains White Matter and Physical Function in Older Women with Cerebral Small Vessel Disease: An Exploratory Analysis of a Randomized Controlled Trial

Background

As the aging population grows, there is an increasing need to develop accessible interventions against risk factors for cognitive impairment and dementia, such as cerebral small vessel disease (CSVD). The progression of white matter hyperintensities (WMHs), a key hallmark of CSVD, can be slowed by resistance training (RT). We hypothesize RT preserves white matter integrity and that this preservation is associated with improved cognitive and physical function.

Objective

To determine if RT preserves regional white matter integrity and if any changes are associated with cognitive and physical outcomes.

Methods

Using magnetic resonance imaging data from a 12-month randomized controlled trial, we compared the effects of a twice-weekly 60-minute RT intervention versus active control on T1-weighted over T2-weighted ratio (T1w/T2w; a non-invasive proxy measure of white matter integrity) in a subset of study participants (N = 21 females, mean age = 69.7 years). We also examined the association between changes in T1w/T2w with two key outcomes of the parent study: (1) selective attention and conflict resolution, and (2) peak muscle power.

Results

Compared with an active control group, RT increased T1w/T2w in the external capsule (p = 0.024) and posterior thalamic radiations (p = 0.013) to a greater degree. Increased T1w/T2w in the external capsule was associated with an increase in peak muscle power (p = 0.043) in the RT group.

Conclusion

By maintaining white matter integrity, RT may be a promising intervention to counteract the pathological changes that accompany CSVD, while improving functional outcomes such as muscle power.

White matter changes underlie hypertension-related cognitive decline in older adults

Hypertension has been well recognized as a risk factor for cognitive impairment and dementia. Although the underlying mechanisms of hypertension-affected cognitive deterioration are not fully understood, white matter changes (WMCs) seem to play an important role. WMCs include low microstructural integrity and subsequent white matter macrostructural lesions, which are common on brain imaging in hypertensive patients and are critical for multiple cognitive domains. This article provides an overview of the impact of hypertension on white matter microstructural and macrostructural changes and its link to cognitive dysfunction. Hypertension may induce microstructural changes in white matter, especially for the long-range fibers such as anterior thalamic radiation (ATR) and inferior fronto-occipital fasciculus (IFOF), and then macrostructural abnormalities affecting different lobes, especially the periventricular area. Different regions' WMCs would further exert different effects to specific cognitive domains and accelerate brain aging. As a modifiable risk factor, hypertension might provide a new perspective for alleviating and delaying cognitive impairment.

Statin Usage Increases White Matter Hyperintensities: A Post Hoc Analysis of SPRINT-MIND

BACKGROUND

Progression of white matter hyperintensities (WMHs), a radiographic marker of cerebral small vessel disease, occurs with uncontrolled conventional cerebrovascular risk factors. Less certain, however, is the influence of dyslipidemia and the impact of 3-hydroxy-3-methylglutaryl-coenzyme-A reductase inhibitors (statins) on WMH progression. The goal of this study was to evaluate the influence of statins on the progression of WMH over a 4-year interval.

METHODS

We performed a post hoc analysis of the SPRINT-MIND database on those with serial volumetric WMH data. WMH progression was calculated as the difference in WMH volume between the 2 scans and then segmented into tertiles due to rightward skew. We defined statin usage as no therapy (0% of visits), partial therapy (1% to 99% of visits) or full therapy (100% of visits) as logged during study visits. Analysis of variance and χ 2 tests were used for continuous and categorical variables with adjustments made for variables known to influence WMH development.

RESULTS

A total of 425 individuals were included in this study: 53% without statins use, 27% partial use, and 20% full use. Demographic characteristics and baseline WMH volumes were similar among the cohort. Those with full statin use were significantly more likely to be in the top tertile of WMH progression (adjusted odds ratio: 2.30, 95% confidence interval: 1.11-4.77, P =0.025), despite improvement in dyslipidemia.

CONCLUSIONS

SPRINT-MIND participants prescribed a statin were nearly 2.5 times more likely to be within the top tertile of WMH progression over 4 years, despite adjustment for synergistic risk factors and improvement in low-density lipoprotein.

