Obesity, Insulin Resistance, and Incident Small Vessel Disease on Magnetic Resonance Imaging: Atherosclerosis Risk in Communities Study

Cross-sectional association of continuous glucose monitoring-derived metrics with cerebral small vessel disease in older adults with type 2 diabetes

AIM

To examine cross-sectional associations between continuous glucose monitoring (CGM)-derived metrics and cerebral small vessel disease (SVD) in older adults with type 2 diabetes.

MATERIALS AND METHODS

In total, 80 patients with type 2 diabetes aged ≥70 years were analysed. Participants underwent CGM for 14 days. From the CGM data, we derived mean sensor glucose, percentage glucose coefficient of variation, mean amplitude of glucose excursion, time in range (TIR, 70-180 mg/dl), time above range (TAR) and time below range metrics, glycaemia risk index and high/low blood glucose index. The presence of cerebral SVD, including lacunes, microbleeds, enlarged perivascular spaces and white matter hyperintensities, was assessed, and the total number of these findings comprised the total cerebral SVD score (0-4). Ordinal logistic regression analyses were performed to examine the association of CGM-derived metrics with the total SVD score.

RESULTS

The median SVD score was 1 (interquartile range 0-2). Higher hyperglycaemic metrics, including mean sensor glucose, TAR >180 mg/dl, TAR >250 mg/dl, and high blood glucose index and glycaemia risk index, were associated with a higher total SVD score. In contrast, a higher TIR (per 10% increase) was associated with a lower total SVD score (odds ratio 0.73, 95% confidence interval 0.56-0.95). Glycated haemoglobin, percentage glucose coefficient of variation, mean amplitude of glucose excursions, time below range and low blood glucose index were not associated with total cerebral SVD scores.

CONCLUSIONS

The hyperglycaemia metrics and TIR, derived from CGM, were associated with cerebral SVD in older adults with type 2 diabetes.

Atherosclerotic burden and cerebral small vessel disease: exploring the link through microvascular aging and cerebral microhemorrhages

Cerebral microhemorrhages (CMHs, also known as cerebral microbleeds) are a critical but frequently underestimated aspect of cerebral small vessel disease (CSVD), bearing substantial clinical consequences. Detectable through sensitive neuroimaging techniques, CMHs reveal an extensive pathological landscape. They are prevalent in the aging population, with multiple CMHs often being observed in a given individual. CMHs are closely associated with accelerated cognitive decline and are increasingly recognized as key contributors to the pathogenesis of vascular cognitive impairment and dementia (VCID) and Alzheimer's disease (AD). This review paper delves into the hypothesis that atherosclerosis, a prevalent age-related large vessel disease, extends its pathological influence into the cerebral microcirculation, thereby contributing to the development and progression of CSVD, with a specific focus on CMHs. We explore the concept of vascular aging as a continuum, bridging macrovascular pathologies like atherosclerosis with microvascular abnormalities characteristic of CSVD. We posit that the same risk factors precipitating accelerated aging in large vessels (i.e., atherogenesis), primarily through oxidative stress and inflammatory pathways, similarly instigate accelerated microvascular aging. Accelerated microvascular aging leads to increased microvascular fragility, which in turn predisposes to the formation of CMHs. The presence of hypertension and amyloid pathology further intensifies this process. We comprehensively overview the current body of evidence supporting this interconnected vascular hypothesis. Our review includes an examination of epidemiological data, which provides insights into the prevalence and impact of CMHs in the context of atherosclerosis and CSVD. Furthermore, we explore the shared mechanisms between large vessel aging, atherogenesis, microvascular aging, and CSVD, particularly focusing on how these intertwined processes contribute to the genesis of CMHs. By highlighting the role of vascular aging in the pathophysiology of CMHs, this review seeks to enhance the understanding of CSVD and its links to systemic vascular disorders. Our aim is to provide insights that could inform future therapeutic approaches and research directions in the realm of neurovascular health.

Higher HbA1c Is Associated With Greater 2-Year Progression of White Matter Hyperintensities

White matter hyperintensity (WMH) lesions on brain MRI images are surrogate markers of cerebral small vessel disease. Longitudinal studies examining the association between diabetes and WMH progression have yielded mixed results. Thus, in this study, we investigated the association between HbA1c, a biomarker for the presence and severity of hyperglycemia, and longitudinal WMH change after adjusting for known risk factors for WMH progression. We recruited 64 participants from South Korean memory clinics to undergo brain MRI at the baseline and a 2-year follow-up. We found the following. First, higher HbA1c was associated with greater global WMH volume (WMHV) changes after adjusting for known risk factors (β = 7.7 × 10-4; P = 0.025). Second, the association between baseline WMHV and WMHV progression was only significant at diabetic levels of HbA1c (P < 0.05, when HbA1c >6.51%), and non-apolipoprotein E (APOE) ε4 carriers had a stronger association between HbA1c and WMHV progression (β = -2.59 × 10-3; P = 0.004). Third, associations of WMHV progression with HbA1c were particularly apparent for deep WMHV change (β = 7.17 × 10-4; P < 0.01) compared with periventricular WMHV change and, for frontal (β = 5.00 × 10-4; P < 0.001) and parietal (β = 1.53 × 10-4; P < 0.05) lobes, WMHV change compared with occipital and temporal WMHV change. In conclusion, higher HbA1c levels were associated with greater 2-year WMHV progression, especially in non-APOE ε4 participants or those with diabetic levels of HbA1c. These findings demonstrate that diabetes may potentially exacerbate cerebrovascular and white matter disease.

ARTICLE HIGHLIGHTS

Blood urea nitrogen to albumin ratio is associated with cerebral small vessel diseases

Blood urea nitrogen (BUN) to albumin ratio (BAR) is a comprehensive parameter that reflects renal, inflammatory, nutritional, and endothelial functions. BAR has been shown to be associated with various cancers, pneumonia, sepsis, and pulmonary and cardiovascular diseases; however, few studies have been conducted on its association with cerebrovascular diseases. In this study, we evaluated the association between BAR and cerebral small vessel disease (cSVD) in health check-up participants. We assessed consecutive health check-up participants between January 2006 and December 2013. For the cSVD subtype, we quantitatively measured the volume of white matter hyperintensity (WMH) and qualitatively measured the presence of lacune and cerebral microbleeds (CMBs). The BAR was calculated by dividing BUN by albumin as follows: BAR = BUN (mg/dl)/albumin (g/dl). A total of 3012 participants were evaluated. In multivariable linear regression analysis, BAR showed a statistically significant association with WMH volume after adjusting for confounders [β = 0.076, 95% confidence interval (CI): 0.027-0.125]. In multivariable logistic regression analyses, BAR was significantly associated with lacunes [adjusted odds ratio (aOR) = 1.20, 95% CI: 1.00-1.44] and CMBs (aOR = 1.28, 95% CI: 1.06-1.55). BAR was associated with all types of cSVD in the health check-up participants.

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.

Associations between adiposity and white matter hyperintensities: Cross-sectional and longitudinal analyses of 34,653 participants

OBJECTIVES

White matter hyperintensities (WMH) increase the risk of stroke and cognitive impairment. This study aims to determine the cross-sectional and longitudinal associations between adiposity and WMH.

METHODS

Participants were enrolled from the UK Biobank cohort. Associations of concurrent, past, and changes in overall and central adiposity with WMH were investigated by linear and nonlinear regression models. The association of longitudinal adiposity and WMH volume changes was determined by a linear mixed model. Mediation analysis investigated the potential mediating effect of blood pressure.

RESULTS

In 34,653 participants with available adiposity measures and imaging data, the concurrent obese group had a 25.3% (β [95% CI] = 0.253 [0.222-0.284]) higher WMH volume than the ideal weight group. Increment in all adiposity measures was associated with a higher WMH volume. Among them, waist circumference demonstrated the strongest effect (β [95% CI] = 0.113 [0.101-0.125]). Past adiposity also demonstrated similar effects. Among the subset of 2664 participants with available WMH follow-up data, adiposity measures were predictive of WMH change. Regarding changes of adiposity, compared with ideal weight stable group, those who turned from ideal weight to overweight/obese had a 8.1% higher WMH volume (β [95% CI] = 0.081 [0.039-0.123]), while participants who turned from overweight/obese to ideal weight demonstrated no significant WMH volume change. Blood pressure partly meditates the associations between adiposity and WMH.

