Hippocampal atrophy, whole brain volume, and white matter lesions in older hypertensive subjects

Methodological challenges and biases in the field of cognitive function among patients with chronic kidney disease

Chronic kidney disease (CKD) affects approximately 850 million people globally and is associated with an increased risk of cognitive impairment. The prevalence of cognitive impairment among CKD patients ranges from 30 to 60%, and the link between CKD and cognitive impairment is partially understood. Methodological challenges and biases in studying cognitive function in CKD patients need to be addressed to improve diagnosis, treatment, and management of cognitive impairment in this population. Here, we review the methodological challenges and study design issues, including observational studies' limitations, internal validity, and different types of bias that can impact the validity of research findings. Understanding the unique challenges and biases associated with studying cognitive function in CKD patients can help to identify potential sources of error and improve the quality of future research, leading to more accurate diagnoses and better treatment plans for CKD patients.

Association of brain morphology and phenotypic profile in patients with unruptured intracranial aneurysm

Introduction

Studies have found a varying degree of cognitive, psychosocial, and functional impairments in patients with unruptured intracranial aneurysms (UIAs), whereas the neural correlates underlying these impairments remain unknown.

Methods

To examine the brain morphological alterations and white matter lesions in patients with UIA, we performed a range of structural analyses to examine the brain morphological alterations in patients with UIA compared with healthy controls (HCs). Twenty-one patients with UIA and 23 HCs were prospectively enrolled into this study. Study assessment consisted of a brain magnetic resonance imaging (MRI) scan with high-resolution T1-weighted and T2-weighted imaging data, a Montreal Cognitive Assessment (MoCA), and laboratory tests including blood inflammatory markers and serum lipids. Brain MRI data were processed for cortical thickness, local gyrification index (LGI), volume and shape of subcortical nuclei, and white matter lesions.

Results

Compared to the HCs, patients with UIA showed no significant differences in cortical thickness but decreased LGI values in the right posterior cingulate cortex, retrosplenial cortex, cuneus, and lingual gyrus. In addition, decreased LGI values correlated with decreased MoCA score (r = 0.498, p = 0.021) and increased white matter lesion scores (r = -0.497, p = 0.022). The LGI values were correlated with laboratory values such as inflammatory markers and serum lipids. Patients with UIA also showed significant regional atrophy in bilateral thalami as compared to the HCs. Moreover, the LGI values were significantly correlated with thalamic volume in the HCs (r = 0.4728, p = 0.0227) but not in the patients with UIA (r = 0.11, p = 0.6350).

Discussion

The decreased cortical gyrification, increased white matter lesions, and regional thalamic atrophy in patients with UIA might be potential neural correlates of cognitive changes in UIA.

Association of blood pressure with brain perfusion and structure: A population-based prospective study

PURPOSE

To explore the association of blood pressure (BP) measurements with cerebral blood flow (CBF) and brain structure in general population.

METHOD

This prospective study included 902 participants from Kailuan community. All participants underwent brain MRI and BP measurements. The association of BP indicators with CBF, brain tissue volume and white matter hyperintensity (WMH) volume were investigated. In addition, mediation analysis was used to determine whether significantly changed brain tissue volume explained associations between BP and CBF.

RESULTS

Elevated diastolic BP (DBP), but not systolic BP (SBP), was associated with lower CBF in the total brain (β [95 % CI]: -0.62 [-1.14, -0.10]), total gray matter (β [95 % CI]: -0.71 [-1.27, -0.14]), hippocampus (β [95 % CI]: -0.59 [-1.13, -0.05]), frontal (β [95 % CI]: -0.72 [-1.31, -0.13]), parietal (β [95 % CI]: -0.92 [-1.54, -0.3]), temporal (β [95 % CI]: -0.63 [-1.18, -0.08]), and occipital lobe (β [95 % CI]: -0.69 [-1.37, -0.01]). Higher SBP and DBP were associated with reduced total and regional brain tissue volume (all p < 0.05). Increased SBP and PP were associated with higher total and periventricular WMH volume (all p < 0.05). In addition, mediation analysis identified that significantly decreased brain volume did not mediate the associations of BP measurements and lower CBF in corresponding region (all p > 0.05).

CONCLUSIONS

Elevated BP level was associated with decreased total and regional CBF and brain tissue volume and increased WMH burden.

The etiology and evolution of magnetic resonance imaging-visible perivascular spaces: Systematic review and meta-analysis

Objectives

Perivascular spaces have been involved in neuroinflammatory and neurodegenerative diseases. Upon a certain size, these spaces can become visible on magnetic resonance imaging (MRI), referred to as enlarged perivascular spaces (EPVS) or MRI-visible perivascular spaces (MVPVS). However, the lack of systematic evidence on etiology and temporal dynamics of MVPVS hampers their diagnostic utility as MRI biomarker. Thus, the goal of this systematic review was to summarize potential etiologies and evolution of MVPVS.

Methods

In a comprehensive literature search, out of 1,488 unique publications, 140 records assessing etiopathogenesis and dynamics of MVPVS were eligible for a qualitative summary. 6 records were included in a meta-analysis to assess the association between MVPVS and brain atrophy.

Results

Four overarching and partly overlapping etiologies of MVPVS have been proposed: (1) Impairment of interstitial fluid circulation, (2) Spiral elongation of arteries, (3) Brain atrophy and/or perivascular myelin loss, and (4) Immune cell accumulation in the perivascular space. The meta-analysis in patients with neuroinflammatory diseases did not support an association between MVPVS and brain volume measures [R: −0.15 (95%-CI −0.40–0.11)]. Based on few and mostly small studies in tumefactive MVPVS and in vascular and neuroinflammatory diseases, temporal evolution of MVPVS is slow.

Conclusion

Collectively, this study provides high-grade evidence for MVPVS etiopathogenesis and temporal dynamics. Although several potential etiologies for MVPVS emergence have been proposed, they are only partially supported by data. Advanced MRI methods should be employed to further dissect etiopathogenesis and evolution of MVPVS. This can benefit their implementation as an imaging biomarker.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=346564, identifier CRD42022346564.

Septal E/e' Ratio Is Associated With Cerebral White Matter Hyperintensity Progression in Young-Old Hypertensive Patients

Background: The incidence of hypertension increases with age, as does that of brain abnormalities associated with cerebral pathologic and functional degeneration. Little is known about the relationship between hypertension-related cardiac changes and cerebral pathologic degeneration. We examined the relationship between left ventricular (LV) diastolic dysfunction and cerebral white matter hyperintensity (WMH) progression in young-old hypertensive patients. Methods and Results: This single-center prospective longitudinal observational study included 156 individuals aged 65-75 years with well-controlled hypertension, normal LV contraction, and no history of symptomatic heart failure. WMH was quantified on brain magnetic resonance imaging (MRI). The primary outcome was the rate of WMH volume progression between the baseline and follow-up MRI (∆WMH). Participants were classified into tertiles on the basis of ∆WMH (small, medium, and large ∆WMH). The mean (±SD) age at recruitment was 69.6±2.8 years, and the mean follow-up period was 4.6 years. The ratio of early diastolic mitral inflow velocity to early diastolic septal mitral annulus velocity (septal E/e') was significantly higher in the large ∆WMH group than in the small and medium ∆WMH groups. On multiple regression analysis, septal E/e' was significantly positively associated with square-root-transformed ∆WMH (β=0.457, P<0.001). Conclusions: Septal E/e' was significantly positively associated with the rate of progression of WMH volume, suggesting that LV diastolic dysfunction is associated with the progression of abnormal brain aging.

Association of regional white matter hyperintensities with hypertension and cognition in the population-based 1000BRAINS study

BACKGROUND

White matter hyperintensities of presumed vascular origin (WMH) are frequent in cerebral magnetic resonance imaging of older people. They are promoted by vascular risk factors, especially hypertension, and are associated with cognitive deficits at the group level. It has been suggested that not only the severity, but also the location, of lesions might critically influence cognitive deficits and represent different pathologies.

