C-Reactive Protein, Plasma Amyloid-β Levels, and Their Interaction With Magnetic Resonance Imaging Markers

Inflammatory protein associations with brain MRI measures: Framingham Offspring Cohort

INTRODUCTION

Brain magnetic resonance imaging (MRI) and inflammatory biomarkers are crucial for investigating preclinical neurocognitive disorders. Current investigations focus on a few inflammatory markers. The study aims to investigate the associations between inflammatory biomarkers and MRI measures and to examine sex differences among the associations in the Framingham Heart Study.

METHODS

Dementia and stroke-free participants underwent OLINK Proteomics profiling and MRI measurements within 5 years. Pairwise cross-sectional analysis assessed 68 biomarkers with 13 brain MRI volumes, adjusting for covariates and familial correlations.

RESULTS

Elevated CDCP1, IL6, OPG, and 4E.BP1 were related to smaller total cerebral brain volume (TCBV), whereas higher HGF, IL8, and MMP10 were associated with smaller TCBV, total and frontal white matter volumes. Higher SCF and TWEAK were associated with larger TCBV. In sex-stratified analyses, associations were observed exclusively among males.

DISCUSSION

We report several associations between inflammatory biomarkers and brain volumes, highlighting different associations within sex subgroups.

HIGHLIGHTS

Higher CDCP1, IL6, OPG, and 4E.BP1 levels were associated with smaller TCBV. Higher levels of HGF, IL8 and MMP10 were associated with smaller TCBV, CWV and FWV. Higher levels of SCF and TWEAK, were associated with larger TCBV. Significance diminished in models adjusting for CVD risk factors. Associations were observed exclusively in males.

Sex-specific implications of inflammation in covert cerebral small vessel disease

BACKGROUND

The relationship between inflammation and covert cerebral small vessel disease (SVD) with regards to sex difference has received limited attention in research. We aim to unravel the intricate associations between inflammation and covert SVD, while also scrutinizing potential sex-based differences in these connections.

METHODS

Non-stroke/dementia-free study population was from the I-Lan longitudinal Aging Study. Severity and etiology of SVD were assessed by 3T-MRI in each participant. Systemic and vascular inflammatory-status was determined by the circulatory levels of high-sensitivity C-reactive protein (hsCRP) and homocysteine, respectively. Sex-specific multivariate logistic regression to calculate odds ratios (ORs) and interaction models to scrutinize women-to-men ratios of ORs (RORs) were used to evaluate the potential impact of sex on the associations between inflammatory factors and SVD.

RESULTS

Overall, 708 participants (62.19 ± 8.51 years; 392 women) were included. Only women had significant associations between homocysteine levels and covert SVD, particularly in arteriosclerosis/lipohyalinosis SVD (ORs[95%CI]: 1.14[1.03-1.27] and 1.15[1.05-1.27] for more severe and arteriosclerosis/lipohyalinosis SVD, respectively). Furthermore, higher circulatory levels of homocysteine were associated with a greater risk of covert SVD in women compared to men, as evidenced by the RORs [95%CI]: 1.14[1.01-1.29] and 1.14[1.02-1.28] for more severe and arteriosclerosis/lipohyalinosis SVD, respectively. No significant associations were found between circulatory hsCRP levels and SVD in either sex.

CONCLUSION

Circulatory homocysteine is associated with covert SVD of arteriosclerosis/lipohyalinosis solely in women. The intricacies underlying the sex-specific effects of homocysteine on SVD at the preclinical stage warrant further investigations, potentially leading to personalized/tailored managements.

TRIAL REGISTRATION

Not applicable.

Genetic evidence suggests a genetic association between major depressive disorder and reduced cortical gray matter volume: A Mendelian randomization study and mediation analysis

BACKGROUND

Several studies have suggested an association between major depressive disorder (MDD) and abnormal brain structure. However, it is unclear whether MDD affects cortical gray matter volume, a common indicator of cognitive function. We aimed to determine whether MDD was associated with decreased cortical gray matter volume (GMV) through a Mendelian randomization (MR) study.

METHODS

We obtained summary genetic data from a study conducted by the Psychiatric Genomics Consortium, which recruited a total of 480,359 participants (135,458 cases and 344,901 controls). Genetic tools-single nucleotide polymorphisms (SNPs)-of MDD were extracted from the study and their effects on gray matter volumes of the cortex and total brain were evaluated in a large cohort from the UK Biobank (n = 8427). The effects of the SNPs were pooled using inverse variance weighted (IVW) analysis and further tested in several sensitivity analyses. We tested whether C-reactive protein (CRP) levels and interleukin-6 signaling were the mediators of the effects using a multivariate MR model.

RESULTS

Thirty-three SNPs were identified and adopted as genetic tools for predicting MDD. IVW analysis showed that MDD was associated with lower overall GMV (beta value -0.106, 95%CI -0.188 to -0.023, p = 0.011) in the frontal pole (left frontal pole, -0.152, 95%CI -0.177 to -0.127, p = 0.013; right frontal pole, -0.133, 95%CI -0.253 to -0.013, p = 0.028). Multivariate and mediation analysis showed that interleukin-6 was an important mediator of GMV reduction. Reverse causality analysis found no evidence that total GMV affected the risk of MDD, but showed that increased left precuneus cortex volume and left posterior cingulate cortex volume were associated with increased risk of MDD.

LIMITATIONS

Potential pleiotropic effects and overestimation of real-world effects. Key assumptions for MR analysis may not be satisfactorily met.

CONCLUSION

MDD was associated with a reduced GMV, and interleukin-6 might be a mediator of GMV reduction.

Different inflammatory signatures based on CSF biomarkers relate to preserved or diminished brain structure and cognition

Neuroinflammation is a hallmark of Alzheimer's disease (AD) and both positive and negative associations of individual inflammation-related markers with brain structure and cognitive function have been described. We aimed to identify inflammatory signatures of CSF immune-related markers that relate to changes of brain structure and cognition across the clinical spectrum ranging from normal aging to AD. A panel of 16 inflammatory markers, Aβ42/40 and p-tau181 were measured in CSF at baseline in the DZNE DELCODE cohort (n = 295); a longitudinal observational study focusing on at-risk stages of AD. Volumetric maps of gray and white matter (GM/WM; n = 261) and white matter hyperintensities (WMHs, n = 249) were derived from baseline MRIs. Cognitive decline (n = 204) and the rate of change in GM volume was measured in subjects with at least 3 visits (n = 175). A principal component analysis on the CSF markers revealed four inflammatory components (PCs). Of these, the first component PC1 (highly loading on sTyro3, sAXL, sTREM2, YKL-40, and C1q) was associated with older age and higher p-tau levels, but with less pathological Aβ when controlling for p-tau. PC2 (highly loading on CRP, IL-18, complement factor F/H and C4) was related to male gender, higher body mass index and greater vascular risk. PC1 levels, adjusted for AD markers, were related to higher GM and WM volumes, less WMHs, better baseline memory, and to slower atrophy rates in AD-related areas and less cognitive decline. In contrast, PC2 related to less GM and WM volumes and worse memory at baseline. Similar inflammatory signatures and associations were identified in the independent F.ACE cohort. Our data suggest that there are beneficial and detrimental signatures of inflammatory CSF biomarkers. While higher levels of TAM receptors (sTyro/sAXL) or sTREM2 might reflect a protective glia response to degeneration related to phagocytic clearance, other markers might rather reflect proinflammatory states that have detrimental impact on brain integrity.

Periodontitis and brain magnetic resonance imaging markers of Alzheimer's disease and cognitive aging

INTRODUCTION

We examined the association of clinical, microbiological, and host response features of periodontitis with MRI markers of atrophy/cerebrovascular disease in the Washington Heights Inwood Columbia Aging Project (WHICAP) Ancillary Study of Oral Health.

METHODS

We analyzed 468 participants with clinical periodontal data, microbial plaque and serum samples, and brain MRIs. We tested the association of periodontitis features with MRI features, after adjusting for multiple risk factors for Alzheimer's disease/Alzheimer's disease-related dementia (AD/ADRD).