CONCLUSIONS

Both concurrent and past adiposity were associated with a higher WMH volume. The detrimental effects of adiposity on WMH occurred throughout midlife and in the elderly and may still exist after changes in obesity status.

Correlation between body composition and white matter hyperintensity in patients with acute ischemic stroke

White matter hyperintensity (WMH) burden is associated with a higher risk of ischemic stroke. The relationship between WMH and obesity is somewhat controversial which might be interfered by different body composition such as skeletal muscle, fat and bone density. However, few researchers have evaluated the relationship between WMH burden and disaggregated body constituents in acute ischemic stroke (AIS) patients systematically. A total of 352 AIS patients were enrolled in this study. The subcutaneous adipose tissue, erector spinae muscle area and bone density were evaluated on the computed tomography scanning. The burden of WMH was evaluated using the Fazekas scale based on the fluid-attenuated inversion recovery sequence. The severity of overall WMH was defined as none-mild WMH (total Fazekas score 0-2) or moderate-severe WMH (total Fazekas score 3-6). Based on the severity of periventricular WMH (P-WMH) and deep WMH, patients were categorized into either a none-mild (Fazekas score 0-1) group or a moderate-severe (Fazekas score 2-3) group. We found that patients with moderate-severe WMH showed lower bone density and smaller erector spinae muscle area and subcutaneous adipose tissue than none-mild. The logistic regression analysis showed that the bone density was independently associated with moderate-severe overall WMH (odds radio = 0.98, 95% confidence interval, 0.972-0.992, P < .001) and similar results were found in the analyses according to P-WMH (odds radio = 0.98, 95% confidence interval, 0.972-0.992, P < .001). These findings suggest that among the AIS body composition, the bone density is independently associated with the severity of overall WMH and P-WMH.

Dementia risk in patients with type 2 diabetes: Comparing metformin with no pharmacological treatment

INTRODUCTION

Metformin has been suggested as a therapeutic agent for dementia, but the relevant evidence has been partial and inconsistent.

METHODS

We established a national cohort of 210,237 type 2 diabetes patients in the UK Clinical Practice Research Datalink. Risks of incident dementia were compared between metformin initiators and those who were not prescribed any anti-diabetes medication during follow-up.

RESULTS

Compared with metformin initiators (n = 114,628), patients who received no anti-diabetes medication (n = 95,609) had lower HbA1c and better cardiovascular health at baseline. Both Cox regression and propensity score weighting analysis showed metformin initiators had lower risk of dementia compared to those non-users (adjusted hazard ratio = 0.88 [95% confidence interval: 0.84-0.92] and 0.90 [0.84-0.96]). Patients on long-term metformin treatment had an even lower risk of dementia.

DISCUSSION

Metformin may act beyond its glycemic effect and reduce dementia risk to an even lower level than that of patients with milder diabetes and better health profiles.

HIGHLIGHTS

Metformin initiators had a significantly lower risk of dementia compared with patients not receiving anti-diabetes medication. Compared with metformin initiators, diabetes patients not receiving pharmacological treatment had better glycemic profiles at baseline and during follow-up. Patients on long-term metformin treatment had an even lower risk of subsequent dementia incidence. Metformin may act beyond its effect on hyperglycemia and has the potential of being repurposed for dementia prevention.

Exploring the Role of Insulin Resistance in Fueling Stroke Vulnerability and Worsening Post-stroke Prognosis: A Narrative Review of Current Literature

Stroke remains one of the world's greatest causes of disability and death. Insulin resistance (IR) impairs insulin's beneficial effects on the brain and can change the course of illness in post-stroke patients. This review aims to find sufficient evidence to support the causal association of IR in ischemic stroke and with post-stroke prognosis (PSP). The review will also list probable mechanisms to better understand how IR affects stroke pathology. Various articles from PubMed Central, MEDLINE, and PubMed databases were reviewed, and then after careful consideration, 17 articles were selected. The studies, using various genetic and metabolic markers, have linked IR to increased incidence of ischemic stroke. Among the various types of strokes investigated from this standpoint, silent lacunar infarct stands out as a widely researched subtype. Even though the exact pathogenesis is still unclear, current evidence shows an interplay of atherosclerosis, embolism, and platelet dysfunction. The development of early neurological decline (END) in post-stroke patients has been used to link IR to poor PSP. It is also acknowledged to have contributed in some way to poor three-month outcomes. Modifying inflammatory pathways and developing glucotoxicity are some of the pathways by which IR affects PSP. After reviewing the studies, significant evidence was found to support the role of IR in causing ischemic stroke as well as in poor PSP. Additional investigation is required to assess its influence on three-month prognosis and its significance in various stroke subcategories.

Correlation between insulin resistance and cerebral microbleeds among Chinese patients with cerebral small vessel disease

BACKGROUND AND OBJECTIVES

Insulin resistance (IR) plays an important role in the pathogenesis of cerebral small vessel disease (CSVD); however, little is known about the relationship between IR and the incidence of cerebral microbleeds (CMBs) in Asian populations. The aim of this study is to investigate the relationship between CMBs and IR in Chinese patients with CSVD.

METHODS

This retrospective study included 240 patients with CSVD. Patients were categorized by the homeostatic model assessment of insulin resistance (HOMA-IR): Quartile 1 (≤1.26), Quartile 2 (1.27-1.92), Quartile 3 (1.93-2.89), and Quartile 4 (>2.89). The medical record of each patient was reviewed, and demographic, clinical and laboratory information was abstracted. All patients completed an MRI scan, and CMBs were defined as round or ovoid hypointense lesions on SWI sequence.

RESULTS

CMBs were present in 82 (34.17%) of the 240 patients that were included in the study (mean age, 71 years; male, 54.89%). After adjustment for potential confounding variables, insulin resistance was associated with the presence of CMBs (adjusted odds ratio 2.298, 95% confidence interval 1.017-5.194 for Q4:Q1; P = 0.046). According to receiver operating characteristic analysis, the best discriminating factor for CMBs was a HOMA-IR level ≥2.215 (area under the curve 0.595; sensitivity 51.2%; specificity 65.2%).

CONCLUSIONS

IR is significantly associated with the presence of CMBs, suggesting the potential role of IR as a predictive marker for CMBs in patients with CSVD.

Insulin Resistance and Cognitive Impairment: Evidence From Neuroimaging

Insulin is a peptide well known for its role in regulating glucose metabolism in peripheral tissues. Emerging evidence from human and animal studies indicate the multifactorial role of insulin in the brain, such as neuronal and glial metabolism, glucose regulation, and cognitive processes. Insulin resistance (IR), defined as reduced sensitivity to the action of insulin, has been consistently proposed as an important risk factor for developing neurodegeneration and cognitive impairment. Although the exact mechanism of IR-related cognitive impairment still awaits further elucidation, neuroimaging offers a versatile set of novel contrasts to reveal the subtle cerebral abnormalities in IR. These imaging contrasts, including but not limited to brain volume, white matter (WM) microstructure, neural function and brain metabolism, are expected to unravel the nature of the link between IR, cognitive decline, and brain abnormalities, and their changes over time. This review summarizes the current neuroimaging studies with multiparametric techniques, focusing on the cerebral abnormalities related to IR and therapeutic effects of IR-targeting treatments. According to the results, brain regions associated with IR pathophysiology include the medial temporal lobe, hippocampus, prefrontal lobe, cingulate cortex, precuneus, occipital lobe, and the WM tracts across the globe. Of these, alterations in the temporal lobe are highly reproducible across different imaging modalities. These structures have been known to be vulnerable to Alzheimer's disease (AD) pathology and are critical in cognitive processes such as memory and executive functioning. Comparing to asymptomatic subjects, results are more mixed in patients with metabolic disorders such as type 2 diabetes and obesity, which might be attributed to a multifactorial mechanism. Taken together, neuroimaging, especially MRI, is beneficial to reveal early abnormalities in cerebral structure and function in insulin-resistant brain, providing important evidence to unravel the underlying neuronal substrate that reflects the cognitive decline in IR. EVIDENCE LEVEL: 5 TECHNICAL EFFICACY: Stage 2.

Insulin resistance based on postglucose load measure is associated with prevalence and burden of cerebral small vessel disease

INTRODUCTION

Cerebral small vessel disease (cSVD) is highly prevalent and results in irreversible cognitive impairment and reduced quality of life. Previous studies reported controversial associations between insulin resistance and cSVD. Here, we estimated the association between insulin resistance and cSVD in non-diabetic communities in southeastern China.

