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.

Complement Proteins in Serum Astrocyte-Derived Exosomes Are Associated with Poststroke Cognitive Impairment in Type 2 Diabetes Mellitus Patients

Background

The complement system plays crucial roles in cognitive impairment and acute ischemic stroke (AIS). High levels of complement proteins in plasma astrocyte-derived exosomes (ADEs) were proven to be associated with Alzheimer's disease. We aimed to investigate the relationship of complement proteins in serum ADEs with poststroke cognitive impairment in type 2 diabetes mellitus (T2DM) patients.

Methods

This study analyzed 197 T2DM patients who suffered AIS. The Beijing version of the Montreal Cognitive Assessment (MoCA) was used to assess cognitive function. Complement proteins in serum ADEs were quantified using ELISA kits.

Results

Mediation analyses showed that C5b-9 and C3b in serum ADEs partially mediate the impact of obstructive sleep apnea (OSA), depression, small vessel disease (SVD), and infarct volume on cognitive function at the acute phase of AIS in T2DM patients. After adjusting for age, sex, time, and interaction between time and complement proteins in serum ADEs, the mixed linear regression showed that C3b and complement protein Factor B in serum ADEs were associated with MoCA scores at three-, six-, and twelve-months after AIS in T2DM patients.

Conclusions

Our study suggested that the impact of OSA, depression, SVD, and infarct volume on cognitive impairment in the acute stage of AIS may partially mediate through the complement proteins in serum ADEs. Additionally, the complement proteins in serum ADEs at the acute phase of AIS associated with MoCA scores at three-, six-, twelve months after AIS in T2DM patients.REGISTRATION: URL: http://www.chictr.org.cn/,ChiCTR1900021544.

MRI factors associated with cognitive functioning after acute onset brain injury: Systematic review and meta-analysis

Impairments of memory, attention, and executive functioning are frequently reported after acute onset brain injury. MRI markers hold potential to contribute to identification of patients at risk for cognitive impairments and clarification of mechanisms. The aim of this systematic review was to summarize and value the evidence on MRI markers of memory, attention, and executive functioning after acute onset brain injury. We included ninety-eight studies, on six classes of MRI factors (location and severity of damage (n = 15), volume/atrophy (n = 36), signs of small vessel disease (n = 15), diffusion-weighted imaging measures (n = 36), resting-state functional MRI measures (n = 13), and arterial spin labeling measures (n = 1)). Three measures showed consistent results regarding their association with cognition. Smaller hippocampal volume was associated with worse memory in fourteen studies (pooled correlation 0.58 [95% CI: 0.46-0.68] for whole, 0.11 [95% CI: 0.04-0.19] for left, and 0.34 [95% CI: 0.17-0.49] for right hippocampus). Lower fractional anisotropy in cingulum and fornix was associated with worse memory in six and five studies (pooled correlation 0.20 [95% CI: 0.08-0.32] and 0.29 [95% CI: 0.20-0.37], respectively). Lower functional connectivity within the default-mode network was associated with worse cognition in four studies. In conclusion, hippocampal volume, fractional anisotropy in cingulum and fornix, and functional connectivity within the default-mode network showed consistent associations with cognitive performance in all types of acute onset brain injury. External validation and cut off values for predicting cognitive impairments are needed for clinical implementation.

White matter hyperintensities and longitudinal cognitive decline in cognitively normal populations and across diagnostic categories: A meta-analysis, systematic review, and recommendations for future study harmonization

INTRODUCTION

The primary aim of this paper is to improve the clinical interpretation of white matter hyperintensities (WMHs) and provide an overarching summary of methodological approaches, allowing researchers to design future studies targeting current knowledge gaps.

METHODS

A meta-analysis and systematic review was performed investigating associations between baseline WMHs and longitudinal cognitive outcomes in cognitively normal populations, and populations with mild cognitive impairment (MCI), Alzheimer's disease (AD), and stroke.

