Correlation Between Insulin Resistance and Intracranial Atherosclerosis in Patients With Ischemic Stroke Without Diabetes

Effect of atherogenic index of plasma and triglyceride-glucose index on early neurological deterioration of patients with large artery atherosclerotic ischemic stroke

BACKGROUND

Stroke due to large artery atherosclerosis (LAA-stroke) has a poor early prognosis despite appropriate medical treatment. Recently, various parameters reflecting pathological conditions such as insulin resistance or atherogenic dyslipidemia have been proposed using triglyceride (TG) and other biomarkers. In this study, we evaluated the association between TG andTG-related parameters and early neurological deterioration (END) in patients with acute LAA stroke.

METHODS

We evaluated consecutive patients with acute LAA-stroke between January 2010 and December 2020. TG-related parameters were calculated using the following formulas: the atherogenic index of plasma (AIP) = log10 (TG level/high-density lipoprotein level) and TG-glucose (TyG) index = Ln (TG level x glucose level/2). END was defined as an increase of ≥ 2 in the total National Institutes of Health Stroke Scale (NIHSS) score or ≥ 1 in the motor NIHSS score within the first 72 h of admission.

RESULTS

Six hundred and forty patients with acute LAA-stroke were evaluated. In multivariable analyses, AIP (adjusted odds ratio [aOR]: 1.93, 95% confidence interval: 1.32-2.82) was closely associated with END after adjustment for confounders. The TyG index (aOR: 2.22, 95% confidence interval: 1.51-3.27) also showed close association with END. The AIP and TyG index showed significant differences between the END and no END groups only in patients with LAA-stroke caused by intracranial atherosclerosis. In addition, AIP and TyG index were closely related to END only in patients with LAA-stroke caused by artery-to-artery embolism and branch atheromatous disease mechanisms.

CONCLUSIONS

We found that TG and TG-related parameters were associated with the occurrence of END in patients with acute LAA-stroke. This association appeared differently depending on the location or mechanism of the relevant vessel that caused LAA-stroke.

The guardian of intracranial vessels: Why the pericyte?

Intracranial atherosclerotic stenosis (ICAS) is a pathological condition characterized by progressive narrowing or complete blockage of intracranial blood vessels caused by plaque formation. This condition leads to reduced blood flow to the brain, resulting in cerebral ischemia and hypoxia. Ischemic stroke (IS) resulting from ICAS poses a significant global public health challenge, especially among East Asian populations. However, the underlying causes of the notable variations in prevalence among diverse populations, as well as the most effective strategies for preventing and treating the rupture and blockage of intracranial plaques, remain incompletely comprehended. Rupture of plaques, bleeding, and thrombosis serve as precipitating factors in the pathogenesis of luminal obstruction in intracranial arteries. Pericytes play a crucial role in the structure and function of blood vessels and face significant challenges in regulating the Vasa Vasorum (VV)and preventing intraplaque hemorrhage (IPH). This review aims to explore innovative therapeutic strategies that target the pathophysiological mechanisms of vulnerable plaques by modulating pericyte biological function. It also discusses the potential applications of pericytes in central nervous system (CNS) diseases and their prospects as a therapeutic intervention in the field of biological tissue engineering regeneration.

Triglyceride-Related Parameters and Symptomatic Atherosclerotic Lesions in Patients With Ischemic Stroke

Objective

Recently, evidence has suggested that the pathophysiology and risk factors of intracranial atherosclerosis (ICAS) differs from those of extracranial atherosclerosis (ECAS). In addition, novel parameters reflecting metabolic conditions, such as insulin resistance or atherogenic dyslipidemia, based on triglycerides (TG) and other biomarkers, have emerged. In this study, we evaluated the association between TG-related parameters and symptomatic cerebral atherosclerosis in patients with acute ischemic stroke resulting from large artery atherosclerosis (LAA).

Methods

We assessed consecutive acute LAA-stroke patients between January 2010 and December 2020. Based on the radiological findings, we classified the relevant symptomatic arteries that caused the index stroke into LAA-ICAS and LAA-ECAS. As TG-related parameters, the atherogenic index of plasma (AIP) and TG-glucose (TyG) index were calculated according to the following formulas: AIP = log10 (TG Level/High-density Lipoprotein Cholesterol Level), TyG Index = Ln (TG Level × Glucose Level/2).

Results

A total of 519 patients with LAA-stroke were evaluated. In multivariable logistic regression analysis to identify predictors of LAA-ICAS, AIP was significantly associated with LAA-ICAS (adjusted odds ratio [aOR], 3.60; 95% confidence interval [CI], 1.60-8.06). TyG index also showed a statistically significant relationship with LAA-ICAS (aOR, 1.60; 95% CI, 1.11-2.32). However, TG per se did not show a statistical association with LAA-ECAS.