Cerebral Small Vessel Disease-Related Dementia: More Questions Than Answers

Cerebral small vessel disease (CSVD) has emerged as a common factor driving age-dependent diseases, including stroke and dementia. CSVD-related dementia will affect a growing fraction of the aging population, requiring improved recognition, understanding, and treatments. This review describes evolving criteria and imaging biomarkers for the diagnosis of CSVD-related dementia. We describe diagnostic challenges, particularly in the context of mixed pathologies and the absence of highly effective biomarkers for CSVD-related dementia. We review evidence regarding CSVD as a risk factor for developing neurodegenerative disease and potential mechanisms by which CSVD leads to progressive brain injury. Finally, we summarize recent studies on the effects of major classes of cardiovascular medicines relevant to CSVD-related cognitive impairment. Although many key questions remain, the increased attention to CSVD has resulted in a sharper vision for what will be needed to meet the upcoming challenges imposed by this disease.

Xanthine oxidase inhibition and white matter hyperintensity progression following ischaemic stroke and transient ischaemic attack (XILO-FIST): a multicentre, double-blinded, randomised, placebo-controlled trial

BACKGROUND

People who experience an ischaemic stroke are at risk of recurrent vascular events, progression of cerebrovascular disease, and cognitive decline. We assessed whether allopurinol, a xanthine oxidase inhibitor, reduced white matter hyperintensity (WMH) progression and blood pressure (BP) following ischaemic stroke or transient ischaemic attack (TIA).

METHODS

In this multicentre, prospective, randomised, double-blinded, placebo-controlled trial conducted in 22 stroke units in the United Kingdom, we randomly assigned participants within 30-days of ischaemic stroke or TIA to receive oral allopurinol 300 mg twice daily or placebo for 104 weeks. All participants had brain MRI performed at baseline and week 104 and ambulatory blood pressure monitoring at baseline, week 4 and week 104. The primary outcome was the WMH Rotterdam Progression Score (RPS) at week 104. Analyses were by intention to treat. Participants who received at least one dose of allopurinol or placebo were included in the safety analysis. This trial is registered with ClinicalTrials.gov, NCT02122718.

FINDINGS

Between 25th May 2015 and the 29th November 2018, 464 participants were enrolled (232 per group). A total of 372 (189 with placebo and 183 with allopurinol) attended for week 104 MRI and were included in analysis of the primary outcome. The RPS at week 104 was 1.3 (SD 1.8) with allopurinol and 1.5 (SD 1.9) with placebo (between group difference -0.17, 95% CI -0.52 to 0.17, p = 0.33). Serious adverse events were reported in 73 (32%) participants with allopurinol and in 64 (28%) with placebo. There was one potentially treatment related death in the allopurinol group.

INTERPRETATION

Allopurinol use did not reduce WMH progression in people with recent ischaemic stroke or TIA and is unlikely to reduce the risk of stroke in unselected people.

FUNDING

The British Heart Foundation and the UK Stroke Association.

Targeting cerebral small vessel disease to promote healthy aging: Preserving physical and cognitive functions in the elderly

Cerebral small vessel disease (SVD), which is highly age-related, is the most common neuroimaging finding in community-dwelling elderly individuals. In addition to increasing the risk of dementia and stroke, SVD is associated with cognitive and physical (particularly gait speed) functional impairments in the elderly. Here, we provide evidence suggesting covert SVD, e.g. without clinically evident stroke or dementia, as a critical target to preserve the functional ability that enables well-being in older age. First, we discuss the relationship between covert SVD and geriatric syndrome. SVD lesions found in non-demented, stroke-free elderly are actually not "silent" but are associated with accelerated age-related functional decline. We also review the brain structural and functional abnormalities associated with covert SVD and the possible mechanisms underlying their contributions to SVD-related cognitive and physical functional impairments. Finally, we reveal current data, though limited, on the management of elderly patients with covert SVD to prevent SVD lesion progression and functional decline. Although it is important in aging health, covert SVD is still under-recognized or misjudged by physicians in both neurological and geriatric professions. Improving the acknowledgment, detection, interpretation, and understanding of SVD would be a multidisciplinary priority to maintain cognitive and physical functions in the elderly. The dilemmas and future directions of clinical practice and research for the elderly with covert SVD are also included in the present review.