RESULTS

In fully adjusted models, having more teeth was associated with lower odds for infarcts, lower white matter hyperintensity (WMH) volume, higher entorhinal cortex volume, and higher cortical thickness. Higher extent of periodontitis was associated with lower entorhinal cortex volume and lower cortical thickness. Differential associations emerged between colonization by specific bacteria/serum antibacterial IgG responses and MRI outcomes.

DISCUSSION

In an elderly cohort, clinical, microbiological, and serological features of periodontitis were associated with MRI findings related to ADRD risk. Further investigation of causal associations is warranted.

Correlation of Plasmatic Amyloid Beta Peptides (Aβ-40, Aβ-42) with Myocardial Injury and Inflammatory Biomarkers in Acute Coronary Syndrome

Background/Objective: Amyloid beta (β) -40 levels increase with age and inflammation states and appear to be associated with clinical manifestations of acute coronary syndrome (ACS). We investigated the correlation of Aβ peptides with myocardial injury and inflammation biomarkers in patients with or without ST elevation myocardial infarction (STEMI, NSTEMI). Methods: This singe-center, cross-sectional, observational, and correlation study included 65 patients with ACS (n = 34 STEMI, 29 males, age = 58 ± 12 years; n = 31 NSTEMI, 22 males, age = 60 ± 12 years) who were enrolled in the coronary care unit within 12 h after symptom onset from February 2022 to May 2023. Aβ peptide levels and biochemical parameters were assessed. Results: NSTEMI patients had a higher prevalence of hypertension (p = 0.039), diabetes (p = 0.043), smoking (p = 0.003), and prior myocardial infarction (p = 0.010) compared to STEMI patients. We observed a higher level of Aβ-42 in NSTEMI (p = 0.001) but no difference in Aβ-40 levels. We also found a correlation between age and NT-proBNP with both Aβ peptides (Aβ-40, Aβ-42) (p = 0.001, p = 0.002 respectively). Conclusions: Our results show that patients with NSTEMI had a higher prevalence of cardiovascular risk factors (hypertension, diabetes, smoking, and prior myocardial infarction). Considering these results, we propose that Aβ-42 can add value to risk stratification in NSTEMI patients.

White matter hyperintensity volume modifies the association between CSF vascular inflammatory biomarkers and regional FDG-PET along the Alzheimer's disease continuum

In older adults with abnormal levels of Alzheimer's disease neuropathology, lower cerebrospinal fluid (CSF) vascular endothelial growth factor (VEGF) levels are associated with lower [¹⁸F]-fluorodeoxyglucose positron emission tomography (FDG-PET) signal, but whether this association is (1) specific to VEGF or broadly driven by vascular inflammation, or (2) modified by vascular risk (e.g., white matter hyperintensities [WMHs]) remains unknown. To address this and build upon our past work, we evaluated whether 5 CSF vascular inflammation biomarkers (vascular cell adhesion molecule 1, VEGF, C-reactive protein, fibrinogen, and von Willebrand factor)-previously associated with CSF amyloid levels-were related to FDG-PET signal and whether WMH volume modified these associations in 158 Alzheimer's Disease Neuroimaging Initiative participants (55-90 years old, 39 cognitively normal, 80 mild cognitive impairment, 39 Alzheimer's disease). We defined regions both by cortical boundary and by the 3 major vascular territories: anterior, middle, and posterior cerebral arteries. We found that WMH volume had interactive effects with CSF biomarkers (VEGF and C-reactive protein) on FDG-PET throughout the cortex in both vascular territories and conventionally defined regions of interest.

Networks of C-reactive protein and depression symptoms in patients with stable coronary heart disease: Findings from the Heart and Soul Study

OBJECTIVE

Research addressing the associations between C-reactive protein (CRP) and depression among patients with stable coronary heart disease (CHD) has produced inconsistent results. This might be attributable to varying associations of CRP with specific depression symptom profiles. We responded to this challenge using various network analysis techniques.

METHODS

A total of 967 outpatients with documented CHD were drawn from the baseline cross-sectional data of the Heart and Soul Study. We first estimated mixed graphical models that included CRP and individual depression symptoms, before and after adjusting for relevant covariates, to explore whether CRP is correlated with specific facets of depression. We also investigated whether CRP levels moderated the associations between specific depression symptoms using moderated network models. Finally, we performed a network comparison test and compared the symptom network properties between non-elevated and elevated CRP groups.

RESULTS

In the network model without covariates, CRP was positively associated with fatigue, appetite changes, and psychomotor problems. CRP maintained its negative association with concentration difficulty regardless of covariate adjustment. Few symptom-symptom associations, especially those involving appetite changes, were moderated by CRP. Further, the elevated CRP group showed greater overall symptom connectivity as compared to the non-elevated group.

CONCLUSION

This study segues into CRP-depression relationship with sophisticated methodology.

Association between Life's Essential 8 and Cerebral Small Vessel Disease

BACKGROUND

Given that associations of Life's Essential 8 (LE8) and cerebral small vessel disease (CSVD) or its imaging markers were unclear, we examined relationship between them.

METHODS

The cross-sectional study included community residents from the PolyvasculaR Evaluation for Cognitive Impairment and vaScular Events study. We calculated the total LE8 score, medical LE8 score and behavioural score, and categorised them into low (<60), moderate (60-79) or high (≥80) group. MRI markers included lacunes, white matter hyperintensities (WMH), enlarged perivascular spaces in basal ganglia (BG-EPVS) and cerebral microbleeds (CMB). In respect of, total CSVD score (0-4 points), WMH, lacunes or CMB were categorised as two grades, and BG-EPVS (N>10) was allocated one point. Based on modified total CSVD score (0-6 points), WMH or CMB was modified to three grades, and BG-EPVS (N>20) was allocated one point.

RESULTS

Among 3061 participants in this study, 1424 (46.5%) were male. Higher LE8 score was associated with lower total CSVD score (moderate vs low: cOR 0.78, 95% CI 0.63 to 0.96; high vs low: cOR 0.44, 95% CI 0.33 to 0.59), and the medical score was inversely related to the total CSVD score. Furthermore, the medical score was inversely related to odds of WMH (p<0.05), modified WMH (p<0.05), lacunes (p<0.05) or BG-EPVS (p<0.05), and the behavioural score were inversely related to the odds of lacunes and BG-EPVS.

CONCLUSIONS

Higher LE8 score which indicates better cardiovascular status was associated with lower burden of CSVD and its MRI markers. Longitudinal studies are needed to examine the causality.

The Presence and Severity of NAFLD are Associated With Cognitive Impairment and Hippocampal Damage

CONTEXT

Although cognitive impairment in nonalcoholic fatty liver disease (NAFLD) has received attention in recent years, little is known about detailed cognitive functions in histologically diagnosed individuals.

OBJECTIVE

This study aimed to investigate the association of liver pathological changes with cognitive features and further explore the underlying brain manifestations.

METHODS AND PATIENTS

We performed a cross-sectional study in 320 subjects who underwent liver biopsy. Among the enrolled participants, 225 underwent assessments of global cognition and cognitive subdomains. Furthermore, 70 individuals received functional magnetic resonance imaging scans for neuroimaging evaluations. The associations among liver histological features, brain alterations, and cognitive functions were evaluated using structural equation model.

RESULTS

Compared with controls, patients with NAFLD had poorer immediate memory and delayed memory. Severe liver steatosis (odds ratio, 2.189; 95% CI, 1.020-4.699) and ballooning (OR, 3.655; 95% CI, 1.419-9.414) were related to a higher proportion of memory impairment. Structural magnetic resonance imaging showed that patients with nonalcoholic steatohepatitis exhibited volume loss in left hippocampus and its subregions of subiculum and presubiculum. Task-based magnetic resonance imaging showed that patients with nonalcoholic steatohepatitis had decreased left hippocampal activation. Path analysis demonstrated that higher NAFLD activity scores were associated with lower subiculum volume and reduced hippocampal activation, and such hippocampal damage contributed to lower delayed memory scores.