METHODS

In 560 participants (65.2 ± 7.5 years, 51.4% males) of the population-based 1000BRAINS study, we analyzed the association of regional WMH using Fazekas scoring separately for cerebral lobes, with hypertension and cognition.

RESULTS

WMH most often affected the frontal lobe (83.7% score >0), followed by the parietal (75.8%), temporal (32.7%), and occipital lobe (7.3%). Higher Fazekas scores in the frontal, parietal, and temporal lobe were associated with higher blood pressure and antihypertensive treatment in unadjusted ordinal regression models and in models adjusted for age, sex, and vascular risk factors (e.g., age- and sex-adjusted odds ratio = 1.14, 95% confidence interval = 1.03-1.25 for the association of frontal lobe WMH Fazekas score with systolic blood pressure [SBP] [per 10 mm Hg]; 1.13 [1.02-1.23] for the association of parietal lobe score with SBP; 1.72 [1.19-2.48] for the association of temporal lobe score with antihypertensive medications). In linear regressions, higher frontal lobe scores were associated with lower performance in executive function and non-verbal memory, and higher parietal lobe scores were associated with lower performance in executive function, verbal-, and non-verbal memory.

CONCLUSIONS

Hypertension promotes WMH in the frontal, parietal, and temporal lobe. WMH in the frontal and parietal lobe are associated with reduced executive function and memory.

Investigating changes in blood-cerebrospinal fluid barrier function in a rat model of chronic hypertension using non-invasive magnetic resonance imaging

Chronic hypertension is a major risk factor for the development of neurodegenerative disease, yet the etiology of hypertension-driven neurodegeneration remains poorly understood. Forming a unique interface between the systemic circulation and the brain, the blood-cerebrospinal fluid barrier (BCSFB) at the choroid plexus (CP) has been proposed as a key site of vulnerability to hypertension that may initiate downstream neurodegenerative processes. However, our ability to understand BCSFB's role in pathological processes has, to date, been restricted by a lack of non-invasive functional measurement techniques. In this work, we apply a novel Blood-Cerebrospinal Fluid Barrier Arterial Spin Labeling (BCSFB-ASL) Magnetic resonance imaging (MRI) approach with the aim of detecting possible derangement of BCSFB function in the Spontaneous Hypertensive Rat (SHR) model using a non-invasive, translational technique. SHRs displayed a 36% reduction in BCSFB-mediated labeled arterial water delivery into ventricular cerebrospinal fluid (CSF), relative to normotensive controls, indicative of down-regulated choroid plexus function. This was concomitant with additional changes in brain fluid biomarkers, namely ventriculomegaly and changes in CSF composition, as measured by T1 lengthening. However, cortical cerebral blood flow (CBF) measurements, an imaging biomarker of cerebrovascular health, revealed no measurable change between the groups. Here, we provide the first demonstration of BCSFB-ASL in the rat brain, enabling non-invasive assessment of BCSFB function in healthy and hypertensive rats. Our data highlights the potential for BCSFB-ASL to serve as a sensitive early biomarker for hypertension-driven neurodegeneration, in addition to investigating the mechanisms relating hypertension to neurodegenerative outcomes.

Brain atrophy in middle age using magnetic resonance imaging scans from Japan’s health screening programme

Although health screening plays a key role in the management of chronic diseases associated with lifestyle choices, brain health is not generally monitored, remaining a black box prior to the manifestation of clinical symptoms. Japan is unique in this regard, as brain MRI scans have been widely performed for more than two decades as part of Brain Dock, a comprehensive health screening programme. A vast number of stored images (well over a million) of longitudinal scans and extensive health data are available, offering a valuable resource for investigating the prevalence of various types of brain-related health conditions occurring throughout adulthood.

In this paper, we report on the findings of our preliminary quantitative analysis of T₁-weighted MRIs of the brain obtained from 13 980 subjects from three participating sites during the period 2015–19. We applied automated segmentation analysis and observed age-dependent volume loss of various brain structures. We subsequently investigated the effects of scan protocols and the feasibility of calibration for pooling the data. Last, the degree of brain atrophy was correlated with four known risk factors of dementia; blood glucose level, hypertension, obesity, and alcohol consumption.

In this initial analysis, we identified brain ventricular volume as an effective marker of age-dependent brain atrophy, being highly sensitive to ageing and evidencing strong robustness against protocol variability. We established the normal range of ventricular volumes at each age, which is an essential first step for establishing criteria used to interpret data obtained for individual participants. We identified a subgroup of individuals at midlife with ventricles that substantially exceeded the average size. The correlation studies revealed that all four risk factors were associated with greater ventricular volumes at midlife, some of which reached highly significant sizes.

This study demonstrates the feasibility of conducting a large-scale quantitative analysis of existing Brain Dock data in Japan. It will importantly guide future efforts to investigate the prevalence of large ventricles at midlife and the potential reduction of this prevalence, and hence of dementia risk, through lifestyle changes.

Effects of Obesity, Blood Pressure, and Blood Metabolic Biomarkers on Grey Matter Brain Healthcare Quotient: A Large Cohort Study of a Magnetic Resonance Imaging Brain Screening System in Japan

This study investigated the relationship between grey matter (GM) volume and blood biomarkers, blood pressure, and obesity. We aimed to elucidate lifestyle factors that promote GM volume loss. A total of 1799 participants underwent the brain dock as a medical checkup. Data regarding blood pressure, obesity measurements, and standard blood biomarkers were obtained. Further, brain magnetic resonance imaging (MRI), including high-resolution T1-weighted imaging, was performed. We calculated the grey matter brain healthcare quotient (GM-BHQ), which represents GM volume as a deviation value. After adjusting for confounding variables, multiple regression analysis revealed that body mass index (BMI) (b = −0.28, p < 0.001), gamma-glutamyltransferase (γ-GTP) (b = −0.01, p = 0.16), and fasting blood glucose (b = −0.02, p = 0.049) were significantly correlated with GM-BHQ. Although the current cross-sectional study cannot determine a cause-and-effect relationship, elevated BMI, γ-GTP, and fasting blood glucose could promote GM volume loss.

The relationship between isolated hypertension with brain volumes in UK Biobank

BACKGROUND

Hypertension is a well-established risk factor for cognitive impairment, brain atrophy, and dementia. However, the relationship of other types of hypertensions, such as isolated hypertension on brain health and its comparison to systolic-diastolic hypertension (where systolic and diastolic measures are high), is still relatively unknown. Due to its increased prevalence, it is important to investigate the impact of isolated hypertension to help understand its potential impact on cognitive decline and future dementia risk. In this study, we compared a variety of global brain measures between participants with isolated hypertension to those with normal blood pressure (BP) or systolic-diastolic hypertension using the largest cohort of healthy individuals.

METHODS

Using the UK Biobank cohort, we carried out a cross-sectional study using 29,775 participants (mean age 63 years, 53% female) with BP measurements and brain magnetic resonance imaging (MRI) data. We used linear regression models adjusted for multiple confounders to compare a variety of global, subcortical, and white matter brain measures. We compared participants with either isolated systolic or diastolic hypertension with normotensives and then with participants with systolic-diastolic hypertension.

RESULTS

The results showed that participants with isolated systolic or diastolic hypertension taking BP medications had smaller gray matter but larger white matter microstructures and macrostructures compared to normotensives. Isolated systolic hypertensives had larger total gray matter and smaller white matter traits when comparing these regions with participants with systolic-diastolic hypertension.

CONCLUSIONS

These results provide support to investigate possible preventative strategies that target isolated hypertension as well as systolic-diastolic hypertension to maintain brain health and/or reduce dementia risk earlier in life particularly in white matter regions.