Twenty-four hour blood pressure variability and the prevalence and the progression of cerebral white matter hyperintensities

Blood pressure variability (BPV) is related to cerebral white matter hyperintensities (WMH), but longitudinal studies assessing WMH progression are scarce. Patients with cardiovascular disease and control participants of the Heart-Brain Connection Study underwent 24-hour ambulatory blood pressure monitoring and repeated brain MRI at baseline and after 2 years. Using linear regression, we determined whether different measures of BPV (standard deviation, coefficient of variation, average real variability (ARV), variability independent of the mean) and nocturnal dipping were associated with WMH and whether this association was mediated or moderated by baseline cerebral perfusion. Among 177 participants (mean age: 65.9 ± 8.1 years, 33.9% female), the absence of diastolic nocturnal dipping was associated with higher WMH volume at baseline (β = 0.208, 95%CI: 0.025-0.392), but not with WMH progression among 91 participants with follow-up imaging. None of the BPV measures were associated with baseline WMH. Only 24-hour diastolic ARV was significantly associated with WMH progression (β = 0.144, 95%CI: 0.030-0.258), most profound in participants with low cerebral perfusion at baseline (p-interaction = 0.042). In conclusion, absent diastolic nocturnal dipping and 24-hour diastolic ARV were associated with higher WMH volume. Whilst requiring replication, these findings suggest that blood pressure patterns and variability may be a target for prevention of small vessel disease.

Study on the Interaction between the Characteristics of Retinal Microangiopathy and Risk Factors for Cerebral Small Vessel Disease

Objective

This study was designed to explore the characteristics of retinal microangiopathy in patients with cerebral small vessel disease (CSVD) and clarify its interaction with the risk factors for CSVD.

Methods

Sixty patients with CSVD and 15 healthy individuals were enrolled. Demographic data, risk factors, and medical history were recorded, and magnetic resonance imaging was performed to detect and analyze the characteristics of retinal microangiopathy in the two groups. The interaction among retinal microangiopathy, vascular risk factors, and total imaging load of CSVD was compared.

Results

(1) Hypertension, standard deviation of systolic blood pressure (SBPSD), standard deviation of blood glucose (SDBG), and atherogenic index of plasma (AIP) were independent vascular risk factors for CSVD. (2) Statistically significant differences in hypertension, SBPSD, SDBG, and AIP were observed between the two groups in terms of the total imaging burden of CSVD (p < 0.05). (3) Multivariate logistic linear regression showed that CSVD was associated with a wider central retinal vein equivalent (CRVE) (p = 0.015), a smaller arteriole-to-venule ratio (AVR) (p = 0.001), and a higher incidence of vessel tortuosity (p = 0.027). (4) When the total imaging burden of CSVD ranges from 0 to 4 points, the CRVE is larger, the AVR is smaller, and the incidence of vascular tortuosity is higher, with a statistically significant difference (p < 0.05). (5) The characteristics of retinal microangiopathy were correlated with hypertension, SBPSD, SDBG, and AIP (p < 0.05). (6) An association was observed between the characteristics of retinal microangiopathy and vascular risk factors and the total imaging burden of CSVD (p < 0.05).

Conclusions

(1) Hypertension, SBP variability, BG fluctuation, and AIP are independent vascular risk factors for CSVD. (2) Retinal microvessels are changed in patients with CSVD, and venous dilatation, decreased arteriovenous ratio, and vascular tortuosity are the main characteristics of the disease. (3) The characteristics of retinal microangiopathy are interactively correlated with the total imaging load and risk factors for CSVD and can be used as indicators of the severity of CSVD.