Conclusion

TG-related parameters were more closely associated with stroke by ICAS than by ECAS. The metabolic conditions reflected by the AIP or TyG index, rather than hypertriglyceridemia itself, may play a greater role in determining the relevant vessel causally involved in a stroke.

Association between the triglyceride-glucose index and stroke in middle-aged and older non-diabetic population: A prospective cohort study

BACKGROUND AND AIMS

Data regarding the association between insulin resistance (IR) and stroke among the non-diabetic population is still limited and inconsistent. This study aimed to investigate the association between IR measured by the triglyceride-glucose (TyG) index and the risk of stroke among the middle-aged and elderly Chinese without diabetes.

METHODS AND RESULTS

A total of 17,708 middle-aged and elderly (main respondents≥45 years) individuals without diabetes were enrolled from the China Health and Retirement Longitudinal Study. Participants were divided into 4 categories according to quartiles of the TyG index. During a median follow-up of 7.00 years, a total of 305 (3.93%) incident strokes occurred. With the increase in the TyG index quartiles, stroke incidence increased substantially, compared with the Q1 group, the fully adjusted hazard ratios (HRs) were 1.64 (95% confidence interval [CI], 1.13-2.38), 1.65 (95% CI, 1.10-2.46), and 1.76 (95% CI, 1.21-2.57) for Q2, Q3, and Q4 groups, respectively. The cutoff value we determined for the TyG index was 8.28. Furthermore, the addition of the TyG index to a conventional risk model had an incremental effect on the predictive value for stroke (integrated discrimination improvement 0.17%, P = 0.0025; category-free net reclassification improvement 17.91%, P = 0.0025).

CONCLUSION

TyG index was significantly associated with a higher risk of stroke among the middle-aged and elderly non-diabetic population. Our findings indicated that the TyG index may be a good tool in the prediction of stroke risk for clinical and public health fields.

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.

Association between lipid profile changes and risk of in-stent restenosis in ischemic stroke patients with intracranial stenosis: A retrospective cohort study

OBJECTIVE

The risk of ischemic stroke with intracranial stenosis is associated with various serum lipid levels. However, the effects of changes in the lipid profile on the risk of in-stent restenosis have not been verified. Therefore, we investigated the association between the occurrence of in-stent restenosis at 12-month follow-up and changes in various lipid profiles.

METHODS

In this retrospective cohort study, we included ischemic stroke patients who had undergone intracranial stenting for symptomatic intracranial stenosis between February 2010 and May 2020. We collected data about serum low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), total cholesterol (TC), and triglyceride (TG) levels, and calculated the TC/HDL-C and LDL-C/HDL-C ratios at baseline and after 12 months. We conducted multivariable logistic regression analyses to verify the association between various lipid profile changes and in-stent restenosis at 12 months.

RESULTS

Among the 100 patients included in the study (mean age, 60.8 ± 10.0 years; male: 80 [80.0%]), in-stent restenosis was found in 13 (13.0%) patients. The risk of in-stent restenosis of more than 50% was significantly decreased when TC/HDL-C ratio (odds ratio [OR] 0.22, [95% confidence interval (CI) 0.05-0.87]) and LDL-C/HDL-C ratio (OR 0.23, [95% CI 0.06-0.93]) decreased or when HDL-C levels (OR 0.10, [95% CI 0.02-0.63]) were increased at 12 months compared with baseline measurements.

CONCLUSIONS

Improvement of HDL-C levels, TC/HDL-C ratio, and LDL-C/HDL-C ratio were associated with decreased risk of in-stent restenosis at 12-month follow-up. Management and careful monitoring of various lipid profiles including HDL-C levels, TC/HDL-C ratio, and LDL-C/HDL-C ratio may be important to prevent in-stent restenosis in patients with intracranial stenting.

Changes in Cerebral Blood Flow and Diffusion-Weighted Imaging Lesions After Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a common subtype of stroke and places a great burden on the family and society with a high mortality and disability rate and a poor prognosis. Many findings from imaging and pathologic studies have suggested that cerebral ischemic lesions visualized on diffusion-weighted imaging (DWI) in patients with ICH are not rare and are generally considered to be associated with poor outcome, increased risk of recurrent (ischemic and hemorrhagic) stroke, cognitive impairment, and death. In this review, we describe the changes in cerebral blood flow (CBF) and DWI lesions after ICH and discuss the risk factors and possible mechanisms related to the occurrence of DWI lesions, such as cerebral microangiopathy, cerebral atherosclerosis, aggressive early blood pressure lowering, hyperglycemia, and inflammatory response. We also point out that a better understanding of cerebral DWI lesions will be a key step toward potential therapeutic interventions to improve long-term recovery for patients with ICH.

