A Comparison Between Early Presentation of Dementia with Lewy Bodies, Alzheimer's Disease, and Parkinson's Disease: Evidence from Routine Primary Care and UK Biobank Data.

OBJECTIVE: The purpose of this study was to simultaneously contrast prediagnostic clinical characteristics of individuals with a final diagnosis of dementia with Lewy Bodies (DLB), Parkinson's disease (PD), and Alzheimer's disease (AD) compared with controls without neurodegenerative disorders. METHODS: Using the longitudinal THIN database in the United Kingdom, we tested the association of each neurodegenerative disorder with a selected list of symptoms and broad families of treatments, and compared the associations between disorders to detect disease-specific effects. We replicated the main findings in the UK Biobank. RESULTS: We used data of 28,222 patients with PD, 20,214 with AD, 4,682 with DLB, and 20,214 healthy controls. All neurodegenerative disorders were significantly associated with the presence of multiple clinical characteristics before their diagnosis, including sleep disorders, falls, psychiatric symptoms, and autonomic dysfunctions. When comparing patients with DLB with patients with PD and patients with AD patients, falls, psychiatric symptoms, and autonomic dysfunction were all more strongly associated with DLB in the 5 years preceding the first neurodegenerative diagnosis. The use of statins was lower in patients who developed PD and higher in patients who developed DLB compared to patients with AD. In patients with PD, the use of statins was associated with the development of dementia in the 5 years following PD diagnosis. INTERPRETATION: Prediagnostic presentations of falls, psychiatric symptoms, and autonomic dysfunctions were more strongly associated with DLB than PD and AD. This study also suggests that although several associations with medications are similar in neurodegenerative disorders, statin usage is negatively associated with PD but positively with DLB and AD as well as development of dementia in PD. ANN NEUROL 2023;94:259-270.

Amyloid-ß peptide signature associated with cerebral amyloid angiopathy in familial Alzheimer's disease with APPdup and Down syndrome.

Alzheimer's disease (AD) is characterized by extracellular amyloid plaques containing amyloid-ß (Aß) peptides, intraneuronal neurofibrillary tangles, extracellular neuropil threads, and dystrophic neurites surrounding plaques composed of hyperphosphorylated tau protein (pTau). Aß can also deposit in blood vessel walls leading to cerebral amyloid angiopathy (CAA). While amyloid plaques in AD brains are constant, CAA varies among cases. The study focuses on differences observed between rare and poorly studied patient groups with APP duplications (APPdup) and Down syndrome (DS) reported to have higher frequencies of elevated CAA levels in comparison to sporadic AD (sAD), most of APP mutations, and controls. We compared Aß and tau pathologies in postmortem brain tissues across cases and Aß peptides using mass spectrometry (MS). We further characterized the spatial distribution of Aß peptides with MS-brain imaging. While intraparenchymal Aß deposits were numerous in sAD, DS with AD (DS-AD) and AD with APP mutations, these were less abundant in APPdup. On the contrary, Aß deposits in the blood vessels were abundant in APPdup and DS-AD while only APPdup cases displayed high Aß deposits in capillaries. Investigation of Aß peptide profiles showed a specific increase in Aßx-37, Aßx-38 and Aßx-40 but not Aßx-42 in APPdup cases and to a lower extent in DS-AD cases. Interestingly, N-truncated Aß2-x peptides were particularly increased in APPdup compared to all other groups. This result was confirmed by MS-imaging of leptomeningeal and parenchymal vessels from an APPdup case, suggesting that CAA is associated with accumulation of shorter Aß peptides truncated both at N- and C-termini in blood vessels. Altogether, this study identified striking differences in the localization and composition of Aß deposits between AD cases, particularly APPdup and DS-AD, both carrying three genomic copies of the APP gene. Detection of specific Aß peptides in CSF or plasma of these patients could improve the diagnosis of CAA and their inclusion in anti-amyloid immunotherapy treatments.

Cognitive impairment in children and adults with cerebrotendinous xanthomatosis: A French cohort study.