CONCLUSIONS

We are the first to report the presence and severity of NAFLD to be associated with an increased risk of memory impairment and hippocampal structural and functional abnormalities. These findings stress the significance of early cognitive evaluation in patients with NAFLD.

The association of diffusion tensor MRI measures of normal appearing white matter and cognition

Objective

Median and peak height of fractional anisotropy (FA) and mean diffusivity (MD) are diffusion tensor imaging (DTI) markers used to quantify white matter microstructure changes. We examine the association of DTI histogram-derived measures in global normal appearing white matter (NAWM) and cognitive decline in patients with normal cognition and cognitive impairment no dementia from a memory clinic in Singapore.

Methods

A total of 252 patients (mean age: 71.1 ± 7.6 years, 53.2% women) were included. All patients underwent clinical assessments, a brain MRI scan at baseline, and neuropsychological assessments annually for 2 years. DTI scans were processed to obtain MD and FA histogram-derived measures. The National Institute of Neurological Disorders and Stroke and the Canadian Stroke Network harmonization neuropsychological battery were used to assess cognitive function. Linear regression models with generalised estimating equation (GEE) and logistic regression models were used to examine the association between DTI histogram measures and cognitive decline.

Results

When compared to baseline, MD and FA measures at Year 2 were associated with an accelerated worsening in global cognition (all p for interaction <0.001; Year 0 vs 2, MD median: -0.29 (95%CI: -0.49, -0.09) vs -0.45 (95%CI: -0.65,-0.25); MD peak height: 0.22 (95%CI: 0.07, 0.37) vs 0.37 (95%CI: 0.21, 0.53); FA median: 0.11 (95%CI: -0.05, 0.26) vs 0.22 (95%CI: 0.07, 0.37); FA peak height: -0.14 (95%CI: -0.28, 0.00) vs -0.24 (95%CI: -0.38, -0.10);). Similar findings were observed for executive function and visuomotor speed while only MD measures predicted worsening in memory domain.

Interpretation

This study shows that DTI histogram measures are associated with accelerated cognitive decline suggesting the utility of DTI as a pre-clinical marker in predicting the worsening of cognition in clinical trials.

Perivascular spaces in Alzheimer's disease are associated with inflammatory, stress-related, and hypertension biomarkers

Perivascular spaces (PVS) are fluid-filled spaces surrounding the brain vasculature. Literature suggests that PVS may play a significant role in aging and neurological disorders, including Alzheimer's disease (AD). Cortisol, a stress hormone, has been implicated in the development and progression of AD. Hypertension, a common condition in older adults, has been found to be a risk factor for AD. Hypertension may contribute to PVS enlargement, impairing the clearance of waste products from the brain and promoting neuroinflammation. This study aims to understand the potential interactions between PVS, cortisol, hypertension, and inflammation in the context of cognitive impairment. Using MRI scans acquired at 1.5T, PVS were quantified in a cohort of 465 individuals with cognitive impairment. PVS was calculated in the basal ganglia and centrum semiovale using an automated segmentation approach. Levels of cortisol and angiotensin-converting enzyme (ACE) (an indicator of hypertension) were measured from plasma. Inflammatory biomarkers, such as cytokines and matrix metalloproteinases, were analyzed using advanced laboratory techniques. Main effect and interaction analyses were performed to examine the associations between PVS severity, cortisol levels, hypertension, and inflammatory biomarkers. In the centrum semiovale, higher levels of inflammation reduced cortisol associations with PVS volume fraction. For ACE, an inverse association with PVS was seen only when interacting with TNFr2 (a transmembrane receptor of TNF). There was also a significant inverse main effect of TNFr2. In the PVS basal ganglia, a significant positive association was found with TRAIL (a TNF receptor inducing apoptosis). These findings show for the first time the intricate relationships between PVS structure and the levels of stress-related, hypertension, and inflammatory biomarkers. This research could potentially guide future studies regarding the underlying mechanisms of AD pathogenesis and the potential development of novel therapeutic strategies targeting these inflammation factors.

The Role of Oxidative Stress and Inflammation in Obesity and Its Impact on Cognitive Impairments-A Narrative Review

Obesity is a chronic low-grade inflammatory condition that induces the generation of oxidative stress and inflammation. This oxidative stress and inflammation stimulate brain atrophy and some morphological changes in the brain that eventually result in cognitive impairments. However, there is no exact study that has summarized the role of oxidative stress and inflammation in obesity and its impact on cognitive impairments. Thus, the objective of this review is to recapitulate the current role of oxidative stress and inflammation in cognitive decline based on in vivo evidence. A comprehensive search was performed in Nature, Medline and Ovid, ScienceDirect, and PubMed, and the search was limited to the past 10 years of publication. From the search, we identified 27 articles to be further reviewed. The outcome of this study indicates that a greater amount of fat stored in individual adipocytes in obesity induces the formation of reactive oxygen species and inflammation. This will lead to the generation of oxidative stress, which may cause morphological changes in the brain, suppress the endogenous antioxidant system, and promote neuroinflammation and, eventually, neuronal apoptosis. This will impair the normal function of the brain and specific regions that are involved in learning, as well as memory. This shows that obesity has a strong positive correlation with cognitive impairments. Hence, this review summarizes the mechanism of oxidative stress and inflammation that induce memory loss based on animal model evidence. In conclusion, this review may serve as an insight into therapeutic development focusing on oxidative stress and inflammatory pathways to manage an obesity-induced cognitive decline in the future.

Plasma inflammatory biomarkers in cerebral small vessel disease: A review

Cerebral small vessel disease (CSVD) is a group of pathological processes affecting small arteries, arterioles, capillaries, and small veins of the brain. It is one of the most common subtypes of cerebrovascular diseases, especially highly prevalent in elderly populations, and is associated with stroke occurrence and recurrence, cognitive impairment, gait disorders, psychological disturbance, and dysuria. Its diagnosis mainly depends on MRI, characterized by recent small subcortical infarcts, lacunes, white matter hyperintensities (WMHs), enlarged perivascular spaces (EPVS), cerebral microbleeds (CMBs), and brain atrophy. While the pathophysiological processes of CSVD are not fully understood at present, inflammation is noticed as playing an important role. Herein, we aimed to review the relationship between plasma inflammatory biomarkers and the MRI features of CSVD, to provide background for further research.

Glymphatic system in the thalamus, secondary degeneration area was severely impaired at 2nd week after transient occlusion of the middle cerebral artery in rats

Background and objectives

The glymphatic system is a recently discovered cerebrospinal fluid transport system and little is known about its dynamic changes after stroke. This study aimed to dynamically observe the structural and functional changes of the impaired glymphatic system in the thalamus after ischemic stroke by pathology and MRI.

Materials and methods

Ischemic stroke was induced by the middle cerebral artery occlusion (MCAO) model. A total of 20 Sprague-Dawley rats were randomly assigned into four groups: sham, MCAO 1 week, MCAO 2 week, and MCAO 2 month. All rats successively underwent neurological examination, dynamic contrast-enhanced MRI (DCE-MRI), and immunofluorescence staining. Immunofluorescence staining of glial fibrillary acidic protein (GFAP), aquaporin-4 (AQP4), ionized calcium-binding adaptor molecule 1 (Iba1), and beta-amyloid precursor protein (APP) were done in thalamus ventroposterior nucleus.

Results

The astrocyte and microglial activation and the APP deposition in the MCAO 2 week group were the highest (P < 0.05 for all). The AQP4 polarization rates of the MCAO 2 week and 2 month groups were the lowest (P < 0.05 for all). Although there was no correlation between histological changes and MRI metrics in all four groups (P > 0.05 for all), the tendency of the APP deposition was nearly consistent with the one of the contrast agent retention in DCE-MRI.