Association of triglyceride-glucose index with intra- and extra-cranial arterial stenosis: a combined cross-sectional and longitudinal analysis

PURPOSE

This study aimed to assess the cross-sectional and longitudinal associations of the triglyceride glucose (TyG) index, a simple surrogate marker of insulin resistance, with intra-cranial and extra-cranial artery stenosis (ICAS and ECAS) in Chinese adults.

METHODS

Participants were recruited from the Asymptomatic Polyvascular Abnormalities Community study, 5381 participants were enrolled in the cross-sectional analysis, then 3447 and 1853 participants in the longitudinal analysis for incident ICAS and ECAS, respectively. The TyG index was calculated as ln [fasting triglyceride (mg/dL) × fasting glucose (mg/dL)/2]. Multivariable logistic analysis was used to calculate odds ratio (OR) and 95% confidence interval (CI).

RESULTS

The results of the cross-sectional and longitudinal analysis were basically the same, as the fully adjusted OR comparing participants in the highest tertile versus lowest tertile of the TyG index was 1.34 (95% CI, 1.13-1.59) for the prevalence of ECAS and 1.85 (95% CI, 1.26-2.71) for incident ECAS, respectively. The addition of TyG index to a conventional model had an incremental effect on the predictive value for ECAS. However, we did not observe any significant association between the TyG index and ICAS.

CONCLUSIONS

Elevated TyG index was significantly associated with a higher risk of ECAS, but not with ICAS in Chinese adults. This conclusion lends support to the clinical significance of the TyG index for the assessment of artery stenosis, especially for ECAS.

Components of metabolic syndrome and their relation to the risk of incident cerebral infarction

Metabolic syndrome (MetS) consists of 5 metabolic components, which are recognized as risk factors for cerebral infarction. The present study was to evaluate the relative influence of individual metabolic component on incident cerebral infarction. Using a data of 209,339 Koreans registered in National Health Information Corporation, we evaluated the risk for incident cerebral infarction according to the number of metabolic component and each metabolic component for 4.37 years' follow-up. Cox proportional hazards model was used to calculate hazard ratios (HRs) for cerebral infarction and their confidence interval (CI). The more metabolic components accompanied the worse metabolic profile, leading increased incidence of cerebral infarction. The risk of cerebral infarction increased proportionally to the number of present metabolic components (number 0: reference, number 1: 1.78 [1.42-2.23], number 2: 2.20 [1.76-2.74], number 3: 2.61 [2.09-3.25] and number 4-5: 3.18 [2.54-3.98]). Compared to subjects without metabolic component, the impact of each component on cerebral infarction was relatively higher in elevated fasting glucose (1.56 [1.14-2.13]) and elevated BP (2.13 [1.66-2.73]), indicating no statistical significance in low HDL-cholesterol (1.53 [0.96-2.44]), high triglyceride (1.24 [0.84-1.84]) and abdominal obesity (1.05 [0.63-1.73]). Proportional relationship was found between the number of metabolic component and risk of cerebral infarction. Out of metabolic components, fasting glucose and BP are more powerful predictor for cerebral infarction.

Triglyceride/HDL-Cholesterol Ratio as an Index of Intracranial Atherosclerosis in Nonstroke Individuals

Background: Triglyceride (TG)/high-density lipoprotein cholesterol ratio (THR) is a marker of dyslipidemia, and high THR is associated with an increase in cardiovascular events. In the present study, whether THR was associated with various markers of cerebral vascular pathologies, atherosclerosis of major cerebral arteries, including large artery atherosclerosis (LAA) and cerebral small vessel disease (SVD), in neurologically healthy individuals was investigated. Methods: Vascular risk factors, brain magnetic resonance imaging (MRI) scans, and MR angiograms of 851 study subjects were evaluated. Findings of extracranial atherosclerosis (ECAS) and intracranial atherosclerosis (ICAS) were considered indices of LAA based on brain MR angiograms. The presence of silent lacunar infarct (SLI) and white matter hyperintensities (WMHs) were evaluated as indices of SVD based on brain MRIs. Results: Subjects with ICAS (odds ratio, 1.83; 95% confidence interval, 1.06-3.16; P = 0.03) were significantly more likely to have high THR tertile (THR > 2.06) than low THR tertile (THR < 1.37) after adjusting for cardiovascular risk factors. THR was higher in subjects with multiple ICAS lesions than in those with single ECAS or without ICAS lesions. Associations among THR tertiles in ECAS, SLI, and WMHs were not significant. Conclusion: In the present study, a positive association between high THR and the development of ICAS was observed in neurologically healthy participants.

