Cerebral amyloid angiopathy (CAA) and hypertensive (HTN) small vessel disease are causes of spontaneous intracerebral hemorrhage (ICH). We identified ICH rates in patients with all-cause mild cognitive impairment (MCI) or Alzheimer's disease (AD), and explored feasibility of using location-based approach to differentiate CAA- and HTN-related ICH using comorbidities in electronic health records (EHRs). This administrative study combined Veterans Affairs Healthcare System plus Centers for Medicare and Medicaid Services (VAHS/CMS) databases. Patients with MCI/AD aged ≥ 50 years (2016-2023) were 1:1 matched to non-MCI/AD controls. Inpatient primary discharge International Classification of Diseases-10th Edition (ICD-10) codes identified acute ICH; anatomical location within codes classified events as likely CAA- or HTN-related ICH. Incidence rates of ICH after MCI/AD were summarized. Cluster analysis of variables related to ICH was used to describe whether data-driven groupings matched clinician-postulated classifications. The MCI/AD cohort (n = 747,475) and controls were aged 77.7 ± 10.1 years (96% men, 75-76% White, 87-88% non-Hispanic). Demographic- and comorbidity-adjusted rates of ICH/1000 person-years were 0.84 (overall), 1.05 (MCI/AD), and 0.68 (non-MCI/AD). Adjusted events/1000 person-years were higher in MCI/AD vs. non-MCI/AD cohorts: CAA-related ICH, 0.19 vs. 0.12 (Incidence Rate Ratio (IRR) 1.63; P < 0.001); HTN-related ICH, 0.16 vs. 0.12 (IRR 1.35; P < 0.001); non-specific-ICH, 0.68 vs. 0.43 (IRR 1.59; P < 0.001). Hierarchical clustering analysis of our cohorts revealed an association of CAA-related ICH with older age, cardiovascular and rheumatic disorders, and an association of HTN-related ICH with cerebrovascular disease, hypertension and diabetes. In sum, the estimated incidence of ICH over the study period was 0.84/1000 person-years. CAA-related ICH incidence in MCI/AD was 63% greater than that in controls. Outcomes from cluster analysis are consistent with ICD-based CAA- vs. HTN-related ICH classifications. These findings support future exploration of using ICD coding-based ICH event identification in EHRs and claims databases for epidemiological studies.

Background/Objectives: Currently available treatments approved by the Food and Drug Administration for Alzheimer's disease (AD) either only target the symptoms of AD or, if disease-modifying, have severe side effects. This study aims to explore the potential of the FDA-approved Rho-associated kinase (ROCK) inhibitor netarsudil to reduce tau, a pathological protein in AD. Methods: We explored the pharmacokinetic and pharmacodynamic properties of netarsudil following a single intraperitoneal (i.p.) injection in wild-type mice. The efficacy of netarsudil was assessed using ELISA targeting tau/phosphorylated tau (ptau), as well as mass spectrometry-based proteomics. Results: We found that netarsudil is brain permeable, reaches peak concentrations rapidly and has moderate but sustained exposure in the central nervous system (CNS). Additionally, there was a statistically significant negative association between brain netarsudil exposure and tau and phosphorylated tau at residue 181 (ptau181). The exploratory proteomic analysis of mouse brains exposed to netarsudil revealed changes in mitochondrial function, enrichment of metallothioneins Mt1 and Mt2, and suppression of the AD-related genes Pzp and Serpina3m. Conclusions: The apparent reduction in AD pathological protein tau/ptau and a neuroprotective proteomic profile in vivo suggest the potential for netarsudil to be developed as a new AD therapeutic agent.

BackgroundRetinal thickness has been associated with neurocognitive conditions such as Alzheimer's disease (AD).ObjectiveRetinal cell layer thickness was evaluated for associations with neurodegenerative protein biomarkers glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) in plasma, vitreous humor, and aqueous humor.MethodsThis cross-sectional study included 50 patients who underwent vitrectomy and optical coherence tomography imaging of the inner macular ring (IM) and outer macular ring (OM). Associations between inner retinal cell layer thicknesses and GFAP or NfL levels were evaluated with linear regression adjusted for demographic and clinical factors. p-values less than 0.05 and with a false discovery rate less than 10% were considered significant.ResultsHigher plasma GFAP levels were significantly associated with a thinner retinal nerve fiber layer at the superior, nasal, and inferior OM as well as a thinner ganglion cell layer at the superior IM, inferior IM, temporal IM, nasal OM, and temporal OM. Plasma GFAP was also associated with a thinner inner plexiform layer at the nasal IM, inferior IM, temporal IM, nasal OM, and temporal OM. Plasma NfL was negatively associated with GCL thickness only in the superior IM.ConclusionsHigher plasma GFAP levels were associated with thinner inner cell layers, whereas plasma NfL levels showed a more limited association. These findings suggest that systemic astroglial activation may be associated with retinal structural changes.