RESEARCH DESIGN AND METHODS

The Polyvascular Evaluation for Cognitive Impairment and Vascular Events study (NCT03178448) recruited 3670 community-dwelling adults. We estimated the association of insulin resistance, assessed by the insulin sensitivity index (ISI_0,120) and the homeostatic model assessment for insulin resistance (HOMA-IR) based on the standard oral glucose tolerance test, with cSVD in those without a history of diabetes mellitus. cSVD was measured for both main neuroimaging manifestations of cSVD and total SVD burden scores.

RESULTS

A total of 2752 subjects were enrolled. In the multivariable logistic regression analysis, the first quartile of ISI_0,120 was found to be potentially associated with an increased risk of lacunes (OR 1.96, 95% CI 1.15 to 3.36), severe age-related white matter changes (OR 1.97, 95% CI 1.15 to 3.38), and higher total SVD burden (4-point scale: common OR (cOR) 1.34, 95% CI 1.04 to 1.72; 6-point scale: cOR 1.43, 95% CI 1.14 to 1.79). The associations between HOMA-IR and lacunes (OR 1.90, 95% CI 1.11 to 3.25) and the 4-point scale of total SVD burden (cOR 1.33, 95% CI 1.04 to 1.70) were also significant after adjustment for age, gender, medical history, and medications. However, the associations were not statistically significant after further adjustment for blood pressure/hypertension and body mass index (BMI).

CONCLUSIONS

A potential association was found between insulin resistance and cSVD, and the ISI_0,120 index presented a greater association with increased risk of cSVD as compared with the HOMA-IR. However, these associations were greatly influenced by blood pressure and BMI.

The triglyceride glucose index is associated with the cerebral small vessel disease in a memory clinic population

BACKGROUND AND OBJECTIVES

Insulin resistance (IR) has been associated with the cerebral small vessel disease (cSVD). However, as the surrogate marker of IR, there is little known about the relationship between the triglyceride glucose (TyG) index and cSVD. In this cross-sectional study, we aimed to evaluate the relationship between the TyG index and cSVD in a memory clinic population and explore the value of TyG index to improve the risk stratification of cSVD.

METHODS

We included participants who attended our memory clinic from January 2016 to December 2020. TyG index was determined as ln [fasting triglyceride (mg/dL) × fasting plasma glucose (mg/dL)/2]. We assessed lacunes, microbleeds, white matter hyperintensity (WMH) and enlarged perivascular spaces (EPVS) on MRI and calculated the total cSVD burden.

RESULTS

A total of 297 subjects were included (median age: 65 years, male sex: 64.98%). In the adjusted model, when dividing TyG index into quartiles, subjects with TyG index in the top quartile, compared with those in the bottom quartile, were more likely to have lacunes (P = 0.035), moderate-severe WMH (P = 0.001), a higher grade of deep WMH (P = 0.004), a higher grade of PVWMH (P = 0.032), a higher grade of EPVS (P = 0.002), and a higher cSVD score (P < 0.001). When introducing TyG index into traditional risk factors to predict moderate to severe cSVD, both area under the curve (0.745 vs 0.802, P = 0.003) and integrated discrimination index (0.080, 95% CI 0.050-0.110, P < 0.001) displayed an improvement from TyG index.

CONCLUSIONS

The TyG index is correlated with cSVD and may have the potential to be a surrogate marker of insulin resistance and optimize the risk stratification.

Mechanisms linking obesity and its metabolic comorbidities with cerebral grey and white matter changes

Obesity is a preventable risk factor for cerebrovascular disorders and it is associated with cerebral grey and white matter changes. Specifically, individuals with obesity show diminished grey matter volume and thickness, which seems to be more prominent among fronto-temporal regions in the brain. At the same time, obesity is associated with lower microstructural white matter integrity, and it has been found to precede increases in white matter hyperintensity load. To date, however, it is unclear whether these findings can be attributed solely to obesity or whether they are a consequence of cardiometabolic complications that often co-exist with obesity, such as low-grade systemic inflammation, hypertension, insulin resistance, or dyslipidemia. In this narrative review we aim to provide a comprehensive overview of the potential impact of obesity and a number of its cardiometabolic consequences on brain integrity, both separately and in synergy with each other. We also identify current gaps in knowledge and outline recommendations for future research.

Nonalcoholic Fatty Liver Disease and Altered Neuropsychological Functions in Patients with Subcortical Vascular Dementia

NAFLD is the most common cause of abnormality in liver function tests. NAFLD is considered a potential cardiovascular risk factor and is linked to cardiovascular risk factors such as obesity, hypertension, type 2 diabetes, and dyslipidemia. Few previous studies have investigated whether NAFLD could be independently associated with cognitive impairment. The current study aims to find a possible role of NAFLD in the development of subcortical vascular dementia (sVaD). We considered NAFLD as a possible independent vascular risk factor or, considering its metabolic role, associated with other commonly accepted sVaD risk factors, i.e., lack of folate, vitamin B12, and vitamin D-OH25, and increased levels of homocysteine. We studied 319 patients diagnosed with sVaD. All patients underwent an abdominal ultrasound examination to classify steatosis into four levels (1-none up to 4-severe). sVaD patients were divided into two groups according to the presence or absence of NAFLD. Our results demonstrated a strong correlation between NAFLD and sVaD. Patients with the two comorbidities had worse neuropsychological outcomes and a worse metabolic profile. We also found a robust relationship between NAFLD and severe vitamin B12, folate, vitamin D hypovitaminosis, and higher hyperhomocysteinemia levels. This way, it is evident that NAFLD contributes to a more severe metabolic pathway. However, the strong relationship with the three parameters (B12, folate and vitamin D, and homocysteinemia) suggests that NAFLD can contribute to a proinflammatory condition.

Visceral Adiposity and Risk of Stroke: A Mendelian Randomization Study

Purpose

In recent years, metabolic syndrome has risen in prevalence and brought a heavy disease burden to modern society. As the representative aspect of metabolic syndrome, obesity has been shown to be related to an increased risk of stroke. Given that visceral adipose tissue (VAT) forms the fundamental basis of central obesity, we sought to explore a causal relationship between VAT and stroke by using mendelian randomization (MR) methods.

Methods

Based on two large genome-wide association studies (GWAS) including 325,153 and 35,762 cases of VAT and stroke, respectively, we conducted a MR study which has the inherent advantage of reducing the noise of confounding and reverse causation.

Results

VAT had a significant causal association with ischemic stroke (OR, per 1kg increase in VAT mass, 1.30; 95% CI, 1.18 ~ 1.45; P = 5.87E-07) as opposed to intracranial hemorrhage (ICH) (OR, 1.15; 95% CI, 0.70 ~ 1.88, P = 5.81E-01) as evaluated with inverse-variance weighting (IVW). Regarding subtypes of ischemic stroke, there was a significant causal effect for cardioembolic stroke (OR, 1.34; 95% CI, 1.13 ~ 1.58, P = 8.07E-04), and potential causal effect for small-vessel stroke (OR, 1.32; 95% CI, 1.06 ~ 1.65, P = 1.39E-02) and large-artery atherosclerotic stroke (OR, 1.33; 95% CI, 1.03 ~ 1.70, P = 2.59E-02).

Conclusions

This study provides potential evidence for a causal role of VAT in ischemic stroke and could suggest novel genetical therapeutic strategies for distinct subtypes of ischemic stroke.

Causal effect of insulin resistance on small vessel stroke and Alzheimer's disease: A Mendelian randomization analysis

BACKGROUND AND PURPOSE

The causal effect of insulin resistance on small vessel stroke and Alzheimer's disease (AD) was controversial in previous studies. We therefore applied Mendelian randomization (MR) analyses to identify the causal effect of insulin resistance on small vessel stroke and AD.

METHODS

We selected 12 single-nucleotide polymorphisms (SNPs) associated with fasting insulin levels and five SNPs associated with "gold standard" measures of insulin resistance as instrumental variables in MR analyses. Summary statistical data on SNP-small vessel stroke and on SNP-AD associations were derived from studies by the Multi-ancestry Genome-Wide Association Study of Stroke consortium (MEGASTROKE) and the Psychiatric Genomics Consortium-Alzheimer Disease Workgroup (PGC-ALZ) in individuals of European ancestry. Two-sample MR estimates were conducted with inverse-variance-weighted, robust inverse-variance-weighted, simple median, weighted median, weighted mode-based estimator, and MR pleiotropy residual sum and outlier (MR-PRESSO) methods.

