Lecanemab in Early Alzheimer's Disease.

BACKGROUND: The accumulation of soluble and insoluble aggregated amyloid-beta (Aß) may initiate or potentiate pathologic processes in Alzheimer's disease. Lecanemab, a humanized IgG1 monoclonal antibody that binds with high affinity to Aß soluble protofibrils, is being tested in persons with early Alzheimer's disease. METHODS: We conducted an 18-month, multicenter, double-blind, phase 3 trial involving persons 50 to 90 years of age with early Alzheimer's disease (mild cognitive impairment or mild dementia due to Alzheimer's disease) with evidence of amyloid on positron-emission tomography (PET) or by cerebrospinal fluid testing. Participants were randomly assigned in a 1:1 ratio to receive intravenous lecanemab (10 mg per kilogram of body weight every 2 weeks) or placebo. The primary end point was the change from baseline at 18 months in the score on the Clinical Dementia Rating-Sum of Boxes (CDR-SB; range, 0 to 18, with higher scores indicating greater impairment). Key secondary end points were the change in amyloid burden on PET, the score on the 14-item cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-cog14; range, 0 to 90; higher scores indicate greater impairment), the Alzheimer's Disease Composite Score (ADCOMS; range, 0 to 1.97; higher scores indicate greater impairment), and the score on the Alzheimer's Disease Cooperative Study-Activities of Daily Living Scale for Mild Cognitive Impairment (ADCS-MCI-ADL; range, 0 to 53; lower scores indicate greater impairment). RESULTS: A total of 1795 participants were enrolled, with 898 assigned to receive lecanemab and 897 to receive placebo. The mean CDR-SB score at baseline was approximately 3.2 in both groups. The adjusted least-squares mean change from baseline at 18 months was 1.21 with lecanemab and 1.66 with placebo (difference, -0.45; 95% confidence interval [CI], -0.67 to -0.23; P<0.001). In a substudy involving 698 participants, there were greater reductions in brain amyloid burden with lecanemab than with placebo (difference, -59.1 centiloids; 95% CI, -62.6 to -55.6). Other mean differences between the two groups in the change from baseline favoring lecanemab were as follows: for the ADAS-cog14 score, -1.44 (95% CI, -2.27 to -0.61; P<0.001); for the ADCOMS, -0.050 (95% CI, -0.074 to -0.027; P<0.001); and for the ADCS-MCI-ADL score, 2.0 (95% CI, 1.2 to 2.8; P<0.001). Lecanemab resulted in infusion-related reactions in 26.4% of the participants and amyloid-related imaging abnormalities with edema or effusions in 12.6%. CONCLUSIONS: Lecanemab reduced markers of amyloid in early Alzheimer's disease and resulted in moderately less decline on measures of cognition and function than placebo at 18 months but was associated with adverse events. Longer trials are warranted to determine the efficacy and safety of lecanemab in early Alzheimer's disease. (Funded by Eisai and Biogen; Clarity AD ClinicalTrials.gov number, NCT03887455.).

Trial of Solanezumab in Preclinical Alzheimer's Disease.

BACKGROUND: Trials of monoclonal antibodies that target various forms of amyloid at different stages of Alzheimer's disease have had mixed results. METHODS: We tested solanezumab, which targets monomeric amyloid, in a phase 3 trial involving persons with preclinical Alzheimer's disease. Persons 65 to 85 years of age with a global Clinical Dementia Rating score of 0 (range, 0 to 3, with 0 indicating no cognitive impairment and 3 severe dementia), a score on the Mini-Mental State Examination of 25 or more (range, 0 to 30, with lower scores indicating poorer cognition), and elevated brain amyloid levels on 18F-florbetapir positron-emission tomography (PET) were enrolled. Participants were randomly assigned in a 1:1 ratio to receive solanezumab at a dose of up to 1600 mg intravenously every 4 weeks or placebo. The primary end point was the change in the Preclinical Alzheimer Cognitive Composite (PACC) score (calculated as the sum of four z scores, with higher scores indicating better cognitive performance) over a period of 240 weeks. RESULTS: A total of 1169 persons underwent randomization: 578 were assigned to the solanezumab group and 591 to the placebo group. The mean age of the participants was 72 years, approximately 60% were women, and 75% had a family history of dementia. At 240 weeks, the mean change in PACC score was -1.43 in the solanezumab group and -1.13 in the placebo group (difference, -0.30; 95% confidence interval, -0.82 to 0.22; P = 0.26). Amyloid levels on brain PET increased by a mean of 11.6 centiloids in the solanezumab group and 19.3 centiloids in the placebo group. Amyloid-related imaging abnormalities (ARIA) with edema occurred in less than 1% of the participants in each group. ARIA with microhemorrhage or hemosiderosis occurred in 29.2% of the participants in the solanezumab group and 32.8% of those in the placebo group. CONCLUSIONS: Solanezumab, which targets monomeric amyloid in persons with elevated brain amyloid levels, did not slow cognitive decline as compared with placebo over a period of 240 weeks in persons with preclinical Alzheimer's disease. (Funded by the National Institute on Aging and others; A4 ClinicalTrials.gov number, NCT02008357.).