BACKGROUND: Midlife obesity is a major modifiable risk factor for Alzheimer’s disease (AD), yet the lipid-mediated mechanisms linking peripheral metabolic dysfunction to brain pathology remain poorly understood. In particular, how adipose-derived lipid perturbations influence immune and neuronal compartments in the brain has not been fully elucidated. METHODS: We employed an integrative multi-omics approach combining quantitative lipidomics, single-nucleus RNA sequencing, proteomics, and high-resolution imaging to characterize the metabolic alterations associated with obesity in both peripheral and central tissues. Functional assessments were performed in AD mouse models to evaluate neuroimmune responses and behavioral outcomes. Statistical analyses were performed using appropriate univariate and multivariate methods, with multiple testing correction applied where applicable. RESULTS: We identified elevated phosphatidylethanolamine (PE) abundance as a metabolic hallmark of obesity. Excess PE accumulation led to disrupted lipid homeostasis and ectopic lipid droplet deposition in the brain, resulting in functional exhaustion of T cells, impaired microglial identity and signaling, and enhanced amyloidogenic processing in excitatory neurons. These effects were linked by membrane remodeling as a unifying structural mechanism. Pharmacological targeting of PE homeostasis using the redox-active compound ebselen ameliorated lipid dysregulation, restored neuroimmune function, and improved cognitive performance in AD models. CONCLUSIONS: Our study reveals a critical role for PE in coordinating immune-neuronal crosstalk under metabolic stress. These findings suggest that lipid remodeling serves as a structural nexus linking obesity to AD progression, and support the potential of lipid-directed interventions as therapeutic strategies for metabolic-risk-associated neurodegeneration.

Alzheimer’s disease (AD) is the most common age-related neurodegenerative disease and cause of dementia. AD pathology primarily involves the formation of amyloid β (Aβ) plaques and neurofibrillary tangles containing hyperphosphorylated tau (p-tau). While Aβ targeted treatments have shown clinical promise, other aspects of AD pathology such as microgliosis, astrocytosis, synaptic loss, and hypometabolism may be viable targets for treatment. Among notable novel therapeutic approaches, the Ras homolog (Rho)-associated kinases (ROCKs) are being investigated as targets for AD treatment, based on the observations that ROCK1/2 levels are elevated in AD, and activation or inhibition of ROCKs changes dendritic/synaptic structures, protein aggregate accumulation, inflammation, and gliosis. This review will highlight key findings on the effects of ROCK inhibition in Aβ and ptau pathologies, as well as its effects on neuroinflammation, synaptic density, and potentially metabolism and bioenergetics.

Successful Alzheimer’s disease (AD) interventions in preclinical models often fail in human trials. While preclinical models offer insights into AD mechanisms, there is no systematic approach to verify whether preclinical target mechanisms retain therapeutic relevance in humans. Bridging this preclinical-to-clinical translational gap accelerates therapeutic development by precisely addressing whether failures are due to testing ineffective drugs, targeting the wrong mechanism, or relying on unrepresentative models. We have developed a novel bioinformatics platform, named Integrative Pathway Activity Analysis (IPAA), that maps pathway activity from omics data. IPAA precisely captures the degree to which disease functions in models match those in human brains and prioritizes targetable pathways in the most representative models. We assessed the mechanistic similarities between the transcriptomes of three AD brain regions and multiple 2D/3D human AD cellular models to define targetable functions. We performed phosphoproteomics analysis and compared pathway activity changes with transcriptomic findings. Top pathways were pharmacologically evaluated for their impact on AD pathology in 3D models. IPAA found high correlation of pathway dysregulation between brain regions (r=0.84, temporal cortex and parahippocampal gyrus), suggesting IPAA’s ability to detect conserved AD functions. IPAA found 83 dysregulated transcriptomic pathways shared between AD brains and a 3D model with a high Amyloid-beta (Aβ) 42/40 ratio. Shared dysregulated pathways included p38 MAPK, YAP1/TAZ, E-cadherin, CDC20, and APC/C, which were confirmed at the protein level. Elevated active p38 MAPK was observed in the 3D models, human AD brains, and 5XFAD mice, localized to presynaptic dystrophic neurites. Phosphoproteomic analysis confirmed an increase in p38 MAPK substrate phosphorylation driven by Aβ42 accumulation. Targeting p38 MAPK with a clinical p38α/β MAPK inhibitor (Losmapimod)– which has not been tested for AD– significantly reduced Aβ-induced tau, Aβ accumulation, neuronal loss, and microglial activation in 3D models and human microglia. We further found that MAPK-activated protein kinase 2 (MK2) plays crucial roles in mediating Aβ-induced tau pathology. IPAA enables rapid preclinical assessment of target pathways with confidence for impact on AD pathology prior to clinical trials. Our findings highlight the critical role of protein kinase networks, particularly the p38 MAPK-MK2 axis, in driving AD pathology in humans.

