Data-driven decomposition and staging of flortaucipir uptake in Alzheimer's disease

INTRODUCTION

Previous approaches pursuing in vivo staging of tau pathology in Alzheimer's disease (AD) have typically relied on neuropathologically defined criteria. In using predefined systems, these studies may miss spatial deposition patterns which are informative of disease progression.

METHODS

We selected discovery (n = 418) and replication (n = 132) cohorts with flortaucipir imaging. Non-negative matrix factorization (NMF) was applied to learn tau covariance patterns and develop a tau staging system. Flortaucipir components were also validated by comparison with amyloid burden, gray matter loss, and the expression of AD-related genes.

RESULTS

We found eight flortaucipir covariance patterns which were reproducible and overlapped with relevant gene expression maps. Tau stages were associated with AD severity as indexed by dementia status and neuropsychological performance. Comparisons of flortaucipir uptake with amyloid and atrophy also supported our model of tau progression.

DISCUSSION

Data-driven decomposition of flortaucipir uptake provides a novel framework for tau staging which complements existing systems.

HIGHLIGHTS

NMF reveals patterns of tau deposition in AD. Data-driven staging of flortaucipir tracks AD severity. Learned flortaucipir patterns overlap with AD-related gene expression.

Comparison of cerebrospinal fluid, plasma and neuroimaging biomarker utility in Alzheimer's disease

Alzheimer's disease biomarkers are crucial to understanding disease pathophysiology, aiding accurate diagnosis and identifying target treatments. Although the number of biomarkers continues to grow, the relative utility and uniqueness of each is poorly understood as prior work has typically calculated serial pairwise relationships on only a handful of markers at a time. The present study assessed the cross-sectional relationships among 27 Alzheimer's disease biomarkers simultaneously and determined their ability to predict meaningful clinical outcomes using machine learning. Data were obtained from 527 community-dwelling volunteers enrolled in studies at the Charles F. and Joanne Knight Alzheimer Disease Research Center at Washington University in St Louis. We used hierarchical clustering to group 27 imaging, CSF and plasma measures of amyloid beta, tau [phosphorylated tau (p-tau), total tau t-tau)], neuronal injury and inflammation drawn from MRI, PET, mass-spectrometry assays and immunoassays. Neuropsychological and genetic measures were also included. Random forest-based feature selection identified the strongest predictors of amyloid PET positivity across the entire cohort. Models also predicted cognitive impairment across the entire cohort and in amyloid PET-positive individuals. Four clusters emerged reflecting: core Alzheimer's disease pathology (amyloid and tau), neurodegeneration, AT8 antibody-associated phosphorylated tau sites and neuronal dysfunction. In the entire cohort, CSF p-tau181/Aβ40lumi and Aβ42/Aβ40lumi and mass spectrometry measurements for CSF pT217/T217, pT111/T111, pT231/T231 were the strongest predictors of amyloid PET status. Given their ability to denote individuals on an Alzheimer's disease pathological trajectory, these same markers (CSF pT217/T217, pT111/T111, p-tau/Aβ40lumi and t-tau/Aβ40lumi) were largely the best predictors of worse cognition in the entire cohort. When restricting analyses to amyloid-positive individuals, the strongest predictors of impaired cognition were tau PET, CSF t-tau/Aβ40lumi, p-tau181/Aβ40lumi, CSF pT217/217 and pT205/T205. Non-specific CSF measures of neuronal dysfunction and inflammation were poor predictors of amyloid PET and cognitive status. The current work utilized machine learning to understand the interrelationship structure and utility of a large number of biomarkers. The results demonstrate that, although the number of biomarkers has rapidly expanded, many are interrelated and few strongly predict clinical outcomes. Examining the entire corpus of available biomarkers simultaneously provides a meaningful framework to understand Alzheimer's disease pathobiological change as well as insight into which biomarkers may be most useful in Alzheimer's disease clinical practice and trials.

Structural Connectivity and Emotion Recognition Impairment in Children and Adolescents with Chromosome 22q11.2 Deletion Syndrome

Children with chromosome 22q11.2 deletion syndrome (22q11.2DS) exhibit impaired ability to process and understand emotions in others. We measured structural connectivity in children and adolescents with 22q11.2DS (n = 28) and healthy controls (n = 29). Compared to controls, those with 22q11.2DS had poorer social skills and more difficulty recognizing facial emotions. Children with 22q11.2DS also had higher fractional anisotropic diffusion in right amygdala to fusiform gyrus white matter pathways. Right amygdala to fusiform gyrus fractional anisotropy values partially mediated the relationship between 22q11.2DS and social skills, as well as the relationship between 22q11.2DS and emotion recognition accuracy. These findings provide insight into the neural origins of social skills deficits seen in 22q11.2DS and may serve as a biomarker for risk of future psychiatric problems.