Cerebrotendinous xanthomatosis is a rare and treatable metabolic disorder related to the accumulation of cholestanol. This disorder is primarily associated with motor and cognitive impairments, although the latter has not been extensively characterized. The objectives of this work were to define the cognitive profile found in cerebrotendinous xanthomatosis patients, investigate the progression of cognitive impairment over time, and search for radio-clinical correlations. Through a multicentric chart review study, we collected cognitive and radiological data from nine children and eighteen adults with genetically proven cerebrotendinous xanthomatosis. We performed a volumetric and morphological analysis of the brain magnetic resonance imaging. In our cohort, 44% (4/9) of children and 78% (14/18) of adults exhibited cognitive impairment that can be severe. The study revealed a significant impairment in various cognitive domains, specifically executive, attentional, language, and visuo-spatial. Among adults, 16% (3/18) developed dementia after age 50. These three patients had delayed chenodeoxycholic acid treatment and important cerebral atrophy. Besides these three cases of late-onset cognitive decline, Mini-Mental State Evaluation was generally stable, suggesting cognitive impairment due to a neurodevelopmental disorder and persisting in adulthood. Cognitive impairment was less common in children, possibly related to early chenodeoxycholic acid treatment in our cohort. The severity of magnetic resonance imaging abnormalities did not predict cognitive impairment in patients. Overall, in cerebrotendinous xanthomatosis, cognitive impairment can be severe and mainly neurodevelopmental. Early chenodeoxycholic acid treatment might be associated with a reduced risk of cognitive decline.

What is Alzheimer's disease? An analysis of nosological perspectives from the 20th and 21st centuries.

BACKGROUND: Recent US proposals suggest defining Alzheimer's disease (AD) based on ß-amyloidosis alone. This sparked debates that echoed historical ones about the significance of brain lesions and clinical phenotype. METHODS: This review covers debates on AD nosology through three key periods: AD's discovery in German-speaking countries in the early 20th century, its redefinition in Anglo-Saxon countries in the 1960s-1980s, and current debates on the biological or clinicobiological definitions of AD. Key players' opinions are focused on. RESULTS: At the beginning of the 20th century, AD was defined as a clinicopathological entity. Debates arose around the pathological anchor, which included extended neurofibrillary tangles versus neuritic plaques (Alzheimer vs. Fischer) and its association with senile dementia (Kraepelin). In the 1960s-1980s, the debate shifted towards whether AD could be diagnosed using qualitative or quantitative neuropathological features and whether it was a unique process (Terry and Katzman) or had subtypes (Roth). The current definition proposed by the US Alzheimer's Association is based purely on biological ß-amyloid abnormalities and represents a double break: from the historical clinicopathological definition of AD and from the historical emphasis on tau or combined tau and ß-amyloid high levels of pathology. Conversely, the clinicobiological proposal of the International Working Group remains aligned with historical concepts of AD. CONCLUSIONS: This historical perspective illustrates the unresolved questions surrounding AD pathogenesis, role of lesions, and the clinical phenotype, especially for sporadic cases. The intense nosological debates throughout the history of AD also illustrate the diversity of theoretical frameworks for defining disease in medicine.

Scenarios for the long-term efficacy of amyloid-targeting therapies in the context of the natural history of Alzheimer's disease.

INTRODUCTION: Recent clinical trials of amyloid beta (Aß)-targeting therapies in Alzheimer's disease (AD) have demonstrated a clinical benefit over 18 months, but their long-term impact on disease trajectory is not yet understood. We propose a framework for evaluating realistic long-term scenarios. METHODS: Results from recent phase 3 trials of Aß-targeting antibodies were integrated with an estimate of the long-term patient-level natural history trajectory of the Clinical Dementia Rating-Sum of Boxes (CDR-SB) score to explore realistic long-term efficacy scenarios. RESULTS: Three distinct long-term efficacy scenarios were examined, ranging from conservative to optimistic. These extrapolations of positive phase 3 trials suggested treatments delayed onset of severe dementia by 0.3 to 0.6 years (conservative), 1.1 to 1.9 years (intermediate), and 2.0 to 4.2 years (optimistic). DISCUSSION: Our study provides a common language for long-term impact of disease-modifying treatments. Our work calls for studies with longer follow-up and results from early intervention trials to provide a comprehensive assessment of these therapies' true long-term impact. HIGHLIGHTS: We present long-term scenarios of the efficacy of AD therapies. In this framework, scenarios are defined relative to the natural history of AD. Long-term projections with different levels of optimism can be compared. It provides a common language for expressing beliefs about long-term efficacy.