The Effect of APOE ɛ4 on the Functional Connectivity in Frontoparietal Network in Hypertensive Patients

Allele 4 of the apolipoprotein E gene (APOE ε4) and hypertension are considered risk factors for Alzheimer’s Disease (AD). The detection of differences in cognitive function and brain networks between hypertensive patients who are APOE ε4 carriers and non-carriers may help in understanding how hypertension and risk genes cumulatively impair brain function, which could provide critical insights into the genetic mechanism by which hypertension serves as a potential risk factor for cognitive decline and even AD. Using behavioral data from 233 elderly hypertensive patients and neuroimaging data from 38 of them from Beijing, China; the study aimed to assess the effects of APOE ε4 on cognition and to explore related changes in functional connectivity. Cognitively, the patients with APOE ε4 showed decreased executive function, memory and language. In the MRI sub-cohort, the frontoparietal networks in the APOE ε4 carrier group exhibited an altered pattern, mainly in the left precentral regions, inferior frontal lobe and angular gyrus. More importantly, the decline of cognitive function was correlated with abnormal FC in the left precentral regions in APOE ε4 carriers. APOE ε4 aggravated the dysfunction in frontal and parietal regions in hypertensive patients. This highlights the importance of brain protection in hypertensive patients, especially those with a genetic risk of AD.

Cerebrospinal Fluid Biomarkers, Brain Structural and Cognitive Performances Between Normotensive and Hypertensive Controlled, Uncontrolled and Untreated 70-Year-Old Adults

Background: Hypertension is an important risk factor for Alzheimer's disease (AD). The pathophysiological mechanisms underlying the relationship between AD and hypertension are not fully understood, but they most likely involve microvascular dysfunction and cerebrovascular pathology. Although previous studies have assessed the impact of hypertension on different markers of brain integrity, no study has yet provided a comprehensive comparison of cerebrospinal fluid (CSF) biomarkers and structural brain differences between normotensive and hypertensive groups in a single and large cohort of older adults in relationship to cognitive performances. Objective: The aim of the present work was to investigate the differences in cognitive performances, CSF biomarkers and magnetic resonance imaging (MRI) of brain structure between normotensive, controlled hypertensive, uncontrolled hypertensive, and untreated hypertensive older adults from the Gothenburg H70 Birth Cohort Studies. Methods: As an indicator of vascular brain pathology, we measured white matter hyperintensities (WMHs), lacunes, cerebral microbleeds, enlarged perivascular space (epvs), and fractional anisotropy (FA). To assess markers of AD pathology/neurodegeneration, we measured hippocampal volume, temporal cortical thickness on MRI, and amyloid-β42, phosphorylated tau, and neurofilament light protein (NfL) in cerebrospinal fluid. Various neuropsychological tests were used to assess performances in memory, attention/processing speed, executive function, verbal fluency, and visuospatial abilities. Results: We found more white matter pathology in hypertensive compared to normotensive participants, with the highest vascular burden in uncontrolled participants (e.g., lower FA, more WMHs, and epvs). No significant difference was found in any MRI or CSF markers of AD pathology/neurodegeneration when comparing normotensive and hypertensive participants, nor among hypertensive groups. No significant difference was found in most cognitive functions between groups. Conclusion: Our results suggest that good blood pressure control may help prevent cerebrovascular pathology. In addition, hypertension may contribute to cognitive decline through its effect on cerebrovascular pathology rather than AD-related pathology. These findings suggest that hypertension is associated with MRI markers of vascular pathology in the absence of a significant decline in cognitive functions.

Cerebral Amyloid Positivity Prediction Models Using Clinical Data in Subjects With Mild Cognitive Impairment and Dementia

OBJECTIVE

Due to high cost of amyloid imaging, its use of amyloid imaging to confirm amyloid pathology is limited in clinical practice. It is of importance to develop a model to predict cerebral amyloid positivity using clinical data obtained from a memory clinic.

METHODS

A total of 410 participants who had symptom of subjective cognitive decline and underwent amyloid PET and apolipoprotein ε (APOE) genotyping were retrospectively enrolled from January 2016 to January 2019. Models for cerebral amyloid positivity prediction were developed in all subjects, mild cognitive impairment (MCI) subjects, and Alzheimer's disease (AD) dementia subjects through multivariate logistic regression analysis. The performance of the models was assessed using receiver operating characteristic (ROC) curve analysis and the area under the curve (AUC) values.

RESULTS

Age, sex, years of education, body mass index (BMI), APOE4, and mini mental state examination score (MMSE) were selected for the final model for all subjects. The AUC value of the ROC curve was 0.775. Age, sex, years of education, BMI, and APOE4 were selected for the final model for MCI subjects. The AUC value was 0.735. Age, sex, years of education, BMI, APOE4, MMSE, and history of hypertension were selected for the final model for AD dementia subjects. The AUC value was 0.845.

CONCLUSION

This study found that models using clinical data can predict cerebral amyloid positivity according to cognitive status. These models can be useful as a screening tool predict cerebral amyloid deposition in cognitively impaired patients in a memory clinic.

Obesity and Gray Matter Volume Assessed by Neuroimaging: A Systematic Review

Obesity has become a major public and individual health problem due to its high worldwide prevalence and its relation with comorbid conditions. According to previous studies, obesity is related to an increased risk of cognitive impairment and dementia. This systematic review aims to further examine the present state of the art about the association between obesity and gray matter volume (GMV) as assessed by magnetic resonance imaging (MRI). A search was conducted in Pubmed, SCOPUS and Cochrane of those studies released before 1 February 2021 including MRIs to assess the GMVs in obese participants. From this search, 1420 results were obtained, and 34 publications were finally included. Obesity was mainly measured by the body mass index, although other common types of evaluations were used (e.g., waist circumference, waist-to-hip ratio and plasma leptin levels). The selected neuroimaging analysis methods were voxel-based morphometry (VBM) and cortical thickness (CT), finding 21 and 13 publications, respectively. There were 30 cross-sectional and 2 prospective longitudinal studies, and 2 articles had both cross-sectional and longitudinal designs. Most studies showed a negative association between obesity and GMV. This would have important public health implications, as obesity prevention could avoid a potential risk of GMV reductions, cognitive impairment and dementia.

Cerebral Structure and Function in Stroke-free Patients with Atrial Fibrillation

OBJECTIVES

Atrial fibrillation (AF) is associated with high risk of dementia and brain atrophy in stroke-free patients, but the mechanisms underlying this association remain unclear. We aimed to examine the brain volume and connectivity of paramount cognitive brain networks in stroke-free patients with AF without dementia.

MATERIALS AND METHODS

Twenty-six stroke-free patients with AF and 26 age and sex-matched subjects without AF were submitted to a 3-tesla brain structural and functional MRI. An extensive clinical evaluation excluded stroke, dementia, low cardiac output, carotid stenosis and metabolic diseases without optimal therapy. We used CHA₂DS₂-VASc score to classify the cardiovascular risk factor burden and a broad neuropsychological battery to assess the cognitive performance. Voxel based morphometry analysis of. structural MRI defined whole-brain gray and white matter volumes. Finally, we used eco-plannar MRI images to compare the differences of functional connectivity of 7 large-scale resting-state networks between AF patients and controls.

RESULTS

Taking into account the history of hypertension and heart failure, AF was associated to volume decrease of the right basal frontal lobe and right inferior cerebellum. Decreased connectivity of the ventral Default Mode Network (vDMN) was observed in the AF group. No disruption of connectivity was observed in the executive, visuospatial and salience networks.

CONCLUSION

Individuals with AF without stroke or dementia have subtle reduction of gray and white matter, restricted to frontal areas and cerebellum. These patients show decreased vDMN connectivity, without other large-scale brain network disruption.

Impact of Cardiovascular Hemodynamics on Cognitive Aging

[Figure: see text].

Higher Blood Pressure is Associated with Greater White Matter Lesions and Brain Atrophy: A Systematic Review with Meta-Analysis

BACKGROUND

To summarise and quantify the evidence on the association between Blood pressure (BP), white matter lesions (WMLs), and brain volumes.

METHOD

Electronic databases PubMed, Scopus, and Clarivate were searched in February 2020 using an established methodology and pre-determined search terms. Studies were eligible for inclusion if they reported on the association between BP and WMLs or brain volume in cognitively healthy individuals, while adjusting for age and intra-cranial volume.