Conclusion

The glymphatic system in the thalamus was severely impaired at 2nd week after MCAO, and may be revealed by DCE-MRI. This study may provide a relevant theoretical basis for making a thorough inquiry of the mechanism of brain injury after stroke and clinical treatment of ischemic stroke and help readers appreciate the importance of DCE-MRI.

Biomarkers involved in the pathogenesis of cerebral small-vessel disease

Cerebral small-vessel disease (CSVD) has been found to have a strong association with vascular cognitive impairment (VCI) and functional loss in elderly patients. At present, the diagnosis of CSVD mainly relies on brain neuroimaging markers, but they cannot fully reflect the overall picture of the disease. Currently, some biomarkers were found to be related to CSVD, but the underlying mechanisms remain unclear. We aimed to systematically review and summarize studies on the progress of biomarkers related to the pathogenesis of CSVD, which is mainly the relationship between these indicators and neuroimaging markers of CSVD. Concerning the pathophysiological mechanism of CSVD, the biomarkers of CSVD have been described as several categories related to sporadic and genetic factors. Monitoring of biomarkers might contribute to the early diagnosis and progression prediction of CSVD, thus providing ideas for better diagnosis and treatment of CSVD.

Modulation of High-Fat Diet-Induced Brain Oxidative Stress by Ferulate-Rich Germinated Brown Rice Ethyl Acetate Extract

The oxidative stress resulting from the production of reactive oxygen species plays a vital role in inflammatory processes and is associated with neurodegenerative changes. In view of the ability of germinated brown rice (GBR) to improve learning and memory, this present study aimed to investigate the mechanistic basis of GBR’s neuroprotection in a high-fat diet (HFD)-induced oxidative changes in adult Sprague–Dawley rats. Ferulate-rich GBR ethyl acetate extract (GBR-EA; 100 mg/kg and 200 mg/kg body weight) was supplemented orally for the last 3 months of 6 months HFD feeding during the study. GBR-EA supplementation was found to improve lipid profile and serum antioxidant status, when compared to the HFD group. Elevated mRNA expressions of SOD1, SOD2, SOD3, Catalase, and GPX were demonstrated in the frontal cortex and hippocampus of GBR-EA treated animals. The pro-inflammatory changes induced by HFD in the hippocampus were attenuated by GBR-EA through the downregulation of CRP and TNF- α and upregulation of PPAR-γ. GBR also reduced the hippocampal mRNA expression and enzyme level of acetylcholinesterase. In conclusion, this study proposed the possible transcriptomic regulation of antioxidant and inflammation in neurodegenerative processes resulting from high cholesterol consumption, with an emphasis on GBR’s potential to ameliorate such changes.

The association of enlarged perivascular space with microglia-related inflammation and Alzheimer's pathology in cognitively normal elderly

BACKGROUND

Glymphatic dysfunction may contribute to the accumulation of Alzheimer's disease (AD) pathologies. Conversely, AD pathologic change might also cause neuroinflammation and aggravate glymphatic dysfunction, forming a loop that accelerates AD progression. In vivo validations are needed to confirm their relationships.

METHODS

In this study, we included 144 cognitively normal participants with AD pathological biomarker data (baseline CSF Aβ_1-42, T-Tau, P-Tau₁₈₁; plasma P-Tau₁₈₁ at baseline and at least one follow-up) from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Each subject had completed structural MRI scans. Among them, 117 subjects have available neuroinflammatory biomarker (soluble triggering receptor expressed on myeloid cells 2 (sTREM2), and 123 subjects have completed two times [18F]-florbetapir PET. The enlarged PVS (EPVS) visual rating scores in basal ganglia (BG) and centrum semiovale (CS) were assessed on T1-weighted images to reflect glymphatic dysfunction. Intracranial volume and white matter hyperintensities (WMH) volume were also calculated for further analysis. We performed stepwise linear regression models and mediation analyses to estimate the association between EPVS severity, sTREM2, and AD biomarkers.

RESULTS

CS-EPVS degree was associated with CSF sTREM2, annual change of plasma P-tau₁₈₁ and total WMH volume, whereas BG-EPVS severity was associated with age, gender and intracranial volume. The sTREM2 mediated the association between CSF P-tau₁₈₁ and CS-EPVS.

CONCLUSION

Impaired glymphatic dysfunction could contribute to the accumulation of pathological tau protein. The association between tauopathy and glymphatic dysfunction was mediated by the microglia inflammatory process. These findings may provide evidence for novel treatment strategies of anti-neuroinflammation therapy in the early stage.

Potential Protein Blood-Based Biomarkers in Different Types of Dementia: A Therapeutic Overview

Abstract:

Biomarkers capable of identifying and distinguishing types of dementia such as Alzheimer's disease (AD), Parkinson's disease dementia (PDD), Lewy body dementia (LBD), and frontotemporal dementia (FTD) have been become increasingly relentless. Studies of possible biomarker proteins in the blood that can help formulate new diagnostic proposals and therapeutic visions of different types of dementia are needed. However, due to several limitations of these biomarkers, especially in discerning dementia, their clinical applications are still undetermined. Thus, the updating of biomarker blood proteins that can help in the diagnosis and discrimination of these main dementia conditions is essential to enable new pharmacological and clinical management strategies, with specificities for each type of dementia. To review the literature concerning protein blood-based AD and non-AD biomarkers as new pharmacological targets and/or therapeutic strategies. Recent findings for protein-based AD, PDD, LBD, and FTD biomarkers are focused on in this review. Protein biomarkers were classified according to the pathophysiology of the dementia types. The diagnosis and distinction of dementia through protein biomarkers is still a challenge. The lack of exclusive biomarkers for each type of dementia highlights the need for further studies in this field. Only after this, blood biomarkers may have a valid use in clinical practice as they are promising to help in diagnosis and in the differentiation of diseases.

Inflammatory biomarkers and cerebral small vessel disease: a community-based cohort study

Background and purpose

Although inflammation has been proposed to be a candidate risk factor for cerebral small vessel disease (CSVD), previous findings remain largely inconclusive and vary according to disease status and study designs. The present study aimed to investigate possible associations between inflammatory biomarkers and MRI markers of CSVD.

Methods

A group of 15 serum inflammatory biomarkers representing a variety of those putatively involved in the inflammatory cascade was grouped and assessed in a cross-sectional study involving 960 stroke-free subjects. The biomarker panel was grouped as follows: systemic inflammation (high-sensitivity C reactive protein (hsCRP), interleukin 6 and tumour necrosis factor α), endothelial-related inflammation (E-selectin, P-selectin, intercellular adhesion molecule 1, vascular cell adhesion molecule 1 (VCAM-1), CD40 ligand, lipoprotein-associated phospholipase A2, chitinase-3-like-1 protein and total homocysteine (tHCY)) and media-related inflammation (matrix metalloproteinases 2, 3 and 9, and osteopontin). The association(s) between different inflammatory groups and white matter hyperintensity (WMH), lacunes, cerebral microbleeds (CMBs), enlarged perivascular space (PVS) and the number of deep medullary veins (DMVs) were investigated.

Results

High levels of serum endothelial-related inflammatory biomarkers were associated with both increased WMH volume (R²=0.435, p=0.015) and the presence of lacunes (R²=0.254, p=0.027). Backward stepwise elimination of individual inflammatory biomarkers for endothelial-related biomarkers revealed that VCAM-1 was significant for WMH (β=0.063, p=0.005) and tHCY was significant for lacunes (β=0.069, p<0.001). There was no association between any group of inflammatory biomarkers and CMBs or PVS. Systemic inflammatory biomarkers were associated with fewer DMVs (R²=0.032, p=0.006), and backward stepwise elimination of individual systemic-related inflammatory biomarkers revealed that hsCRP (β=−0.162, p=0.007) was significant.

Conclusion

WMH and lacunes were associated with endothelial-related inflammatory biomarkers, and fewer DMVs were associated with systemic inflammation, thus suggesting different underlying inflammatory processes and mechanisms.