Early detection of Alzheimer’s disease is essential for effective treatment and the development of therapies that modify disease progression. Developing sensitive and specific noninvasive diagnostic tools is crucial for improving clinical outcomes and advancing our understanding of this condition. Liquid biopsy techniques, especially those involving plasma biomarkers, provide a promising noninvasive method for early diagnosis and disease monitoring. In this study, we analyzed the plasma proteomic profiles of 38 healthy individuals, with an average age of 66.5 years, and 22 patients with Alzheimer’s disease, with an average age of 79.7 years. Proteins in the plasma were quantified using specialized panels designed for proteomic extension assays. Through computational analysis using a linear support vector machine algorithm, we identified 82 differentially expressed proteins between the two groups. From these, we calculated 6,642 possible protein ratios and identified specific combinations of these ratios as significant features for distinguishing between individuals with Alzheimer’s disease and healthy individuals. Notably, the protein ratios kynureninase to macrophage scavenger receptor type 1, Neurocan to protogenin, and interleukin-5 receptor alpha to glial cell line-derived neurotrophic factor receptor alpha 1 achieving accuracy up to 98% in differentiating between the two groups. This study underscores the potential of leveraging protein relationships, expressed as ratios, in advancing Alzheimer’s disease diagnostics. Furthermore, our findings highlight the promise of liquid biopsy techniques as a noninvasive and accurate approach for early detection and monitoring of Alzheimer’s disease using blood plasma.

ABSTRACTRecent findings indicate a correlation between the peripheral adaptive immune system and neuroinflammation in Alzheimer’s disease (AD). To characterize the composition of adaptive immune cells in the peripheral blood of AD patients, we utilized single-cell mass cytometry (CyTOF) to profile peripheral blood mononuclear cells (PBMCs). Concurrently, we assessed the concentration of proteins associated with AD and neuroinflammation in the plasma of the same subjects. We found that the abundance of proinflammatory CXCR3+CD127+Type 1 T helper (Th1) cells in AD patients was negatively correlated with the abundance of neurofilament light chain (NfL) protein. This correlation is apolipoprotein E (ApoE) ε4-dependent. Analyzing public single-cell RNA-sequencing (scRNA-seq) data, we found that, contrary to the scenario in the peripheral blood, the cell frequency of CXCR3+CD127+Th1 cells in the cerebrospinal fluid (CSF) of AD patients was increased compared to healthy controls (HCs). Moreover, the proinflammatory capacity of CXCR3+CD127+Th1 cells in the CSF of AD patients was further increased compared to HCs. These results reveal an association of a peripheral T-cell change with neuroinflammation in AD and suggest that dysregulation of peripheral adaptive immune responses, particularly involving CXCR3+CD127+Th1 cells, may potentially be mediated by factors such as ApoE ε4 genotype.One sentence summaryAn apolipoprotein E (ApoE) ε4-dependent alteration of CD4 T cell subpopulation in peripheral blood is associated with neuroinflammation in patients with Alzheimer’s disease.

The Alzheimer’s disease (AD)-affected brain is known to be deficient in the utilization of glucose, its main energy substrate, and systemic diabetes is a significant risk factor for AD. In the course of biochemical and molecular investigations into this puzzling relationship, it has been shown that resistance to insulin action is a prominent feature of early stages of AD in the brain, thereby contributing to an energy failure state and a decline in synaptic function. In one AD-like cellular model, we found that β-amyloid (Aβ) accumulation inhibited insulin signaling and cell viability through an alteration of the PI3K/PDK-1/Akt signal pathway, an effect overcome by mTORC2 stimulation. A PDK-1 allosteric agonist, PS48, as well as newly synthesized analogs, were also found to reverse the metabolic defects caused by intracellular Aβ42 accumulation. In vivo, we previously showed that oral dosing of PS48 significantly improves learning and memory in APP/PS1 transgenic mice. Herein, we present evidence using unbiased immunohistological quantification and Western blot analyses demonstrating that ingested PS48 crosses into brain tissue where it targeted Akt and GSK3-β activities. Beneficial effects on neuronal number and Tau phosphorylation were found. Not unexpectedly, Aβ levels remained unchanged. These results support a path toward a future therapeutic trial of this untested strategy and agent in humans.