RESULTS

Searches yielded 7509 articles, of which 52 (26 longitudinal and 33 cross-sectional), were eligible and had a combined sample size of 343,794 individuals. Analyses found that 93.7% of studies reported that higher BP was associated with poorer cerebral health (higher WMLs and lower brain volumes). Meta-analysis of compatible results indicated a dose-dependent relationship with every one standard deviation increase in systolic BP (SBP) above 120 mmHg being associated with a 11.2% (95% CI 2.3, 19.9, p = 0.0128) increase in WMLs and -0.13% (95% CI -0.25, -0.023, p = 0.0183) smaller hippocampal volume.

CONCLUSION

The association between BP and brain volumes appears across the full range of BP measurements and is not limited to hypertensive individuals. Higher BP in community-residing individuals is associated with poorer cerebral health.

Associations Between Brain Volumes and Cognitive Tests with Hypertensive Burden in UK Biobank

BACKGROUND

Mid-life hypertension is an established risk factor for cognitive impairment and dementia and related to greater brain atrophy and poorer cognitive performance. Previous studies often have small sample sizes from older populations that lack utilizing multiple measures to define hypertension such as blood pressure, self-report information, and medication use; furthermore, the impact of the duration of hypertension is less extensively studied.

OBJECTIVE

To investigate the relationship between hypertension defined using multiple measures and length of hypertension with brain measure and cognition.

METHODS

Using participants from the UK Biobank MRI visit with blood pressure measurements (n = 31,513), we examined the cross-sectional relationships between hypertension and duration of hypertension with brain volumes and cognitive tests using generalized linear models adjusted for confounding.

RESULTS

Compared with normotensives, hypertensive participants had smaller brain volumes, larger white matter hyperintensities (WMH), and poorer performance on cognitive tests. For total brain, total grey, and hippocampal volumes, those with greatest duration of hypertension had the smallest brain volumes and the largest WMH, ventricular cerebrospinal fluid volumes. For other subcortical and white matter microstructural regions, there was no clear relationship. There were no significant associations between duration of hypertension and cognitive tests.

CONCLUSION

Our results show hypertension is associated with poorer brain and cognitive health however, the impact of duration since diagnosis warrants further investigation. This work adds further insights by using multiple measures defining hypertension and analysis on duration of hypertension which is a substantial advance on prior analyses-particularly those in UK Biobank which present otherwise similar analyses on smaller subsets.

Interplay of White Matter Hyperintensities, Cerebral Networks, and Cognitive Function in an Adult Population: Diffusion-Tensor Imaging in the Maastricht Study

Background Lesions of cerebral small vessel disease, such as white matter hyperintensities (WMHs) in individuals with cardiometabolic risk factors, interfere with the trajectories of the white matter and eventually contribute to cognitive decline. However, there is no consensus yet about the precise underlying topological mechanism. Purpose To examine whether WMH and cognitive function are associated and whether any such association is mediated or explained by structural connectivity measures in an adult population. In addition, to investigate underlying local abnormalities in white matter by assessing the tract-specific WMH volumes and their tract-specific association with cognitive function. Materials and Methods In the prospective type 2 diabetes-enriched population-based Maastricht Study, structural and diffusion-tensor MRI was performed (December 2013 to February 2017). Total and tract-specific WMH volumes; network measures; cognition scores; and demographic, cardiovascular, and lifestyle characteristics were determined. Multivariable linear regression and mediation analyses were used to investigate the association of WMH volume, tract-specific WMH volumes, and network measures with cognitive function. Associations were adjusted for age, sex, education, diabetes status, and cardiovascular risk factors. Results A total of 5083 participants (mean age, 59 years ± 9 [standard deviation]; 2592 men; 1027 with diabetes) were evaluated. Larger WMH volumes were associated with stronger local (standardized β coefficient, 0.065; P < .001), but not global, network efficiency and lower information processing speed (standardized β coefficient, -0.073; P < .001). Moreover, lower local efficiency (standardized β coefficient, -0.084; P < .001) was associated with lower information processing speed. In particular, the relationship between WMHs and information processing speed was mediated (percentage mediated, 7.2% [95% CI: 3.5, 10.9]; P < .05) by the local network efficiency. Finally, WMH load was larger in the white matter tracts important for information processing speed. Conclusion White matter hyperintensity volume, local network efficiency, and information processing speed scores are interrelated, and local network properties explain lower cognitive performance due to white matter network alterations. © RSNA, 2020 Online supplemental material is available for this article.

Cerebral alterations in West African HIV and non-HIV adults aged ≥50: An MRI study

Objectives:

To cross-sectionally describe brain alterations in PLHIV aged above 50 years old, receiving antiretroviral treatment (ART) and living in Senegal compared to HIV-negative subjects.

Methods:

Twenty PLHIV and 26 HIV-negative subjects with comparable socio-demographic and clinical characteristics underwent an MRI exam (3D-T1 and FLAIR sequences). Global atrophy and White Matter Hyperintensities (WMH) were evaluated. After assessing the feasibility and acceptability of MRI scans in this population, we described atrophy and WHM prevalence and associated factors using logistic regressions.

Results:

Overall, 43.5% of the study sample were aged ≥60 years, 58.7% were women, and 28.3% had hypertension. The overall prevalence of atrophy and WMH was 19.6% [95% CI: 8.1–31.1] and 30.4% [95% CI: 17.1–43.7]. HIV status had no significant effect on atrophy or WMH. Unemployment and hypertension were significantly associated with atrophy, whereas women were less likely to present atrophy. Aged ≥60 years was the only factor associated with WMH.

Conclusions:

A high prevalence of atrophy and WMH was observed in West African adults aged over 50 years without a clear HIV impact. As brain MRI studies are critical to better understand cognitive and emotional outcomes, we encourage those studies in older PLHIV in West Africa.

Common Brain Structural Alterations Associated with Cardiovascular Disease Risk Factors and Alzheimer's Dementia: Future Directions and Implications

Recent reports suggest declines in the age-specific risk of Alzheimer's dementia in higher income Western countries. At the same time, investigators believe that worldwide trends of increasing mid-life modifiable risk factors [e.g., cardiovascular disease (CVD) risk factors] coupled with the growth of the world's oldest age groups may nonetheless lead to an increase in Alzheimer's dementia. Thus, understanding the overlap in neuroanatomical profiles associated with CVD risk factors and AD may offer more relevant targets for investigating ways to reduce the growing dementia epidemic than current targets specific to isolated AD-related neuropathology. We hypothesized that a core group of common brain structural alterations exist between CVD risk factors and Alzheimer's dementia. Two co-authors conducted independent literature reviews in PubMed using search terms for CVD risk factor burden (separate searches for 'cardiovascular disease risk factors', 'hypertension', and 'Type 2 diabetes') and 'aging' or 'Alzheimer's dementia' with either 'grey matter volumes' or 'white matter'. Of studies that reported regionally localized results, we found support for our hypothesis, determining 23 regions commonly associated with both CVD risk factors and Alzheimer's dementia. Within this context, we outline future directions for research as well as larger cerebrovascular implications for these commonalities. Overall, this review supports previous as well as more recent calls for the consideration that both vascular and neurodegenerative factors contribute to the pathogenesis of dementia.

Spatial distribution and cognitive impact of cerebrovascular risk-related white matter hyperintensities

OBJECTIVES

White matter hyperintensities (WMHs) are considered macroscale markers of cerebrovascular burden and are associated with increased risk of vascular cognitive impairment and dementia. However, the spatial location of WMHs has typically been considered in broad categories of periventricular versus deep white matter. The spatial distribution of WHMs associated with individual cerebrovascular risk factors (CVR), controlling for frequently comorbid risk factors, has not been systematically investigated at the population level in a healthy ageing cohort. Furthermore, there is an inconsistent relationship between total white matter hyperintensity load and cognition, which may be due to the confounding of several simultaneous risk factors in models based on smaller cohorts.

METHODS

We examined trends in individual CVR factors on total WMH burden in 13,680 individuals (aged 45-80) using data from the UK Biobank. We estimated the spatial distribution of white matter hyperintensities associated with each risk factor and their contribution to explaining total WMH load using voxel-wise probit regression and univariate linear regression. Finally, we explored the impact of CVR-related WMHs on speed of processing using regression and mediation analysis.