Association of Longitudinal Glycemia with Diffusion Weighted Imaging Lesions in Spontaneous Intracerebral Hemorrhage

OBJECTIVES

Higher glycemia on admission has been associated with diffusion weighted imaging (DWI) lesions in patients with spontaneous intracerebral hemorrhage (sICH). However, the influence of longitudinal glycemia after admission and during a patient's hospitalization on DWI lesions in sICH has not been studied. Our aim was to compare longitudinal glycemia in sICH patients with and without DWI lesions.

MATERIAL AND METHODS

Glycemia measurements were abstracted on participants enrolled in a prospective observational study examining predictors for DWI lesions in sICH. Univariate analysis was used to compare mean longitudinal glycemia in sICH patients with and without DWI lesions. Logistical regression was used to determine whether mean longitudinal glycemia was predictive of DWI lesions.

RESULTS

DWI lesions were found in 60 of the 121 (49.6%) participants. Mean time-to-MRI was 99.6 h (SD ± 89). During this time interval, 2,101 glucose measurements were analyzed with a median number of 7 (IQR 12, 1-261) measurements per patient. Mean longitudinal glycemia was higher in the DWI positive group compared to the DWI negative group until time-to-MRI (132 mg/dL vs 122 mg/dL, p = 0.03). Mean longitudinal glycemia was found to be predictive of DWI lesions (OR 1.02, 95% CI 1.005 to 1.035, p = 0.011).

CONCLUSIONS

Mean longitudinal glycemia was higher in sICH patients with DWI lesions compared to those without DWI lesions. Future research into the association between higher glycemia and DWI lesions in sICH may provide insight into a pathophysiologic mechanism.

Recent glycemic control can predict the progressive motor deficits of acute subcortical infarction with diabetes or prediabetes

BACKGROUND AND PURPOSE

The predictors of progressive motor deficits in acute subcortical infarctions are still controversial. It is not known whether glycemic control influences on stroke progression.

METHODS

A total of 268 consecutive patients with diabetes or prediabetes who had acute (< 24 h) subcortical infarction were enrolled. (1) All patients were divided into 4 groups by quartile of glycated hemoglobin (HbA1c). (2) Only the patients with diabetes were divided by effective glycemic control. Progressive motor deficits were prospectively captured and defined as an increase of motor score ≥ 1 on the upper or lower limb items of the National Institute of Health Stroke Scale within 72 h from stroke onset.

RESULTS

Progressive motor deficits occur in 8/78 (10.3%) for ≤ 5.9, 15/61 (24.6%) for 6.0-6.4, 16/62 (25.8%) for 6.5-7.4, and 30/67 (44.8%) for ≥ 7.5. In diabetic patients alone, those occur in 5/37 (13.5%) for ≤ 6.5, 10/42 (23.8%) for 6.6-7.0, 12/42 (28.6%) for 7.1-8.0, and 24/50 (48.0%) for ≥ 8.1. An adjusted OR of progressive motor deficits was 2.61 (95% confidence interval [CI] 0.98-7.00, P = .056) for 6.0-6.4, 3.42 (95% CI 1.27-9.18, P = .015) for 6.5-7.4, and 6.65 (95% CI 2.38-18.62, P < .001) for ≥ 7.5. In diabetic patients alone, those were 3.15 (95% CI 0.89-11.15, P = .075) for 6.6-7.0, 2.90 (95% CI 0.79-10.61, P = .107) for 7.1-8.0, and 4.17 (95% CI 1.07-16.25, P = .038) for ≥ 8.1. The optimal cutoff value of HbA1c was 6.65% in discriminating progressive motor deficits.

CONCLUSION

Increased HbA1c was associated with higher incidence of progressive motor deficits in acute subcortical infarction with diabetes and prediabetes.

Causal associations of insulin resistance with coronary artery disease and ischemic stroke: a Mendelian randomization analysis

INTRODUCTION

The relationship between insulin resistance (IR) and cardiovascular diseases is unclear. We aimed to examine the causal associations of IR with cardiovascular diseases, including coronary artery disease, myocardial infarction, ischemic stroke and its subtypes, using Mendelian randomization.

RESEARCH DESIGN AND METHODS

Due to low sample size for gold standard measures and in order to well reflect the underlying phenotype of IR, we used 53 single nucleotide polymorphisms associated with IR phenotypes (ie, fasting insulin, high-density lipoprotein cholesterol and triglycerides) from recent genome-wide association studies (GWASs) as instrumental variables. Summary-level data from four GWASs of European individuals were used. Data on IR phenotypes were obtained from meta-analysis of GWASs of up to 188 577 individuals and data on the outcomes from GWASs of up to 446 696 individuals. Mendelian randomization (MR) estimates were calculated with inverse-variance weighted, simple and weighted-median approaches and MR-Egger regression was used to explore pleiotropy.