Erythrocytes Are an Independent Protective Factor for Vascular Cognitive Impairment in Patients With Severe White Matter Hyperintensities

Background and Purpose: Hemoglobin is one of the main proteins in erythrocytes. There are significant correlations between low hemoglobin and white matter hyperintensities (WMH) and cognitive impairment. This study explored whether erythrocytopenia has predictive value for vascular cognitive impairment (VCI) in patients with WMH.

Method: We conducted a cross-sectional study of 302 patients, including 62 with cerebral small vessel disease and 240 with stroke. Basic demographic data and fasting blood were collected. First, all patients were divided into normal cognition (NC), mild VCI (mVCI), and severe VCI (sVCI) groups (subgroups later) based on cognitive behavior scores. Second, all patients were divided into mild WMH (mWMH) and severe WMH (sWMH) groups based on Fazekas scores. The differences in blood markers between different groups or subgroups with different cognitive levels were analyzed by univariate analysis. Then, binary logistic regression was used to analyze the diagnostic value of erythrocyte counts for VCI in the sWMH group, and ordinal logistic regression was used to analyze the predictive value of multiple variables for different cognitive levels.

Results: Univariate analysis showed that erythrocytes, hemoglobin, high-sensitivity C-reactive protein, retinol binding protein and prealbumin were potential blood markers for different cognitive levels in sWMH patients. Among them, erythrocytopenia has good predictive value for the diagnosis of mVCI (AUC = 0.685, P = 0.008) or sVCI (AUC = 0.699, P = 0.003) in patients with sWMH. Multivariate joint analysis showed that erythrocytes were an independent protective factor reducing the occurrence of VCI in patients with sWMH (OR = 0.633, P = 0.045). Even after adjusting for age, there was still a significant difference (P = 0.047).

Conclusion: Erythrocytes are an independent protective factor for VCI in patients with sWMH. Promoting hematopoietic function may have potential value for prevention of cognitive decline in patients with cerebrovascular disease.

Systemic Inflammation and Cognitive Decrements in Patients With Stage B Heart Failure

OBJECTIVE

This study aimed to investigate the role of systemic inflammation in reduced cognitive functioning in patients with early-stage heart failure (HF) while determining associations with other cardiovascular risk factors.

METHODS

Patients with stage B HF (n = 270; mean [standard deviation] age = 66.1 [10.1] years) were examined cross-sectionally for relationships among cardiovascular disease (CVD) and psychological risk factors, C-reactive protein (CRP), and Montreal Cognitive Assessment (MoCA) scores. A subsample (n = 83) at high risk for stage C HF (B-type natriuretic peptide levels ≥65 pg/ml) were followed up for 12 months for relationships between CRP levels and cognitive function.

RESULTS

Baseline smoking (χ2 = 6.33), unmarried (χ2 = 12.0), hypertension (χ2 = 5.72), greater body mass index (d = 0.45), and physical fatigue (d = 0.25) were related to higher CRP levels (p values < .05). Cross-sectionally, CRP levels were negatively related to MoCA scores, beyond CVD (ΔR2 = 0.022, β = -0.170, p < .010) and psychological risk factors (ΔR2 = 0.016, β = 0.145, p < .027), and related to mild cognitive impairment criteria (odds ratio = 1.35, 95% confidence interval [CI] = 1.00-1.81, p = .046). Across 12 months, B-type natriuretic peptide high-risk patients with CRP levels ≥3 mg/L had lower MoCA scores (23.6; 95% CI = 22.4-24.8) than did patients with CRP levels <3 mg/L (25.4; 95% CI = 24.4-26.5; p = .024).

CONCLUSIONS

Patients with stage B HF and heightened CRP levels had greater cognitive impairment at baseline and follow-up, independent of CVD and potentially psychological risk factors. Low-grade systemic inflammation may be one mechanism involved in cognitive dysfunction at early stages of HF.

Serum Inflammatory Factors and Oxidative Stress Factors Are Associated With Increased Risk of Frailty and Cognitive Frailty in Patients With Cerebral Small Vessel Disease

Objective: To study the correlation between serum inflammatory factors, oxidative stress factors and frailty, and cognitive frailty in patients with cerebral small vessel disease (CSVD).

Methods: A total of 281 patients with CSVD were selected from Tianjin Huanhu Hospital and Inner Mongolia People's Hospital from March 2019 to March 2021. CSVD was diagnosed by MRI. The FRAIL scale was used to evaluate the frailty of patients. Patients with CSVD with frailty and MMSE score <27 were considered to have cognitive frailty. Patients with non-cognitive frailty were included in the control group. The Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE) were used to evaluate the cognitive function of patients with CSVD. The serum interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), matrix metalloproteinase 3 (MMP-3), superoxide dismutase (SOD), and malondialdehyde (MDA) of patients with CSVD were detected. The correlation between blood inflammatory factors and oxidative stress factors with the frailty and cognitive frailty patients of CSVD were analyzed. Univariate and multivariate logistic regression were used to analyze the correlation between cognitive frailty and CSVD.

Results: Among the patients with CSVD selected in this study, female patients and older patients had a higher proportion of frailty (p < 0.001). In the Frail group, MoCA score and MMSE score were significantly lower than in the Pre-Frail and Robust groups, Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA) scores were significantly higher than the Pre-Frail and Robust groups, and the differences were statistically significant (p < 0.05). Serum CRP, IL-6, TNF-α, MMP-3, and MDA levels in the Frail group were higher, but SOD levels were lower. The levels of serum CRP, IL-6, TNF-α, MMP-3, and MDA in patients with CSVD in the Cognitive Frailty group were significantly higher than those of the Control group, while the levels of SOD were significantly lower than those of the Control group, and the differences were significant (p < 0.001). The results of univariate and multivariate logistic regression analysis showed that CRP, TNF-α, MMP-3, and MDA levels were associated with cognitive frailty in patients with CSVD (p < 0.05).

Conclusion: The increase of serum CRP, TNF-α, MMP-3, and MDA levels are significantly related to the increased risk of frailty and cognitive frailty in patients with CSVD.

Association of Plasma Oligomerized Amyloid-β and Cerebral White Matter Lesions in a Health Screening Population

BACKGROUND

Cerebral white matter lesions (WML) are related to a higher risk of vascular and Alzheimer's dementia. Moreover, oligomerized amyloid-β (OAβ) can be measured from blood for dementia screening.

OBJECTIVE

We aimed to investigate the relationship of plasma OAβ levels with clinical and radiological variables in a health screening population.

METHODS

WML, other volumetric parameters of magnetic resonance images, cognitive assessment, and plasma OAβ level were evaluated.

RESULTS

Ninety-two participants were analyzed. The majority of participants' clinical dementia rating was 0 or 0.5 (96.7%). White matter hyperintensities (WMH) increased with age, but OAβ levels did not (r2 = 0.19, p < 0.001, r2 = 0.03, p = 0.10, respectively). No volumetric data, including cortical thickness/hippocampal volume, showed any significant correlation with OAβ. Log-WMH volume was positively correlated with OAβ (r = 0.24, p = 0.02), and this association was significant in the periventricular area. White matter signal abnormalities from 3D-T1 images were also correlated with the OAβ in the periventricular area (p = 0.039). Multivariate linear regression showed that log-WMH values were independently associated with OAβ (B = 0.879 (95% confidence interval 0.098 -1.660, p = 0.028)). Higher tertiles of WMH showed higher OAβ levels than lower tertiles showed (p = 0.044). Using a cutoff of 0.78 ng/mL, the high OAβ group had a larger WMH volume, especially in the periventricular area, than the low OAβ group (p = 0.036).

CONCLUSION

Both WML and plasma OAβ levels can be early markers for neurodegeneration in the healthcare population. The lesions, especially in the periventricular area, might be related to amyloid pathogenesis, which strengthens the importance of WML in the predementia stage.

Total magnetic resonance imaging of cerebral small vessel disease burden predicts dysphagia in patients with a single recent small subcortical infarct

Background

This study was performed to identify the association between the total magnetic resonance imaging burden of small vessel disease and the occurrence of post-stroke dysphagia in patients with a single recent small subcortical infarct (RSSI).