RESULTS

Contrary to the assumed dominance of hypertension as the biggest predictor of WMH burden, we show associations with a number of risk factors including diabetes, heavy smoking, APOE ε4/ε4 status and high waist-to-hip ratio of similar, or greater magnitude to hypertension. The spatial distribution of WMHs varied considerably with individual cerebrovascular risk factors. There were independent effects of visceral adiposity, as measured by waist-to-hip ratio, and carriage of the APOE ε4 allele in terms of the unique spatial distribution of CVR-related WMHs. Importantly, the relationship between total WMH load and speed of processing was mediated by waist-to-hip ratio suggesting cognitive consequences to WMHs associated with excessive visceral fat deposition.

CONCLUSION

Waist-to-hip ratio, diabetes, heavy smoking, hypercholesterolemia and homozygous APOE ε4 status are important risk factors, beyond hypertension, associated with WMH total burden and warrant careful control across ageing. The spatial distribution associated with different risk factors may provide important clues as to the pathogenesis and cognitive consequences of WMHs. High waist-to-hip ratio is a key risk factor associated with slowing in speed of processing. With global obesity levels rising, focused management of visceral adiposity may present a useful strategy for the mitigation of cognitive decline in ageing.

Association of White Matter Hyperintensities and Cardiovascular Disease

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

Altered brain fluid management in a rat model of arterial hypertension

Background

Proper neuronal function is directly dependent on the composition, turnover, and amount of interstitial fluid that bathes the cells. Most of the interstitial fluid is likely to be derived from ion and water transport across the brain capillary endothelium, a process that may be altered in hypertension due to vascular pathologies as endothelial dysfunction and arterial remodelling. In the current study, we investigated the effects of hypertension on the brain for differences in the water homeostasis.

Methods

Magnetic resonance imaging (MRI) was performed on a 7T small animal MRI system on male spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY) of 10 months of age. The MRI protocol consisted of T2-weighted scans followed by quantitative apparent diffusion coefficient (ADC) mapping to measure volumes of different anatomical structures and water diffusion respectively. After MRI, we assessed the spatial distribution of aquaporin 4 expression around blood vessels.

Results

MRI analysis revealed a significant reduction in overall brain volume and remarkably higher cerebroventricular volume in SHR compared to WKY. Whole brain ADC, as well as ADC values of a number of specific anatomical structures, were significantly lower in hypertensive animals. Additionally, SHR exhibited higher brain parenchymal water content. Immunohistochemical analysis showed a profound expression of aquaporin 4 around blood vessels in both groups, with a significantly larger area of influence around arterioles. Evaluation of specific brain regions revealed a decrease in aquaporin 4 expression around capillaries in the corpus callosum of SHR.

Conclusion

These results indicate a shift in the brain water homeostasis of adult hypertensive rats.

Atrial Fibrillation, Brain Volumes, and Subclinical Cerebrovascular Disease (from the Atherosclerosis Risk in Communities Neurocognitive Study [ARIC-NCS])

The aim of the present study was to investigate the association between atrial fibrillation (AF) and total and regional brain volumes among participants in the community-based Atherosclerosis Risk in Communities Neurocognitive study (ARIC-NCS). A total of 1,930 participants (130 with AF) with a mean age of 76.3 ± 5.2, who underwent 3T brain MRI scans in 2011 to 2013 were included. Prevalent AF was ascertained from study ECGs and hospital discharge codes. Brain volumes were measured using FreeSurfer image analysis software. Markers of subclinical cerebrovascular disease included lobar microhemorrhages, subcortical microhemorrhages, cortical infarcts, subcortical infarcts, lacunar infarcts, and volume of white matter hyperintensities. Linear regression models were used to assess the associations between AF status and brain volumes. In adjusted analyses, AF was not associated with markers of subclinical cerebrovascular disease. However, AF was associated with smaller regional brain volumes (including temporal, occipital, and parietal lobes; deep gray matter; Alzheimer disease signature region; and hippocampus [all p <0.05]) after controlling for demographics, cardiovascular risk factors, prevalent cardiovascular disease, and markers of subclinical cerebrovascular disease. Subgroup analysis revealed a significant interaction between AF and total brain volume with respect to age (p = 0.02), with associations between AF and smaller brain volumes being stronger for older individuals. In conclusion, AF was associated with smaller brain volumes, and the association was stronger among older individuals. This finding may be related to the longer exposure period of the older population to AF or the possibility that older people are more susceptible to the effects of AF on brain volume.

Does Gender Influence the Relationship Between High Blood Pressure and Dementia? Highlighting Areas for Further Investigation

BACKGROUND

Gender differences have been noted in studies linking blood pressure to all-cause dementia, and the two most common forms of dementia: Alzheimer's disease (AD) and vascular dementia (VaD). However, how gender modifies the relationship between blood pressure and dementia remains unclear.

OBJECTIVE

To review evidence for a gender modifying effect on the link between blood pressure and all-cause dementia.

METHODS

A systematic review was conducted according to PRISMA guidelines. Sixteen out of 256 reviewed articles met inclusion criteria.

RESULTS

For women, higher midlife systolic blood pressure (SBP) and hypertension were both associated with greater risk of all-cause dementia, AD, and VaD, in six out of seven studies. Two of these studies reported higher midlife SBP/hypertension were associated with greater risk for all-cause dementia in women, but not men. One study reported higher midlife SBP associated with greater AD risk in women, but not men. However, another study reported that midlife hypertension associated with AD risk in men, but not women. No clear gender differences were reported in the relationship between late-life high blood pressure/hypertension with all-cause dementia or AD.

CONCLUSION

Studies rarely, and inconsistently, analyzed or reported gender effects. Therefore, interpretation of available evidence regarding the role of gender in blood pressure associated dementia was difficult. Several studies indicated higher midlife SBP was associated with greater risk of all-cause dementia for women, compared to men. Future studies should evaluate women-specific aging processes that occur in midlife when considering the association between blood pressure and dementia risk.

Cardiovascular disease risk factors, tract-based structural connectomics, and cognition in older adults

Cardiovascular disease risk factors (CVD-RFs) are associated with decreased gray and white matter integrity and cognitive impairment in older adults. Less is known regarding the interplay between CVD-RFs, brain structural connectome integrity, and cognition. We examined whether CVD-RFs were associated with measures of tract-based structural connectivity in 94 non-demented/non-depressed older adults and if alterations in connectivity mediated associations between CVD-RFs and cognition. Participants (age = 68.2 years; 52.1% female; 46.8% Black) underwent CVD-RF assessment, MRI, and cognitive evaluation. Framingham 10-year stroke risk (FSRP-10) quantified CVD-RFs. Graph theory analysis integrated T1-derived gray matter regions of interest (ROIs; 23 a-priori ROIs associated with CVD-RFs and dementia), and diffusion MRI-derived white matter tractography into connectivity matrices analyzed for local efficiency and nodal strength. A principal component analysis resulted in three rotated factor scores reflecting executive function (EF; FAS, Trail Making Test (TMT) B-A, Letter-Number Sequencing, Matrix Reasoning); attention/information processing (AIP; TMT-A, TMT-Motor, Digit Symbol); and memory (CVLT-II Trials 1-5 Total, Delayed Free Recall, Recognition Discriminability). Linear regressions between FSRP-10 and connectome ROIs adjusting for word reading, intracranial volume, and white matter hyperintensities revealed negative associations with nodal strength in eight ROIs (p-values<.05) and negative associations with efficiency in two ROIs, and a positive association in one ROI (p-values<.05). There was mediation of bilateral hippocampal strength on FSRP-10 and AIP, and left rostral middle frontal gyrus strength on FSRP-10 and AIP and EF. Stroke risk plays differential roles in connectivity and cognition, suggesting the importance of multi-modal neuroimaging biomarkers in understanding age-related CVD-RF burden and brain-behavior.