RESULTS

Genetically predicted 1-SD increase in IR phenotypes were associated with a substantial increase in risk of coronary artery disease (OR=1.79, 95% CI: 1.57 to 2.04, p<0.001), myocardial infarction (OR=1.78, 95% CI: 1.54 to 2.06, p<0.001), ischemic stroke (OR=1.21, 95% CI: 1.05 to 1.40, p=0.007) and the small-artery occlusion subtype of stroke (OR=1.80, 95% CI: 1.30 to 2.49, p<0.001), but not associated with the large-artery atherosclerosis and cardioembolism subtypes of stroke. There was no evidence of pleiotropy. Results were broadly consistent in sensitivity analyses using simple and weighted-median approaches accounting for potential genetic pleiotropy.

CONCLUSIONS

This study provides evidence to support that IR was causally associated with risk of coronary artery disease, myocardial infarction, ischemic stroke and the small-artery occlusion subtype of stroke.

Value of triglyceride-glucose index for the estimation of ischemic stroke risk: Insights from a general population

BACKGROUND AND AIMS

Recent studies have recognized triglyceride-glucose index (TyG) as a practical surrogate of insulin resistance. Previous studies have demonstrated that insulin resistance contributes to ischemic stroke via multiple mechanisms. Our study aimed to investigate the association between TyG and prevalent ischemic stroke, exploring the value of TyG to optimize the risk stratification of ischemic stroke.

METHODS AND RESULTS

This cross-sectional study included 10,900 subjects (mean age: 59.95 years, 59.8% females) from rural areas of northeast China between September 2017 to May 2018. TyG was calculated as ln[fasting triglyceride (mg/dl) × fasting plasma glucose (mg/dl)/2]. The prevalence of ischemic stroke was 5.49%. After adjusting for all covariates, each SD increment of TyG caused 22.8% additional risk for ischemic stroke. When dividing TyG into quartiles, the top quartile had a 1.776 times risk for ischemic stroke against the bottom category. Furthermore, smoothing curve fitting demonstrated this association was linear in the whole range of TyG. Finally, AUC revealed an improvement when introducing TyG into clinical risk factors (0.746 vs 0.751, p = 0.029). Consistently, category-free net reclassification index (0.195, 95% CI: 0.112-0.277, P < 0.001) and integrated discrimination index (0.003, 95% CI: 0.001-0.004, P < 0.001) confirmed the improvement by TyG to stratify ischemic stroke risk.

CONCLUSION

The prevent ischemic stroke correlated proportionally with the increment of TyG, implicating the linearity of TyG as an indicator of ischemic stroke. Our findings suggest the potential value of TyG to optimize the risk stratification of ischemic stroke in a general population.

Risk factors for intracranial atherosclerosis: A systematic review and meta-analysis

BACKGROUND AND AIMS

Intracranial atherosclerosis (ICAS) is a predictable and preventable condition, but existing evidence concerning its risk factors has not been quantitatively assessed. The aim of this meta-analysis is to identify the non-modifiable and modifiable risk factors for ICAS.

METHODS

PubMed and EMBASE were searched (1995-May 15, 2018) for cross-sectional and longitudinal studies exploring risk factors for ICAS. The risk estimates and 95% confidence intervals (CIs) in multivariate analysis were aggregated using random-effect models.

RESULTS

Thirty-four studies comprising 59,736 subjects met the inclusion criteria for the systematic review involving thirty-one risk or protective factors. Seven factors were associated with ICAS, as suggested by the meta-analysis, including advanced age (odds ratio (OR) 1.05, 95% CI 1.03-1.08), metabolic syndrome (OR 2.13, 95% CI 1.35-3.37), diabetes mellitus (OR 1.98, 95% CI 1.69-2.31), hypertension (OR 1.97, 95% CI 1.69-2.31), dyslipidemia (OR 1.29, 95% CI 1.04-1.59), high levels of low-density lipoprotein cholesterol (OR 1.06, 95% CI 1.00-1.12) and high levels of apolipoprotein A1 (OR 0.34, 95% CI 0.15-0.75). The subgroup analysis for study populations indicated advanced age, metabolic syndrome, diabetes mellitus and hypertension as an elevated risk of ICAS among community subjects and stroke patients; according to the subgroup analysis for ethnicity, similar associations remained in Asians, but only metabolic syndrome and diabetes mellitus were correlated with ICAS in Caucasians.