Sex differences in the pleiotropy of hearing difficulty with imaging-derived phenotypes: a brain-wide investigation.

Hearing difficulty (HD) is a major health burden in older adults. While ageing-related changes in the peripheral auditory system play an important role, genetic variation associated with brain structure and function could also be involved in HD predisposition. We analysed a large-scale HD genome-wide association study (GWAS; ntotal = 501 825, 56% females) and GWAS data related to 3935 brain imaging-derived phenotypes (IDPs) assessed in up to 33 224 individuals (52% females) using multiple MRI modalities. To investigate HD pleiotropy with brain structure and function, we conducted genetic correlation, latent causal variable, Mendelian randomization and multivariable generalized linear regression analyses. Additionally, we performed local genetic correlation and multi-trait co-localization analyses to identify genomic regions and loci implicated in the pleiotropic mechanisms shared between HD and brain IDPs. We observed a widespread genetic correlation of HD with 120 IDPs in females, 89 in males and 171 in the sex-combined analysis. The latent causal variable analysis showed that some of these genetic correlations could be due to cause-effect relationships. For seven of them, the causal effects were also confirmed by the Mendelian randomization approach: vessel volume→HD in the sex-combined analysis; hippocampus volume→HD, cerebellum grey matter volume→HD, primary visual cortex volume→HD and HD→fluctuation amplitudes of node 46 in resting-state functional MRI dimensionality 100 in females; global mean thickness→HD and HD→mean orientation dispersion index in superior corona radiata in males. The local genetic correlation analysis identified 13 pleiotropic regions between HD and these seven IDPs. We also observed a co-localization signal for the rs13026575 variant between HD, primary visual cortex volume and SPTBN1 transcriptomic regulation in females. Brain structure and function may have a role in the sex differences in HD predisposition via possible cause-effect relationships and shared regulatory mechanisms.

The regional pattern of age-related synaptic loss in the human brain differs from gray matter volume loss: in vivo PET measurement with [11C]UCB-J.

PURPOSE: Aging is a major societal concern due to age-related functional losses. Synapses are crucial components of neural circuits, and synaptic density could be a sensitive biomarker to evaluate brain function. [11C]UCB-J is a positron emission tomography (PET) ligand targeting synaptic vesicle glycoprotein 2A (SV2A), which can be used to evaluate brain synaptic density in vivo. METHODS: We evaluated age-related changes in gray matter synaptic density, volume, and blood flow using [11C]UCB-J PET and magnetic resonance imaging (MRI) in a wide age range of 80 cognitive normal subjects (21-83 years old). Partial volume correction was applied to the PET data. RESULTS: Significant age-related decreases were found in 13, two, and nine brain regions for volume, synaptic density, and blood flow, respectively. The prefrontal cortex showed the largest volume decline (4.9% reduction per decade: RPD), while the synaptic density loss was largest in the caudate (3.6% RPD) and medial occipital cortex (3.4% RPD). The reductions in caudate are consistent with previous SV2A PET studies and likely reflect that caudate is the site of nerve terminals for multiple major tracts that undergo substantial age-related neurodegeneration. There was a non-significant negative relationship between volume and synaptic density reductions in 16 gray matter regions. CONCLUSION: MRI and [11]C-UCB-J PET showed age-related decreases of gray matter volume, synaptic density, and blood flow; however, the regional patterns of the reductions in volume and SV2A binding were different. Those patterns suggest that MR-based measures of GM volume may not be directly representative of synaptic density.

Assessment of Gray Matter Microstructure and Synaptic Density in Alzheimer's Disease: A Multimodal Imaging Study With DTI and SV2A PET.