RESULTS

Baseline WMHs increase the risk of cognitive impairment and dementia across diagnostic categories and most consistently in MCI and post-stroke populations. Apolipoprotein E (APOE) genotype and domain-specific cognitive changes relating to strategic anatomical locations, such as frontal WMH and executive decline, represent important considerations. Meta-analysis reliability was assessed using multiple methods of estimation, and results suggest that heterogeneity in study design and reporting remains a significant barrier.

DISCUSSION

Recommendations and future directions for study of WMHs are provided to improve cross-study comparison and translation of research into consistent clinical interpretation.

Severity of Lesions Involving the Cortical Cholinergic Pathways May Be Associated With Cognitive Impairment in Subacute Ischemic Stroke

Purpose: Impairment of cortical cholinergic pathways (CCP) is an important risk factor for chronic vascular cognitive impairment. However, this phenomenon has rarely been studied in post-stroke cognitive impairment (PSCI). We investigated the relationship between PSCI and CCP lesions assessed by structural magnetic resonance imaging (MRI). Patients and methods: We prospectively enrolled 103 patients within 7 days of ischemic stroke onset. CCP was measured by the cholinergic pathways hyperintensities scale (CHIPS), which semiquantitatively grades MR lesions strategically located on the CCP identified in human brains. We also measured other MRI parameters, including the location and volumes of acute infarcts, cerebral microbleeds, medial temporal lobe atrophy, and white matter lesions. Neuropsychological assessments were performed using the 60-min modified vascular dementia battery (VDB) at 3 months after the index stroke, and PSCI was defined according to VDB as well as ADL. Results: Of all 103 patients, 69 men (67.0%) and 34 women (33.0%) with a mean age of 57.22 ± 12.95 years, 55 patients (53.4%) were judged to have PSCI at 3 months, including 43 (41.7%) patients with PSCI-no dementia and 12 (11.7%) patients with poststroke dementia. According to the VBD assessment, the most commonly impaired cognitive domain was visuomotor speed (27.2%) followed by verbal memory (25.2%). Univariate analysis showed that patients with PSCI were older; had higher informant questionnaire on cognitive decline in the elderly (IQCODE) scores; had more frequent previous stroke history and atrial fibrillation; and had higher CHIPS scores, more severe white matter lesions, and medial temporal lobe atrophy. PSCI patients also had higher depression scores at 3 months. In the multivariate regression analysis, age, IQCODE score, CHIPS score, and Hamilton depression rating scale score were independent predictors of PSCI. Ordinal regression analysis for risk factors of poor functional outcomes revealed that IQCODE scores and cognitive function status were related to mRS score at 3 months after stroke. Conclusion: In patients with early subacute ischemic stroke, the severity of lesions involving the CCP may be associated with cognitive impairment at 3 months. Clinical Trial Registration: Chinese Clinical Trial Registry, identifier: ChiCTR1800014982.

Association between Striatal Brain Iron Deposition, Microbleeds and Cognition 1 Year After a Minor Ischaemic Stroke

Brain iron deposits (IDs) are inversely associated with cognitive function in community-dwelling older people, but their association with cognition after ischemic stroke, and whether that differs from microbleeds, is unknown. We quantified basal ganglia IDs (BGID) and microbleeds (BMBs) semi-automatically on brain magnetic resonance images from patients with minor stroke (NIHSS < 7), at presentation and 12 months after stroke. We administered the National Adult Reading Test (NART, estimates premorbid or peak adult cognition) and the Revised Addenbrooke's Cognitive Examination (ACE-R; current cognition) at 1 and 12 months after stroke. We adjusted analyses for baseline cognition, age, gender, white matter hyperintensity (WMH) volume and vascular risk factors. In 200 patients, mean age 65 years, striatal IDs and BMBs volumes did not change over the 12 months. Baseline BGID volumes correlated positively with NART scores at both times (ρ = 0.19, p < 0.01). Baseline and follow-up BGID volumes correlated positively with age (ρ = 0.248, p < 0.001 and ρ = 0.271, p < 0.001 respectively), but only baseline (and not follow-up) BMB volume correlated with age (ρ = 0.129, p < 0.05). Both smoking and baseline WMH burden predicted verbal fluency and visuospatial abilities scores (B = -1.13, p < 0.02 and B = -0.22, p = 0.001 respectively) at 12 months after stroke. BGIDs and BMBs are associated differently with cognition post-stroke; studies of imaging and post-stroke cognition should adjust for premorbid cognition. The positive correlation of BGID with NART may reflect the lower premorbid cognition in patients with stroke at younger vs older ages.

