Faculty Bibliography

INTRODUCTION/BACKGROUND:Neutrophil-to-lymphocyte ratio (NLR), a marker of systemic inflammation, has been linked to dementia risk, but prior studies were limited by small sample sizes. METHODS:We assessed the association between baseline NLR and incident Alzheimer's disease (AD) and Alzeimer's disease and related dementias (AD/ADRD) using electronic health records from New York University (NYU) (n = 284,530) and the Veterans Health Administration [VA] (n = 85,836) Hospitals from 2011 to 2023. AD/ADRD diagnoses were identified via International Classification of Diseases (ICD) codes ≥6 months post-baseline. Cox models and cumulative incidence functions (CIFs) adjusted for demographic and clinical variables, with death as a competing risk. RESULTS:Higher NLR was associated significantly with increased AD/ADRD risk in both cohorts (NYU hazard ratio [HR] = 1.07, 95% confidence interval [CI] 1.02-1.15; VA HR = 1.21, 95% CI 1.10-1.34). Spline analysis further confirmed a continuous dose-response relationship, and subgroup analyses showed higher risk among female and Hispanic patients. DISCUSSION/CONCLUSIONS:Elevated NLR is independently associated with higher AD/ADRD risk across diverse populations, highlighting the role of systemic inflammation and neutrophil-mediated pathways in neurodegeneration.

INTRODUCTION/BACKGROUND:Though brain fog is common in Long-coronavirus disease 2019 (Long-COVID), the incidence of mild cognitive impairment (MCI) is unknown. METHODS:In an observational cohort study, recovered COVID-positive, Long-COVID, and COVID-negative subjects underwent blinded evaluation using National Alzheimer's Coordinating Center (NACC) and National Institute on Aging (NIA) -Alzheimer's Association diagnostic criteria for dementia and MCI. The cumulative incidence of MCI was calculated for each group, and the hazard of MCI was compared between groups. RESULTS:Among 260 subjects, the cumulative incidence of MCI over 4.4 years was higher with Long-COVID (27%) versus recovered-COVID (5%) or COVID-negative status (1%). There was a higher hazard of MCI for patients with Long-COVID compared to those without (hazard ratio [HR] 3.93, 95% confidence interval [CI] 1.86-8.31, p < 0.001), and specifically for the Alzheimer's disease (AD) -related MCI subtype (HR 3.20, 95% confidence interval [CI] 1.14-9.00, p = 0.027). DISCUSSION/CONCLUSIONS:The cumulative incidence and adjusted hazard of MCI (and specifically AD-related MCI) at 4.4 years was significantly higher among Long-COVID patients compared to recovered-COVID and COVID-negative controls.

PURPOSE OF REVIEW/UNASSIGNED:Alzheimer disease (AD) and epilepsy are major causes of neurologic disability and are reciprocally related: epileptiform discharges, subclinical seizures, and epilepsy are more prevalent in patients with AD compared with controls; progressive cognitive impairment commonly afflicts epilepsy patients; and late-onset epilepsy patients have higher rates of new-onset dementia. RECENT FINDINGS/UNASSIGNED:Epidemiologic studies support shared risk factors (e.g., genetic variants, vascular disease, sleep disorders, microbiome) with notable divergences. AD and epilepsy have some overlapping anatomic (e.g., hippocampus, entorhinal, and association cortex), clinical (e.g., memory, attentional, and executive) impairments, and neuropathologic (e.g., amyloid, tau, neurofibrillary tangles) features. Shared clinical and translational challenges include underlying mechanisms (e.g., genetic variants, neuroinflammation, metabolic and mitochondrial dysfunction, excitatory/inhibitory imbalance, microbiome, and sociodemographic factors) and identifying valid and reliable biomarkers (e.g., total tau and phosphorylated tau (p-tau), amyloid deposition, Aβ42/Aβ40 ratio) to assess disease progression, predict outcomes, and assess potentially disease-modifying interventions. SUMMARY/UNASSIGNED:Identifying convergences and divergences between epilepsy and AD may inform our understanding. The clinical, neurophysiologic, neuropathologic, and molecular pathologic changes in AD and epilepsy may reveal pathophysiologic insights and therapeutic opportunities.