OBJECTIVE: Multimodal imaging techniques have furthered our understanding of how different aspects of Alzheimer's disease (AD) pathology relate to one another. Diffusion tensor imaging (DTI) measures such as mean diffusivity (MD) may be a surrogate measure of the changes in gray matter structure associated with AD. Positron emission tomography (PET) imaging of synaptic vesicle glycoprotein 2A (SV2A) has been used to quantify synaptic loss, which is the major pathological correlate of cognitive impairment in AD. In this study, we investigated the relationship between gray matter microstructure and synaptic density. METHODS: DTI was used to measure MD and [11C]UCB-J PET to measure synaptic density in 33 amyloid-positive participants with AD and 17 amyloid-negative cognitively normal (CN) participants aged 50-83. Univariate regression analyses were used to assess the association between synaptic density and MD in both the AD and CN groups. RESULTS: Hippocampal MD was inversely associated with hippocampal synaptic density in participants with AD (r = -0.55, p <0.001, df = 31) but not CN (r = 0.13, p = 0.62, df = 15). Exploratory analyses across other regions known to be affected in AD suggested widespread inverse associations between synaptic density and MD in the AD group. CONCLUSION: In the setting of AD, an increase in gray matter MD is inversely associated with synaptic density. These co-occurring changes may suggest a link between synaptic loss and gray matter microstructural changes in AD. Imaging studies of gray matter microstructure and synaptic density may allow important insights into AD-related neuropathology.

Adverse effects of methylphenidate for apathy in patients with Alzheimer's disease (ADMET2 trial).

OBJECTIVES: To examine clinically important adverse events (AEs) associated with methylphenidate (MPH) treatment of apathy in Alzheimer's Disease (AD) versus placebo, including weight loss, vital signs, falls, and insomnia. METHODS: The Apathy in Dementia Methylphenidate Trial 2 (ADMET2) trial was a multicenter randomized, placebo-controlled trial of MPH to treat apathy in individuals with apathy and AD. Participants in ADMET2 had vital signs and weight measured at monthly visits through 6 months. AEs, including insomnia, falls, and cardiovascular events, were reported at every visit by participants and families using a symptom checklist. RESULTS: The study included 98 participants in the MPH group and 101 in the placebo group. Participants in the MPH group experienced greater weight loss on average than the placebo through the 6-month follow-up, with a difference in change between MPH and placebo of 2.8 lb (95% confidence interval, CI: 0.7, 4.9 lb). No treatment group differences in change during the trial were found in systolic and diastolic blood pressure. More participants in the MPH group reported falls during the follow-up, 10 versus 6 in MPH and placebo groups, respectively. No differences in post-baseline insomnia were observed between the treatment groups. No participants reported instances of myocardial infarction, congestive heart failure, arrhythmia, stroke, or cardiomyopathy throughout the study period. CONCLUSIONS: MPH use in AD patients for treating apathy is relatively safe, particularly notable given the many medical comorbidities in this population. There was a statistically significant but modest weight loss associated with MPH use, and clinicians are thus advised to monitor weight during MPH treatment.

Localization of PDE4D, HCN1 channels, and mGluR3 in rhesus macaque entorhinal cortex may confer vulnerability in Alzheimer's disease.

Alzheimer's disease cortical tau pathology initiates in the layer II cell clusters of entorhinal cortex, but it is not known why these specific neurons are so vulnerable. Aging macaques exhibit the same qualitative pattern of tau pathology as humans, including initial pathology in layer II entorhinal cortex clusters, and thus can inform etiological factors driving selective vulnerability. Macaque data have already shown that susceptible neurons in dorsolateral prefrontal cortex express a "signature of flexibility" near glutamate synapses on spines, where cAMP-PKA magnification of calcium signaling opens nearby potassium and hyperpolarization-activated cyclic nucleotide-gated channels to dynamically alter synapse strength. This process is regulated by PDE4A/D, mGluR3, and calbindin, to prevent toxic calcium actions; regulatory actions that are lost with age/inflammation, leading to tau phosphorylation. The current study examined whether a similar "signature of flexibility" expresses in layer II entorhinal cortex, investigating the localization of PDE4D, mGluR3, and HCN1 channels. Results showed a similar pattern to dorsolateral prefrontal cortex, with PDE4D and mGluR3 positioned to regulate internal calcium release near glutamate synapses, and HCN1 channels concentrated on spines. As layer II entorhinal cortex stellate cells do not express calbindin, even when young, they may be particularly vulnerable to magnified calcium actions and ensuing tau pathology.