Effect of small-vessel disease on cognitive trajectory after atrial fibrillation-related ischaemic stroke or TIA

Post-stroke dementia is common but has heterogenous mechanisms that are not fully understood, particularly in patients with atrial fibrillation (AF)-related ischaemic stroke or TIA. We investigated the relationship between MRI small-vessel disease markers (including a composite cerebral amyloid angiopathy, CAA, score) and cognitive trajectory over 12 months. We included patients from the CROMIS-2 AF study without pre-existing cognitive impairment and with Montreal Cognitive Assessment (MoCA) data. Cognitive impairment was defined as MoCA < 26. We defined “reverters” as patients with an “acute” MoCA (immediately after the index event) score < 26, who then improved by ≥ 2 points at 12 months. In our cohort (n = 114), 12-month MoCA improved overall relative to acute performance (mean difference 1.69 points, 95% CI 1.03–2.36, p < 0.00001). 12-month cognitive impairment was associated with increasing CAA score (per-point increase, adjusted OR 4.09, 95% CI 1.36–12.33, p = 0.012). Of those with abnormal acute MoCA score (n = 66), 59.1% (n = 39) were “reverters”. Non-reversion was associated with centrum semi-ovale perivascular spaces (per-grade increase, unadjusted OR 1.83, 95% CI 1.06–3.15, p = 0.03), cerebral microbleeds (unadjusted OR 10.86, 95% CI 1.22–96.34, p = 0.03), and (negatively) with multiple ischaemic lesions at baseline (unadjusted OR 0.11, 95% CI 0.02–0.90, p = 0.04), as well as composite small-vessel disease (per-point increase, unadjusted OR 2.91, 95% CI 1.23–6.88, p = 0.015) and CAA (per-point increase, unadjusted OR 6.71, 95% CI 2.10–21.50, p = 0.001) scores. In AF-related acute ischaemic stroke or TIA, cerebral small-vessel disease is associated both with cognitive performance at 12 months and failure to improve over this period.

Systematic review and meta-analysis of the prevalence of cognitive impairment no dementia in the first year post-stroke

Introduction

Increasing attention is being paid to interventions for cognitive impairment (CI) post-stroke, including for CI that does not meet dementia criteria. The aim of this paper was to conduct a systematic review and meta-analysis of the prevalence of cognitive impairment no dementia (CIND) within one year post-stroke.

Patients and methods

Pubmed, EMBASE and PsychInfo were searched for papers published in English in 1995-2017. Included studies were population or hospital-based cohort studies for first-ever/recurrent stroke, assessing CIND using standardised criteria at 1-12 months post-stroke. Abstracts were screened, followed by full text review of potentially relevant articles. Data were extracted using a standard form, and study quality was appraised using the Crowe Critical Appraisal Tool. A pooled prevalence of CIND with 95% confidence intervals (CI) was estimated using random-effects meta-analysis. Heterogeneity was measured using the I² statistic.

Results

A total of 7000 abstracts were screened, followed by 1028 full text articles. Twenty-three articles were included in the systematic review, and 21 in the meta-analysis. The pooled CIND prevalence was 38% [95% CI = 32-43%] (I²=92.5%, p < 0.01). Study quality emerged as one source of heterogeneity. The five studies with the highest quality scores had no heterogeneity (I²=0%, p = 0.99), with a similar pooled prevalence (39%, 95%CI = 35-42%). Other sources of heterogeneity were stroke type, inclusion of pre-stroke CI, and age at assessment time.Discussion and conclusion: Meta-analysis of available studies indicates that in the first year post-stroke, 4 in 10 patients display a level of cognitive impairment that does not meet the criteria for dementia.