The spatiotemporal changes in dopamine, neuromelanin and iron characterizing Parkinson's disease.

In Parkinson's disease, there is a progressive reduction in striatal dopaminergic function, and loss of neuromelanin-containing dopaminergic neurons and increased iron deposition in the substantia nigra. We tested the hypothesis of a relationship between impairment of the dopaminergic system and changes in the iron metabolism. Based on imaging data of patients with prodromal and early clinical Parkinson's disease, we assessed the spatiotemporal ordering of such changes and relationships in the sensorimotor, associative and limbic territories of the nigrostriatal system. Patients with Parkinson's disease (disease duration < 4 years) or idiopathic REM sleep behaviour disorder (a prodromal form of Parkinson's disease) and healthy controls underwent longitudinal examination (baseline and 2-year follow-up). Neuromelanin and iron sensitive MRI and dopamine transporter single-photon emission tomography were performed to assess nigrostriatal levels of neuromelanin, iron, and dopamine. For all three functional territories of the nigrostriatal system, in the clinically most and least affected hemispheres separately, the following was performed: cross-sectional and longitudinal intergroup difference analysis of striatal dopamine and iron, and nigral neuromelanin and iron; in Parkinson's disease patients, exponential fitting analysis to assess the duration of the prodromal phase and the temporal ordering of changes in dopamine, neuromelanin or iron relative to controls; and voxel-wise correlation analysis to investigate concomitant spatial changes in dopamine-iron, dopamine-neuromelanin and neuromelanin-iron in the substantia nigra pars compacta. The temporal ordering of dopaminergic changes followed the known spatial pattern of progression involving first the sensorimotor, then the associative and limbic striatal and nigral regions. Striatal dopaminergic denervation occurred first followed by abnormal iron metabolism and finally neuromelanin changes in the substantia nigra pars compacta, which followed the same spatial and temporal gradient observed in the striatum but shifted in time. In conclusion, dopaminergic striatal dysfunction and cell loss in the substantia nigra pars compacta are interrelated with increased nigral iron content.

Dopamine denervation in the functional territories of the striatum: a new MR and atlas-based 123I-FP-CIT SPECT quantification method.

Current quantification methods of 123I-FP-CIT SPECT rely on anatomical parcellation of the striatum. We propose here to implement a new method based on MRI segmentation and functional atlas of the basal ganglia (MR-ATLAS) that could provide a reliable quantification within the sensorimotor, associative, and limbic territories of the striatum. Patients with Parkinson's disease (PD), idiopathic rapid eye movement sleep behavioral disorder (iRBD), and healthy controls underwent 123I-FP-CIT SPECT, MRI, motor, and cognitive assessments. SPECT data were corrected for partial volume effects and registered to a functional atlas of the striatum to allow quantification in every functional region of the striatum (nucleus accumbens, limbic, associative, and sensorimotor parts of the striatum). The MR-ATLAS quantification method is proved to be reliable in every territory of the striatum. In addition, good correlations were found between cognitive dysexecutive tests and the binding within the functional (limbic) territories of the striatum using the MR-ATLAS method, slightly better than correlations found using the anatomical quantification method. This new MR-ATLAS method provides a robust and useful tool for studying the dopaminergic system in PD, particularly with respect to cognitive functions. It may also be relevant to further unravel the relationship between dopaminergic denervation and cognitive or behavioral symptoms.

Alzheimer's Disease Including Focal Presentations.

Alzheimer's disease (AD) is the commonest neurodegenerative disease and the most frequent cause of dementia. It affects 30 million people worldwide. Current research criteria focus on biomarkers' status for amyloid and tau using positron emission tomography and cerebrospinal fluid analysis, independent of clinical status. Current epidemiological data, which mostly rely on biomarker-undetermined AD cases, have highlighted ApoE4 and age as the main risk factors. Rare autosomal dominant mutations also account for a small fraction of early-onset AD. The main clinical phenotype at presentation is the amnestic phenotype targeting episodic memory. This is followed by rarer phenotypes such as posterior cortical atrophy, logopenic variant of primary progressive aphasia, frontal variant AD, corticobasal syndrome, and other even rarer presentations mimicking language variants of frontotemporal dementia. Main differential diagnoses include hippocampal sclerosis with TDP-43, primary age-related tauopathy, argyrophilic grain disease, frontotemporal lobar degeneration, Lewy body disease, chronic traumatic encephalopathy as well as nondegenerative disorders such as cerebrovascular disease, chronic alcohol consumption, limbic encephalitis, medial temporal lobe epilepsy, and others. Co-occurrence of AD pathology with other neurodegenerative and vascular diseases is common and increases with age. This presents a challenge in current clinical practice due to a lack of reliable biomarkers for non-AD neurodegenerative diseases.