Methods

We retrospectively identified all patients with a magnetic resonance imaging-confirmed single RSSI. The water-swallowing test and volume-viscosity swallow test were performed within the first 24 h following admission to assess swallowing. Demographic and clinical data were extracted from our stroke database. Based on brain magnetic resonance imaging, we independently rated the presence of cerebral microbleeds, lacunes, white matter hyperintensities and enlarged perivascular spaces. The presence of each small vessel disease feature was summed to determine the total small vessel disease burden, ranging from 0 to 4.

Results

In total, 308 patients with a single RSSI were enrolled. Overall, 54 (17.5%) were diagnosed with post-stroke dysphagia. The risk factors related to post-stroke dysphagia included the following: older age, higher National Institute of Health Stroke Scale scores, higher C-reactive protein level and higher fibrinogen level. Based on multiple logistic regression, National Institute of Health Stroke Scale scores and total small vessel disease burden were independent risk factors of post-stroke dysphagia in patients with a single RSSI, after adjusting for age, gender, history of hypertension, C-reactive protein level and fibrinogen level.

Conclusions

Dysphagia in patients with a single RSSI was associated with a more severe total small vessel disease burden as reflected by MRI. Total MRI of cerebral small vessel disease burden may predict dysphagia in these patients. Furthermore, more severe total small vessel disease burden was associated with systemic inflammation.

Heterogeneous effects of genetic risk for Alzheimer's disease on the phenome

Here we report how four major forms of Alzheimer's disease (AD) genetic risk-APOE-ε4, APOE-ε2, polygenic risk and familial risk-are associated with 273 traits in ~500,000 individuals in the UK Biobank. The traits cover blood biochemistry and cell traits, metabolic and general health, psychosocial health, and cognitive function. The difference in the profile of traits associated with the different forms of AD risk is striking and may contribute to heterogenous presentation of the disease. However, we also identify traits significantly associated with multiple forms of AD genetic risk, as well as traits showing significant changes across ages in those at high risk of AD, which may point to their potential roles in AD etiology. Finally, we highlight how survivor effects, in particular those relating to shared risks of cardiovascular disease and AD, can generate associations that may mislead interpretation in epidemiological AD studies. The UK Biobank provides a unique opportunity to powerfully compare the effects of different forms of AD genetic risk on the phenome in the same cohort.

Inflammatory markers and tract-based structural connectomics in older adults with a preliminary exploration of associations by race

Peripheral inflammation has been implicated in cognitive dysfunction and dementia. While studies outline the relationship between elevated inflammation and individual gray or white matter alterations, less work has examined inflammation as related to connectivity between gray and white matter or variability in these associations by race. We examined the relationship between peripheral inflammation and tract-based structural connectomics in 74 non-demented participants (age = 69.19 ± 6.80 years; 53% female; 45% Black) who underwent fasting venipuncture and MRI. Serum was assayed for C-reactive protein, interleukin-6, and interleukin-1β. Graph theory analysis integrated T1-derived gray matter volumes and DTI-derived white matter tractography into connectivity matrices analyzed for local measures of nodal strength and efficiency in a priori regions of interest associated with cardiovascular disease risk factors and dementia. Linear regressions adjusting for relevant covariates showed associations between inflammatory markers and nodal strength in the isthmus, posterior and caudal anterior cingulate (p's ≤ .042). Adding an inflammatory marker*race term showed race-modified associations between C-reactive protein and efficiency in the thalamus and amygdala, and nodal strength in the putamen (p's ≤ .048), between interleukin-6 and efficiency in the pars triangularis and amygdala (p's ≤ .024), and between interleukin-1β and nodal strength in the pars opercularis (p = .048). Higher levels of inflammation associated with lower efficiency and higher strength for White participants but higher efficiency and lower strength for Black participants. Results suggest inflammation is associated with tract-based structural connectomics in an older diverse cohort and that differential relationships may exist by race within prefrontal and limbic brain regions.

Cerebral microbleeds in vascular dementia from clinical aspects to host-microbial interaction

Vascular dementia is the second leading cause of dementia after Alzheimer's disease in the elderly population worldwide. Cerebral microbleeds (CMBs) are frequently observed in MRI of elderly subjects and considered as a possible surrogate marker. The number and location of CMBs reflect the severity of diseases and the underlying pathologies may involve cerebral amyloid angiopathy or hypertensive vasculopathy. Accumulating evidence demonstrated the clinicopathological discrepancies of CMBs, the clinical significance of CMBs associated with other MRI markers of cerebral small vessel disease, cognitive impairments, serum, and cerebrospinal fluid biomarkers. Moreover, emerging evidence has shown that genetic factors and gene-environmental interactions might shed light on the underlying etiologies of CMBs, focusing on blood-brain-barrier and inflammation. In this review, we introduce recent genetic and microbiome studies as a cutting-edge approach to figure out the etiology of CMBs through the "microbe-brain-oral axis" and "microbiome-brain-gut axis." Finally, we propose novel concepts, "microvascular matrisome" and "imbalanced proteostasis," which may provide better perspectives for elucidating the pathophysiology of CMBs and future development of therapeutics for vascular dementia using CMBs as a surrogate marker.

Is microvascular dysfunction a systemic disorder with common biomarkers found in the heart, brain, and kidneys? - A scoping review

Although microvascular dysfunction (MVD) has been well characterized in individual organs as different disease entities, clinical evidence is mounting in support of an underlying systemic process. To address this hypothesis, we systematically searched PubMed and Medline for studies in adults published between 2014 and 2019 that measured blood biomarkers of MVD in three vital organs i.e. brain, heart, and the kidney. Of the 9706 unique articles 321 met the criteria, reporting 49 biomarkers of which 16 were common to the three organs. Endothelial dysfunction, inflammation including reactive oxidation, immune activation, and coagulation were the commonly recognized pathways. Triglyceride, C-reactive protein, Cystatin C, homocysteine, uric acid, IL-6, NT-proBNP, thrombomodulin, von Willebrand Factor, and uric acid were increased in MVD of all three organs. In contrast, vitamin D was decreased. Adiponectin, asymmetric dimethylarginine, total cholesterol, high-density and low-density cholesterol were found to be variably increased or decreased in studies. We review the pathways underlying MVD in the three organs and summarize evidence supporting its systemic nature. This scoping review informs clinicians and researchers in the multi-system manifestation of MVD. Future work should focus on longitudinal investigations to evaluate the multi-system involvement of this disease.

Blood-based Biomarkers of Alzheimer's Disease: The Long and Winding Road

BACKGROUND

Blood-based biomarkers can be very useful in formulating new diagnostic and treatment proposals in the field of dementia, especially in Alzheimer's disease (AD). However, due to the influence of several factors on the reproducibility and reliability of these markers, their clinical use is still very uncertain. Thus, up-to-date knowledge about the main blood biomarkers that are currently being studied is extremely important in order to discover clinically useful and applicable tools, which could also be used as novel pharmacological strategies for the AD treatment.

METHODS

A narrative review was performed based on the current candidates of blood-based biomarkers for AD to show the main results from different studies, focusing on their clinical applicability and association with AD pathogenesis.

OBJECTIVE

The aim of this paper was to carry out a literature review on the major blood-based biomarkers for AD, connecting them with the pathophysiology of the disease.

RESULTS

Recent advances in the search of blood-based AD biomarkers were summarized in this review. The biomarkers were classified according to the topics related to the main hallmarks of the disease such as inflammation, amyloid, and tau deposition, synaptic degeneration and oxidative stress. Moreover, molecules involved in the regulation of proteins related to these hallmarks were described, such as non-coding RNAs, neurotrophins, growth factors and metabolites. Cells or cellular components with the potential to be considered as blood-based AD biomarkers were described in a separate topic.

CONCLUSION

A series of limitations undermine new discoveries on blood-based AD biomarkers. The lack of reproducibility of findings due to the small size and heterogeneity of the study population, different analytical methods and other assay conditions make longitudinal studies necessary in this field to validate these structures, especially when considering a clinical evaluation that includes a broad panel of these potential and promising blood-based biomarkers.