INTRODUCTION/BACKGROUND:Choroid plexus (ChP) enlargement is a neuroimaging biomarker of neuroinflammation and neurodegeneration. However, evidence of ChP structural and perfusion alterations in long coronavirus disease (COVID) and their clinical relevance remains limited. METHODS:This study included 86 long COVID, 67 recovered COVID, and 26 COVID-negative healthy controls (HCs). ChP volume and cerebral blood flow (CBF) were quantified, and their associations with Alzheimer's disease (AD) symptoms and plasma biomarkers were examined. RESULTS:Both patient groups showed higher ChP volume and lower CBF than HC. Relative to recovered COVID, long COVID patients had a larger ChP volume, but no significant difference in CBF. ChP volume correlated positively with glial fibrillary acidic protein (r = 0.35) and phosphorylated tau217 (p-tau217; r = 0.54), while CBF correlated negatively with p-tau217 (r = -0.56). Both ChP volume and CBF were associated with cognitive decline measured with Mini-Mental State Examination and Clinical Dementia Rating. DISCUSSION/CONCLUSIONS:These findings suggest that ChP differences in long COVID are associated with AD-related cognitive decline and increased plasma biomarkers. HIGHLIGHTS/CONCLUSIONS:Long coronavirus disease (COVID) patients show choroid plexus (ChP) enlargement and reduced cerebral blood flow. ChP alterations are associated with Alzheimer's disease (AD)-related symptoms and plasma biomarker changes. ChP alterations on magnetic resonance imaging may serve as imaging markers for tracking neurological symptoms and AD-related pathology in post-COVID patients.

IMPORTANCE/UNASSIGNED:Neuroscientific, epidemiological, and electronic health record studies implicate herpes simplex virus (HSV) as potentially etiological for Alzheimer disease (AD). OBJECTIVE/UNASSIGNED:To compare the efficacy and adverse effects of valacyclovir vs placebo in participants with early symptomatic AD and HSV seropositivity (HSV-1 or HSV-2). DESIGN, SETTING, AND PARTICIPANTS/UNASSIGNED:This randomized clinical trial included adults with a clinical diagnosis of probable AD or a clinical diagnosis of mild cognitive impairment with positive biomarkers for AD, a positive serum antibody test (IgG or IgM) for HSV-1 or HSV-2, and a Mini-Mental State Examination score of 18 to 28. The trial was conducted at 3 US outpatient clinics specializing in memory disorders. Recruitment occurred from January 2018 to May 2022; the last follow-up occurred in September 2024. INTERVENTION/UNASSIGNED:Either 4 g/d of valacyclovir (n = 60) or matching placebo (n = 60). MAIN OUTCOMES AND MEASURES/UNASSIGNED:The primary outcome was least-squares mean (LSM) change at 78 weeks in the 11-item Alzheimer's Disease Assessment Scale Cognitive (ADAS-Cognitive) Subscale score (range, 0-70; higher scores indicate greater impairment). The secondary outcomes were LSM change in the Alzheimer's Disease Cooperative Study-Activities of Daily Living (ADCS-ADL) Scale score; LSM change in the 18F-florbetapir amyloid positron emission tomography (PET) standardized uptake value ratio (SUVR; higher scores indicate higher amyloid levels) for 6 brain regions (medial orbitofrontal, anterior cingulate, parietal lobe, posterior cingulate, temporal lobe, and precuneus); and LSM change in 18F-MK-6240 tau PET medial temporal SUVR (higher scores indicate higher tau levels) for 4 brain regions (amygdala, hippocampus, entorhinal, and parahippocampus). The frequency of adverse events was the safety outcome. RESULTS/UNASSIGNED:Of the 120 participants (mean age, 71.4 [SD, 8.6] years; 55% were female), 93 (77.5%) completed the trial. At 78 weeks, the LSM change in the 11-item ADAS-Cognitive Subscale score was 10.86 (95% CI, 8.80 to 12.91) in the valacyclovir group vs 6.92 (95% CI, 4.88 to 8.97) in the placebo group, indicating greater cognitive worsening with valacyclovir than placebo (between-group difference, 3.93 [95% CI, 1.03 to 6.83]; P = .01). The LSM change in the ADCS-ADL Scale score at 78 weeks was -13.78 (95% CI, -17.00 to -10.56) in the valacyclovir group vs -10.16 (95% CI, -13.37 to -6.96) in the placebo group (between-group difference, -3.62 [95% CI, -8.16 to 0.93]). At 78 weeks, the LSM change in the 18F-florbetapir amyloid PET SUVR was 0.03 (95% CI, -0.04 to 0.10) in the valacyclovir group vs 0.01 (95% CI, -0.06 to 0.08) in the placebo group (between-group difference, 0.02 [95% CI, -0.08 to 0.12]). The LSM change in the 18F-MK-6240 tau PET medial temporal SUVR at 78 weeks was 0.07 (95% CI, -0.06 to 0.19) in the valacyclovir group vs -0.04 (95% CI, -0.15 to 0.07) in the placebo group (between-group difference, 0.11 [95% CI, -0.06 to 0.28]). The most common adverse events were elevated serum creatinine level (5 participants [8.3%] in the valacyclovir group vs 2 participants [3.3%] in the placebo group) and COVID-19 infection (3 [5%] vs 2 [3.3%], respectively). CONCLUSIONS AND RELEVANCE/UNASSIGNED:Valacyclovir was not efficacious with cognitive worsening for the primary outcome and it is not recommended to treat individuals with early symptomatic AD and HSV seropositivity. TRIAL REGISTRATION/UNASSIGNED:ClinicalTrials.gov Identifier: NCT03282916.