Positron emission tomography and magnetic resonance imaging methods and datasets within the Dominantly Inherited Alzheimer Network (DIAN)

The Dominantly Inherited Alzheimer Network (DIAN) is an international collaboration studying autosomal dominant Alzheimer disease (ADAD). ADAD arises from mutations occurring in three genes. Offspring from ADAD families have a 50% chance of inheriting their familial mutation, so non-carrier siblings can be recruited for comparisons in case-control studies. The age of onset in ADAD is highly predictable within families, allowing researchers to estimate an individual's point in the disease trajectory. These characteristics allow candidate AD biomarker measurements to be reliably mapped during the preclinical phase. Although ADAD represents a small proportion of AD cases, understanding neuroimaging-based changes that occur during the preclinical period may provide insight into early disease stages of 'sporadic' AD also. Additionally, this study provides rich data for research in healthy aging through inclusion of the non-carrier controls. Here we introduce the neuroimaging dataset collected and describe how this resource can be used by a range of researchers.

Longitudinal head-to-head comparison of 11C-PiB and 18F-florbetapir PET in a Phase 2/3 clinical trial of anti-amyloid-β monoclonal antibodies in dominantly inherited Alzheimer's disease

PURPOSE

Pittsburgh Compound-B (11C-PiB) and 18F-florbetapir are amyloid-β (Aβ) positron emission tomography (PET) radiotracers that have been used as endpoints in Alzheimer's disease (AD) clinical trials to evaluate the efficacy of anti-Aβ monoclonal antibodies. However, comparing drug effects between and within trials may become complicated if different Aβ radiotracers were used. To study the consequences of using different Aβ radiotracers to measure Aβ clearance, we performed a head-to-head comparison of 11C-PiB and 18F-florbetapir in a Phase 2/3 clinical trial of anti-Aβ monoclonal antibodies.

METHODS

Sixty-six mutation-positive participants enrolled in the gantenerumab and placebo arms of the first Dominantly Inherited Alzheimer Network Trials Unit clinical trial (DIAN-TU-001) underwent both 11C-PiB and 18F-florbetapir PET imaging at baseline and during at least one follow-up visit. For each PET scan, regional standardized uptake value ratios (SUVRs), regional Centiloids, a global cortical SUVR, and a global cortical Centiloid value were calculated. Longitudinal changes in SUVRs and Centiloids were estimated using linear mixed models. Differences in longitudinal change between PET radiotracers and between drug arms were estimated using paired and Welch two sample t-tests, respectively. Simulated clinical trials were conducted to evaluate the consequences of some research sites using 11C-PiB while other sites use 18F-florbetapir for Aβ PET imaging.

RESULTS

In the placebo arm, the absolute rate of longitudinal change measured by global cortical 11C-PiB SUVRs did not differ from that of global cortical 18F-florbetapir SUVRs. In the gantenerumab arm, global cortical 11C-PiB SUVRs decreased more rapidly than global cortical 18F-florbetapir SUVRs. Drug effects were statistically significant across both Aβ radiotracers. In contrast, the rates of longitudinal change measured in global cortical Centiloids did not differ between Aβ radiotracers in either the placebo or gantenerumab arms, and drug effects remained statistically significant. Regional analyses largely recapitulated these global cortical analyses. Across simulated clinical trials, type I error was higher in trials where both Aβ radiotracers were used versus trials where only one Aβ radiotracer was used. Power was lower in trials where 18F-florbetapir was primarily used versus trials where 11C-PiB was primarily used.

CONCLUSION

Gantenerumab treatment induces longitudinal changes in Aβ PET, and the absolute rates of these longitudinal changes differ significantly between Aβ radiotracers. These differences were not seen in the placebo arm, suggesting that Aβ-clearing treatments may pose unique challenges when attempting to compare longitudinal results across different Aβ radiotracers. Our results suggest converting Aβ PET SUVR measurements to Centiloids (both globally and regionally) can harmonize these differences without losing sensitivity to drug effects. Nonetheless, until consensus is achieved on how to harmonize drug effects across radiotracers, and since using multiple radiotracers in the same trial may increase type I error, multisite studies should consider potential variability due to different radiotracers when interpreting Aβ PET biomarker data and, if feasible, use a single radiotracer for the best results.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01760005. Registered 31 December 2012. Retrospectively registered.