Cognitive Dysfunction in Relation to Topography and Burden of Cerebral Microbleeds

Introduction

Contribution of cerebral microbleeds (CMBs) on cognitive dysfunctions in elderly patients with otherwise asymptomatic white matter lesions (WMLs) is not well-documented.

Methods

MRI parameters of cerebral atrophy, CMBs and WMLs were herein analyzed in relation to global and main domains (attention, executive, memory, visuospatial, language) of cognitive function. Eighty-five patients older than 50, without neurodegenerative/cerebrovascular disease, but had CMBs were recruited from 2562 with T2*-gradient-echo MR imaging during one-year period.

Results

Global cognition, evaluated by mini-mental status examination (MMSE), was impaired (score ≤24) in 42%. In contrast to CMBs load, WML burden and temporal atrophy were significantly higher in cases with MMSE≤24. Cholinergic Pathways HyperIntensities Scale (CHIPS) was positively correlated with global cognitive dysfunction but its CMB counterpart, Cholinergic Pathways Bleeding Scale described herein, was not. However, burden of CMBs in thalamic/cortical regions predicted language dysfunction.

Conclusion

Cognitive dysfunction associated with CMBs may be dependent on their distribution rather than their absolute number.

Microbleeds in fronto-subcortical circuits are predictive of dementia conversion in patients with vascular cognitive impairment but no dementia

Cerebral small vessel disease (CSVD) is a common etiology of vascular cognitive impairment with no dementia (V-CIND). Studies have revealed that cerebral microbleeds (CMBs), a feature of CSVD, contribute to cognitive impairment. However, the association between CMBs and dementia conversion in individuals with V-CIND is still unclear. Here, we analyzed the predictive role of CMBs in the conversion from V-CIND to dementia in CSVD patients. We recruited and prospectively assessed 85 patients with CSVD and V-CIND. V-CIND was evaluated using a series of comprehensive neuropsychological scales, including the Chinese version of the Montreal Cognitive Assessment and the Clinical Dementia Rating. MRI assessments were used to quantify lacunar infarcts, white matter hyperintensities, CMBs, and medial temporal lobe atrophy. Eighty-two of the 85 patients completed the assessment for dementia conversion at a 1-year follow-up assessment. Multivariate logistic regression analyses were conducted to examine independent clinical and MRI variables associated with dementia conversion. Twenty-four patients (29.3%) had converted to dementia at the 1-year follow-up, and these individuals had significantly more CMBs in the fronto-subcortical circuits. Multivariate logistic regression analyses revealed that the patients with CMBs in the fronto-subcortical circuits (odds ratio = 4.4; 95% confidence interval: 1.602–12.081, P = 0.004) and 5 or more CMBs overall (odds ratio = 17.6, 95% confidence interval: 3.23–95.84, P = 0.001) had a significantly increased risk of dementia at the 1-year follow-up. These findings indicate that CMBs in the fronto-subcortical circuits may be predictive of dementia conversion in CSVD patients with V-CIND, and thus extend the clinical significance of CMBs. This trial was registered with the Chinese Clinical Trial Registry (registration number: ChiCTR1800017077). Protocol version: 1.0.

Cerebral microhemorrhages: mechanisms, consequences, and prevention

The increasing prevalence of multifocal cerebral microhemorrhages (CMHs, also known as "cerebral microbleeds") is a significant, newly recognized problem in the aging population of the Western world. CMHs are associated with rupture of small intracerebral vessels and are thought to progressively impair neuronal function, potentially contributing to cognitive decline, geriatric psychiatric syndromes, and gait disorders. Clinical studies show that aging and hypertension significantly increase prevalence of CMHs. CMHs are also now recognized by the National Institutes of Health as a major factor in Alzheimer's disease pathology. Moreover, the presence of CMHs is an independent risk factor for subsequent larger intracerebral hemorrhages. In this article, we review the epidemiology, detection, risk factors, clinical significance, and pathogenesis of CMHs. The potential age-related cellular mechanisms underlying the development of CMHs are discussed, with a focus on the structural determinants of microvascular fragility, age-related alterations in cerebrovascular adaptation to hypertension, the role of oxidative stress and matrix metalloproteinase activation, and the deleterious effects of arterial stiffening, increased pulse pressure, and impaired myogenic autoregulatory protection on the brain microvasculature. Finally, we examine potential treatments for the prevention of CMHs based on the proposed model of aging- and hypertension-dependent activation of the reactive oxygen species-matrix metalloproteinases axis, and we discuss critical questions to be addressed by future studies.