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease caused by repetitive head impacts (RHI). However, individuals with similar RHI exposure can show differing pathology, suggesting a role for genetic variation. A common Transmembrane Protein 106B ( TMEM106B ) risk variant is associated with greater CTE severity, though its mechanism remains unclear. To determine whether TMEM106B alters the inflammatory response to pathology in CTE, we examined associations between microglia, via immunohistochemistry, and inflammatory cytokines, via immunoassay, in brain donors with CTE with and without the risk genotype ( rs3173615) . We analyzed 323 RHI-exposed brain donors: 55 without pathology (controls) and 268 with CTE. Regression models tested associations between TMEM106B risk and CTE presence, CTE stage, TDP-43, and dementia in those < = 65 and > 65 years of age. Within a subset of 122 brain donors, we examined associations between microglia, cytokines, and pathology stratified by TMEM106B genotype. Among donors > 65 years old, the TMEM106B risk genotype was associated with increased CTE stage (OR = 2.748 [95% CI 1.183–6.383], p = 0.019), comparable to the effect of playing > 8 years of contact sports, and with greater odds of having TDP-43 inclusions (OR = 3.649 [95% CI 1.278–10.422], p = 0.016). In donors < = 65, TMEM106B risk was associated with higher odds of dementia (OR = 6.912 [95% CI 2.015–23.705], p = 0.002). TMEM106B gene variation had a significant effect on associations between inflammatory markers and CTE-related pathology. In the protective genotype, IL-8 and IL-6 demonstrated positive associations with CD68, TREM2, and tau pathology within the dorsolateral prefrontal cortex. In the risk genotype, IFN-γ, IL-4, TNF-α, TNF-β, and IL-10 demonstrated negative associations with TREM2 ( p ’s < 0.05), and TNF-α was negatively associated with cortical tau ( p = 0.003). These results suggest that the microglial production of TREM2-associated cytokines and their association with pathology is aberrant in the TMEM106B risk genotype in CTE. Overall, TMEM106B rs3173615 is associated with an increased risk of developing higher stage CTE and TDP-43 pathology, potentially via impaired microglial activation and aberrant cytokine production.

Background: Comorbidities such as hypertension and hypercholesterolemia are risk factors associated with Mild Cognitive Impairment (MCI) and Alzheimer’s disease (AD). The most significant genetic risk factor is the ε4 allele of the apolipoprotein E gene (APOE). The aim of this paper is to determine whether hypertension is the most significant but modifiable risk factor to delay AD onset. Method: A cohort of patients with MCI (N = 3052) is developed from the documented database (N = 43,999) within the National Alzheimer’s Coordinating Center (NACC) during the time period from June 2005 to May 2021. Cox proportional hazard models with propensity score weights on demographic information and comorbidities at baseline are applied to examine association of hypertension and hypercholesterolemia with AD onset among MCI patients. Associations are compared to APOE genotypes and AD onset. In addition, the association of hypertension with decline rates in Mini-Mental State Examination (MMSE) scores are reported. Results: After controlling for age, sex, race, APOEε4, and reported comorbidities, the results show that MCI patients who subsequently develop hypertension within 18 months after their first diagnosis of MCI have a significantly higher risk of AD onset (HR = 2.77, 95%CI (1.66, 4.65), p value < 0.0001), compared to MCI patients with no hypertension or a late occurrence of hypertension after 18 months. This significant association is validated through a Random Forest method, a machine learning approach with bootstrap simulations. In addition, patients with early hypertension have significantly higher MMSE score declining rates compared to those without hypertension (coefficient = 0.988, p = 0.0054.). Conclusions: Hypertension is the most significant risk factor comparable to the genetic risk factor APOEε4 allele. Our finding is unique, as we did not observe a similar outcome in those with early hypercholesterolemia. Thus, among all comorbidities, hypertension is the most significant risk factor similar to the genetic risk factor APOEε4 allele.