RESULTS

Genetically predicted higher insulin resistance had a higher odds ratio (OR) of small vessel stroke (OR 1.23, 95% confidence interval [CI] 1.05-1.44, p = 0.01 using fasting insulin; OR 1.25, 95% CI 1.07-1.46, p = 0.006 using gold standard measures of insulin resistance) and AD (OR 1.13, 95% CI 1.04-1.23, p = 0.004 using fasting insulin; OR 1.02, 95% CI 1.00-1.03, p = 0.03 using gold standard measures of insulin resistance) using the inverse-variance-weighted method. No evidence of pleiotropy was found using MR-Egger regression.

CONCLUSION

Our findings provide genetic support for a potential causal effect of insulin resistance on small vessel stroke and AD.

Relationship between obesity and structural brain abnormality: Accumulated evidence from observational studies

We aimed to evaluate the relationship between obesity and structural brain abnormalities assessed by magnetic resonance imaging using data from 45 observational epidemiological studies, where five articles reported prospective longitudinal results. In cross-sectional studies' analyses, the pooled weighted mean difference for total brain volume (TBV) and gray matter volume (GMV) in obese/overweight participants was -11.59 (95 % CI: -23.17 to -0.02) and -10.98 (95 % CI: -20.78 to -1.18), respectively. TBV was adversely associated with BMI and WC, GMV with BMI, and hippocampal volume with BMI, WC, and WHR. WC/WHR are associated with a risk of lacunar and white matter hyperintensity (WMH). In longitudinal studies' analyses, BMI was not statistically associated with the overall structural brain abnormalities (for continuous BMI: RR = 1.02, 95 % CI: 0.94-1.12; for categorial BMI: RR = 1.18, 95 % CI: 0.75-1.85). Small sample size of prospective longitudinal studies limited the power of its pooled estimates. A higher BMI is associated with lower brain volume while greater WC/WHR, but not BMI, is related to a risk of lacunar infarct and WMH. Future longitudinal research is needed to further elucidate the specific causal relationships and explore preventive measures.

The silent occurrence of cerebral small vessel disease in nonelderly patients with type 2 diabetes mellitus

BACKGROUND

The prevalence of cerebral small vessel disease (SVD) increases in elderly patients with type 2 diabetes (T2DM), exacerbating cognitive decline. However, the prevalence and the severity of SVD in dementia-free nonelderly T2DM patients were largely unknown. Our primary aim is to investigate SVD in such patients, with a specific focus on the correlation between SVD and diabetic peripheral sensorimotor polyneuropathy (DSP).

METHODS

We recruited 180 young and middle-aged subjects without cognitive impairment (106 with T2DM, 74 controls). Signs of cerebral SVD on magnetic resonance image were investigated, and the overall SVD burden was evaluated by a combined score. Patients with T2DM underwent further detailed DSP assessment. Regression models were used to investigate the association of SVD with the presence of T2DM, and the associations of the prevalence and severity of SVD and DSP were also explored in patients with T2DM.

RESULTS

The prevalence of microbleeds and overall burden of SVD were significantly higher in T2DM patients than in the controls. Further, the presence of DSP related to an increased risk of SVD after adjustment in diabetic group. Moreover, Toronto Clinical Scoring System values were positively associated with the increased SVD scores, and bilateral sural sensory nerve conduction velocities were negatively associated with increasingly severity of SVD scores.

CONCLUSION

The current findings extended the increasing prevalence of SVD to dementia-free nonelderly patients with T2DM, suggesting that the time for cognitive screening and prevention might be moved forward in T2DM patients, especially for those with DSP.

Relationships between metabolic syndrome and aspects of abdominal aortic aneurysm

BACKGROUND

Metabolic syndrome (MetS) is a cluster of metabolic abnormalities strongly associated with risks of cardiovascular diseases. However, a relationship between MetS and aneurysmal disease as compared with occlusive disease has not been confirmed. Therefore, correlations of MetS and abdominal aortic aneurysm (AAA) were evaluated.

METHODS

Between March 2011 and February 2020, 354 patients diagnosed with AAA were enrolled and divided into the MetS (n = 164) and the no-MetS (n = 190) groups. Individual components of MetS, characteristics of AAA, rupture rate, and survival rate were evaluated for both groups. Additionally, correlations between MetS and AAA were evaluated with focusing on effects of diabetes mellitus (DM).

RESULTS

The size of AAA was significantly larger in the MetS group compared with the no-MetS group (P < 0.05). The rupture rate was significantly higher in the MetS group compared with the no-MetS group (P < 0.05) and the survival rate was significantly higher in the no-MetS group (P < 0.05). In terms of DM, the size of AAA was significantly larger in the no-DM group compared with the DM group (P < 0.05). MetS was significantly more prevalent in the DM group compared with the no-DM group (P < 0.05). Finally, the rupture and survival rates were not statistically different between the DM and the no-DM groups (P > 0.05).

CONCLUSIONS

Although larger prospective studies are necessary, we suggest that MetS proportionally aggravates the status of AAA and survival rate. Therefore, surveillance for MetS and individual components may help to restrict the expansion of AAA.

Investigating the relationship between BMI across adulthood and late life brain pathologies

Background

In view of reported associations between high adiposity, particularly in midlife and late-life dementia risk, we aimed to determine associations between body mass index (BMI), and BMI changes across adulthood and brain structure and pathology at age 69–71 years.

Methods

Four hundred sixty-five dementia-free participants from Insight 46, a sub-study of the British 1946 birth cohort, who had cross-sectional T1/FLAIR volumetric MRI, and florbetapir amyloid-PET imaging at age 69–71 years, were included in analyses. We quantified white matter hyperintensity volume (WMHV) using T1 and FLAIR 3D-MRI; β-amyloid (Aβ) positivity/negativity using a SUVR approach; and whole brain (WBV) and hippocampal volumes (HV) using 3D T1-MRI. We investigated the influence of BMI, and BMI changes at and between 36, 43, 53, 60–64, 69 and 71 years, on late-life WMHV, Aβ-status, WBV and mean HV. Analyses were repeated using overweight and obese status.

Results

At no time-point was BMI, change in BMI or overweight/obese status associated with WMHV or WBV at age 69–71 years. Decreasing BMI in the 1–2 years before imaging was associated with an increased odds of being β-amyloid positive (OR 1.45, 95% confidence interval 1.09, 1.92). There were associations between being overweight and larger mean HV at ages 60–64 (β = 0.073 ml, 95% CI 0.009, 0.137), 69 (β = 0.076 ml, 95% CI 0.012, 0.140) and 71 years (β = 0.101 ml, 95% CI 0.037, 0.165). A similar, albeit weaker, trend was seen with obese status.

Conclusions

Using WMHV, β-amyloid status and brain volumes as indicators of brain health, we do not find evidence to explain reported associations between midlife obesity and late-life dementia risk. Declining BMI in later life may reflect preclinical Alzheimer’s disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-021-00830-7.

Insulin resistance accounts for metabolic syndrome-related alterations in brain structure

Metabolic syndrome (MetS) is a major public health burden worldwide and associated with brain abnormalities. Although insulin resistance is considered a pivotal feature of MetS, its role in the pathogenesis of MetS‐related brain alterations in the general population is unclear. Therefore, in 973 participants (mean age 52.5 years) of the population‐based Rhineland Study, we assessed brain morphology in relation to MetS and insulin resistance, and evaluated to what extent the pattern of structural brain changes seen in MetS overlap with those associated with insulin resistance. Cortical reconstruction and volumetric segmentation were obtained from high‐resolution brain images at 3 Tesla using FreeSurfer. The relations between metabolic measures and brain structure were assessed through (generalized) linear models. Both MetS and insulin resistance were associated with smaller cortical gray matter volume and thickness, but not with white matter or subcortical gray matter volume. Age‐ and sex‐adjusted vertex‐based brain morphometry demonstrated that MetS and insulin resistance were related to cortical thinning in a similar spatial pattern. Importantly, no independent effect of MetS on cortical gray matter was observed beyond the effect of insulin resistance. Our findings suggest that addressing insulin resistance is critical in the prevention of MetS‐related brain changes in later life.