Cerebral small vessel disease and post-stroke cognitive impairment

Cerebral small vessel disease (CSVD) refers to a group of pathological processes with multifarious etiologies that affect the small arteries, arterioles, venules, and capillaries of the brain. Features seen on neuroimaging include white matter hyperintensities, lacunar infarction, cerebral microbleeds, brain atrophy, microinfarcts and enlarged perivascular spaces (EPVS). CSVD gives rise to one in five strokes worldwide and is a leading cause of cognitive impairment and dementia, especially in the elderly. Post-stroke cognitive impairment (PSCI) is one of the most common subtypes of cognitive impairment. The underlying mechanisms of PSCI are not known in detail. A growing body of evidence has been suggesting that CSVD plays an important role in the pathogenesis of PSCI. This article reviews the advances in research on the relationship between CSVD and PSCI.

Evaluating the Role of Reduced Oxygen Saturation and Vascular Damage in Traumatic Brain Injury Using Magnetic Resonance Perfusion-Weighted Imaging and Susceptibility-Weighted Imaging and Mapping

The cerebral vasculature, along with neurons and axons, is vulnerable to biomechanical insult during traumatic brain injury (TBI). Trauma-induced vascular injury is still an underinvestigated area in TBI research. Cerebral blood flow and metabolism could be important future treatment targets in neural critical care. Magnetic resonance imaging offers a number of key methods to probe vascular injury and its relationship with traumatic hemorrhage, perfusion deficits, venous blood oxygen saturation changes, and resultant tissue damage. They make it possible to image the hemodynamics of the brain, monitor regional damage, and potentially show changes induced in the brain's function not only acutely but also longitudinally following treatment. These methods have recently been used to show that even mild TBI (mTBI) subjects can have vascular abnormalities, and thus they provide a major step forward in better diagnosing mTBI patients.

A Review of Risk Factors for Cognitive Impairment in Stroke Survivors

In this review, we aimed to identify the risk factors that may influence cognitive impairment among stroke survivors, namely, demographic, clinical, psychological, and physical determinants. A search from Medline, Scopus, and ISI Web of Science databases was conducted for papers published from year 2004 to 2015 related to risk factors of cognitive impairment among adult stroke survivors. A total of 1931 articles were retrieved, but only 27 articles met the criteria and were reviewed. In more than half of the articles it was found that demographical variables that include age, education level, and history of stroke were significant risk factors of cognitive impairment among stroke survivors. The review also indicated that diabetes mellitus, hypertension, types of stroke and affected region of brain, and stroke characteristics (e.g., size and location of infarctions) were clinical determinants that affected cognitive status. In addition, the presence of emotional disturbances mainly depressive symptoms showed significant effects on cognition. Independent relationships between cognition and functional impairment were also identified as determinants in a few studies. This review provided information on the possible risk factors of cognitive impairment in stroke survivors. This information may be beneficial in the prevention and management strategy of cognitive impairments among stroke survivors.

The Influence of Demographic, Clinical, Psychological and Functional Determinants on Post-stroke Cognitive Impairment at Day Care Stroke Center, Malaysia

BACKGROUND

This study aims to estimate the prevalence and explore the predictors for post-stroke cognitive impairment at the community level in Malaysia.

METHODS

A total of 50 stroke patients aged 29 to 81-year-old were included in this study. A face to face interview was conducted to gather the demographic and clinical data. Subsequently, assessments including Barthel ADL Index (BI), Addenbrooke's Cognitive Examination-Revised (ACE-R) and Hospital Anxiety and Depression Scale (HADS) were administered to the subjects.

