High-clearance anti-amyloid immunotherapies in Alzheimer's disease. Part 2: putative scenarios and timeline in case of approval, recommendations for use, implementation, and ethical considerations in France

Regulatory roles of microRNAs in modulating mitochondrial dynamics, amyloid beta fibrillation, microglial activation, and cholinergic signaling: Implications for alzheimer's disease pathogenesis

Alzheimer's Disease (AD) remains a formidable challenge due to its complex pathology, notably involving mitochondrial dysfunction and dysregulated microRNA (miRNA) signaling. This study delves into the underexplored realm of miRNAs' impact on mitochondrial dynamics and their interplay with amyloid-beta (Aβ) aggregation and tau pathology in AD. Addressing identified gaps, our research utilizes advanced molecular techniques and AD models, alongside patient miRNA profiles, to uncover miRNAs pivotal in mitochondrial regulation. We illuminate novel miRNAs influencing mitochondrial dynamics, Aβ, and tau, offering insights into their mechanistic roles in AD progression. Our findings not only enhance understanding of AD's molecular underpinnings but also spotlight miRNAs as promising therapeutic targets. By elucidating miRNAs' roles in mitochondrial dysfunction and their interactions with hallmark AD pathologies, our work proposes innovative strategies for AD therapy, aiming to mitigate disease progression through targeted miRNA modulation. This contribution marks a significant step toward novel AD treatments, emphasizing the potential of miRNAs in addressing this complex disease.

Estimated effects of amyloid reduction on cognitive change: A Bayesian update across a range of priors

INTRODUCTION

The results of the CLARITY-AD, GRADUATE I and II, and TRAILBLAZER-ALZ 2 trials have rekindled discussion on the impact of amyloid-targeting drugs. We use a Bayesian approach to quantify how rational observers would have updated their prior beliefs based on new trial results.

METHODS

We used publicly available data from the CLARITY-AD, GRADUATE I and II, and TRAILBLAZER-ALZ 2 trials to estimate the effect of reducing amyloid on the clinical dementia rating scale, sum of boxes (CDR-SB) score. A range of prior positions were then updated according to Bayes' theorem using these estimates.

RESULTS

After updating with new trial data, a wide range of starting positions resulted in credible intervals that did not include no effect of amyloid reduction on CDR-SB score.

DISCUSSION

For a range of starting beliefs and assuming the veracity of the underlying data, rational observers would conclude there is a small benefit of amyloid reductions on cognition. This benefit must be weighed against opportunity cost and side-effect risk.

HIGHLIGHTS

The results of recent trials of amyloid-targeting drugs have rekindled discussion on the impact of amyloid reductions achieved with amyloid-targeting drugs on cognition. Prior to the announcement of trial results, beliefs about the effects of altering amyloid levels varied. For a range of starting beliefs, one would conclude there is a small benefit of amyloid reductions due to amyloid-targeting drugs on cognition. The perceived value of individual drugs must balance the magnitude of this benefit against opportunity cost and risk of side effects.

The Catastrophe of Intracerebral Hemorrhage Drives the Capillary-Hemorrhage Dementias, Including Alzheimer's Disease

This review advances an understanding of several dementias, based on four premises. One is that capillary hemorrhage is prominent in the pathogenesis of the dementias considered (dementia pugilistica, chronic traumatic encephalopathy, traumatic brain damage, Alzheimer's disease). The second premise is that hemorrhage introduces four neurotoxic factors into brain tissue: hypoxia of the tissue that has lost its blood supply, hemoglobin and its breakdown products, excitotoxic levels of glutamate, and opportunistic pathogens that can infect brain cells and induce a cytotoxic immune response. The third premise is that where organisms evolve molecules that are toxic to itself, like the neurotoxicity ascribed to hemoglobin, amyloid- (A), and glutamate, there must be some role for the molecule that gives the organism a selection advantage. The fourth is the known survival-advantage roles of hemoglobin (oxygen transport), of A (neurotrophic, synaptotrophic, detoxification of heme, protective against pathogens) and of glutamate (a major neurotransmitter). From these premises, we propose 1) that the brain has evolved a multi-factor response to intracerebral hemorrhage, which includes the expression of several protective molecules, including haptoglobin, hemopexin and A; and 2) that it is logical, given these premises, to posit that the four neurotoxic factors set out above, which are introduced into the brain by hemorrhage, drive the progression of the capillary-hemorrhage dementias. In this view, A expressed at the loci of neuronal death in these dementias functions not as a toxin but as a first responder, mitigating the toxicity of hemoglobin and the infection of the brain by opportunistic pathogens.

Don't forget primary progressive aphasia for anti-amyloid drugs: An estimation of eligible patients from the Lausanne Memory Center registry

The study recently published on the clinical effect of lecanemab in early Alzheimer's disease (AD) only includes patients with amnestic presentation. However, a significant portion of AD patients presents a non-amnestic phenotype of AD, such as primary progressive aphasia (PPA) and could benefit of rather than on lecanemab. Therefore, we conducted a 10-year retrospective study at the Leenaards Memory Center in Lausanne (Switzerland) to identify how many PPA patients would be eligible for lecanemab. Among 54 patients with PPA, we identified 11 (20%) eligible patients. Furthermore, almost half of the 18 patients with logopenic variant would be eligible for lecanemab treatment.