Assessing clinical cure of empirical piperacillin/tazobactam for ESBL urinary tract infections (ACCEPT-UTI)

Background

Data are limited regarding use of piperacillin/tazobactam for ESBL urinary tract infections (UTIs). The objective of this study was to compare clinical outcomes of patients treated empirically with piperacillin/tazobactam versus carbapenems for ESBL UTIs.

Methods

This retrospective, observational, propensity score-matched study evaluated adults with an ESBL on urine culture. Patients who had UTI symptoms or leukocytosis, and who received a carbapenem or piperacillin/tazobactam empirically for at least 48 h were included. The primary outcome was clinical success within 48 h, defined as resolution of temperature (36-38°C), resolution of symptoms or leukocytosis (WBC <12 × 10³/μL) in the absence of documented symptoms, and the absence of readmission for an ESBL UTI within 6 months. Secondary outcomes included time to clinical resolution, hospital length of stay, and in-hospital and 30 day all-cause mortality.

Results

Overall, 223 patients were included in the full cohort and 200 patients in the matched cohort (piperacillin/tazobactam = 100, carbapenem = 100). Baseline characteristics were similar between the groups. There was no difference in the primary outcome of clinical success between the carbapenem and piperacillin/tazobactam groups (58% versus 56%, respectively; P = 0.76). Additionally, there was no difference in median (IQR) time to clinical resolution [38.9 h (21.5, 50.9 h) versus 40.3 h (27.4, 57.5 h); P = 0.37], in-hospital all-cause mortality (3% versus 3%; P = 1.00), or 30 day all-cause mortality (4% versus 2%; P = 0.68) between the carbapenem and piperacillin/tazobactam groups, respectively.

Conclusions

There was no significant difference in clinical success for patients treated empirically with piperacillin/tazobactam compared with carbapenems for ESBL UTIs.

Can't keep it SECRET: system evaluation of carbapenem restriction against empirical therapy

Objectives

Carbapenems are appealing agents for empirical use given their broad spectrum of activity; however, selective use is vital in minimizing the risk for development of carbapenem-resistant pathogens. We aimed to examine the impact of carbapenem restriction criteria and a pre-authorization process on utilization and cost savings across a health system.

Methods

This retrospective study was conducted across five adult hospitals. The pre-implementation period was 8 February 2020 to 30 April 2020 and the post-implementation period was 8 February 2022 to 30 April 2022. The primary outcome was to compare the number of orders for carbapenems between the study periods for both the intervention and non-intervention hospitals. Secondary outcomes included projected annual cost and an estimated cost-savings evaluation using a stratified analysis for the intervention and non-intervention facilities to account for more resource-limited settings.

Results

The total number of carbapenem orders decreased between study periods at the intervention hospital (246 versus 61, P < 0.01). At the non-intervention hospitals, orders decreased, although not significantly (333 versus 279, P = 0.58). Meropenem orders decreased by 66% compared with 12% for the intervention and the non-intervention hospitals, respectively (P < 0.001). Annual estimated cost for all facilities was $255 561 in the pre-implementation period compared with $29 593 in the post-implementation period (P < 0.001). Using a stratified analysis to account for available resources, the estimated annual cost saving was $225 968 for the system.

Conclusions

Implementation of carbapenem restriction at the intervention hospital decreased utilization and provided significant cost savings. Furthermore, resource-limited facilities can still experience significant cost savings using a stratified antimicrobial stewardship intervention approach.

Amyloid-Related Imaging Abnormalities in the DIAN-TU-001 Trial of Gantenerumab and Solanezumab: Lessons from a Trial in Dominantly Inherited Alzheimer Disease

OBJECTIVE

To determine the characteristics of participants with amyloid-related imaging abnormalities (ARIA) in a trial of gantenerumab or solanezumab in dominantly inherited Alzheimer disease (DIAD).

METHODS

142 DIAD mutation carriers received either gantenerumab SC (n = 52), solanezumab IV (n = 50), or placebo (n = 40). Participants underwent assessments with the Clinical Dementia Rating® (CDR®), neuropsychological testing, CSF biomarkers, β-amyloid positron emission tomography (PET), and magnetic resonance imaging (MRI) to monitor ARIA. Cross-sectional and longitudinal analyses evaluated potential ARIA-related risk factors.