RESULTS

The results showed that the prevalence of cognitive impairment was 76% among the studied populations. The subjects' race (Fisher's value= 9.56, P < 0.05) and education level (Fisher's value = 7.29, P < 0.05) were significantly associated with the cognitive status. The depression score was significantly higher in cognitively impaired group [t (48) = -4.42, P < 0.001] while the Barthel Index score was significantly lower in cognitively impaired group (median = 18.00, P < 0.05). The univariate logistic analysis demonstrated that Chinese (OR 7.33, 95% CI = 1.61-33.51), lower education level (OR 9.33, 95% CI = 0.89-97.62), right sided lesion (OR 0.29, 95% CI = 0.06-1.54), left face weaknesses (OR 0.40, 95% CI 0.09-1.83), high cholesterol (OR 0.45, 95% CI = 0.12-1.75), depression (OR 2.16, 95% CI = 0.85-1.35), and Barthel Index (OR 0.79, 95% CI = 0.57-1.10) were significant predictors. Finally, multivariate logistic regression verified that depression was the only significant predictor of post-stroke cognitive impairment (OR 2.03, 95% CI = 1.20-3.45).

CONCLUSION

In conclusion, the prevalence of cognitive impairment in this study was higher than other community based studies and depression was a risk factor for cognitive impairment.

Cerebral Microbleeds, CSF p-Tau, and Cognitive Decline: Significance of Anatomic Distribution

BACKGROUND AND PURPOSE

Cerebral microbleeds are associated with aging, hypertension, and Alzheimer disease. Microbleeds in a lobar distribution are believed to reflect underlying amyloid angiopathy, whereas microbleeds in the deep gray matter and infratentorial brain are commonly seen with hypertension. However, it is unknown how microbleeds in either distribution are related to Alzheimer pathogenesis. The purpose of this analysis was to test whether lobar and deep gray/infratentorial microbleeds demonstrate differential associations with CSF amyloid-β and phosphorylated tau 181 protein levels and longitudinal cognitive decline.

MATERIALS AND METHODS

A total of 626 subjects (151 cognitively normal, 389 with mild cognitive impairment, and 86 with Alzheimer disease) from the Alzheimer's Disease Neuroimaging Initiative who had undergone 3T MR imaging and lumbar puncture were included in the analysis. The number and location of microbleeds were assessed visually. Associations between lobar or deep gray/infratentorial microbleeds with CSF amyloid-β levels, abnormal CSF phosphorylated tau 181 protein levels, and longitudinal cognitive decline were assessed by using ordinary least-squares, logistic, and mixed-effects regression models while adjusting for covariates.

RESULTS

Having ≥3 lobar microbleeds was associated with lower levels of CSF amyloid-β (P = .001). After adjusting for CSF amyloid-β level, lobar microbleeds were independently associated with a higher likelihood of having an abnormal CSF phosphorylated tau 181 protein level (P = .004). Lobar microbleeds were associated with accelerated longitudinal cognitive decline (P = .007). Deep gray/infratentorial microbleeds revealed no significant associations.

CONCLUSIONS

The distribution of microbleeds revealed different associations with amyloid-β and phosphorylated tau 181 protein levels and cognition. Lobar and deep gray/infratentorial microbleeds should be considered separately with regard to Alzheimer disease pathogenesis.

Susceptibility Weighted Imaging and Mapping of Micro-Hemorrhages and Major Deep Veins after Traumatic Brain Injury