CONCLUSIONS

Individuals with advanced age, metabolic syndrome, diabetes mellitus, hypertension and dyslipidemia might have a higher risk of ICAS, whereas high levels of apolipoprotein A1 might protect against ICAS.

Insulin resistance in ischemic stroke

Insulin resistance often refers to a pathological condition in which cells fail to respond to the normal actions of insulin. Increasing literature has noted a critical role of insulin resistance in the pathogenesis of ischemic stroke. Insulin resistance plays an important role in the pathogenesis of ischemic stroke via enhancing advanced changes of atherosclerosis. A variety of literature indicates that insulin resistance enhances platelet adhesion, activation and aggregation which are conducive to the occurrence of ischemic stroke. Insulin resistance also induces hemodynamic disturbances and contributes to the onset of ischemic stroke. In addition, insulin resistance may augment the role of the modifiable risk factors in ischemic stroke and induce the occurrence of ischemic stroke. Preclinical and clinical studies have supported that improving insulin resistance may be an effective measure to prevent or delay ischemic stroke.

Location of cerebral atherosclerosis: Why is there a difference between East and West?

Intracranial atherosclerosis is more prevalent in Asian patients, whereas extracranial atherosclerosis is more common in individuals from western countries. The reasons for this discrepancy remain unknown. We reviewed the relevant literature and discussed the currently available information. Although the study population, diagnostic modality, and risk factor definitions differ between studies, hypercholesterolemia is more correlated with extracranial atherosclerosis than intracranial atherosclerosis. The difference in hypercholesterolemia prevalence is one of the main reasons for racial differences. Intracranial arteries contain higher antioxidant level than extracranial arteries and may be more vulnerable to risk factors for antioxidant depletion (e.g., metabolic syndrome and diabetes mellitus). Intracranial arteries may be vulnerable to factors associated with hemodynamic stress (e.g., advanced, salt-retaining hypertension and arterial tortuosity) because of a smaller diameter, thinner media and adventitia, and fewer elastic medial fibers than extracranial arteries. Additionally, non-atherosclerotic arterial diseases (e.g., moyamoya disease) that commonly occur in the intracranial arteries of East Asians may contaminate the reports of intracranial atherosclerosis cases. Genes, including RNF 213 or those associated with high salt sensitivity, may also explain racial differences in atherosclerotic location. To understand racial differences, further well-designed studies on various risk and genetic factors should be performed in patients with cerebral atherosclerosis. Additionally, improvements in diagnostic accuracy via advancements in imaging technologies and increased genetic data will aid in the differentiation of atherosclerosis from non-atherosclerotic intracranial diseases.

Higher Levels of Cystatin C Are Associated with Extracranial Carotid Artery Steno-Occlusive Disease in Patients with Noncardioembolic Ischemic Stroke

Background

Large artery atherosclerosis is a major cause of ischemic stroke worldwide. Differential biomarker profiles associated with extra- and intracranial atherosclerosis are a topic of considerable interest. Cystatin C (CysC), a marker of renal function, is a risk factor for cardiovascular disease.

Aim

We sought to determine whether CysC levels were associated with extra- and intracranial large artery stenosis (LAS) in patients with acute ischemic stroke.

Methods

We retrospectively analyzed data of acute noncardioembolic ischemic stroke patients who were admitted to our stroke center within 5 days from symptom onset. Serum CysC levels were measured using latex agglutination turbidimetric immunoassay. Extra- and intracranial LAS were defined as ≥50% diameter stenosis or occlusion of the relevant internal carotid artery (ICA) and/or middle cerebral artery (MCA) using carotid echography and volume rendering on magnetic resonance angiography. Multivariate logistic analyses were used to assess the association between CysC levels and LAS after adjustment for potential confounders.

Results

Of 205 patients (mean age 70.2 years), 76 (37.1%) had LAS. The distribution of LAS was 29 extracranial ICA, 34 intracranial ICA/MCA (8 ICA only, 25 MCA only, 1 ICA+MCA) and 13 tandem stenosis (both extracranial ICA and intracranial ICA/MCA). Levels of CysC were higher in patients with extracranial ICA stenosis than in those with intracranial ICA/MCA stenosis (1.23 ± 0.33 vs. 0.97 ± 0.21 mg/l, p < 0.001). In multivariate analysis, the highest CysC tertile (>1.04 mg/l) was significantly associated with extracranial ICA stenosis (adjusted odds ratio [OR] 5.01, 95% confidence interval [CI] 1.51-16.63, p = 0.009) after adjustment for age, sex, diabetes, chronic kidney disease, current smoking, systolic blood pressure, HDL cholesterol, high-sensitivity C-reactive protein (hs-CRP) and premorbid lipid-lowering drugs use. When CysC was considered as a continuous variable, 1 SD increase in CysC was significantly associated with extracranial ICA stenosis (adjusted OR 3.01, 95% CI 1.58-5.72, p = 0.001). However, there were no significant associations between CysC levels and intracranial ICA/MCA stenosis. In addition, CysC levels showed a weak but statistically significant correlation with hs-CRP levels (r = 0.195, p = 0.021). Using receiver operating characteristic curve analysis, CysC value displayed good performance in discriminating extracranial ICA stenosis (c-statistic 0.79, 95% CI 0.69-0.89, p < 0.001).