Brain Morphometry and Longitudinal Relaxation Time of Spontaneously Hypertensive Rats (SHRs) in Early and Intermediate Stages of Hypertension Investigated by 3D VFA-SPGR MRI

Cerebral small vessel disease(s) (SVD) results from pathological changes of the small blood vessels in the brain and is common in older people. The diagnostic features by which SVD manifests in brain includes white matter hyperintensities, lacunes, dilated perivascular spaces, microbleeds, and atrophy. In the present study, we use in vivo magnetic resonance imaging (MRI) to characterize brain morphometry and longitudinal relaxation time (T1) of spontaneously hypertensive rats (SHRs) to study the contribution of chronic hypertension to SVD relevant pathology. Male SHR and Wistar-Kyoto (WKY) rats underwent 3D variable flip angle spoiled gradient echo brain MRI at 9.4 T at early (seven weeks old) and established (19 weeks old) stages of hypertension. The derived proton density weighted and T1 images were utilized for morphometry and to characterize T1 properties in gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF). Custom tissue probability maps were constructed for accurate computerized whole brain tissue segmentations and voxel-wise analyses. Characteristic morphological differences between the two strains included enlarged ventricles, smaller corpus callosum (CC) volumes and general 'thinning' of CC in SHR compared to WKY rats at both age groups. While we did not observe parenchymal T1 differences, the T1 of CSF was elevated in SHR compared to controls. Collectively these findings indicate that SHRs develop WM atrophy which is a clinically robust MRI biomarker associated with WM degeneration.

Vascular Risk Factors and Findings on Brain MRI of Elderly Adult American Indians: The Strong Heart Study

BACKGROUND

Clinical stroke is prevalent in American Indians, but the risk factors for cerebrovascular pathology have not been well-studied in this population. The purpose of this study was to correlate abnormalities on brain magnetic resonance imaging (MRI) with clinical risk factors in a cohort of elderly American Indians.

METHODS

Brain MRI scans from 789 participants of the Strong Heart Study were analyzed for infarcts, hemorrhage, white matter disease, and measures of cerebral atrophy including ventricular and sulcal grade and total brain volume. Clinical risk factors included measures of hypertension, diabetes, and high levels of low-density lipoprotein (LDL) cholesterol. Regression models adjusted for potential confounders were used to estimate associations between risk factors and brain MRI outcomes.

RESULTS

-Hypertension was associated with the presence of infarcts (p = 0.001), ventricle enlargement (p = 0.01), and increased white matter hyperintensity volume (p = 0.01). Diabetes was associated with increased prevalence of cerebral atrophy (p < 0.001), ventricular enlargement (p = 0.001), and sulcal widening (p = 0.001). High LDL was not significantly associated with any of the measured cranial imaging outcomes.

CONCLUSIONS

This study found risk factors for cerebrovascular disease in American Indians similar to those seen in other populations and provides additional evidence for the important roles of hypertension and diabetes in promoting cerebral infarcts and brain atrophy, respectively.

Prediction of Cerebral Amyloid With Common Information Obtained From Memory Clinic Practice

Background: Given the barriers prohibiting the broader utilization of amyloid imaging and high screening failure rate in clinical trials, an easily available and valid screening method for identifying cognitively impaired patients with cerebral amyloid deposition is needed. Therefore, we developed a prediction model for cerebral amyloid positivity in cognitively impaired patients using variables that are routinely obtained in memory clinics.

Methods: Six hundred and fifty two cognitively impaired subjects from the Korean Brain Aging Study for the Early diagnosis and prediction of Alzheimer disease (KBASE) and the Alzheimer’s Disease Neuroimaging Initiative-2 (ADNI-2) cohorts were included in this study (107 amnestic mild cognitive impairment (MCI) and 69 Alzheimer’s disease (AD) dementia patients for KBASE cohort, and 332 MCI and 144 AD dementia patients for ADNI-2 cohort). Using the cross-sectional dataset from the KBASE cohort, a multivariate stepwise logistic regression analysis was conducted to develop a cerebral amyloid prediction model using variables commonly obtained in memory clinics. For each participant, the logit value derived from the final model was calculated, and the probability for being amyloid positive, which was calculated from the logit value, was named the amyloid prediction index. The final model was validated using an independent dataset from the ADNI-2 cohort.

Results: The final model included age, sex, years of education, history of hypertension, apolipoprotein ε4 positivity, and score from a word list recall test. The model predicted that younger age, female sex, higher educational level, absence of hypertension history, presence of apolipoprotein ε4 allele, and lower score of word list recall test are associated with higher probability for being amyloid positive. The amyloid prediction index derived from the model was proven to be valid across the two cohorts. The area under the curve was 0.873 (95% confidence interval 0.815 to 0.918) for the KBASE cohort, and 0.808 (95% confidence interval = 0.769 to 0.842) for ADNI-2 cohort.

Conclusion: The amyloid prediction index, which was based on commonly available clinical information, can be useful for screening cognitively impaired individuals with a high probability of amyloid deposition in therapeutic trials for early Alzheimer’s disease as well as in clinical practice.

Cardiovascular disease and brain health: Focus on white matter hyperintensities

Diseases affecting the brain contribute to a substantial proportion of morbidity and mortality in the general population. Conditions such as stroke, dementia and cognitive impairment have a prominent impact on global public health. Despite the heterogeneous clinical manifestations of these conditions and their diverse prognostic implications, current evidence supports a role for cardiovascular disease as a common pathophysiological ground. Brain white matter hyperintensities (WMH) are patchy white matter signal hyperintensity on T2-weighted magnetic resonance imaging sequences commonly found in elderly individuals. WMH appear to have a vascular pathogenesis and have been shown to confer an increased risk of stroke and cognitive decline. Indeed, they were proposed as a marker for central nervous system frailty. Cardiovascular diseases seem to play a key role in the etiology of WMH. Carotid atherosclerosis and atrial fibrillation were shown to be associated with higher WMH burden, while adequate blood pressure control has been reported reducing WMH progression. Aim of the present work is to review the available evidence linking WMH to cardiovascular disease, highlighting the complex interplay between cerebral and cardiovascular health.

Atrial fibrillation and cognitive decline in the Framingham Heart Study

BACKGROUND

There is a paucity of longitudinal research investigating the relations between atrial fibrillation (AF) and domain-specific cognitive performance.

OBJECTIVE

The purpose of this study was to investigate the association between AF and cognitive performance cross-sectionally and longitudinally.

METHODS

Eligible participants were dementia- and stroke-free at the time of baseline neuropsychological (NP) assessment and underwent at least 1 additional NP assessment with at least 1-year inter-test interval. AF status was examined as a 2-level variable (prevalent AF, no AF) in cross-sectional analyses and then separately as a 3-level variable (prevalent AF, interim AF, no AF) in longitudinal analyses. We examined the association between AF status and cognitive performance with linear regression. We first adjusted models for age and sex and then for vascular risk factors and apolipoprotein ε4 (APOE4) status.

RESULTS

We studied 2682 participants of the Framingham Heart Study original and offspring cohorts. At the baseline NP assessment, 112 participants (4%) had AF (mean age 72 ± 9 years; 32% women). After adjustment for vascular risk factors and APOE4 status, prevalent AF was significantly associated with poorer attention; sex differences were also noted with men performing worse on tests of abstract reasoning and executive function, while women did better on a measure of executive function. Prevalent AF was significantly associated with longitudinal decline in executive function in the original cohort, and interim AF was significantly associated with longitudinal decline in executive function in the offspring cohort.

CONCLUSION

After accounting for vascular risk factor burden and APOE4 status, AF was associated with a vascular profile of change in cognitive function.

Synucleinopathies: common features and hippocampal manifestations

Parkinson's disease (PD), dementia with Lewy Bodies (DLB), and multiple system atrophy (MSA) are three major synucleinopathies characterized by α-synuclein-containing inclusions in the brains of patients. Because the cell types and brain structures that are affected vary markedly between the disorders, the patients have different clinical manifestations in addition to some overlapping symptoms, which are the basis for differential diagnosis. Cognitive impairment and depression associated with hippocampal dysfunction are frequently observed in these disorders. While various α-synuclein-containing inclusions are found in the hippocampal formation, increasing evidence supports that small α-synuclein aggregates or oligomers may be the real culprit, causing deficits in neurotransmission and neurogenesis in the hippocampus and related brain regions, which constitute the major mechanism for the hippocampal dysfunctions and associated neuropsychiatric manifestations in synucleinopathies.