Prospective Analysis of Leisure-Time Physical Activity in Midlife and Beyond and Brain Damage on MRI in Older Adults

OBJECTIVE

To test the hypothesis that greater levels of leisure-time moderate to vigorous intensity physical activity (MVPA) in midlife or late life are associated with larger gray matter volumes, less white matter disease, and fewer cerebrovascular lesions measured in late life, we utilized data from 1,604 participants enrolled in the Atherosclerosis Risk in Communities study.

METHODS

Leisure-time MVPA was quantified using a past-year recall, interviewer-administered questionnaire at baseline and 25 years later and classified as none, low, middle, and high at each time point. The presence of cerebrovascular lesions, white matter hyperintensities (WMH), white matter integrity (mean fractional anisotropy [FA] and mean diffusivity [MD]), and gray matter volumes were quantified with 3T MRI in late life. The odds of cerebrovascular lesions were estimated with logistic regression. Linear regression estimated the mean differences in WMH, mean FA and MD, and gray matter volumes.

RESULTS

Among 1,604 participants (mean age 53 years, 61% female, 27% Black), 550 (34%), 176 (11%), 250 (16%), and 628 (39%) reported no, low, middle, and high MVPA in midlife, respectively. Compared to no MVPA in midlife, high MVPA was associated with more intact white matter integrity in late life (mean FA difference 0.13 per SD [95% confidence interval (CI) 0.004, 0.26]; mean MD difference -0.11 per SD [95% CI -0.21, -0.004]). High MVPA in midlife was also associated with a lower odds of lacunar infarcts (odds ratio 0.68, 95% CI 0.46, 0.99). High MVPA was not associated with gray matter volumes. High MVPA compared to no MVPA in late life was associated with most brain measures.

CONCLUSION

Greater levels of physical activity in midlife may protect against cerebrovascular sequelae in late life.

Independent and Synergistic Effects of High Blood Pressure and Obesity on Retinal Vasculature in Young Children: The Hong Kong Children Eye Study

Background High blood pressure (BP) and obesity are becoming increasingly prevalent among children globally. Although prior studies have shown their adverse impacts on macrovascular health, less is known about their effects on microvascular heath. This study aims to evaluate the independent and synergistic effects of hypertensive BP and obesity on retinal vasculature in young children. Method and Results 1006 children aged 6 to 8 years were recruited from the Hong Kong Children Eye Study. Quantitative retinal vascular parameters, including central retinal arteriolar and venular equivalents and retinal arteriolar and venular fractal dimensions, were measured from retinal photographs following a standardized protocol. BP and body mass index were categorized according to reference values from American Academy of Pediatrics and International Obesity Task Force guidelines respectively. Children with hypertensive systolic BP had the narrowest central retinal arteriolar equivalents compared with children with either elevated or normotensive systolic BP (162.4, 164.6, and 167.1 µm; P-trend <0.001). Increased standardized systolic BP was associated with narrower central retinal arteriolar equivalents (β=-2.276 µm, P<0.001), wider central retinal venular equivalents (1.177, P=0.007), and decreased arteriolar fractal dimensions (β=-0.004, P=0.034). Children with obesity had the smallest arteriolar fractal dimensions compared with children with overweightness and normal weight (1.211, 1.234, and 1.240; P-trend=0.004). Children with both hypertensive BP and either overweightness or obesity had the narrowest central retinal arteriolar equivalents and smallest arteriolar D_f (P-trend<0.001 and P-trend=0.007). Conclusions Our findings demonstrate the potential synergistic or additive effects for both hypertensive BP and obesity on retinal vasculature in children.

Clinical, Imaging, and Lab Correlates of Severe COVID-19 Leukoencephalopathy

BACKGROUND AND PURPOSE

Patients infected with the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) can develop a spectrum of neurological disorders, including a leukoencephalopathy of variable severity. Our aim was to characterize imaging, lab, and clinical correlates of severe coronavirus disease 2019 (COVID-19) leukoencephalopathy, which may provide insight into the SARS-CoV-2 pathophysiology.

MATERIALS AND METHODS

Twenty-seven consecutive patients positive for SARS-CoV-2 who had brain MR imaging following intensive care unit admission were included. Seven (7/27, 26%) developed an unusual pattern of "leukoencephalopathy with reduced diffusivity" on diffusion-weighted MR imaging. The remaining patients did not exhibit this pattern. Clinical and laboratory indices, as well as neuroimaging findings, were compared between groups.

RESULTS

The reduced-diffusivity group had a significantly higher body mass index (36 versus 28 kg/m², P < .01). Patients with reduced diffusivity trended toward more frequent acute renal failure (7/7, 100% versus 9/20, 45%; P = .06) and lower estimated glomerular filtration rate values (49 versus 85 mL/min; P = .06) at the time of MRI. Patients with reduced diffusivity also showed lesser mean values of the lowest hemoglobin levels (8.1 versus 10.2 g/dL, P < .05) and higher serum sodium levels (147 versus 139 mmol/L, P = .04) within 24 hours before MR imaging. The reduced-diffusivity group showed a striking and highly reproducible distribution of confluent, predominantly symmetric, supratentorial, and middle cerebellar peduncular white matter lesions (P < .001).

CONCLUSIONS

Our findings highlight notable correlations between severe COVID-19 leukoencephalopathy with reduced diffusivity and obesity, acute renal failure, mild hypernatremia, anemia, and an unusual brain MR imaging white matter lesion distribution pattern. Together, these observations may shed light on possible SARS-CoV-2 pathophysiologic mechanisms associated with leukoencephalopathy, including borderzone ischemic changes, electrolyte transport disturbances, and silent hypoxia in the setting of the known cytokine storm syndrome that accompanies severe COVID-19.

Deciphering the Irregular Risk of Stroke Increased by Obesity Classes: A Stratified Mendelian Randomization Study

BACKGROUND

To investigate the relationship between different classes of obesity and stroke, we conducted a stratified Mendelian randomization (MR) study.

METHODS

The body mass index (BMI) data of 263,407 Europeans with three classes of obesity (obesity class I, 30 kg/m² ≤ BMI < 35 kg/m²; obesity class II, 35 kg/m² ≤ BMI < 40 kg/m²; obesity class III, 40 kg/m² ≤ BMI) were extracted from the Genetic Investigation of ANthropometric Traits (GIANT) consortium. Summary-level data of stroke and its subtypes [ischemic stroke (IS) and intracerebral hemorrhage (ICH)] were obtained from the genome-wide association study (GWAS) meta-analysis, which was performed by the MEGASTROKE consortium. MR methods were used to identify the causal relationships.

RESULTS

The MR analysis revealed that both obesity class I [odds ratio (OR) = 1.08, 95% CI: 1.05-1.12, p = 1.0 × 10^-5] and obesity class II (OR = 1.06, 95% CI: 1.03-1.09, p = 1 × 10^-4) were significantly positively related to IS, while obesity class III was not (OR = 1.01, 95% CI: 0.96-1.06, p = 0.65). In contrast to IS, there was no class of obesity associated with ICH risk. Further examination of the relationship between obesity classification and IS subtypes revealed that certain degrees of obesity were related to large artery stroke (LAS) (OR = 1.14, 95% CI: 1.04-1.24, p = 2.8 × 10^-3 for class I; OR = 1.08, 95% CI: 1.01-1.16, p = 0.002 for class II) and cardioembolic stroke (CES) (OR = 1.11, 95% CI: 1.02-1.20, p = 0.02 for class I; OR = 1.08, 95% CI: 1.02-1.15, p = 0.007 for class II).

CONCLUSIONS

A higher risk of IS, but not ICH, could be linked to obesity classes I and II. A strong association between LAS and CES and obesity was observed among all IS subtypes in the obese population.

Midlife Insulin Resistance as a Predictor for Late-Life Cognitive Function and Cerebrovascular Lesions

Background:

Type 2 diabetes (T2DM) increases the risk for Alzheimer’s disease (AD) but not for AD neuropathology. The association between T2DM and AD is assumed to be mediated through vascular mechanisms. However, insulin resistance (IR), the hallmark of T2DM, has been shown to associate with AD neuropathology and cognitive decline.

Objective:

To evaluate if midlife IR predicts late-life cognitive performance and cerebrovascular lesions (white matter hyperintensities and total vascular burden), and whether cerebrovascular lesions and brain amyloid load are associated with cognitive functioning.