Different Perivascular Space Burdens in Idiopathic Rapid Eye Movement Sleep Behavior Disorder and Parkinson's Disease

BACKGROUND

Excessive aggregation of α-synuclein is the key pathophysiological feature of Parkinson's disease (PD). Rapid eye movement sleep behavior disorder (RBD) is also associated with synucleinopathies and considered as a powerful predictor of PD. Growing evidence suggests the diminished clearance of α-synuclein may be partly attributable to poor interstitial fluid drainage, which can be reflected by magnetic resonance imaging (MRI)-visible enlarged perivascular space (EPVS). However, the effect of MRI-visible EPVS on iRBD and PD, and their correlation with clinical characteristics remain unclear.

OBJECTIVE

To evaluate the clinical and neuroimaging significance of MRI-visible EPVS in iRBD and PD patients.

METHODS

We enrolled 33 iRBD patients, 82 PD (with and without RBD) patients, and 35 healthy controls (HCs), who underwent clinical evaluation and 3.0 Tesla MRI. Two neurologists assessed MRI-visible EPVS in centrum semiovale (CSO), basal ganglia (BG), substantia nigra (SN), and brainstem (BS). Independent risk factors for iRBD and PD were investigated using multivariable logistic regression analysis. Spearman analysis was used to test the correlation of MRI-visible EPVS with clinical characteristics of patients.

RESULTS

iRBD patients had significantly higher EPVS burdens (CSO, BG, SN, and BS) than PD patients. Higher CSO-EPVS and BS-EPVS burdens were independent risk factors for iRBD. Furthermore, higher CSO-EPVS and SN-EPVS burdens were positively correlated with the severity of clinical symptom in iRBD patients, and higher BG-EPVS burden was positively correlated with the severity of cognitive impairment in PD patients.

CONCLUSION

iRBD and PD patients have different MRI-visible EPVS burdens, which may be related with a compensatory mechanism in glymphatic system. Lower MRI-visible EPVS burden in PD patients may be a manifestation of severe brain waste drainage dysfunction. These findings shed light on the pathophysiologic relationship between iRBD and PD with respect to neuroimaging marker of PD.

AlzRiskMR database: an online database for the impact of exposure factors on Alzheimer's disease

In view of great difficulties in the pathogenesis analysis of Alzheimer's disease (AD) presently, profiling the modifiable risk factors is crucial for early detection and intervention of AD. However, the causal associations among them have yet to be identified, and the effective integration and application of these data also remain considerable challenges due to the lack of efficient collection and analysis procedures. To address this issue, we performed comprehensive analyses by two-sample Mendelian randomization (2SMR) and established the AlzRiskMR database (https://github.com/SDBMC/RiskFactors2AD). Four 2SMR analysis methods, including inverse variance weighted (IVW), MR-Egger, weighted median, and weighted mode, were used for the complementary calculation to test the reliability of the results. The database currently comprises 1870 sets of data of Genome-Wide Association Studies (GWAS) from the MR-Base and NHGRI-EBI GWAS Catalog database. AlzRiskMR database not only estimates causal associations between modifiable risk factors and AD but also offers a useful and timely resource for early intervention of AD development incidence.

Perivascular Unit: This Must Be the Place. The Anatomical Crossroad Between the Immune, Vascular and Nervous System

Most neurological disorders seemingly have heterogenous pathogenesis, with overlapping contribution of neuronal, immune and vascular mechanisms of brain injury. The perivascular space in the brain represents a crossroad where those mechanisms interact, as well as a key anatomical component of the recently discovered glymphatic pathway, which is considered to play a crucial role in the clearance of brain waste linked to neurodegenerative diseases. The pathological interplay between neuronal, immune and vascular factors can create an environment that promotes self-perpetration of mechanisms of brain injury across different neurological diseases, including those that are primarily thought of as neurodegenerative, neuroinflammatory or cerebrovascular. Changes of the perivascular space can be monitored in humans in vivo using magnetic resonance imaging (MRI). In the context of glymphatic clearance, MRI-visible enlarged perivascular spaces (EPVS) are considered to reflect glymphatic stasis secondary to the perivascular accumulation of brain debris, although they may also represent an adaptive mechanism of the glymphatic system to clear them. EPVS are also established correlates of dementia and cerebral small vessel disease (SVD) and are considered to reflect brain inflammatory activity. In this review, we describe the “perivascular unit” as a key anatomical and functional substrate for the interaction between neuronal, immune and vascular mechanisms of brain injury, which are shared across different neurological diseases. We will describe the main anatomical, physiological and pathological features of the perivascular unit, highlight potential substrates for the interplay between different noxae and summarize MRI studies of EPVS in cerebrovascular, neuroinflammatory and neurodegenerative disorders.

Hearing handicap in Asian patients with dementia

BACKGROUND

Hearing loss and hearing handicap may contribute to cognitive impairment and dementia. The purpose of this study was to analyze the association between hearing loss and hearing handicap with dementia in an Asian memory clinic parents.

METHODS

This study includes the data obtained from patients with mild dementia who attended the National University hospital memory clinic and non-demented healthy subjects among spouses and caregivers who are non-genetically related to our patients. All participants underwent comprehensive physical, medical, neuropsychological and audiological assessments (i.e. pure tone audiometry - PTA). Disabling hearing loss was defined as a hearing loss of >40 dB in the better ear on PTA. Amsterdam Inventory for Auditory Disability and Handicap (AIADH) questionnaire was administered through the verbal interview to measure their hearing handicap score. Linear regression models were used to investigate the association between hearing loss and hearing handicap with dementia. Mean differences (β) with 95% confidence intervals (CI) were calculated.

RESULTS

91 participants (65-90 years old) were recruited for this study; 39 of them were patients with dementia and 52 were non-demented healthy controls. 48.7% of the patients with dementia had disabling hearing loss, which is higher than the non-demented controls (25.0%) (p = 0.019). The significant association between hearing handicap (as measured by AIADH) and dementia was observed, which was independent of demographic factors and audiology related history and PTA average (β = -6.40; 95% CI =0.11.99, -0.81, p = 0.025). There was no independent association between hearing loss and dementia (p > 0.05).

CONCLUSION

A significant association between hearing handicap and dementia was found. The mechanism of this association requires further research and may involve higher order central processing disorder.

Salivary biomarkers in Alzheimer's disease

OBJECTIVES

The objective of this study was to evaluate the changes that can occur in saliva components in patients with Alzheimer's disease (AD) of different severity and determine if any of these components could be a biomarker of this disease. Therefore, a panel of selected analytes related to the amyloid cascade, the immune and adrenergic systems, among others, were analyzed in the saliva of patients with Alzheimer's disease.

METHODS

A total of 152 patients with AD and controls were included. The severity of the disease was established according to the Global Deterioration Scale. Unstimulated whole saliva was collected.

RESULTS

Salivary amyloid-β42 was significantly lower, and complement C4 was significantly higher in the patients with AD than in the controls (p < 0.05 in both cases). Only complement C4 maintained its significant effect in the multivariate regression analysis. However, the area under the receiver operating characteristic curve of C4 was 0.613. No changes were found in any analyte regarding the severity of the disease.

CONCLUSIONS

A decrease in amyloid-β42 and an increase in complement C4 were detected in the saliva of patients with AD, but the changes did not show a high diagnostic performance for the detection of AD and were not associated with its severity.

CLINICAL RELEVANCE

Although some analytes showed significant differences in saliva in patients with AD, in our study conditions the salivary biomarkers analyzed were not of enough diagnostic utility for being used in routine.

Critical Steps to be Taken into Consideration Before Quantification of β-Amyloid and Tau Isoforms in Blood can be Implemented in a Clinical Environment

This review aims to document difficulties, limitations, and pitfalls when considering protein analysis in blood samples. It proposes an improved workflow for design, development, and validation of (immuno)assays for blood proteins, without providing reflections on a potential hypothesis of the origin of protein mismetabolism and deposition. There is a special focus on assay development for quantification of β-amyloid (Aβ) and tau in blood for diagnostic use or for integration in clinical trials in the field of Alzheimer's disease (AD).