Association between atrial fibrillation and volumetric magnetic resonance imaging brain measures: Framingham Offspring Study

BACKGROUND

The increased risk of stroke and cognitive impairment associated with atrial fibrillation (AF) is well documented. However, there is a paucity of research investigating the relations between AF and brain morphology.

OBJECTIVE

The purpose of this study was to investigate the association between AF and brain volume measures on magnetic resonance imaging (MRI).

METHODS

The study sample included stroke- and dementia-free participants who attended the Framingham Heart Study offspring cohort 7th examination cycle (1999-2005) and underwent contemporaneous MRI. We examined the association between prevalent AF and brain volume measures (total cerebral volume, frontal lobe volume, temporal lobe volume, temporal horn volume, hippocampal volume, and white matter hyperintensity volume) with linear regression. We first adjusted models for age and sex, and then for vascular risk factors and APOE4.

RESULTS

We studied 2144 individuals (mean age 61.8 ± 9.3 years; 54% women); 73 participants (3.4%) had prevalent AF at the time of MRI. In age- and sex-adjusted models, AF was inversely associated with total cerebral brain volume, frontal brain volume, and temporal brain volume. After further adjustment for vascular risk factors and APOE4, AF remained associated with frontal brain volume.

CONCLUSION

After accounting for vascular risk factor burden, prevalent AF was associated with lobar indexes of vascular brain aging but not with expected white matter changes.

Determinants of cerebral white matter changes in patients with stroke

BACKGROUND/AIM

Cerebral white matter changes (WMC) are commonly observed in magnetic resonance imaging (MRI) scans of elderly people. Information about the prevalence of WMC is limited, and little is known about site-specific risk factors for the subcortical and periventricular regions in patients with ischaemic stroke. The study aims to analyse the prevalence and severity of WMC and investigate the risk factors of periventricular WMC (PVWMC) and deep WMC (DWMC) separately in patients with ischaemic stroke.

METHODS

The data were collected between January and December 2013 from a medical centre in southern Taiwan. Every patient underwent a cerebral MRI scan, and WMC was separately rated as PVWMC and DWMC by using the modified Fazekas scale.

RESULTS

In total, 527 patients who had experienced ischaemic stroke were included. The mean age of the patients was 67.0 ± 12.5 years (range: 31-94) and 62% of them were men. The mean age was significantly different among the four grades of severity in both the PVWMC (P < 0.001) and DWMC (P < 0.001) groups after adjustments for sex and vascular risk factors. Hypertension was independently correlated with severity of DWMC (P = 0.032) but not with PVWMC (P = 0.222). In multiple logistic regressions model, hypertension was a significant independent indicator of DWMC (odds ratio = 4.30; 95% confidence interval = 1.70-10.89).

CONCLUSION

Our results suggest a region-specific pathogenesis of cerebral white matter in Asian patients with ischaemic stroke that may differ from those in the general population.

Disrupted Frontoparietal Network Mediates White Matter Structure Dysfunction Associated with Cognitive Decline in Hypertension Patients

Some previous reports have suggested that hypertension is a risk factor for dementia and cognitive impairments. Using behavioral data from 1007 elderly human subjects (405 hypertensive patients) of Han ethnicity from Beijing, China, the present study aimed to assess the effects of hypertension on cognitive performance and explore related neuronal changes via advanced resting-state functional magnetic resonance imaging and diffusion tensor imaging data from 84 of these subjects (44 hypertensive patients). Cognitively, we found that patients with hypertension showed decreased executive functions and attention compared with those with normotension in the large sample. In magnetic resonance imaging scan sample, using independent component analysis to examine the functional connectivity difference between the two groups, we found that the frontoparietal networks in the hypertensive group exhibited altered patterns compared with the control group, mainly in the inferior parietal lobe, left inferior frontal lobe, and precuneus. Using tract-based spatial statistics to investigate the between-group structural difference, we found that the hypertensive group showed significantly reduced integrity of white matter in the bilateral superior longitudinal fasciculus. Importantly, using the mediation analysis, we found that the functional connectivity of the frontoparietal networks mediates the impact of white matter on executive function in the hypertensive group. The results demonstrate that hypertension targets a specific pattern of cognitive decline, possibly due to deficits in the white matter and functional connectivity in frontal and parietal lobes. Our findings highlight the importance of brain protection in hypertension.

SIGNIFICANCE STATEMENT

Hypertension is a risk factor for cognitive decline and dementia. However, the neural mechanism underlying cognitive decline in hypertension is largely unknown. We studied the relationship among cognitive decline, brain functional, and structural changes in hypertensive patients via advanced resting-state functional magnetic resonance imaging and diffusion tensor imaging data in a Chinese cohort. Hypertensive patients showed executive dysfunction, along with disrupted functional connectivity in frontoparietal (FP) networks and reduced integrity of white matter in the bilateral superior longitudinal fasciculus. Importantly, the functional connectivity changes mediate the impact of white matter alterations on cognitive decline in the hypertensive group. Our findings provide a better understanding of the mechanism of cognitive decline in hypertension and highlight the importance of brain protection in hypertension.

Lower Blood Pressure Is Associated With Smaller Subcortical Brain Volumes in Older Persons

BACKGROUND

Both high and low blood pressure (BP) have been positively as well as negatively associated with brain volumes in a variety of populations. The objective of this study was to investigate whether BP is associated with cortical and subcortical brain volumes in older old persons with mild cognitive deficits.

METHODS

Within the Discontinuation of Antihypertensive Treatment in the Elderly trial, the cross-sectional relation of BP parameters with both cortical and subcortical brain volumes was investigated in 220 older old persons with mild cognitive deficits (43% men, mean age = 80.7 (SD = 4.1), median Mini-Mental State Examination score = 26 (interquartile range: 25-27)), using linear regression analysis. All analyses were adjusted for age, gender, volume of white matter hyperintensities, and duration of antihypertensive treatment. Brain volumes were determined on 3DT1-weighted brain magnetic resonance imaging scans.

RESULTS

Lower systolic BP, diastolic BP, and mean arterial pressure (MAP) were significantly associated with lower volumes of thalamus and putamen (all P ≤ 0.01). In addition, lower MAP was also associated with reduced hippocampal volume (P = 0.035). There were no associations between any of the BP parameters with cortical gray matter or white matter volume.

CONCLUSION

In an older population using antihypertensive medication with mild cognitive deficits, a lower BP, rather than a high BP is associated with reduced volumes of thalamus, putamen, and hippocampus.

Brain imaging changes associated with risk factors for cardiovascular and cerebrovascular disease in asymptomatic patients

Reviews of imaging studies assessing the brain effects of vascular risk factors typically include a substantial number of studies with subjects with a history of symptomatic cardiovascular or cerebrovascular disease and/or events, limiting our ability to disentangle the primary brain effects of vascular risk factors from those of resulting brain and cardiac damage. The objective of this study was to perform a systematic review of brain changes from imaging studies in patients with vascular risk factors but without clinically manifest cardiovascular or cerebrovascular disease or events. The 77 studies included in this review demonstrate that in persons without symptomatic cardiovascular, cerebrovascular, or peripheral vascular disease, the vascular risk factors of hypertension, diabetes mellitus, obesity, hyperlipidemia, and smoking are all independently associated with brain imaging changes before the clinical manifestation of cardiovascular or cerebrovascular disease. We conclude that the identification of brain changes associated with vascular risk factors, before the manifestation of clinically significant cerebrovascular damage, presents a window of opportunity wherein adequate treatment of these modifiable vascular risk factors may prevent the development of irreversible deleterious brain changes and potentially alter patients' clinical course.

Lifetime hypertension as a predictor of brain structure in older adults: cohort study with a 28-year follow-up

BACKGROUND

Hypertension is associated with an increased risk of dementia and depression with uncertain longitudinal associations with brain structure.