Methods:

This exposure-to-control follow-up study examined 60 volunteers without dementia (mean age 70.9 years) with neurocognitive testing, brain 3T-MRI and amyloid-PET imaging. The volunteers were recruited from the Finnish Health 2000 survey (n = 6062) to attend follow-up examinations in 2014–2016 according to their insulin sensitivity in 2000 and their APOE genotype. The exposure group (n = 30) had IR in 2000 and the 30 controls had normal insulin sensitivity. There were 15 APOEɛ4 carriers per group. Statistical analyses were performed with multivariable linear models.

Results:

At follow-up the IR+group performed worse on executive functions (p = 0.02) and processing speed (p = 0.007) than the IR- group. The groups did not differ in cerebrovascular lesions. No associations were found between cerebrovascular lesions and neurocognitive test scores. Brain amyloid deposition associated with slower processing speed.

Conclusion:

Midlife IR predicted poorer executive functions and slower processing speed, but not cerebrovascular lesions. Brain amyloid deposition was associated with slower processing speed. The association between midlife IR and late-life cognition might not be mediated through cerebrovascular lesions measured here.

Clinical management of cerebral small vessel disease: a call for a holistic approach

ABSTRACT

Cerebral small vessel disease (SVD) is a common global brain disease that causes cognitive impairment, ischemic or hemorrhagic stroke, problems with mobility, and neuropsychiatric symptoms. The brain damage, seen as focal white and deep grey matter lesions on brain magnetic resonance imaging (MRI) or computed tomography (CT), typically accumulates "covertly" and may reach an advanced state before being detected incidentally on brain scanning or causing symptoms. Patients have typically presented to different clinical services or been recruited into research focused on one clinical manifestation, perhaps explaining a lack of awareness, until recently, of the full range and complexity of SVD.In this review, we discuss the varied clinical presentations, established and emerging risk factors, relationship to SVD features on MRI or CT, and the current state of knowledge on the effectiveness of a wide range of pharmacological and lifestyle interventions. The core message is that effective assessment and clinical management of patients with SVD, as well as future advances in diagnosis, care, and treatment, will require a more "joined-up"' approach. This approach should integrate clinical expertise in stroke neurology, cognitive, and physical dysfunctions. It requires more clinical trials in order to improve pharmacological interventions, lifestyle and dietary modifications. A deeper understanding of the pathophysiology of SVD is required to steer the identification of novel interventions. An essential prerequisite to accelerating clinical trials is to improve the consistency, and standardization of clinical, cognitive and neuroimaging endpoints.

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.

Incident cerebral lacunes: A review

Lacunes on magnetic resonance imaging (MRI) are considered as a key hallmark for evaluating the progression and severity of cerebral small vessel diseases. We aimed to review the MRI diagnostic criteria, frequency, predictors and clinical impact of incident lacunes in the largest longitudinal studies. Analyses were restricted to cohort studies of more than 50 individuals that investigated incident lacunes over a duration of at least one year. We observed that: (1) MRI parameters and definition of lacunes are inconsistent across studies, (2) the frequency of incident lacunes is strongly related to the previous clinical and MRI status at individual level, (3) both age and hypertension diagnosed at onset predict incident lacunes but the exact impact of blood pressure level during follow-up remains undetermined, (4) the clinical correlates of these lesions on cognition are repeatedly observed but the exact consequences on motor or gait performances are not always evaluated. Homogenization of imaging techniques, the use of strict diagnostic criteria and a broader clinical assessment considering motor and gait performances should be recommended in future longitudinal studies of incident lacunes including clinical trials testing preventative treatments in cerebral small vessel diseases.

Insulin Resistance Is Independently Associated With Enlarged Perivascular Space in the Basal Ganglia in Nondiabetic Healthy Elderly Population

OBJECTIVES

To investigate the association between insulin resistance (IR) and enlarged perivascular space (EPVS) in the basal gangliain nondiabetic healthy elderly population.

METHODS

A total of 235 nondiabetic healthy elderly population were recruited. A 3-level scale was used to evaluate the burden of EPVSs. The homeostasis model assessment-estimated insulin resistance index (HOMA-IR) was used for IR estimation. Correlation between IR and severity of EPVS was assessed using the regression model after adjusting demographics and cardiovascular risk factors.

RESULTS

The top quartile of HOMA-IR was 2.52, and 25.11% of patients showed IR. The proportion of patients with IR was higher in the moderate to severe EPVS group than in the mild group (36.51% vs 20.93%, P = .015). In multivariate logistic analysis, IR was positively correlated with the moderate to severe EPVS (adjusted odds ratio: 3.532, 95% confidence interval: 1.633-7.636, P = .001) after adjusting classical risk factors.

CONCLUSIONS

Insulin resistance was independently correlated with EPVS in the basal ganglia in nondiabetic healthy elderly population.

Clinical and neuroimaging disparity between Chinese and German patients with cerebral small vessel disease: a comparative study

Ethnic disparity of cerebral small vessel disease (CSVD) has been reported previously but understanding of its clinical-anatomical is sparse. Two cohorts of CSVD patients from Peking University First Hospital, China and University Hospital of Ulm, Germany were retrospectively collected between 2013 and 2017. Visual rating scales and semiautomatic computer-assisted quantitative analysis were used to describe the neuroimaging features of CSVD, including lacunes, enlarged perivascular spaces, white matter changes and microbleeds. After exclusion of confounding neurological disorders, 165 out of 220 Chinese and 86 out of 98 German patients’ data were analyzed. Mean age of patients was 64.0 ± 11.9 years in China and 73.9 ± 10.3 years in Germany. Cognitive deficits were more prominent in the German group, mainly in the cognitive domains of language and delayed recall. Neuroimaging comparison showed that lacunes were more common and white matter lesion load was more severe in German than Chinese patients. Spatial distribution analysis suggested that Chinese patients showed more deep and infratentorial lesions (microbleeds and lacunes), while lesions in German patients were more frequently located in the lobes or subcortical white matter. In conclusion, different age of onset and anatomical distribution of lesions exist between Chinese and German CSVD patients in the observed population.

Measures of obesity are associated with MRI markers of brain aging: The Northern Manhattan Study

OBJECTIVE

To examine associations between measures of obesity in middle to early-old age with later-life MRI markers of brain aging.

METHODS

We analyzed data from the Northern Manhattan MRI Sub-Study (n = 1,289). Our exposures of interest were body mass index (BMI), waist circumference (WC), waist-to-hip ratio, and plasma adiponectin levels. Our outcomes of interest were total cerebral volume (TCV), cortical thickness, white matter hyperintensity volume (WMHV), and subclinical brain infarcts (SBI). Using multivariable linear and logistic regression models adjusted for sociodemographics, health behaviors, and vascular risk factors, we estimated β coefficients (or odds ratios) and 95% confidence intervals (CIs) and tested interactions with age, sex, and race/ethnicity.

RESULTS

On average at baseline, participants were aged 64 years and had 10 years of education; 60% were women and 66% were Caribbean Hispanic. The mean (SD) time lag between baseline and MRI was 6 (3) years. Greater BMI and WC were significantly associated with thinner cortices (BMI β [95% CI] -0.089 [-0.153, -0.025], WC β [95% CI] -0.103 [-0.169, -0.037]) in fully adjusted models. Similarly, compared to those with BMI <25, obese participants (BMI ≥30) exhibited smaller cortical thickness (β [95% CI] -0.207 [-0.374, -0.041]). These associations were particularly evident for those aged <65 years. Similar but weaker associations were observed for TCV. Most associations with WMHV and SBI did not reach statistical significance.

CONCLUSIONS

Adiposity in early-old age is related to reduced global gray matter later in life in this diverse sample. Future studies are warranted to elucidate causal relationships and explore region-specific associations.

Abdominal fatness and cerebral white matter hyperintensity

Although obesity has been proven as a risk factor of metabolic and cardiovascular diseases, there have been few studies addressing the association between obesity and cerebral white matter hyperintensity (WMH) volume with controversial findings. In this study, we evaluated the relationship between abdominal fat distribution and WMH volume in a neurologically healthy population. We performed an observational study in a consecutive series of subjects who were examined during voluntary health check-ups between January 2006 and December 2013. We directly measured both visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) using abdominal computed tomography. The WMH volumes were also recorded quantitatively. A total of 2504 subjects were included in this study. In multivariate analysis, the relationship between SAT and WMH volume remained significant (β = -0.170, standard error [SE] = 0.065, P = .006) after adjusting for confounding factors. The protective effects of SAT on the WMH volume were more prominent in female participants (β = -0.295, SE = 0.138, P = .033) and in severely obese participants (β = -0.358, SE = 0.167, P = .033). Conclusively, we demonstrated a negative association between SAT and WMH volume in a healthy population.

