Faculty Bibliography

INTRODUCTION/BACKGROUND:Measuring plasma biomarkers effectively assesses early-stage Alzheimer's disease. METHODS:Subjects were categorized as cognitively unimpaired (CU) (n = 66), CU with subjective cognitive decline (SCD) (n = 100), and mild cognitive impairment (MCI) (n = 25). Plasma biomarkers measured were amyloid beta (Aβ) 40, Aβ42, neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), tau phosphorylated at threonine 181 (pTau181), neuroinflammatory biomarkers, and blood-brain barrier biomarkers. Amyloid and tau positron emission tomography (PET) imaging was performed in 186 and 144 subjects, respectively. RESULTS:Comparing those having MCI, both CU and SCD participants had significantly lower amyloid PET standardized uptake value ratio (SUVR) (p < 0.001; p = 0.005). Higher amyloid PET SUVR was significantly associated with higher pTau181 (p = 0.001) and a higher pTau181/Aβ42 ratio (p < 0.001). Higher tau PET SUVR was associated with lower plasma Aβ42 (p = 0.020), older age (p = 0.005), higher GFAP (p = 0.020), and lower interleukin-8 levels (p < 0.001). DISCUSSION/CONCLUSIONS:Our study supports plasma biomarker monitoring of at-risk patients at various stages of pre-dementia.

Reliable structural brain measurements are essential for studying neurodegeneration and for designing adequately powered aging and Alzheimer's disease (AD) research. We evaluated the test-retest reliability of FreeSurfer 7.1 morphometric measures in 100 older adults (mean age 73.5 years) ranging from cognitively unimpaired to dementia. Each participant underwent two T1-weighted 3T MRI scans on the same scanner within a short interval (mean 5.5 weeks), minimizing biological change. Segmentation was performed in both standard cross-sectional and longitudinal FreeSurfer modes, focusing on AD-relevant volumes of entorhinal cortex, hippocampus, lateral ventricles, choroid plexus, and the AD cortical thickness signature. Reliability was quantified using absolute and root-mean-square test-retest differences, standard deviation of differences, and intraclass correlation coefficients. Longitudinal processing improved precision by 15-50% across most measures compared with cross-sectional processing, with the largest gain observed for entorhinal thickness. Larger, anatomically well-defined regions (e.g., hippocampus, AD signature) demonstrated higher reliability than small structures or those with complex geometry (e.g., entorhinal cortex, choroid plexus). Image quality, indexed by the Euler characteristic, was the only factor significantly associated with measurement variability; reliability was unrelated to age, sex, cognitive status, inter-scan interval, or amyloid/tau PET burden. Power analyses indicated that detecting a 1% within-individual change requires sample sizes ranging from 36 (AD signature) to >300 (entorhinal cortex). We observed low reliability of choroid plexus volumetry by FreeSurfer 7. These results provide practical benchmarks for expected FreeSurfer measurement variability in older adults. They highlight the advantages of longitudinal processing and rigorous quality control for research on brain aging and AD.

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.

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: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.

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.

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.

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.

Ceramide transporter syndrome (CerTra syndrome) is a rare neurodevelopmental disorder caused by pathogenic variants in CERT1 gene encoding ceramide transporter (CERT). These variants disrupt ceramide transport and sphingolipid homeostasis, leading to a clinical phenotype that includes developmental delay, movement abnormalities, and structural brain anomalies. Despite growing recognition of this condition, detailed neuroimaging and neuropathological characterization remain limited. Here, we present a 12-year-old girl with a pathogenic CERT1 variant complicated by sudden unexplained death, who presented with unreported neuroimaging abnormalities in choroid plexus (ChP) and perivascular space (PVS). Clinical Magnetic Resonance Imaging (MRI) obtained approximately 10 years prior to death, as well as postmortem MRI, revealed bilateral cystic enlargement of the ChP and prominent PVS filled with abundant proteinaceous material in white matter. Neuropathological examination demonstrated marked ChP epithelial disorganization, reduced aquaporin-1 (AQP1) expression, cyst formation, and focal calcifications, which may be associated with disturbances in cerebrospinal fluid (CSF) dynamics. These findings raise the possibility that CERT1 variants may be associated with ChP architectural changes and altered perivascular clearance.