Measuring clinically relevant change in apathy symptoms in ADMET and ADMET 2.

OBJECTIVES: Among participants with Alzheimer's disease (AD) we estimated the minimal clinically important difference (MCID) in apathy symptom severity on three scales. DESIGN: Retrospective anchor- and distribution-based analyses of change in apathy symptom scores. SETTING: Apathy in Dementia Methylphenidate Trial (ADMET) and ADMET 2 randomized controlled trials conducted at three and ten clinics specialized in dementia care in United States and Canada, respectively. PARTICIPANTS: Two hundred and sixty participants (60 ADMET, 200 ADMET 2) with clinically significant apathy in Alzheimer's disease. MEASUREMENTS: The Clinical Global Impression of Change in Apathy scale was used as the anchor measure and the MCID on the Neuropsychiatric Inventory - Apathy (NPI-A), Dementia Apathy Interview and Rating (DAIR), and Apathy Evaluation Scale-Informant (AES-I) were estimated with linear mixed models across all study visits. The estimated thresholds were evaluated with performance metrics. RESULTS: Among the MCID was a decrease of four points (95% CI: -4.0 to -4.8) on the NPI-A, 0.56 points (95% CI: -0.47 to -0.65) on the DAIR, and three points on the AES-I (95% CI: -0.9 to -5.4). Distribution-based analyses were largely consistent with the anchor-based analyses. The MCID across the three measures showed ∼60% accuracy. Sensitivity analyses found that MMSE scores and apathy severity at baseline influenced the estimated MCID. CONCLUSIONS: MCIDs for apathy on three scales will help evaluate treatment efficacy at the individual level. However, the modest correspondence between MCID and clinical impression of change suggests the need to consider other scales.

Self-reported hearing loss is associated with faster cognitive and functional decline but not diagnostic conversion in the ADNI cohort.

INTRODUCTION: Hearing loss is identified as one of the largest modifiable risk factors for cognitive impairment and dementia. Studies evaluating this relationship have yielded mixed results. METHODS: We investigated the longitudinal relationship between self-reported hearing loss and cognitive/functional performance in 695 cognitively normal (CN) and 941 participants with mild cognitive impairment (MCI) enrolled in the Alzheimer's Disease Neuroimaging Initiative. RESULTS: Within CN participants with hearing loss, there was a significantly greater rate of cognitive decline per modified preclinical Alzheimer's cognitive composite. Within both CN and MCI participants with hearing loss, there was a significantly greater rate of functional decline per the functional activities questionnaire (FAQ). In CN and MCI participants, hearing loss did not significantly contribute to the risk of progression to a more impaired diagnosis. DISCUSSION: These results confirm previous studies demonstrating a significant longitudinal association between self-reported hearing loss and cognition/function but do not demonstrate an increased risk of conversion to a more impaired diagnosis. CLINICAL TRIAL REGISTRATION INFORMATION: NCT00106899 (ADNI: Alzheimer's Disease Neuroimaging Initiative, clinicaltrials.gov), NCT01078636 (ADNI-GO: Alzheimer's Disease Neuroimaging Initiative Grand Opportunity, clinicaltrials.gov), NCT01231971 (ADNI2: Alzheimer's Disease Neuroimaging Initiative 2, clinicaltrials.gov), NCT02854033 (ADNI3: Alzheimer's Disease Neuroimaging Initiative 3, clinicaltrials.gov). HIGHLIGHTS: Hearing loss is a potential modifiable risk factor for dementia. We assessed the effect of self-reported hearing loss on cognition and function in the ADNI cohort. Hearing loss contributes to significantly faster cognitive and functional decline. Hearing loss was not associated with conversion to a more impaired diagnosis.

Nanoscale imaging of pT217-tau in aged rhesus macaque entorhinal and dorsolateral prefrontal cortex: Evidence of interneuronal trafficking and early-stage neurodegeneration.