Conclusions

This preliminary study suggests that higher levels of CysC were independently associated with symptomatic extracranial ICA stenosis, but not with intracranial ICA/MCA stenosis in patients with noncardioembolic stroke. Our findings provide new insights into the link between serum CysC and carotid atherosclerosis.

Decreased Insulin Sensitivity and Impaired Fibrinolytic Activity in Type 2 Diabetes Patients and Nondiabetics with Ischemic Stroke

We analyzed (a) insulin sensitivity (IS), (b) plasma insulin (PI), and (c) plasminogen activator inhibitor-1 (PAI-1) in type 2 diabetes (T2D) patients with (group A) and without (group B) atherothrombotic ischemic stroke (ATIS), nondiabetics with ATIS (group C), and healthy controls (group D). IS was determined by minimal model (Si). Si was lower in A versus B (1.18 ± 0.67 versus 2.82 ± 0.61 min-1/mU/L × 104; P < 0.001) and in C versus D (3.18 ± 0.93 versus 6.13 ± 1.69 min-1/mU/L × 104; P < 0.001). PI and PAI-1 were higher in A versus B (PI: 19.61 ± 4.08 versus 14.91 ± 1.66 mU/L; P < 0.001, PAI-1: 7.75 ± 1.04 versus 4.57 ± 0.72 mU/L; P < 0.001) and in C versus D (PI: 15.14 ± 2.20 versus 7.58 ± 2.05 mU/L; P < 0.001, PAI-1: 4.78 ± 0.98 versus 3.49 ± 1.04 mU/L; P < 0.001). Si correlated with PAI-1 in T2D patients and nondiabetics, albeit stronger in T2D. Binary logistic regression identified insulin, PAI-1, and Si as independent predictors for ATIS in T2D patients and nondiabetics. The results imply that insulin resistance and fasting hyperinsulinemia might exert their atherogenic impact through the impaired fibrinolysis.

Retinal vessel alterations and cerebral white matter microstructural damage in obese adolescents with metabolic syndrome

IMPORTANCE

Cerebral white matter (WM) damage has been reported in childhood obesity and in metabolic syndrome (MetS) but mechanisms remain unclear.

OBJECTIVES

To ascertain whether adolescents with MetS have retinal vessel alterations and if the anticipated reductions in retinal arteriolar diameter are associated with diminished cerebral WM microstructural integrity and to test a model for vascular etiology of the WM abnormalities.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study of the brain correlates of obesity and related metabolic disease in youths. This study was conducted at the Brain, Obesity, and Diabetes Laboratory, New York University School of Medicine, New York. Thirty-nine obese adolescents with MetS and 51 matched adolescents without MetS received comprehensive endocrine, neuropsychological, retinal vessel, and diffusion tensor imaging-based cerebral WM evaluations.

MAIN OUTCOMES AND MEASURES

Retinal arteriolar diameter, cerebral WM microstructural integrity, waist circumference, and insulin resistance.

RESULTS

Obese adolescents with MetS had significant reductions in retinal arteriolar diameter relative to adolescents without MetS (mean [SD] central retinal arteriolar equivalent, 182.35 [16.10] vs. 198.62 [19.03] μm, respectively; P < .001). The greater the number of MetS criteria present, the greater the reduction was in retinal arteriolar diameter (β = -8.61; ∆r2 = 0.335; ∆F1,83 = 70.79; P < .001). We found that abdominal obesity (waist circumference) was the strongest MetS component related to reductions in retinal arteriolar diameter (rp[85] = -0.661; P < .001), and importantly, for the first time to our knowledge, we demonstrated that its effect was partially mediated by comorbid insulin resistance (indirect effect = -0.1355 [95% CI, -0.2471 to -0.0593]; Z = -2.56; P = .01). Consistent with our prior report of nondiabetic adolescents with MetS, we also uncovered cerebral WM microstructural damage. These subtle WM changes were associated with reductions in retinal arteriolar diameter, a proxy for cerebral microvascular health (3150 voxels or 3.15 cm3; P < .001). Importantly, some of the WM regions showing lower microstructural integrity also demonstrated associations with retinal arteriolar diameter, suggesting that the observed WM pathology is likely vascular in nature.