Previously, we proposed disease staging using the Lawton-Brody Instrumental Activities of Daily Living Scale (IADL) in patients with mild cognitive impairment (MCI) or Alzheimer's dementia (AD), using a crosswalk against the Mini-Mental State Examination (MMSE). This study aimed to estimate disease trajectory based on proposed IADL Alzheimer's stage cut-off scores. Patients with MCI or AD who had an IADL administered between 2016–2024 were identified from the US Veteran's Affairs Healthcare System administrative database. IADL cut-offs were derived in four ways: descriptive values, and least squares (LS) means from linear, categorical, and repeated measures analysis; this study used linear LS means, grouped as >5.4, 4.7-5.4, 4.1-<4.7, 2.7-<4.1, <2.7 for normal, MCI, mild, moderate, and severe stages, respectively. IADL scores were analyzed using mixed effects statistical modeling with patient's state of residence (reflecting care location) as a random effect, controlling for demographics. Disease stage transition over time was estimated, allowing nonlinear trends and interactions with initial diagnosis of MCI vs AD. Our sample ( N  = 90,114) had a mean age of 80.2 years (97.5% men, 14.1% Black, and 17.0% Hispanic). MCI patients ( n  = 54,569) had a mean age of 79.2 years (97.4% men, 14.5% Black, and 13.1% Hispanic); AD patients ( n  = 35,545) were aged 81.7 years (97.7% men, 13.4% Black, and 22.9% Hispanic). Acetylcholinesterase inhibitors and/or memantine was used in 28% of patients overall, and in 23.6% and 34.9% of patients with MCI and AD, respectively. In the MCI group, estimated transition times were 5.2 years from MCI to mild, 2.9 years from mild to moderate, and 4.8 years from moderate AD to severe stages, based on the IADL cut-offs. In the AD group, estimated transition times were 3.5 years from mild to moderate, and 5.3 years form moderate to severe stages. Functional deterioration appeared to progress to severe stage within 9 years for AD and within 13 years for MCI. Polynomial growth curves may tend to skew transition times at more advanced stages; however, trajectory estimations provide an alternative measure of disease progression with IADL, a broadly used assessment in clinical practice, to assess functional decline corresponding to cognitive deterioration.

We utilized the Veterans Affairs Healthcare System administrative database to study the clinical decision-making processes for anti-amyloid therapy (AAT). Patients with clinical notes mentioning lecanemab were identified (March 2023–June 2024) for manual review and structured database queries. From an initial sample (N = 2499), 1064 patients (55,000 notes) were reviewed manually (mean age 76 years; 7.3

Stathmin-2 (STMN2) levels decline in brains with transactive response DNA binding protein-43 (TDP-43) inclusions. TDP-43-related changes could extend to ocular structures, although vitreous STMN2 levels remain uncharacterized. This exploratory study analyzed 72 post-mortem brains and eyes depending on the presence or absence of TDP-43 inclusions in the brain and across neuropathological diagnostic groups (Alzheimer's disease [AD], chronic traumatic encephalopathy [CTE], AD and CTE, or neither). Results showed decreased vitreous STMN2 levels in TDP-43-positive cases but no association with diagnostic groups. Vitreous STMN2 was correlated with vitreous neurofilament light chain. Diminished vitreous STMN2 levels might indicate TDP-43-associated neurodegeneration.

BackgroundDiabetes has been linked to increased prevalence of dementia, but the link between diabetic retinopathy (DR) and Alzheimer's disease (AD) remains unclear.ObjectiveThis study aimed to evaluate potential associations between DR and AD-related protein biomarkers in plasma and ocular fluid.MethodsA prospective, cross-sectional study collected human blood, vitreous, aqueous, and tear samples and measured amyloid-β (Aβ40, Aβ42), total-tau (t-tau), phosphorylated-tau (ptau181), glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL) by digital immunoassays.ResultsThe study included 79 eyes (79 patients) [41 females (59.4%); mean (SD) age 57.1 (12.2) years] of which DR was present in 44 (55.7%). All six biomarkers were significantly higher in plasma in participants with DR compared to those without DR [Aβ40 p = 0.002, Aβ42 p = 0.002, t-tau = 0.013, ptau181 p = 0.005, GFAP p = 0.010, and NfL p < 0.001]. Within vitreous, DR participants had significantly elevated t-tau (p = 0.002), ptau181 (p = 0.049), and NfL (p = 0.006); and within aqueous, higher NfL (p = < 0.001). Neuropsychological testing scores were lower in participants with DR than those without but did not reach statistical significance (Montreal-Cognitive-Assessment: p = 0.070; Mini-Mental-State-Exam: p = 0.057).ConclusionsThis study showed significant increases of AD associated protein biomarkers in plasma, vitreous, and aqueous in patients with DR. These results support a potential biological link between DR and AD pathology and suggest that DR, which tends to occur in younger individuals, may be a predictive factor for AD.