Causal structure discovery identifies risk factors and early brain markers related to evolution of white matter hyperintensities

Our goal was to understand the complex relationship between age, sex, midlife risk factors, and early white matter changes measured by diffusion tensor imaging (DTI) and their role in the evolution of longitudinal white matter hyperintensities (WMH). We identified 1564 participants (1396 cognitively unimpaired, 151 mild cognitive impairment and 17 dementia participants) with age ranges of 30-90 years from the population-based sample of Mayo Clinic Study of Aging. We used computational causal structure discovery and regression analyses to evaluate the predictors of WMH and DTI, and to ascertain the mediating effect of DTI on WMH. We further derived causal graphs to understand the complex interrelationships between midlife protective factors, vascular risk factors, diffusion changes, and WMH. Older age, female sex, and hypertension were associated with higher baseline and progression of WMH as well as DTI measures (P ≤ 0.003). The effects of hypertension and sex on WMH were partially mediated by microstructural changes measured on DTI. Higher midlife physical activity was predictive of lower WMH through a direct impact on better white matter tract integrity as well as an indirect effect through reducing the risk of hypertension by lowering BMI. This study identified key risks factors, early brain changes, and pathways that may lead to the evolution of WMH.

Effect of Antihypertensives by Class on Cerebral Small Vessel Disease: A Post Hoc Analysis of SPRINT-MIND

BACKGROUND

Treatment of uncontrolled arterial hypertension reduces the risk of cerebral small vessel disease (CSVD) progression, although it is unclear whether this reduction occurs due to blood pressure control or class-specific pleiotropic effects, such as improved beat-to-beat arterial pressure variability with calcium channel blockers. The goal of this study was to investigate the influence of antihypertensive medication class, particularly with calcium channel blocker, on accumulation of white matter hyperintensities (WMH), a radiographic marker of CSVD, within a cohort with well-controlled hypertension.

METHODS

We completed an observational cohort analysis of the SPRINT-MIND trial (Systolic Blood Pressure Trial Memory and Cognition in Decreased Hypertension), a large randomized controlled trial of participants who completed a baseline and 4-year follow-up brain magnetic resonance image with volumetric WMH data. Antihypertensive medication data were recorded at follow-up visits between the magnetic resonance images. A percentage of follow-up time participants were prescribed each of the 11 classes of antihypertensive was then derived. Progression of CSVD was calculated as the difference in WMH volume between 2 scans and, to address skew, dichotomized into a top tertile of the distribution compared with the remaining.

RESULTS

Among 448 individuals, vascular risk profiles were similar across WMH progression subgroups except age (70.1±7.9 versus 65.7±7.3 years; P<0.001) and systolic blood pressure (128.3±11.0 versus 126.2±9.4 mm Hg; P=0.039). Seventy-two (48.3%) of the top tertile cohort and 177 (59.2%) of the remaining cohort were in the intensive blood pressure arm. Those within the top tertile of progression had a mean WMH progression of 4.7±4.3 mL compared with 0.13±1.0 mL (P<0.001). Use of angiotensin-converting enzyme inhibitors (odds ratio, 0.36 [95% CI, 0.16-0.79]; P=0.011) and dihydropyridine calcium channel blockers (odds ratio, 0.39 [95% CI, 0.19-0.80]; P=0.011) was associated with less WMH progression, although dihydropyridine calcium channel blockers lost significance when WMH was treated as a continuous variable.

CONCLUSIONS

Among participants of SPRINT-MIND trial, angiotensin-converting enzyme inhibitor was most consistently associated with less WMH progression independent of blood pressure control and age.

White Matter and Alzheimer's Disease: A Bidirectional Mendelian Randomization Study

INTRODUCTION

Observational studies have indicated widespread comorbidity of white matter (WM) lesions and Alzheimer's disease (AD) in the elderly, but the causality and direction of their relationship remained unclear. Our study aims to examine the bidirectional causal relationship between WM change and AD using a genetically informed method.

METHODS

We performed a bidirectional two-sample mendelian randomization (MR) study to investigate the correlation of three WM phenotypes-white matter hyperintensities (WMH, N = 18,381), fractional anisotropy (FA, N = 17,673), and mean diffusivity (MD, N = 17,467)-with AD (N = 63,926) using summary statistics from genome-wide association studies (GWAS). The inverse variance weighted method (IVW) was used to evaluate the causal estimate and alternative methods to test the heterogeneity, horizontal pleiotropy, and outliers.