INTRODUCTION: Tau phosphorylated at threonine-217 (pT217-tau) is a novel fluid-based biomarker that predicts onset of Alzheimer's disease (AD) symptoms, but little is known about how pT217-tau arises in the brain, as soluble pT217-tau is dephosphorylated post mortem in humans. METHODS: We used multilabel immunofluorescence and immunoelectron microscopy to examine the subcellular localization of early-stage pT217-tau in entorhinal and prefrontal cortices of aged macaques with naturally occurring tau pathology and assayed pT217-tau levels in plasma. RESULTS: pT217-tau was aggregated on microtubules within dendrites exhibiting early signs of degeneration, including autophagic vacuoles. It was also seen trafficking between excitatory neurons within synapses on spines, where it was exposed to the extracellular space, and thus accessible to cerebrospinal fluid (CSF)/blood. Plasma pT217-tau levels increased across the age span and thus can serve as a biomarker in macaques. DISCUSSION: These data help to explain why pT217-tau predicts degeneration in AD and how it gains access to CSF and plasma to serve as a fluid biomarker.

CT1812 biomarker signature from a meta-analysis of CSF proteomic findings from two Phase 2 clinical trials in Alzheimer's disease.

INTRODUCTION: CT1812 is in clinical development for the treatment of Alzheimer's disease (AD). Cerebrospinal fluid (CSF) exploratory proteomics was employed to identify pharmacodynamic biomarkers of CT1812 in mild to moderate AD from two independent clinical trials. METHODS: Unbiased analysis of tandem-mass tag mass spectrometry (TMT-MS) quantitative proteomics, pathway analysis and correlation analyses with volumetric magnetic resonance imaging (vMRI) were performed for the SPARC cohort (NCT03493282). Comparative analyses and a meta-analysis with the interim SHINE cohort (NCT03507790; SHINE-A) followed by network analysis (weighted gene co-expression network analysis [WGCNA]) were used to understand the biological impact of CT1812. RESULTS: CT1812 pharmacodynamic biomarkers and biological pathways were identified that replicate across two clinical cohorts. The meta-analysis revealed novel candidate biomarkers linked to S2R biology and AD, and network analysis revealed treatment-associated networks driven by S2R.  DISCUSSION: Early clinical validation of CT1812 candidate biomarkers replicating in independent cohorts strengthens the understanding of the biological impact of CT1812 in patients with AD, and supports CT1812's synaptoprotective mechanism of action and its continued clinical development. HIGHLIGHTS: This exploratory proteomics study identified candidate biomarkers of CT1812 in SPARC (NCT03493282) Comparative analyses identified biomarkers replicating across trials/cohorts Two independent Ph2 trial cohorts (SPARC and interim SHINE [NCT03507790; SHINE-A]) were used in a meta-analysis Amyloid beta (Aß) & synaptic biology impacted by CT1812 and volumetric magnetic resonance imaging (vMRI) treatment-related correlates emerge Network analyses revealed sigma-2 receptor (S2R)-interacting proteins that may be "drivers" of changes.

Examining amyloid reduction as a surrogate endpoint through latent class analysis using clinical trial data for dominantly inherited Alzheimer's disease.

INTRODUCTION: Increasing evidence suggests that amyloid reduction could serve as a plausible surrogate endpoint for clinical and cognitive efficacy. The double-blind phase 3 DIAN-TU-001 trial tested clinical and cognitive declines with increasing doses of solanezumab or gantenerumab. METHODS: We used latent class (LC) analysis on data from the Dominantly Inherited Alzheimer Network Trials Unit 001 trial to test amyloid positron emission tomography (PET) reduction as a potential surrogate biomarker. RESULTS: LC analysis categorized participants into three classes: amyloid no change, amyloid reduction, and amyloid growth, based on longitudinal amyloid Pittsburgh compound B PET standardized uptake value ratio data. The amyloid-no-change class was at an earlier disease stage for amyloid amounts and dementia. Despite similar baseline characteristics, the amyloid-reduction class exhibited reductions in the annual decline rates compared to the amyloid-growth class across multiple biomarker, clinical, and cognitive outcomes. DISCUSSION: LC analysis indicates that amyloid reduction is associated with improved clinical outcomes and supports its use as a surrogate biomarker in clinical trials. HIGHLIGHTS: We used latent class (LC) analysis to test amyloid reduction as a surrogate biomarker. Despite similar baseline characteristics, the amyloid-reduction class exhibited remarkably better outcomes compared to the amyloid-growth class across multiple measures. LC analysis proves valuable in testing amyloid reduction as a surrogate biomarker in clinical trials lacking significant treatment effects.

Pleiotropic effects of telomere length loci with brain morphology and brain tissue expression.