Insulin Resistance Is a Risk Factor for Overall Cerebral Small Vessel Disease Burden in Old Nondiabetic Healthy Adult Population

Background and Purpose: This study aimed to investigate the association between insulin resistance (IR) and the overall cerebral small vessel disease (CSVD) burden.

Methods: We recruited elderly, nondiabetic, healthy subjects prospectively. The overall effect of CSVD on the brain was described by a validated CSVD score. The homeostasis model assessment–estimated insulin resistance index (HOMA-IR) was used for IR estimation, and HOMA-IR ≥2.80 was defined as IR. We evaluated the association between IR and the increasing severity of CSVD score by ordinal regression models adjusting for demographics and cardiovascular risk factors.

Results: A total of 156 healthy participants were recruited. The mean age was older in the IR group than in the non-IR group (70.03 vs. 67.45, p = 0.04), and the prevalence of hypertension was significantly higher in the IR group than in the non-IR group (82.35% vs. 53.28%, p < 0.01). In ordinal regression analysis, IR was positively associated with increasing severity of the total CSVD score (adjusted odds ratio, 3.74; 95% confidence interval, 1.63–5.08; p < 0.01) after adjusting traditional risk factors. Furthermore, HOMA-IR levels showed a positive dose-dependent correlation with the total CSVD score (p < 0.01, p for trend <0.01).

Conclusions: IR is independently associated with increasing severity of the overall CSVD burden, independent of other clinical risk factors in an elderly, nondiabetic, healthy population. Furthermore, HOMA-IR level is correlated with the CSVD burden in a dose-dependent manner.

Suffering from Cerebral Small Vessel Disease with and without Metabolic Syndrome

Background

Cerebral small vessel disease (CSVD) and metabolic syndrome were separately associated with cognitive impairment and depression. However, whether metabolic syndrome adds to cognitive impairment and depression in patients who already have CSVD remained unanswered.

Objective

The aim of our study was to investigate the association of metabolic syndrome with cognitive impairment and depression in patients with CSVD who have lacunar lesions or white matter hyperintensities.

Methods

This prospective cohort study was conducted at Neurology Clinic, Clinical Center, Kragujevac, Serbia. Main outcomes of the study were cognitive assessment, and assessment of depression among hospitalized patients with or without CSVD.

Results

The study included 74 inpatients, 25 of them having lacunary infarctions, 24 with the white matter hyperintensities, and 25 control patients without CSVD. The CSVD was accompanied by impairment of cognition and depression, the patients with lacunary lesions being more cognitively impaired and more depressive than the patients with the white matter hyperintensities. The patients with CSVD who also had metabolic syndrome were more cognitively impaired and depressed than the patients with CSVD alone.

Conclusions

In conclusion, our study showed that metabolic syndrome is associated with further worsening of already impaired cognition and existing depression in patients with CSVD.

Predictive value of transcranial doppler ultrasound for cerebral small vessel disease in elderly patients

ABSTRACT Objective: To investigate the predictive value of transcranial Doppler (TCD) ultrasound for cerebral small vessel disease in elderly patients. Methods: Transcranial Doppler ultrasound and magnetic resonance imaging (MRI) were performed on 184 elderly patients with cerebral small vessel disease. The relationship of clinical characteristics and TCD ultrasound parameters with severe white matter lesions (WMLs) in MRI were investigated by univariate analysis and multivariate analysis. Results: The univariate analysis showed that age, left middle cerebral artery (MCA) mean flow velocity, right MCA mean flow velocity and mean MCA pulsatility index were significantly correlated with severe WMLs (p < 0.05). The multivariate logistic regression analysis showed that only age (odds ratio: 1.21; 95%CI: 1.10–1.36; p < 0.01) and MCA pulsatility index (dominance ratio: 1.13; 95%CI: 1.06–1.80; p = 0.02) were significantly correlated with severe WMLs. The analysis of TCD ultrasound parameters showed that when the cut-off for MCA pulsatility index was 1.04, it could identify severe WMLs. The area under the curve was 0.70 (95%CI: 0.60–0.80). The sensitivity and specificity were 63.0% and 72.0%, respectively. The positive and negative predictive values were 35.4% and 86.6%, respectively. Conclusion: The MCA pulsatility index in TCD ultrasound is significantly correlated with severe WMLs; and TCD ultrasound can guide selective MRI for the detection of WMLs.

Low-Grade Inflammation Is Associated with Apathy Indirectly via Deep White Matter Lesions in Community-Dwelling Older Adults: The Sefuri Study

Low-grade inflammation is implicated in the pathogenesis of atherosclerosis, metabolic syndrome, and apathy as a form of vascular depression. We analyzed the brain magnetic resonance imaging findings in 259 community-dwelling older adults (122 men and 137 women, with a mean age of 68.4 years). The serum concentrations of high-sensitivity C-reactive protein (hsCRP) were measured by a quantitative enzyme-linked immunosorbent assay. Logistic regression analysis revealed that the log₁₀ hsCRP value and the presence of a metabolic syndrome were independently associated with confluent but not punctate deep white matter lesions (DWMLs). Path analysis based on structural equation modeling (SEM) indicated that the direct path from the log₁₀ hsCRP to the DWMLs was significant (β = 0.119, p = 0.039). The direct paths from the metabolic syndrome to the log₁₀ hsCRP and to the DWMLs were also significant. The direct path from the DWMLs to apathy (β = −0.165, p = 0.007) was significant, but the direct path from the log₁₀ hsCRP to apathy was not significant. Inflammation (i.e., elevated serum hsCRP levels) was associated with DWMLs independent of common vascular risk factors, while DWMLs were associated with apathy. The present analysis with SEM revealed the more realistic scheme that low-grade inflammation was associated with apathy indirectly via DWMLs in community-dwelling older adults.

Clinical Correlation of Magnetic Resonance Imaging Features of Cerebral Small Vessel Disease

OBJECTIVE

We have discussed the clinical features and neuroimaging findings and investigated the correlations between the clinical characteristics and different neuroradiologic phenotypes of cerebral small vessel disease (CSVD).

METHODS

A total of 1106 patients with a diagnosis of CSVD were enrolled. The demographic data, medical history, laboratory test results, and neuroimaging findings were retrieved for analysis. The differences in clinical parameters between patient groups were examined. The relationships between the clinical parameters and neuroradiologic phenotypes (i.e., white matter lesions [WMLs] and enlarged perivascular spaces) were assessed. The magnetic resonance imaging features were clustered using the fast clustering algorithm.

RESULTS

Approximately one third of our patients presented with a lacune, which was associated with atrial fibrillation (P = 0.029), lacunar syndrome (P < 0.001), periventricular WMLs (P = 0.001), cerebral WMLs (P = 0.021), basal ganglia perivascular space grade (P < 0.001) and severity (P = 0.001), and semiovale perivascular space grade (P = 0.010) and severity (P = 0.002). Hypertension was associated with periventricular WMLs (P = 0.048), centrum semiovale WMLs (P = 0.026), and basal ganglia perivascular space grade (P < 0.001) and severity (P < 0.001). A novel clustering algorithm was derived to stratify our cohort into 3 different groups according to the differing severity of the cerebral WMLs and perivascular space enlargement.

CONCLUSION

The present study has provided a comprehensive analysis of the clinical correlation of characteristics and neuroradiologic phenotypes in patients with CSVD. The insights from these findings could be used to refine the management strategy for patients with CSVD.