FDG PET (and MRI) for Monitoring Immunotherapy in Alzheimer Disease

ABSTRACT

Passive immunotherapy for Alzheimer disease has been tried for over 10 years without success. However, in 2021 and most recently in January 2023, the US Food and Drug Administration granted accelerated approval of 2 antibodies for this purpose, aducanumab and lecanemab. In both cases, the approval was based on a presumed therapy-related removal of amyloid deposits from the brain and, in the case of lecanemab, also some delay in cognitive decline. We question the validity of the evidence for the removal of amyloid in particular as assessed by amyloid PET imaging, believing that what is observed is more likely a large nonspecific amyloid PET signal in the white matter that diminishes during immunotherapy-in line with dose-dependent increases in amyloid-related imaging abnormalities and increased loss of cerebral volume in treated compared with placebo patients. To investigate this further, we recommend repeat FDG PET and MRI in all future immunotherapy trials.

Estimated Effects of Amyloid Reduction on Cognitive Change: A Bayesian Update across a Range of Priors

Introduction

Results of the CLARITY-AD and GRADUATE I and II trials rekindled discussion on the impact of amyloid-targeting drugs. We use a Bayesian approach to quantify how a rational observer would have updated their prior beliefs based on new trial results.

Methods

We used publicly available data from the CLARITY-AD and GRADUATE I & II trials to estimate the effect of reducing amyloid on CDR-SB score. A range of prior positions were then updated according to Bayes Theorem using these estimates.

Results

After updating with new trial data, a wide range of starting positions resulted in credible intervals that did not include no effect of amyloid reduction on CDR-SB.

Discussion

For a range of starting beliefs and assuming veracity of underlying data, rational observers would conclude there is a small benefit of amyloid-reductions on cognition. This benefit must be weighed against opportunity cost and side effect risk.

Validation study of "Santé-Cerveau", a digital tool for early cognitive changes identification

BACKGROUND

There is a need for a reliable, easy-to-use, widely available, and validated tool for timely cognitive impairment identification. We created a computerized cognitive screening tool (Santé-Cerveau digital tool (SCD-T)) including validated questionnaires and the following neuropsychological tests: 5 Word Test (5-WT) for episodic memory, Trail Making Test (TMT) for executive functions, and a number coding test (NCT) adapted from the Digit Symbol Substitution Test for global intellectual efficiency. This study aimed to evaluate the performance of SCD-T to identify cognitive deficit and to determine its usability.

METHODS

Three groups were constituted including 65 elderly Controls, 64 patients with neurodegenerative diseases (NDG): 50 AD and 14 non-AD, and 20 post-COVID-19 patients. The minimum MMSE score for inclusion was 20. Association between computerized SCD-T cognitive tests and their standard equivalent was assessed using Pearson's correlation coefficients. Two algorithms (a simple clinician-guided algorithm involving the 5-WT and the NCT; and a machine learning classifier based on 8 scores from the SCD-T tests extracted from a multiple logistic regression model, and data from the SCD-T questionnaires) were evaluated. The acceptability of SCD-T was investigated through a questionnaire and scale.

RESULTS

AD and non-AD participants were older (mean ± standard deviation (SD): 72.61 ± 6.79 vs 69.91 ± 4.86 years old, p = 0.011) and had a lower MMSE score (Mean difference estimate ± standard error: 1.74 ± 0.14, p < 0.001) than Controls; post-COVID-19 patients were younger than Controls (mean ± SD: 45.07 ± 11.36 years old, p < 0.001). All the computerized SCD-T cognitive tests were significantly associated with their reference version. In the pooled Controls and NDG group, the correlation coefficient was 0.84 for verbal memory, -0.60 for executive functions, and 0.72 for global intellectual efficiency. The clinician-guided algorithm demonstrated 94.4% ± 3.8% sensitivity and 80.5% ± 8.7% specificity, and the machine learning classifier 96.8% ± 3.9% sensitivity and 90.7% ± 5.8% specificity. The acceptability of SCD-T was good to excellent.

CONCLUSIONS

We demonstrate the high accuracy of SCD-T in screening cognitive disorders and its good acceptance even in individuals with prodromal and mild dementia stages. SCD-T would be useful in primary care to faster refer subjects with significant cognitive impairment (and limit unnecessary referrals) to specialized consultation, improve the AD care pathway and the pre-screening in clinical trials.

Redefinition of dementia care in Italy in the era of amyloid-lowering agents for the treatment of Alzheimer's disease: an expert opinion and practical guideline

No disease-modifying therapies are currently available for Alzheimer's disease (AD) in Europe. Current evidence from clinical trials testing anti-beta amyloid (Aβ) monoclonal antibodies (mAbs) in patients with early AD, though, suggests a likely marketing authorization in the next years. Since the implementation of disease-modifying therapies for AD in the clinical practice will evidently require a huge change of dementia care in all countries, a group of prominent AD clinical experts in Italy met to discuss patients' selection and management strategies. The current diagnostic-therapeutic standard of care in Italy was taken as the starting point. The prescription of new therapies cannot ignore the definition of a biological diagnosis through the assessment of both amyloid- and tau-related biomarkers. The high risk/benefit ratio of anti-Aβ immunotherapies, moreover, needs a highly specialized diagnostic work-up and a thorough exclusion criteria assessment, which should be provided by a neurology specialist. The Expert Panel also suggests a reorganization of the Centers for dementia and cognitive decline in Italy into 3 levels of increasing complexity: community center, first- and second-level center. Tasks and requirements for each level were defined. Finally, specific characteristics of a center deputed to prescribe anti-Aβ mAbs were discussed.

JAD: A Forum for Philosophy in Science

The Journal of Alzheimer's Disease (JAD) is already an established forum for cutting-edge science as well as ethical reflection. But I argue that beyond science and ethics, JAD is also a forum for philosophy in science, and that interdisciplinary researchers asking innovative questions about AD should publish their reflections and findings in JAD.