RESULTS

Eleven participants developed ARIA-E, including 3 with mild symptoms. No ARIA-E was reported under solanezumab while gantenerumab was associated with ARIA-E compared to placebo (odds ratio [OR] = 9.1, confidence interval [CI][1.2, 412.3]; p = 0.021). Under gantenerumab, APOE-ɛ4 carriers were more likely to develop ARIA-E (OR = 5.0, CI[1.0, 30.4]; p = 0.055), as were individuals with microhemorrhage at baseline (OR = 13.7, CI[1.2, 163.2]; p = 0.039). No ARIA-E was observed at the initial 225 mg/month gantenerumab dose, and most cases were observed at doses >675 mg. At first ARIA-E occurrence, all ARIA-E participants were amyloid-PET+, 60% were CDR >0, 60% were past their estimated year to symptom onset, and 60% had also incident ARIA-H. Most ARIA-E radiologically resolved after dose adjustment and developing ARIA-E did not significantly increase odds of trial discontinuation. ARIA-E was more frequently observed in the occipital lobe (90%). ARIA-E severity was associated with age at time of ARIA-E.

INTERPRETATION

In DIAD, solanezumab was not associated with ARIA. Gantenerumab dose over 225 mg increased ARIA-E risk, with additional risk for individuals APOE-ɛ4(+) or with microhemorrhage. ARIA-E was reversible on MRI in most cases, generally asymptomatic, without additional risk for trial discontinuation. ANN NEUROL 2022;92:729-744.

Association of Elevated Amyloid and Tau Positron Emission Tomography Signal With Near-Term Development of Alzheimer Disease Symptoms in Older Adults Without Cognitive Impairment

Importance

National Institute on Aging-Alzheimer's Association (NIA-AA) workgroups have proposed biological research criteria intended to identify individuals with preclinical Alzheimer disease (AD).

Objective

To assess the clinical value of these biological criteria to identify older individuals without cognitive impairment who are at near-term risk of developing symptomatic AD.

Design, Setting, and Participants

This longitudinal cohort study used data from 4 independent population-based cohorts (PREVENT-AD, HABS, AIBL, and Knight ADRC) collected between 2003 and 2021. Participants were older adults without cognitive impairment with 1 year or more of clinical observation after amyloid β and tau positron emission tomography (PET). Median clinical follow-up after PET ranged from 1.94 to 3.66 years.

Exposures

Based on binary assessment of global amyloid burden (A) and a composite temporal region of tau PET uptake (T), participants were stratified into 4 groups (A+T+, A+T-, A-T+, A-T-). Presence (+) or absence (-) of neurodegeneration (N) was assessed using temporal cortical thickness.

Main Outcomes and Measures

Each cohort was analyzed separately. Primary outcome was clinical progression to mild cognitive impairment (MCI), identified by a Clinical Dementia Rating score of 0.5 or greater in Knight ADRC and by consensus committee review in the other cohorts. Clinical raters were blind to imaging, genetic, and fluid biomarker data. A secondary outcome was cognitive decline, based on a slope greater than 1.5 SD below the mean of an independent subsample of individuals without cognitive impairment. Outcomes were compared across the biomarker groups.

Results

Among 580 participants (PREVENT-AD, 128; HABS, 153; AIBL, 48; Knight ADRC, 251), mean (SD) age ranged from 67 (5) to 76 (6) years across cohorts, with between 55% (137/251) and 74% (95/128) female participants. Across cohorts, 33% to 83% of A+T+ participants progressed to MCI during follow-up (mean progression time, 2-2.72 years), compared with less than 20% of participants in other biomarker groups. Progression further increased to 43% to 100% when restricted to A+T+(N+) individuals. Cox proportional hazard ratios for progression to MCI in the A+T+ group vs other biomarker groups were all 5 or greater. Many A+T+ nonprogressors also showed longitudinal cognitive decline, while cognitive trajectories in other groups remained predominantly stable.

Conclusions and Relevance

The clinical prognostic value of NIA-AA research criteria was confirmed in 4 independent cohorts, with most A+T+(N+) older individuals without cognitive impairment developing AD symptoms within 2 to 3 years.

1234. Can Susceptibility to One Carbapenem be Conferred to Another? Frequency of Discordance in Gram-negative Clinical Isolates

Background

Carbapenem-Resistant Enterobacterales (CRE) and Carbapenem-Resistant Pseudomonas aeruginosa (CRPA) can exhibit resistance to one carbapenem while remaining susceptible to another. While case reports describing discrepant carbapenem susceptibilities are available, the authors are unaware of any literature reporting aggregate carbapenem susceptibility discrepancies at a hospital level.