Central Arterial Stiffness Is Associated With Structural Brain Damage and Poorer Cognitive Performance: The ARIC Study

Background Central arterial stiffening and increased pulsatility, with consequent cerebral hypoperfusion, may result in structural brain damage and cognitive impairment. Methods and Results We analyzed a cross-sectional sample of ARIC - NCS (Atherosclerosis Risk in Communities-Neurocognitive Study) participants (aged 67-90 years, 60% women) with measures of cognition (n=3703) and brain magnetic resonance imaging (n=1255). Central arterial hemodynamics were assessed as carotid-femoral pulse wave velocity and pressure pulsatility (central pulse pressure). We derived factor scores for cognitive domains. Brain magnetic resonance imaging using 3-Tesla scanners quantified lacunar infarcts; cerebral microbleeds; and volumes of white matter hyperintensities, total brain, and the Alzheimer disease signature region. We used logistic regression, adjusted for demographics, apolipoprotein E ɛ4, heart rate, mean arterial pressure, and select cardiovascular risk factors, to estimate the odds of lacunar infarcts or cerebral microbleeds. Linear regression, additionally adjusted for intracranial volume, estimated the difference in log-transformed volumes of white matter hyperintensities , total brain, and the Alzheimer disease signature region. We estimated the mean difference in cognitive factor scores across quartiles of carotid-femoral pulse wave velocity or central pulse pressure using linear regression. Compared with participants in the lowest carotid-femoral pulse wave velocity quartile, participants in the highest quartile of carotid-femoral pulse wave velocity had a greater burden of white matter hyperintensities ( P=0.007 for trend), smaller total brain volumes (-18.30 cm3; 95% CI , -27.54 to -9.07 cm3), and smaller Alzheimer disease signature region volumes (-1.48 cm3; 95% CI , -2.27 to -0.68 cm3). These participants also had lower scores in executive function/processing speed (β=-0.04 z score; 95% CI , -0.07 to -0.01 z score) and general cognition (β=-0.09 z score; 95% CI , -0.15 to -0.03 z score). Similar results were observed for central pulse pressure . Conclusions Central arterial hemodynamics were associated with structural brain damage and poorer cognitive performance among older adults.

Photoacoustic microscopy of obesity-induced cerebrovascular alterations

Cerebral small vessel disease has been linked to cognitive, psychiatric and physical disabilities, especially in the elderly. However, the underlying pathophysiology remains incompletely understood, largely due to the limited accessibility of these small vessels in the live brain. Here, we report an intravital imaging and analysis platform for high-resolution, quantitative and comprehensive characterization of pathological alterations in the mouse cerebral microvasculature. By exploiting multi-parametric photoacoustic microscopy (PAM), microvascular structure, blood perfusion, oxygenation and flow were imaged in the awake brain. With the aid of vessel segmentation, these structural and functional parameters were extracted at the single-microvessel level, from which vascular density, tortuosity, wall shear stress, resistance and associated cerebral oxygen extraction fraction and metabolism were also quantified. With the use of vasodilatory stimulus, multifaceted cerebrovascular reactivity (CVR) was characterized in vivo. By extending the classic Evans blue assay to in vivo, permeability of the blood-brain barrier (BBB) was dynamically evaluated. The utility of this enabling technique was examined by studying cerebrovascular alterations in an established mouse model of high-fat diet-induced obesity. Our results revealed increased vascular density, reduced arterial flow, enhanced oxygen extraction, impaired BBB integrity, and increased multifaceted CVR in the obese brain. Interestingly, the 'counterintuitive' increase of CVR was supported by the elevated active endothelial nitric oxide synthase in the obese mouse. Providing comprehensive and quantitative insights into cerebral microvessels and their responses under pathological conditions, this technique opens a new door to mechanistic studies of the cerebral small vessel disease and its implications in neurodegeneration and stroke.

Non-obese fatty liver disease is associated with lacunar infarct

BACKGROUND/AIMS

Lacunar infarct, a small subcortical ischaemic lesion, is a known risk factor for future cognitive impairment, dementia and stroke. We evaluated the relationship between fatty liver disease (FLD) and lacunar infarct in a healthy general population.

METHODS

Subjects who underwent brain magnetic resonance imaging (MRI) and abdominal ultrasonography (US) during health check-ups from 2007 to 2009 were included. FLD was diagnosed by US. Subjects with a history of cerebrovascular disease, radiological findings consistent with cerebrovascular stenosis or cerebral small vessel disease were excluded.

RESULTS

Of the 1277 subjects, 54 (4.2%) exhibited lacunar infarct, and 514 (40.3%) had FLD. Subjects with lacunar infarct had a higher prevalence of FLD (59.3% vs 39.4%, P = .004). There was significant interaction between obesity (BMI < 25 kg/m² vs ≥ 25 kg/m² ) and FLD for lacunar infarct (P for interaction = .024). Subgroup analysis revealed that non-obese FLD was more common in the subjects with lacunar infarct than those without (51.7% vs 23.5%, P = .001). However, there was no significant difference in the obese FLD prevalence between these 2 groups. In multivariate models adjusted by age, sex, smoking, alcohol, hypertension and diabetes, FLD was significantly associated with lacunar infarct (odds ratio [OR] 1.97; 95% confidence interval [CI] 1.08-3.58; P = .027). Non-obese FLD was associated with lacunar infarct (OR 3.58; 95% CI 1.63-7.89; P = .002); however, this association remained insignificant in obese FLD. Instead, ageing and hypertension were independent risk factors for lacunar infarct in the obese population.

CONCLUSIONS

FLD is significantly associated with lacunar infarct, independent of traditional risk factors. This association was prominent in the non-obese population.

Homeostasis model assessment of insulin resistance in relation to the poor functional outcomes in nondiabetic patients with ischemic stroke

Whether insulin resistance (IR) predicts worse functional outcome in ischemic stroke is still a matter of debate. The aim of the present study is to determine the association between IR and risk of poor outcome in 173 Chinese nondiabetic patients with acute ischemic stroke. This is a prospective, population-based cohort study. Insulin sensitivity, expressed by the homeostasis model assessment (HOMA) of insulin sensitivity (HOMA index = (fasting insulin × fasting glucose)/22.5). IR was defined by HOMA-IR index in the top quartile (Q4). Functional impairment was evaluated at discharge using the modified Rankin scale (mRS). The median (interquartile range) HOMA-IR was 2.14 (1.17–2.83), and Q4 was at least 2.83. There was a significantly positive correlation between HOMA-IR and National Institutes of Health Stroke Scale (r = 0.408; P<0.001). In multivariate analyses, patients in IR group were associated with a higher risk of poor functional outcome (odds ratio (OR) = 3.23; 95% confidence interval (CI) = 1.75–5.08; P=0.001). In multivariate models comparing the third and fourth quartiles against the first quartile of the HOMA-IR, levels of HOMA-IR were associated with poor outcome, and the adjusted risk of poor outcome increased by 207% (OR = 3.05 (95% CI 1.70–4.89), P=0.006) and 429% (5.29 (3.05–9.80), P<0.001). In a receiver operating characteristic curve (ROC) analysis of poor outcome, the area under the curve (AUC) increased from 0.80 to 0.84 (95% CI: 0.79–0.88) by adding HOMA-IR to clinical examination variables (P=0.02). High HOMA-IR index is associated with a poor functional outcome in nondiabetic patients with acute ischemic stroke.

Pioglitazone Improved Insulin Sensitivity and First Phase Insulin Secretion Among Obese and Lean People with Diabetes: A Multicenter Clamp Study

INTRODUCTION

To investigate the effects of pioglitazone (PIO) on insulin resistance and first phase insulin secretion among obese and lean Chinese people with type 2 diabetes mellitus (T2DM).

METHODS

Sixty-eight drug-naïve patients with T2DM were treated with PIO for 16 weeks. Before and after the treatment, insulin sensitivity was evaluated by the euglycemic hyperinsulinemic clamp test. Plasma insulin levels at 0, 3, 5, 7, and 10 min during intravenous glucose tolerance test were determined to calculate the first phase insulin secretion and pancreatic β-cell function. Circulating adiponectin levels were quantified.

RESULTS

In both the lean and the obese patients with T2DM, the reduction of HbA_1c following the PIO treatment was more than 1% (P < 0.001) and glucose infusion rate, acute insulin response, glucose disposal index, and β-cell glucose sensitivity increased significantly (P < 0.001). A multiple linear regression analysis showed that the improvements of first phase insulin secretion and insulin sensitivity were independently associated with the changes of HbA_1c, but the change of first phase insulin secretion exhibited a higher correlation coefficient (R² = 0.20, P = 0.001) than the change of insulin sensitivity did (R² = 0.07, P = 0.040). The PIO treatment led to a significant increase in adiponectin levels only in the obese group (P < 0.05).

CONCLUSION

A 16-week treatment of PIO significantly increased insulin sensitivity and β-cell function in the lean group as well as in the obese group among Chinese T2DM patients, demonstrating that both lean and obese diabetic adults would profit from PIO.

TRIAL REGISTRATION

The ChiCTR registry number is ChiCTR-OPC-17011571.

FUNDING

Takeda Pharmaceutical Co. Ltd. and Pfizer Pharmaceutical Co. Ltd.