RESULTS

There was no significant causal evidence of WM MRI markers on AD across all MR methods. We identified significant evidence of causal effects of AD on the risk of WMH (OR 1.06, 95% CI 1.03-1.10, p < 0.01). The same direction of effects was observed in MR-Egger, weighted median, and weighted mode analysis. Besides, we also observed a risk causal relationship between AD with MD in MR-Egger, weighted median, and weighted mode-based methods (MR-Egger OR 1.38, 95% CI 1.07-1.79, p = 0.02; weighted median OR 1.21, 95% CI 1.02-1.45, p = 0.03; weighted mode-based OR 1.32, 95% CI 1.14-1.53, p < 0.01). However, the general significance of the causal effect of AD on WMH and MD disappeared when we removed the single nucleotide polymorphisms (SNPs) near the APOE regions, revealing that the ability of AD to increase the risk of white matter damage might be mediated by APOE to some extent. Unfortunately, we did not observe significant causal evidence of AD on FA across all MR analyses.

CONCLUSIONS

In this bidirectional MR study, we did not observe that WM injuries were associated with a higher risk of AD. Likewise, genetically predicted AD did not result in a causal effect on white matter damage. However, our research revealed that underlying mechanisms linking AD and white matter lesions might be related to the SNPs near APOE regions.

Advances in the Role of Endothelial Cells in Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) poses a serious socio-economic burden due to its high prevalence and severe impact on the quality of life of elderly patients. Pathological changes in CSVD mainly influence small cerebral arteries, microarteries, capillaries, and small veins, which are usually caused by multiple vascular risk factors. CSVD is often identified on brain magnetic resonance imaging (MRI) by recent small subcortical infarcts, white matter hyperintensities, lacune, cerebral microbleeds (CMBs), enlarged perivascular spaces (ePVSs), and brain atrophy. Endothelial cell (EC) dysfunction is earlier than clinical symptoms. Immune activation, inflammation, and oxidative stress may be potential mechanisms of EC injury. ECs of the blood–brain–barrier (BBB) are the most important part of the neurovascular unit (NVU) that ensures constant blood flow to the brain. Impaired cerebral vascular autoregulation and disrupted BBB cause cumulative brain damage. This review will focus on the role of EC injury in CSVD. Furthermore, several specific biomarkers will be discussed, which may be useful for us to assess the endothelial dysfunction and explore new therapeutic directions.

Blood Pressure and Vascular Cognitive Impairment

High blood pressure (BP) is detrimental to brain health. High BP contributes to cognitive impairment and dementia through pathways independent of clinical stroke. Emerging evidence shows that the deleterious effect of high BP on cognition occurs across the life span, increasing the risk for early-onset and late-life dementia. The term vascular cognitive impairment includes cognitive disorders associated with cerebrovascular disease, regardless of the pathogenesis. This focused report is a narrative review that aims to summarize the epidemiology of BP and vascular cognitive impairment, including differences by sex, race, and ethnicity, as well as the management and reversibility of BP and vascular cognitive impairment. It also discusses knowledge gaps and future directions.

Five years of exercise intervention at different intensities and development of white matter hyperintensities in community dwelling older adults, a Generation 100 sub-study

We investigated if a five-year supervised exercise intervention with moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT) versus control; physical activity according to national guidelines, attenuated the growth of white matter hyperintensities (WMH). We hypothesized that supervised exercise, in particular HIIT, reduced WMH growth. Older adults from the general population participating in the RCT Generation 100 Study were scanned at 3T MRI at baseline (age 70–77), and after 1-, 3- and 5-years. At each follow-up, cardiorespiratory fitness was measured with ergospirometry, and physical activity plus clinical data collected. Manually delineated total WMH, periventricular (PWMH), deep (DWMH), and automated total white matter hypointensity volumes were obtained. No group by time interactions were present in linear mixed model analyses with the different WMH measurements as outcomes. In the combined exercise (MICT&HIIT) group, a significant group by time interaction was uncovered for PWMH volume, with a larger increase in the MICT&HIIT group. Cardiorespiratory fitness at the follow-ups or change in cardiorespiratory fitness over time were not associated with any WMH measure. Contrary to our hypothesis, taking part in MICT or HIIT over a five-year period did not attenuate WMH growth compared to being in a control group following national physical activity guidelines.