AIMS

To examine lifetime blood pressure as a predictor of brain structure in old age.

METHOD

A total of 190 participants (mean age 69.3 years) from the Whitehall II study were screened for hypertension six times (1985-2013). In 2012-2013, participants had a 3T-magnetic resonance imaging (MRI) brain scan. Data from the MRI were analysed using automated and visual measures of global atrophy, hippocampal atrophy and white matter hyperintensities.

RESULTS

Longitudinally, higher mean arterial pressure predicted increased automated white matter hyperintensities (P<0.002). Cross-sectionally, hypertensive participants had increased automated white matter hyperintensities and visually rated deep white matter hyperintensities. There was no significant association with global or hippocampal atrophy.

CONCLUSIONS

Long-term exposure to high blood pressure predicts hyperintensities, particularly in deep white matter. The greatest changes are seen in those with severe forms of hypertension, suggesting a dose-response pattern.

Longitudinal systolic blood pressure characteristics and integrity of white matter tracts in a cohort of very old black and white adults

BACKGROUND

We sought to determine which systolic blood pressure (SBP) characteristics are associated with reduced brain integrity and whether these associations are stronger for white or gray matter. We hypothesized that exposure to higher and variable SBP will be associated with lower structural integrity of both gray and white matter.

METHODS

Neuroimaging, SBP, and cognition were obtained in 311 community-dwelling adults in 2006–2008 (average age = 83 years; 58% women; 40% black). Antihypertensive medications, SBP, and health-related factors were collected from 1997 to 1998 to time of neuroimaging. SBP values obtained from 1997 to 1998 to time of neuroimaging were used to compute mean; pulse pressure; coefficient of variation; and peak, load, and group-based trajectories.

RESULTS

Higher mean SBP was associated with lower white matter integrity in uncinate and superior lateral fasciculi bilaterally, independent of age, stroke history, antihypertensive medication use (odds ratio of having white matter hyperintensities greater than or equal to the median for 10mm Hg of SBP = 10.4, 95% confidence interval = 10.2–10.6, P = 0.0001; standardized beta for fractional anisotropy = −13.54, SE = 4.58, P = 0.003). These neuroimaging markers attenuated the association between higher SBP and lower digit symbol substitution test. Results were similar for trajectories of SBP and stronger for those with previously higher and variable SBP even if SBP was normal at neuroimaging. Results were similar for those without stroke. Associations with gray matter measures were not significant.

CONCLUSIONS

If confirmed, these data suggest a history of higher and variable SBP for very old adults may be useful to alert clinicians to potential lower integrity in selected tracts, whereas cross-sectional SBP measurements may obscure the risk of underlying white matter hyperintensities. Whether lowering and/or stabilizing SBP levels in very old adults without a remarkable cardiovascular history would have neuroprotective effects and reduce dementia risk needs further study.

Estrogens are neuroprotective factors for hypertensive encephalopathy

Estrogens are neuroprotective factors for brain diseases, including hypertensive encephalopathy. In particular, the hippocampus is highly damaged by high blood pressure, with several hippocampus functions being altered in humans and animal models of hypertension. Working with a genetic model of primary hypertension, the spontaneously hypertensive rat (SHR), we have shown that SHR present decreased dentate gyrus neurogenesis, astrogliosis, low expression of brain derived neurotrophic factor (BDNF), decreased number of neurons in the hilus of the dentate gyrus, increased basal levels of the estrogen-synthesizing enzyme aromatase, and atrophic dendritic arbor with low spine density in the CA1 region compared to normotensive Wistar Kyoto (WKY) ratsl. Changes also occur in the hypothalamus of SHR, with increased expression of the hypertensinogenic peptide arginine vasopressin (AVP) and its V1b receptor. Following chronic estradiol treatment, SHR show decreased blood pressure, enhanced hippocampus neurogenesis, decreased the reactive astrogliosis, increased BDNF mRNA and protein expression in the dentate gyrus, increased neuronal number in the hilus of the dentate gyrus, further increased the hyperexpression of aromatase and replaced spine number with remodeling of the dendritic arbor of the CA1 region. We have detected by qPCR the estradiol receptors ERα and ERβ in hippocampus from both SHR and WKY rats, suggesting direct effects of estradiol on brain cells. We hypothesize that a combination of exogenously given estrogens plus those locally synthesized by estradiol-stimulated aromatase may better alleviate the hippocampal and hypothalamic encephalopathy of SHR. This article is part of a Special Issue entitled "Sex steroids and brain disorders".

Physical activity, body mass index, and brain atrophy in Alzheimer's disease

The purpose of this study was to use a novel imaging biomarker to assess associations between physical activity (PA), body mass index (BMI), and brain structure in normal aging, mild cognitive impairment, and Alzheimer's dementia. We studied 963 participants (mean age: 74.1 ± 4.4 years) from the multisite Cardiovascular Health Study including healthy controls (n = 724), Alzheimer's dementia patients (n = 104), and people with mild cognitive impairment (n = 135). Volumetric brain images were processed using tensor-based morphometry to analyze regional brain volumes. We regressed the local brain tissue volume on reported PA and computed BMI, and performed conjunction analyses using both variables. Covariates included age, sex, and study site. PA was independently associated with greater whole brain and regional brain volumes and reduced ventricular dilation. People with higher BMI had lower whole brain and regional brain volumes. A PA-BMI conjunction analysis showed brain preservation with PA and volume loss with increased BMI in overlapping brain regions. In one of the largest voxel-based cross-sectional studies to date, PA and lower BMI may be beneficial to the brain across the spectrum of aging and neurodegeneration.

Small vessel disease and memory loss: what the clinician needs to know to preserve patients' brain health

Small vessel disease (SVD) in the brain manifests in the periventricular and deep white matter and radiographically is described as "leukoaraiosis". It is increasingly recognized as a cause of morbidity from middle age onward and this clinical relevance has paralleled advances in the field of neuroradiology. Overall, SVD is a heterogenous group of vascular disorders that may be asymptomatic, or a harbinger of many conditions that jeopardize brain health. Management and prevention focuses on blood pressure control, lifestyle modification, and symptomatic treatment.

Long-term survival in adults 65 years and older with white matter hyperintensity: association with performance on the digit symbol substitution test

OBJECTIVE

White matter hyperintensity (WMH) confers increased mortality risk in patients with cardiovascular diseases. However, little is known about differences in survival times among adults 65 years and older who have WMH and live in the community. To characterize the factors that may reduce mortality risk in the presence of WMH, measures of race, sex, apolipoprotein E4, neuroimaging, and cardiometabolic, physiological, and psychosocial characteristics were examined, with a particular focus on information processing as measured by the Digit Symbol Substitution Test (DSST).

METHODS

Cox proportional models were used to estimate mortality risks in a cohort of 3513 adults (74.8 years, 58% women, 84% white) with WMH (0-9 points), DSST (0-90 points), risk factor assessment in 1992 to 1994, and data on mortality and incident stroke in 2009 (median follow-up [range] = 14.2 [0.5-18.1] years).

RESULTS

WMH predicted a 48% greater mortality risk (age-adjusted hazard ratio [HR; 95% confidence interval {CI}] for WMH >3 points = 1.48 [1.35-1.62]). This association was attenuated after adjustment for DSST (HR [CI] = 1.38 [1.27-1.51]) or lacunar infarcts (HR [CI] = 1.37 [1.25,1.50]) but not after adjustment for other factors. The interaction between DSST and WMH was significant (p = .011). In fully adjusted models stratified by WMH of 3 or higher, participants with DSST greater than or equal to median had a 34% lower mortality risk among those with WMH of 3 or higher (n = 532/1217) and a 28% lower mortality risk among those with WMH lower than 3 (n = 1364/2296), compared with participants with DSST less than median (HR [95% CI] = 0.66 [0.55-0.81] and 0.72 [0.62-0.83], respectively).

CONCLUSIONS

WMH is associated with increased long-term mortality risk in community-dwelling adults 65 years and older. The increased risk is attenuated for those with higher DSST. Assessment of cognitive function with DSST may improve risk stratification of individuals with WMH.