BACKGROUND:Identifying early neuropathological changes in Alzheimer's disease (AD) is important for improving treatment efficacy. Among quantitative MRI measures, transverse relaxation time (T2) has been shown to reflect tissue microstructure relevant in aging and neurodegeneration; however, findings regarding T2 changes in both normal aging and AD have been inconsistent. The association between T2 and amyloid-beta (Aβ) accumulation, a hallmark of AD pathology, is also unclear, particularly in cognitively normal individuals who may be in preclinical stages of the disease. PURPOSE/OBJECTIVE:To investigate longitudinal hippocampal T2 changes in a cognitively normal cohort of older adults and their association with global Aβ accumulation. STUDY TYPE/METHODS:Retrospective, longitudinal. SUBJECTS/METHODS:56 cognitively normal adults between 55 and 90 years of age (17 males and 39 females). FIELD STRENGTH/SEQUENCE/UNASSIGNED:3 Tesla; multi-echo spin echo sequence for T2 mapping; 18F-florbetaben positron emission tomography for Aβ measurement. ASSESSMENT/RESULTS:Bilateral hippocampal T2 and volume were extracted to relate to Aβ PET measurements. To understand variations in AD risk, participants were separated into Aβ-high and Aβ-low subgroups using a predetermined threshold. STATISTICAL TESTS/METHODS:Linear mixed-effect models and general linear models were used. A p-value < 0.025 was considered significant to account for bilateral comparisons. RESULTS:Older age was associated with increased T2 in the bilateral hippocampus (left: β = 0.30, right: β = 0.25) and smaller hippocampal volume on the left (β = -0.12). In the Aβ-low subgroup, both longitudinal T2 increase rates (β = 0.65) in the left hippocampus and bilateral cross-sectional T2 (left: β = 0.64, right: β = 0.46) were positively correlated with Aβ PET, independent of hippocampal volume. DATA CONCLUSION/CONCLUSIONS:This study provided in vivo evidence linking hippocampal T2 to Aβ accumulation in cognitively normal aging individuals, suggesting that quantitative T2 may be sensitive to microstructural changes accompanying early Aβ pathology, such as neuroinflammation, demyelination, and reduced tissue integrity. EVIDENCE LEVEL/METHODS:3. TECHNICAL EFFICACY/UNASSIGNED:Stage 2.