Several studies have reported association between leukocyte telomere length (LTL) and neuropsychiatric disorders. Although telomere length is affected by environmental factors, genetic variants in certain loci are strongly associated with LTL. Thus, we aimed to identify the genomic relationship between genetic variants of LTL with brain-based regulatory changes and brain volume. We tested genetic colocalization of seven and nine LTL loci in two ancestry groups, European (EUR) and East-Asian (EAS), respectively, with brain morphology measures for 101 T1-magnetic resonance imaging-based region of interests (n = 21 821). The posterior probability (>90%) was observed for 'fourth ventricle', 'gray matter' and 'cerebellar vermal lobules I-IV' volumes. We then tested causal relationship using LTL loci for gene and methylation expression. We found causal pleiotropy for gene (EAS = four genes; EUR = five genes) and methylation expression (EUR = 17 probes; EAS = 4 probes) of brain tissues (P ≤ 2.47 × 10-6). Integrating chromatin profiles with LTL-single nucleotide polymorphisms identified 45 genes (EUR) and 79 genes (EAS) (P ≤ 9.78×10-7). We found additional 38 LTL-genes using chromatin-based gene mapping for EUR ancestry population. Gene variants in three LTL-genes-GPR37, OBFC1 and RTEL1/RTEL1-TNFRSF6B-show convergent evidence of pleiotropy with brain morphology, gene and methylation expression and chromatin association. Mapping gene functions to drug-gene interactions, we identified process 'transmission across chemical synapses' (P < 2.78 × 10-4). This study provides evidence that genetic variants of LTL have pleiotropic roles with brain-based effects that could explain the phenotypic association of LTL with several neuropsychiatric traits.

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

PURPOSE: Pittsburgh Compound-B (11C-PiB) and 18F-florbetapir are amyloid-ß (Aß) positron emission tomography (PET) radiotracers that have been used as endpoints in Alzheimer's disease (AD) clinical trials to evaluate the efficacy of anti-Aß monoclonal antibodies. However, comparing drug effects between and within trials may become complicated if different Aß radiotracers were used. To study the consequences of using different Aß radiotracers to measure Aß clearance, we performed a head-to-head comparison of 11C-PiB and 18F-florbetapir in a Phase 2/3 clinical trial of anti-Aß 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 Aß 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 Aß radiotracers. In contrast, the rates of longitudinal change measured in global cortical Centiloids did not differ between Aß 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 Aß radiotracers were used versus trials where only one Aß 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 Aß PET, and the absolute rates of these longitudinal changes differ significantly between Aß radiotracers. These differences were not seen in the placebo arm, suggesting that Aß-clearing treatments may pose unique challenges when attempting to compare longitudinal results across different Aß radiotracers. Our results suggest converting Aß 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 Aß 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.

Relationships of in vivo brain norepinephrine transporter and age, BMI, and gender.

Previous research reported an age-related decline in brain norepinephrine transporter (NET) using (S, S)-[11C]O-methylreboxetine ([11C]MRB) as a radiotracer. Studies with the same tracer have been mixed in regard to differences related to body mass index (BMI). Here, we investigated potential age-, BMI-, and gender-related differences in brain NET availability using [11C]MRB, the most selective available radiotracer. Forty-three healthy participants (20 females, 23 males; age range 18-49 years), including 12 individuals with normal/lean weight, 15 with overweight, and 16 with obesity were scanned with [11C]MRB using a positron emission tomography (PET) high-resolution research tomograph (HRRT). We evaluated binding potential (BPND ) in brain regions with high NET availability using multilinear reference tissue model 2 (MRTM2) with the occipital cortex as a reference region. Brain regions were delineated with a defined anatomic template applied to subjects' structural MR scans. We found a negative association between age and NET availability in the locus coeruleus, raphe nucleus, and hypothalamus, with a 17%, 19%, and 14% decrease per decade, respectively, in each region. No gender or BMI relationships with NET availability were observed. Our findings suggest an age-related decline, but no BMI- or gender-related differences, in NET availability in healthy adults.

Heterogeneity of Response to Methylphenidate in Apathetic Patients in the ADMET 2 Trial.