CONCLUSIONS AND RELEVANCE

We document, for the first time to our knowledge, the associations between retinal vessel alterations and subclinical WM pathology among obese adolescents with MetS. This suggests that the subtle WM pathology in adolescents with MetS may have a vascular origin. Future work should include direct assessments of cerebral microvascular health.

Insulin Resistance and Risk of Cerebral Infarction in a Japanese General Population

The aim of the study was to investigate the relation between insulin resistance and risk of cerebral infarction in a Japanese general population. The subjects were 2610 men and women without past history of stroke or myocardial infarction and who were under treatment for diabetes. Subjects were divided into quartiles by the homeostasis model assessment of insulin resistance (HOMA-IR), and Cox’s proportional hazard model was used to calculate hazard ratios (HRs) for cerebral infarction. In men, the multivariate-adjusted HRs were 2.51 (95% confidence interval [CI] = 0.98-6.42) in quartile 1 (Q1), 1.43 (95% CI = 0.54-3.82) in Q2, and 2.13 (95% CI = 0.82-5.51) in Q4, using Q3 as the reference. In women, the multivariate-adjusted HRs were 2.12 (95% CI = 0.72-6.31) in Q1, 2.96 (95% CI = 1.06-8.26) in Q3, and 2.31 (95% CI = 0.80-6.69) in Q4, using Q2 as the reference. The association between risk of cerebral infarction and HOMA-IR was not dose dependent.

The Barcelona-Asymptomatic Intracranial Atherosclerosis (AsIA) study: prevalence and risk factors

BACKGROUND AND PURPOSE

The ongoing population-based Barcelona-Asymptomatic Intracranial Atherosclerosis (Barcelona-AsIA) study is a prospective study that plans to investigate the natural history of asymptomatic intracranial atherosclerosis (AsIA) in a Caucasian-Mediterranean population, which remains unknown until now. The present study aims to determine the prevalence of AsIA and associated risk factors in the final study cohort.

METHODS

Crossover, population-based study of a representative sample (randomly selected from our reference population) older than 50 with a moderate-high vascular risk assessed by the vascular equation REGICOR and prior history of neither stroke nor ischemic heart disease. Anthropometric, demographic, clinical data and blood samples were collected at baseline. All individuals underwent a complete extracranial and transcranial color-coded duplex (TCCD) examination. TCCD criteria were used to identify and classify the degree of intracranial stenoses.

RESULTS

A total of 933 subjects (64% men, mean age 66.3 years) were included in the study. One or more intracranial stenoses were detected at baseline in 80 subjects (8.6%) of whom 31 (3.3%) had moderate-severe lesions. The higher the REGICOR scores the greater the prevalence of AsIA (6.6%, 10.2% and 25% for REGICOR scores 5-9, 10-14 and ≥15, p<0.001). Diabetes (OR 2.95; 95% CI (1.68-5.18); p<0.001), age (OR 1.05; 95% CI (1.02-1.08); p=0.001) and hypertension (OR 1.78; 95% CI (1.02-3.13); p=0.04) were independently associated with any degree of AsIA, while diabetes (OR 2.85; 95% CI (1.16-6.96); p=0.02) and age kept independently associated with moderate-severe AsIA.

CONCLUSION

The prevalence of AsIA and moderate-severe AsIA in stroke-free Caucasians with a moderate-high vascular risk were 8.6% and 3.3% respectively. Diabetes and age were independently associated with moderate-severe AsIA.

Diabetes, hyperglycemia and the management of cerebrovascular disease

PURPOSE OF REVIEW

Hyperglycemia is frequent in patients with cerebrovascular disease. This review article aims to summarize the recent evidence from observational studies that examined the adverse cerebrovascular effects of dysglycemic states as well as interventional studies assessing intensive management strategies for hyperglycemia.

RECENT FINDINGS

In recent years, diabetes, prediabetic states and insulin resistance and their association with cerebrovascular disease were an important focus of research. The cerebrovascular consequences of these metabolic abnormalities were found to extend beyond ischemic stroke to covert brain infarcts, other structural brain changes and to cognitive impairment with and without dementia. Interventional studies did not reveal that more intensive management of chronic hyperglycemia and of hyperglycemia in the setting of acute stroke improves outcome. There is clear evidence, however, that the overall management of multiple risk factors and behavior modification in patients with dysglycemia may reduce the burden of cerebrovascular disease.

SUMMARY

Observational studies reveal the growing burden and adverse cerebrovascular effects of dysglycemic states. Currently available interventional studies assessing more intensive strategies for the management of hyperglycemia did not prove, however, to be effective. We discuss the current evidence, pathophysiological considerations and management implications.