The choroid plexus (ChP), a highly vascularized brain structure responsible for cerebrospinal fluid (CSF) production, undergoes significant age-related changes that may contribute to neurodegenerative diseases involving disrupted immune regulation, fluid homeostasis and waste clearance. Compared to other brain regions, vascular research on the ChP remains limited despite its critical role as a central interface between the blood and CSF. This review focuses on age-related vascular and structural alterations in the ChP from both histopathological and neuroimaging perspectives, and explores their impact on CSF dynamics, immune regulation, and the integrity of the blood-CSF barrier (BCSFB). Rather than shrinking, the aging ChP often enlarges due to dystrophic changes, as shown in volumetric MRI studies. Histological studies reveal epithelial degeneration, basement membrane thickening, and stromal fibrosis in the normal aging process. In dementia such as Alzheimer's disease (AD), proteomic studies have identified upregulation of AD- and immune-related proteins, along with downregulation of proteins linked to CSF clearance and metabolic support. Emerging high-resolution contrast-enhanced MRI techniques now allow in vivo visualization of microvascular changes within the ChP, shedding light on its normal and abnormal aging processes. Understanding these alterations is critical, as they may influence the onset and progression of various neurological diseases such as AD, Parkinson's disease (PD), normal pressure hydrocephalus, and amyotrophic lateral sclerosis (ALS). The recent advancements and challenges described in this study underscore the need for deeper investigation into ChP aging to inform future diagnostic and therapeutic strategies of neurodegenerative diseases.

BACKGROUND:. However, the microstructural alterations driving these differences are unclear. Here, we assess associations of MK and KFA with neurite orientation dispersion and density imaging (NODDI) and magnetization transfer imaging (MTI) metrics, which provide a more specific characterization of tissue microstructure. METHOD/METHODS:(75 SCD) ages 55-88 were included in the analysis. Participants were defined as SCD if they endorsed problems with their memory and in the control group otherwise. Diffusion images were processed to obtain MK, Radial Kurtosis (RK), Axial Kurtosis (AK) and KFA from DKI and Neurite Density (ND) and Orientation Dispersion (OD), a marker of neurite organization, from NODDI. MTI was used to calculate the Magnetization Transfer Ratio (MTR), a marker of myelin and potentially amyloid aggregation. Mean metric values were calculated for bilateral amygdala (Figure 1). Between-group comparisons were conducted using Wilcoxon rank-sum tests, corrected for multiple testing. Associations between DKI, NODDI, and MTR metrics were examined using linear models corrected for age and sex. RESULT/RESULTS:SCD had lower KFA, higher MK, and higher RK in the right amygdala (Table 1). KFA had a weak negative correlation with ND, while MK and RK had strong positive correlations (Figure 2A-C). Only MK had a weak positive correlation with OD (Figure 2D-F). Neither KFA, MK, nor RK correlated with MTR (Figure 2G-I). CONCLUSION/CONCLUSIONS:DKI metrics are more sensitive to amygdala changes in SCD than NODDI metrics or MTR. Lower KFA, higher MK, and higher RK were associated with higher ND but not MTR, suggestive of dendritic or glial branching. Higher MK was additionally associated with higher OD, potentially indicating reduced neurite organization. Further analyses on the impact of these amygdala changes on SCD related neuropsychiatric symptoms are needed. References 1. Flaherty R, Sui YV, Li M, et al. Alzheimers Dement. 2024;20(S9):e093982. 2. Shafto MA, Tyler LK, Dixon M, et al. BMC Neurol. 2014;14(1):1-25.

INTRODUCTION/BACKGROUND:The Neighborhoods Study (TNS) is a novel investigation of adverse social exposome and brain health leveraging 22 Alzheimer's Disease Research Centers (ADRCs). TNS aims to understand if the adverse social exposures increase Alzheimer's disease and related dementias (ADRD) risk. METHODS:TNS uses innovative methods to determine lifetime addresses of living (n = ≈ 3116) and brain bank cohorts (n = ≈ 8637). Addresses are linked to time-concordant adverse social exposome using the Area Deprivation Index (ADI) and summarized over time. Brain health measures are provided by the National Alzheimer's Coordinating Center. RESULTS:We highlight a general overview and methodology of TNS. Data collection is ongoing; however, preliminary findings indicate that the adverse social exposome is related to ADRD biomarkers, neuropathology, and cognitive function. DISCUSSION/CONCLUSIONS:TNS is the largest study of adverse social exposome and ADRD, using the ADRC network to build robust scientific consortia. Its findings will inform ADRD interventions, precision medicine, and policy. HIGHLIGHTS/CONCLUSIONS:The Neighborhoods Study (TNS) investigates adverse social exposome and brain health. TNS is a collaboration among 22 Alzheimer's Disease Research Centers. TNS will give insight on environmental and exposomal factors which may be modifiable. Participant lifetime addresses are linked to temporal adverse social exposome metrics. This study's findings will inform precision approaches to mitigate dementia risk.