OBJECTIVE: The Apathy in Dementia Methylphenidate Trial 2 (ADMET 2) found that methylphenidate was effective in treating apathy with a small-to-medium effect size but showed heterogeneity in response. We assessed clinical predictors of response to help determine individual likelihood of treatment benefit from methylphenidate. DESIGN: Univariate and multivariate analyses of 22 clinical predictors of response chosen a priori. SETTING: Data from the ADMET 2 randomized, placebo controlled multi-center clinical trial. PARTICIPANTS: Alzheimer's disease patients with clinically significant apathy. MEASUREMENTS: Apathy assessed with the Neuropsychiatric Inventory apathy domain (NPI-A). RESULTS: In total, 177 participants (67% male, mean [SD] age 76.4 [7.9], mini-mental state examination 19.3 [4.8]) had 6-months follow up data. Six potential predictors met criteria for inclusion in multivariate modeling. Methylphenidate was more efficacious in participants without NPI anxiety (change in NPI-A -2.21, standard error [SE]:0.60) or agitation (-2.63, SE:0.68), prescribed cholinesterase inhibitors (ChEI) (-2.44, SE:0.62), between 52 and 72 years of age (-2.93, SE:1.05), had 73-80 mm Hg diastolic blood pressure (-2.43, SE: 1.03), and more functional impairment (-2.56, SE:1.16) as measured by the Alzheimer's Disease Cooperative Study Activities of Daily Living scale. CONCLUSION: Individuals who were not anxious or agitated, younger, prescribed a ChEI, with optimal (73-80 mm Hg) diastolic blood pressure, or having more impaired function were more likely to benefit from methylphenidate compared to placebo. Clinicians may preferentially consider methylphenidate for apathetic AD participants already prescribed a ChEI and without baseline anxiety or agitation.

Aging gene signature of memory CD8+ T cells is associated with neurocognitive functioning in Alzheimer's disease.

BACKGROUND: Memory CD8+ T cells expand with age. We previously demonstrated an age-associated expansion of effector memory (EM) CD8+ T cells expressing low levels of IL-7 receptor alpha (IL-7Rαlow) and the presence of its gene signature (i.e., IL-7Rαlow aging genes) in peripheral blood of older adults without Alzheimer's disease (AD). Considering age as the strongest risk factor for AD and the recent finding of EM CD8+ T cell expansion, mostly IL-7Rαlow cells, in AD, we investigated whether subjects with AD have alterations in IL-7Rαlow aging gene signature, especially in relation to genes possibly associated with AD and disease severity. RESULTS: We identified a set of 29 candidate genes (i.e., putative AD genes) which could be differentially expressed in peripheral blood of patients with AD through the systematic search of publicly available datasets. Of the 29 putative AD genes, 9 genes (31%) were IL-7Rαlow aging genes (P < 0.001), suggesting the possible implication of IL-7Rαlow aging genes in AD. These findings were validated by RT-qPCR analysis of 40 genes, including 29 putative AD genes, additional 9 top IL-7R⍺low aging but not the putative AD genes, and 2 inflammatory control genes in peripheral blood of cognitively normal persons (CN, 38 subjects) and patients with AD (40 mild cognitive impairment and 43 dementia subjects). The RT-qPCR results showed 8 differentially expressed genes between AD and CN groups; five (62.5%) of which were top IL-7Rαlow aging genes (FGFBP2, GZMH, NUAK1, PRSS23, TGFBR3) not previously reported to be altered in AD. Unbiased clustering analysis revealed 3 clusters of dementia patients with distinct expression levels of the 40 analyzed genes, including IL-7Rαlow aging genes, which were associated with neurocognitive function as determined by MoCA, CDRsob and neuropsychological testing. CONCLUSIONS: We report differential expression of "normal" aging genes associated with IL-7Rαlow EM CD8+ T cells in peripheral blood of patients with AD, and the significance of such gene expression in clustering subjects with dementia due to AD into groups with different levels of cognitive functioning. These results provide a platform for studies investigating the possible implications of age-related immune changes, including those associated with CD8+ T cells, in AD.

Cost consequence analysis of Apathy in Dementia Methylphenidate Trial 2 (ADMET 2).