Micro-hemorrhages are a common result of traumatic brain injury (TBI), which can be quantified with susceptibility weighted imaging and mapping (SWIM), a quantitative susceptibility mapping approach. A total of 23 TBI patients (five women, 18 men; median age, 41.25 years old; range, 21.69-67.75 years) with an average Glasgow Coma Scale score of 7 (range, 3-15) at admission were recruited at mean 149 d (range, 57-366) after injury. Susceptibility-weighted imaging data were collected and post-processed to create SWIM images. The susceptibility value of small hemorrhages (diameter ≤10 mm) and major deep veins (right septal, left septal, central septal, right thalamostriate, left thalamostriate, internal cerebral, right basal vein of Rosenthal, left basal vein of Rosenthal, and pial veins) were evaluated. Different susceptibility thresholds were tested to determine SWIM's sensitivity and specificity for differentiating hemorrhages from the veins. A total of 253 deep veins and 173 small hemorrhages were identified and evaluated. The mean susceptibility of hemorrhages was 435±206 parts per billion (ppb) and the mean susceptibility of deep veins was 108±56 ppb. Hemorrhages showed a significantly higher susceptibility than all deep veins (p<0.001). With different thresholds (250, 227 and 200 ppb), the specificity was 97%, 95%, and 92%, and the sensitivity was 84%, 90%, and 92%, respectively. These results show that SWIM could be used to differentiate hemorrhages from veins in TBI patients in a semi-automated manner with reasonable sensitivity and specificity. A larger cohort will be needed to validate these findings.

Post-stroke cognitive impairment: epidemiology, mechanisms and management

Post-stroke cognitive impairment occurs frequently in the patients with stroke. The prevalence of post-stroke cognitive impairment ranges from 20% to 80%, which varies for the difference between the countries, the races, and the diagnostic criteria. The risk of post-stroke cognitive impairment is related to both the demographic factors like age, education and occupation and vascular factors. The underlying mechanisms of post-stroke cognitive impairment are not known in detail. However, the neuroanatomical lesions caused by the stroke on strategic areas such as the hippocampus and the white matter lesions (WMLs), the cerebral microbleeds (CMBs) due to the small cerebrovascular diseases and the mixed AD with stroke, alone or in combination, contribute to the pathogenesis of post-stroke cognitive impairment. The treatment of post-stroke cognitive impairment may benefit not only from the anti-dementia drugs, but also the manage measures on cerebrovascular diseases. In this review, we will describe the epidemiological features and the mechanisms of post-stroke cognitive impairment, and discuss the promising management strategies for these patients.

Cognitive profiles in patients with multi-infarct dementia: an omani study

Background

Studies on neurocognitive impairment among patients presenting with multi-infarct dementia (MID) have received little attention from non-Western societies, and the Arab world is no exception. To our knowledge, this is the first study to characterize neurocognitive, affective and vegetative functioning in patients with MID in Oman.

Methods

In this study, we recruited 20 Omani patients presenting with MID and age- and gender-matched controls at the outpatient clinic of the Department of Behavioral Medicine, Sultan Qaboos University Hospital, Sultan Qaboos University, Muscat, Oman. In addition to the collection of clinical and demographic information, various cognitive batteries were administered to the consenting participants, including those indexing nonverbal reasoning abilities, working memory (attention, concentration and recall) and executive functioning. Questionnaires that elicit the affective range and the quality of sleep were also administered.

Results

Compared with the matched healthy subjects, the patients diagnosed with MID significantly differed in the presently operationalized indices of visuospatial function, semantic memory and affective and vegetative functioning. In contrast, episodic memory and some attentional capacities were not significantly different compared with the control subjects.

Conclusions

The present study was explorative and clinically designed to describe neurocognitive functioning in patients with MID seeking consultation at a tertiary care center in Oman. Our data are necessary for planning and setting up community services and health care programs for demented patients in a society where dementia is a growing silent epidemic.

Cerebral microbleeds: a review of clinical, genetic, and neuroimaging associations

Cerebral microbleeds (microbleeds) are small, punctuate hypointense lesions seen in T2* Gradient-Recall Echo (GRE) and Susceptibility-Weighted (SWI) Magnetic Resonance Imaging (MRI) sequences, corresponding to areas of hemosiderin breakdown products from prior microscopic hemorrhages. They occur in the setting of impaired small vessel integrity, commonly due to either hypertensive vasculopathy or cerebral amyloid angiopathy. Microbleeds are more prevalent in individuals with Alzheimer’s disease (AD) dementia and in those with both ischemic and hemorrhagic stroke. However they are also found in asymptomatic individuals, with increasing prevalence with age, particularly in carriers of the Apolipoprotein (APOE) ε4 allele. Other neuroimaging findings that have been linked with microbleeds include lacunar infarcts and white matter hyperintensities on MRI, and increased cerebral β-amyloid burden using ¹¹C-PiB Positron Emission Tomography. The presence of microbleeds has been suggested to confer increased risk of incident intracerebral hemorrhage – particularly in the setting of anticoagulation – and of complications of immunotherapy for AD. Prospective data regarding the natural history and sequelae of microbleeds are currently limited, however there is a growing evidence base that will serve to inform clinical decision-making in the future.