Methods

Susceptibility data from April 1, 2017 - December 31, 2017 was extracted through an antibiogram report for a 706-bed hospital. Ertapenem, imipenem-cilastatin, and meropenem susceptibilities were captured and compared for common Enterobacterales and Pseudomonas aeruginosa. Organism identification was performed using Matrix Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF) mass spectrometry. Antibiotic susceptibility testing was performed using BD PhoenixTM. Carbapenem susceptibilities were interpreted using the most updated Clinical and Laboratory Standards Institute (CLSI) breakpoints at the time of assessment (2021). Carbapenem discordance was defined as an organism being susceptible to one carbapenem and non- susceptible (intermediate or resistant) to another. Approval was obtained from the institution’s Institutional Review Board.

Results

Meropenem proved to be the most active antimicrobial for all organisms (Figure 1). Carbapenem susceptibility discordance ranged from 0%-23.8% (Table 1). There was a significant difference in the incidence of discordance between Enterobacterales and Pseudomonas aeruginosa isolates (2.6% vs. 6.1%, p &lt; 0.001). Of the 20 Pseudomonas aeruginosa isolates with discordant carbapenem susceptibilities, 70% were meropenem susceptible/imipenem non-susceptible and 30% were imipenem susceptible/meropenem non-susceptible. The most common site for discordance was urine for both Enterobacterales and Pseudomonas aeruginosa. However, while there was a significant rate of discordance between sites for Pseudomonas isolates, this was not the case for Enterobacterales (Table 2).

Figure 1: Carbapenem Susceptibility by Isolate

Conclusion

Due to the wide range of susceptibility discordance, clinical implications can be drastic if an institution is relying on susceptibility of one carbapenem to confer susceptibility to another carbapenem.

Disclosures

All Authors: No reported disclosures

Yogurt consumption is associated with higher nutrient intake, diet quality and favourable metabolic profile in children: a cross-sectional analysis using data from years 1-4 of the National diet and Nutrition Survey, UK

PURPOSE

Yogurt consumption has been associated with higher nutrient intakes, better diet quality and improved metabolic profiles in adults. Few studies have investigated these associations in children. This study investigated the association of yogurt consumption with nutrient intakes, diet quality and metabolic profile in British children.

METHODS

Data from  1687 children aged 4-10 and 11-18 years of the National Diet and Nutrition Survey (NDNS) years 1-4 were analysed. Yogurt consumption was determined using a 4-day diet diary. Diet quality was assessed by the Healthy Eating Index 2010 (HEI-2010). Anthropometric measures, blood pressure, pulse pressure, plasma glucose, HbA1c, C-reactive protein, triacylglycerol, total cholesterol, high-and low-density cholesterol from NDNS were used.

RESULTS

The highest tertile of yogurt consumption (T3) was associated with higher nutrient intakes, particularly for calcium (children 4-10 years: P < 0.0001; children 11-18 years P = 0.001), iodine (both age groups P < 0.0001) and riboflavin (both age groups P < 0.0001), and HEI-2010 score (both age groups P < 0.0001) in children aged 4-10 years (mean ± SD: 98.4 ± 35.7 g yogurt/day) and 11-18 years (mean ± SD: 105.4 ± 37.5 g yogurt/day) compared with non-consumers (0 g yogurt/d). Yogurt consumption was associated with significantly lower pulse pressure in children aged 4-10 years and lower HbA1c concentration, being shorter and having a larger hip circumference in children aged 11-18 years, compared with non-yogurt consumers.

CONCLUSION

This study suggests that British children who are yogurt consumers (> 60 g/day) have higher overall diet quality, nutrient intakes and adequacy, lower pulse pressure (children aged 4-10 years) and HbA1c concentrations (children aged 11-18 years), were shorter and had a smaller hip circumference (children aged 11-18 years).

Working Memory Impairments in Chromosome 22q11.2 Deletion Syndrome: The Roles of Anxiety and Stress Physiology

Stress and anxiety have a negative impact on working memory systems by competing for executive resources and attention. Broad memory deficits, anxiety, and elevated stress have been reported in individuals with chromosome 22q11.2 deletion syndrome (22q11.2DS). We investigated anxiety and physiological stress reactivity in relation to visuospatial working memory impairments in 20 children with 22q11.2DS and 32 typically developing (TD) children ages 7 to 16. Children with 22q11.2DS demonstrated poorer working memory, reduced post-stress respiratory sinus arrhythmia recovery, and overall increased levels of cortisol in comparison to TD children. Anxiety, but not physiological stress responsivity, mediated the relationship between 22q11.2DS diagnosis and visuospatial working memory impairment. Findings indicate that anxiety exacerbates impaired working memory in children with 22q11.2DS.