BACKGROUND: This paper used data from the Apathy in Dementia Methylphenidate Trial 2 (NCT02346201) to conduct a planned cost consequence analysis to investigate whether treatment of apathy with methylphenidate is economically attractive. METHODS: A total of 167 patients with clinically significant apathy randomized to either methylphenidate or placebo were included. The Resource Utilization in Dementia Lite instrument assessed resource utilization for the past 30 days and the EuroQol five dimension five level questionnaire assessed health utility at baseline, 3 months, and 6 months. Resources were converted to costs using standard sources and reported in 2021 USD. A repeated measures analysis of variance compared change in costs and utility over time between the treatment and placebo groups. A binary logistic regression was used to assess cost predictors. RESULTS: Costs were not significantly different between groups whether the cost of methylphenidate was excluded (F(2,330) = 0.626, ηp2 = 0.004, p = 0.535) or included (F(2,330) = 0.629, ηp2 = 0.004, p = 0.534). Utility improved with methylphenidate treatment as there was a group by time interaction (F(2,330) = 7.525, ηp2 = 0.044, p < 0.001). DISCUSSION: Results from this study indicated that there was no evidence for a difference in resource utilization costs between methylphenidate and placebo treatment. However, utility improved significantly over the 6-month follow-up period. These results can aid in decision-making to improve quality of life in patients with Alzheimer's disease while considering the burden on the healthcare system.

Natural cubic splines for the analysis of Alzheimer's clinical trials.

Mixed model repeated measures (MMRM) is the most common analysis approach used in clinical trials for Alzheimer's disease and other progressive diseases measured with continuous outcomes over time. The model treats time as a categorical variable, which allows an unconstrained estimate of the mean for each study visit in each randomized group. Categorizing time in this way can be problematic when assessments occur off-schedule, as including off-schedule visits can induce bias, and excluding them ignores valuable information and violates the intention to treat principle. This problem has been exacerbated by clinical trial visits which have been delayed due to the COVID19 pandemic. As an alternative to MMRM, we propose a constrained longitudinal data analysis with natural cubic splines that treats time as continuous and uses test version effects to model the mean over time. Compared to categorical-time models like MMRM and models that assume a proportional treatment effect, the spline model is shown to be more parsimonious and precise in real clinical trial datasets, and has better power and Type I error in a variety of simulation scenarios.

Randomized Trial of Verubecestat for Prodromal Alzheimer's Disease.

BACKGROUND: Prodromal Alzheimer's disease offers an opportunity to test the effect of drugs that modify the deposition of amyloid in the brain before the onset of dementia. Verubecestat is an orally administered ß-site amyloid precursor protein-cleaving enzyme 1 (BACE-1) inhibitor that blocks production of amyloid-beta (Aß). The drug did not prevent clinical progression in a trial involving patients with mild-to-moderate dementia due to Alzheimer's disease. METHODS: We conducted a randomized, double-blind, placebo-controlled, 104-week trial to evaluate verubecestat at doses of 12 mg and 40 mg per day, as compared with placebo, in patients who had memory impairment and elevated brain amyloid levels but whose condition did not meet the case definition of dementia. The primary outcome was the change from baseline to week 104 in the score on the Clinical Dementia Rating Scale-Sum of Boxes (CDR-SB; scores range from 0 to 18, with higher scores indicating worse cognition and daily function). Secondary outcomes included other assessments of cognition and daily function. RESULTS: The trial was terminated for futility after 1454 patients had been enrolled; 485 had been assigned to receive verubecestat at a dose of 12 mg per day (the 12-mg group), 484 to receive verubecestat at a dose of 40 mg per day (the 40-mg group), and 485 to receive placebo. A total of 234 patients, 231 patients, and 239 patients per group, respectively, completed 104 weeks of the trial regimen. The estimated mean change from baseline to week 104 in the CDR-SB score was 1.65 in the 12-mg group, 2.02 in the 40-mg group, and 1.58 in the placebo group (P = 0.67 for the comparison between the 12-mg group and the placebo group and P = 0.01 for the comparison between the 40-mg group and the placebo group), suggesting a worse outcome in the higher-dose group than in the placebo group. The estimated rate of progression to dementia due to Alzheimer's disease was 24.5, 25.5, and 19.3 events per 100 patient-years in the 12-mg group, the 40-mg group, and the placebo group, respectively (hazard ratio for 40 mg vs. placebo, 1.38; 97.51% confidence interval, 1.07 to 1.79, not adjusted for multiple comparisons), favoring placebo. Adverse events were more common in the verubecestat groups than in the placebo group. CONCLUSIONS: Verubecestat did not improve clinical ratings of dementia among patients with prodromal Alzheimer's disease, and some measures suggested that cognition and daily function were worse among patients who received verubecestat than among those who received placebo. (Funded by Merck Sharp & Dohme; ClinicalTrials.gov number, NCT01953601.).