Cerebral microbleeds as a predictor of 1-year outcome of poststroke depression

BACKGROUND AND PURPOSE

Cerebral microbleeds (CMBs) are common in stroke survivors and community-dwelling elderly. The clinical significance of CMBs in the outcome of poststroke depression (PSD) is unknown. This study examined the association between the 1-year outcome of PSD and CMBs.

METHODS

The study population comprised 774 Chinese patients with acute ischemic stroke who were admitted to the acute stroke unit of a university-affiliated regional hospital in Hong Kong. Three and 15 months after the onset of the index stroke, a research assistant administered the locally validated 15-item Geriatric Depression Scale. PSD was defined as a Geriatric Depression Scale score of ≥7. Of the 213 patients with PSD at the 3-month follow-up, 135 (63.4%) attended the 15-month follow-up, at which time 89 (65.9%) patients remained depressed (nonremitters), and 46 (34.1%) had recovered (remitters). The presence and location of CMBs were evaluated with magnetic resonance imaging.

RESULTS

In comparison with the remitters, nonremitters were more likely to have lobar CMBs (18.4% versus 4.3%; P=0.024). Lobar CMBs remained an independent predictor of PSD in the multivariate analysis, with an odds ratio of 4.96 (P=0.039).

CONCLUSIONS

The results suggest that lobar CMBs may influence the outcome of PSD. The importance of CMBs in the clinical course of depression in stroke survivors warrants further investigation.

Key neuroanatomical structures for post-stroke cognitive impairment

The neuroanatomical substrate of vascular cognitive impairment (VCI) has traditionally included the subcortex of the brain, especially sub-frontal white matter circuits, strategic areas of single infarction that may mediate cognitive impairment such as the dominant thalamus or angular gyrus, and the left hemisphere, and bilateral brain infarcts or volume-driven cortical-subcortical infarctions reaching a critical threshold of tissue loss or injury. We provide an update on the neuroanatomical substrates of VCI and emphasize the following structures or areas: (1) new concepts in relation to hippocampal involvement in VCI based on neuropathological and MRI studies of microinfarcts and the role of traditional cardiovascular risk factors in possibly mediating or potentiating cognitive impairment; (2) advances in our understanding of cerebral microbleeds; and (3) an update on white matter hyperintensities and small vessel disease.

Relationship between cerebral microbleeds and cognitive function in lacunar infarct

OBJECTIVE

Little is known about the impact of cerebral microbleeds on cognitive function. This study investigated the distribution of cerebral microbleeds and their impact on cognitive function, in patients with lacunar infarct.

METHODS

Patients with lacunar infarct were enrolled prospectively. Cerebral microbleeds were classified as absent, mild, moderate or severe, based on magnetic resonance imaging findings. Cognitive function was measured using the Montreal Cognitive Assessment (MoCA) questionnaire, with a total score of <26 indicating cognitive impairment.

RESULTS

Of the 85 patients included in the study, 35 (41.2%) had cerebral microbleeds. They were more frequently observed in mixed and deep brain regions, but rarely in the cerebral lobes. Multiple logistic regression analysis demonstrated that presence of cerebral microbleeds (odds ratio [OR] 5.320), duration of education (OR 0.938) and age (OR 1.464) were independent predictors of cognitive impairment. There was a significant correlation between cerebral microbleed severity and MoCA score.

CONCLUSION

The number and location of cerebral microbleeds were both closely associated with cognitive impairment, in patients with lacunar infarct.