Inflammation and cerebral small vessel disease: A systematic review

Inflammation is increasingly implicated as a risk factor for dementia, stroke, and small vessel disease (SVD). However, the underlying mechanisms and causative pathways remain unclear. We systematically reviewed the existing literature on the associations between markers of inflammation and SVD (i.e., white matter hyperintensities (WMH), lacunes, enlarged perivascular spaces (EPVS), cerebral microbleeds (CMB)) in cohorts of older people with good health, cerebrovascular disease, or cognitive impairment. Based on distinctions made in the literature, markers of inflammation were classified as systemic inflammation (e.g. C-reactive protein, interleukin-6, fibrinogen) or vascular inflammation/endothelial dysfunction (e.g. homocysteine, von Willebrand factor, Lp-PLA2). Evidence from 82 articles revealed relatively robust associations between SVD and markers of vascular inflammation, especially amongst stroke patients, suggesting that alterations to the endothelium and blood-brain barrier may be a driving force behind SVD. Conversely, cross-sectional findings on systemic inflammation were mixed, although longitudinal investigations demonstrated that elevated levels of systemic inflammatory markers at baseline predicted subsequent SVD severity and progression. Importantly, regional analysis revealed that systemic and vascular inflammation were differentially related to two distinct forms of SVD. Specifically, markers of vascular inflammation tended to be associated with SVD in areas typical of hypertensive arteriopathy (e.g., basal ganglia), while systemic inflammation appeared to be involved in CAA-related vascular damage (e.g., centrum semiovale). Nonetheless, there is insufficient data to establish whether inflammation is causal of, or secondary to, SVD. Findings have important implications on interventions, suggesting the potential utility of treatments targeting the brain endothelium and blood brain barrier to combat SVD and associated neurodegenerative diseases.

Emerging Biomarkers in Vascular Cognitive Impairment and Dementia: From Pathophysiological Pathways to Clinical Application

Vascular pathology is the second most common neuropathology of dementia after Alzheimer’s disease (AD), with small vessels disease (SVD) being considered the major cause of vascular cognitive impairment and dementia (VCID). This review aims to evaluate pathophysiological pathways underlying a diagnosis of VCID. Firstly, we will discuss the role of endothelial dysfunction, blood-brain barrier disruption and neuroinflammation in its pathogenesis. Then, we will analyse different biomarkers including the ones of inflammatory responses to central nervous system tissue injuries, of coagulation and thrombosis and of circulating microRNA. Evidences on peripheral biomarkers for VCID are still poor and large-scale, prospectively designed studies are needed to translate these findings into clinical practice, in order to set different combinations of biomarkers to use for differential diagnosis among types of dementia.

Associations between rare microglia-linked Alzheimer's disease risk variants and subcortical brain volumes in young individuals

Introduction

Recent exome sequencing studies have identified three novel risk variants associated with Alzheimer's disease (AD). However, the mechanisms by which these variants confer risk are largely unknown.

Methods

In the present study, the impact of these rare coding variants (in ABI3, PLCG2, and TREM2) on all subcortical volumes is determined in a large sample of young healthy individuals (N = 756–765; aged 22–35 years).

Results

After multiple testing correction (P_CORRECTED < .05), rare variants were associated with basal ganglia volumes (TREM2 and PLCG2 effects within the putamen and pallidum, respectively). Nominal associations between TREM2 and reduced hippocampal and thalamic volumes were also observed.

Discussion

Our observations suggest that rare variants in microglia-mediated immunity pathway may contribute to the subcortical alterations observed in AD cases. These observations provide further evidence that genetic risk for AD may influence the volume of subcortical volumes and increase AD risk in early life processes.

Characterization of White Matter Hyperintensities in Large-Scale MRI-Studies

Background: White matter hyperintensities of presumed vascular origin (WMH) are a common finding in elderly people and a growing social malady in the aging western societies. As a manifestation of cerebral small vessel disease, WMH are considered to be a vascular contributor to various sequelae such as cognitive decline, dementia, depression, stroke as well as gait and balance problems. While pathophysiology and therapeutical options remain unclear, large-scale studies have improved the understanding of WMH, particularly by quantitative assessment of WMH. In this review, we aimed to provide an overview of the characteristics, research subjects and segmentation techniques of these studies.

Methods: We performed a systematic review according to the PRISMA statement. One thousand one hundred and ninety-six potentially relevant articles were identified via PubMed search. Six further articles classified as relevant were added manually. After applying a catalog of exclusion criteria, remaining articles were read full-text and the following information was extracted into a standardized form: year of publication, sample size, mean age of subjects in the study, the cohort included, and segmentation details like the definition of WMH, the segmentation method, reference to methods papers as well as validation measurements.

Results: Our search resulted in the inclusion and full-text review of 137 articles. One hundred and thirty-four of them belonged to 37 prospective cohort studies. Median sample size was 1,030 with no increase over the covered years. Eighty studies investigated in the association of WMH and risk factors. Most of them focussed on arterial hypertension, diabetes mellitus type II and Apo E genotype and inflammatory markers. Sixty-three studies analyzed the association of WMH and secondary conditions like cognitive decline, mood disorder and brain atrophy. Studies applied various methods based on manual (3), semi-automated (57), and automated segmentation techniques (75). Only 18% of the articles referred to an explicit definition of WMH.

Discussion: The review yielded a large number of studies engaged in WMH research. A remarkable variety of segmentation techniques was applied, and only a minority referred to a clear definition of WMH. Most addressed topics were risk factors and secondary clinical conditions. In conclusion, WMH research is a vivid field with a need for further standardization regarding definitions and used methods.

Recurrence Rate and Relevant Associated Factors of Stroke among Patients with Small Artery Occlusion in Northern China

Small artery occlusion (SAO) is responsible for 31.3% of all ischemic strokes in China. However, reports regarding the recurrence rate of SAO in China are rare. We aimed to assess the recurrence rate and factors associated with SAO in China. All consecutive patients with SAO hospitalized at Tianjin Huanhu Hospital from 2005 to 2014 were recruited. We assessed the association between stroke subtype, severity, and disease history with recurrence at 3, 12, and 36 months of onset using multivariate logistic regression analysis. A total of 2,524 SAO patients were included in this study, including 1696 (67.2%) men and 828 (32.8%) women. The recurrence rates were 3.1% at 3 months, 12.7% at 12 months, and 36.5% at 36 months. Compared with women, men had a higher risk of recurrence at 3 months after SAO (P = 0.003). Old age and severity of stroke were also associated with a higher risk of recurrence (P < 0.05). Patients with an elevated C-reactive protein had a higher risk of recurrence at 12 months (P = 0.003). On the other hand, the risk of recurrence at 12 months was 39% lower in patients who consumed alcohol than in those who did not (P = 0.037). Hypertension, atrial fibrillation, and obesity were independent risk factors of recurrence at 36 months. These findings suggest that modification of risk factors in patients with SAO, particularly men, is essential for reducing the rate of recurrence and the overall burden of stroke in China.

Advances in biomarkers of cerebral small vessel disease

Cerebral small vessel disease (CSVD) refers to a type of syndrome caused by lesions in perforating arteries, small veins, small arteries, or capillaries, resulting in clinical, imaging, or pathological alterations. The occurrence and development of CSVD are related to various cerebrovascular risk factors, such as metabolism and genetic factors. CSVD is diagnosed based on brain imaging biomarkers; however, biomarkers capable of predicting and diagnosing CSVD early in its progression have not been found. Exploring biomarkers closely related to disease progression is of great significance for early diagnosis, prognosis, prevention, and treatment of CSVD. This article examines the research progress of CSVD biomarkers, from inflammatory biomarkers, coagulation and fibrinolysis markers, biomarkers of endothelial dysfunction, biomarkers related to cerebrospinal fluid, and gene markers.