Risk Factors, Lifestyle Behaviors, and Vascular Brain Health

Although a relationship between traditional cardiovascular risk factors and stroke has long been recognized, these risk factors likely play a role in other aspects of brain health. Clinical stroke is only the tip of the iceberg of vascular brain injury that includes covert infarcts, white matter hyperintensities, and microbleeds. Furthermore, an individual's risk for not only stroke but poor brain health includes not only these traditional vascular risk factors but also lifestyle and genetic factors. The purpose of this narrative review is to summarize the state of the evidence on traditional and nontraditional vascular risk factors and their contributions to brain health. Additionally, we will review important modifiers that interact with these risk factors to increase, or, in some cases, reduce risk of adverse brain health outcomes, with an emphasis on genes and biomarkers associated with Alzheimer disease. Finally, we will consider the importance of social determinants of health in brain health outcomes.

Rate of, and risk factors for, white matter hyperintensity growth: a systematic review and meta-analysis with implications for clinical trial design

BACKGROUND

White matter hyperintensities (WMHs) are a highly prevalent MRI marker of cerebral small vessel disease (SVD), which predict stroke and dementia risk, and are being increasingly used as a surrogate marker in clinical trials. However, the influence of study population selection on WMH progression rate has not been studied and the effect of individual patient factors for WMH growth are not fully understood.

METHODS

We performed a systematic review and meta-analysis of the literature on progression of WMHs in longitudinal studies to determine rates of WMH growth, and how these varied according to population characteristics and cardiovascular risk factors. We used these data to calculate necessary sample sizes for clinical trials using WMH as an endpoint.

RESULTS

WMH growth rate was highest in SVD (2.50cc/year), intermediate in unselected stroke patients (1.29cc/year) and lower in patients with non-stroke cardiovascular disease, and with cognitive impairment. Age was significantly associated with progression (correlation coefficient 0.15cc/year, 95% CI 0.02 to 0.28cc/year) as was baseline lesion volume (0.6cc/year, 95% CI 0.13 to 1.06 cc/year). Both hypertension (OR 1.72, 95% CI 1.19 to 2.46) and current smoking (OR 1.48, 95% CI 1.02 to 2.16) were associated with WMH growth. Sample sizes for a clinical trial varied greatly with patient population selection and baseline lesion volume; estimates are provided.

CONCLUSIONS

WMH progression varies markedly according to the characteristics of the population being studied and this will have a major impact on sample sizes required in a clinical trial. Our sample size estimates provide data for planning clinical trials using WMH as an outcome measure.

PROSPERO REGISTRATION NUMBER

CRD42020191781.

ESO Guideline on covert cerebral small vessel disease

'Covert' cerebral small vessel disease (ccSVD) is common on neuroimaging in persons without overt neurological manifestations, and increases the risk of future stroke, cognitive impairment, dependency, and death. These European Stroke Organisation (ESO) guidelines provide evidence-based recommendations to assist with clinical decisions about management of ccSVD, specifically white matter hyperintensities and lacunes, to prevent adverse clinical outcomes. The guidelines were developed according to ESO standard operating procedures and Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. We prioritised the clinical outcomes of stroke, cognitive decline or dementia, dependency, death, mobility and mood disorders, and interventions of blood pressure lowering, antiplatelet drugs, lipid lowering, lifestyle modifications, glucose lowering and conventional treatments for dementia. We systematically reviewed the literature, assessed the evidence, formulated evidence-based recommendations where feasible, and expert consensus statements. We found little direct evidence, mostly of low quality. We recommend patients with ccSVD and hypertension to have their blood pressure well controlled; lower blood pressure targets may reduce ccSVD progression. We do not recommend antiplatelet drugs such as aspirin in ccSVD. We found little evidence on lipid lowering in ccSVD. Smoking cessation is a health priority. We recommend regular exercise which may benefit cognition, and a healthy diet, good sleep habits, avoiding obesity and stress for general health reasons. In ccSVD, we found no evidence for glucose control in the absence of diabetes or for conventional Alzheimer dementia treatments. Randomised controlled trials with clinical endpoints are a priority for ccSVD.