Social huddling and physiological thermoregulation are related to melanism in the nocturnal barn owl.

Endothermic animals vary in their physiological ability to maintain a constant body temperature. Since melanin-based coloration is related to thermoregulation and energy homeostasis, we predict that dark and pale melanic individuals adopt different behaviours to regulate their body temperature. Young animals are particularly sensitive to a decrease in ambient temperature because their physiological system is not yet mature and growth may be traded-off against thermoregulation. To reduce energy loss, offspring huddle during periods of cold weather. We investigated in nestling barn owls (Tyto alba) whether body temperature, oxygen consumption and huddling were associated with melanin-based coloration. Isolated owlets displaying more black feather spots had a lower body temperature and consumed more oxygen than those with fewer black spots. This suggests that highly melanic individuals display a different thermoregulation strategy. This interpretation is also supported by the finding that, at relatively low ambient temperature, owlets displaying more black spots huddled more rapidly and more often than those displaying fewer spots. Assuming that spot number is associated with the ability to thermoregulate not only in Swiss barn owls but also in other Tytonidae, our results could explain geographic variation in the degree of melanism. Indeed, in the northern hemisphere, barn owls and allies are less spotted polewards than close to the equator, and in the northern American continent, barn owls are also less spotted in colder regions. If melanic spots themselves helped thermoregulation, we would have expected the opposite results. We therefore suggest that some melanogenic genes pleiotropically regulate thermoregulatory processes.

Evaluation of SP3 for antibody-free quantification of tau in CSF mimic and brain by mass spectrometry.

Tubulin-associated unit (tau) has an important role in the pathogenesis and the diagnosis of Alzheimer's disease (AD) and other tauopathies. In view of the diversity of tau proteoforms, antibody-free methods represent a good approach for unbiased quantification. We adapted and evaluated the single-pot, solid-phase-enhanced sample-preparation (SP3) protocol for antibody-free extraction of the tau protein in cerebro-spinal fluid (CSF) mimic and in human brain. A total of 13 non-modified peptides were quantified by high-resolution mass spectrometry (HRMS) after digestion of tau by trypsin. We significantly improved the basic SP3 protocol by carefully optimizing the organic solvents and incubation time for tau binding, as well as the digestion step for the release directly from the SP3 beads of the 13 tau peptides. These optimizations proved to be primarily beneficial for the most hydrophilic tau peptides, increasing the sequence coverage of recombinant tau. Mean recovery in CSF mimic of the 13 non-modified peptides was of 53%, with LODs ranging from 0.75 to 10 ng/mL. Next, we tested the optimized SP3 protocol on pathological tau extracted from the soluble fraction from an AD brain sample (middle frontal gyrus). We could successfully identify and quantify biologically relevant tau peptides including representative peptides of two isoforms and two phospho-peptides (pTau217 and pTau181).

Prognostic and Predictive Factors in Early Alzheimer's Disease: A Systematic Review.

Background: Alzheimer's disease (AD) causes progressive decline of cognition and function. There is a lack of systematic literature reviews on prognostic and predictive factors in its early clinical stages (eAD), i.e., mild cognitive impairment due to AD and mild AD dementia. Objective: To identify prognostic factors affecting eAD progression and predictive factors for treatment efficacy and safety of approved and/or under late-stage development disease-modifying treatments. Methods: Databases were searched (August 2022) for studies reporting prognostic factors associated with eAD progression and predictive factors for treatment response. The Quality in Prognostic Factor Studies tool or the Cochrane risk of bias tool were used to assess risk of bias. Two reviewers independently screened the records. A single reviewer performed data extraction and quality assessment. A second performed a 20% check. Content experts reviewed and interpreted the data collected. Results: Sixty-one studies were included. Self-reporting, diagnosis definition, and missing data led to high risk of bias. Population size ranged from 110 to 11,451. Analyses found data indicating that older age was and depression may be associated with progression. Greater baseline cognitive impairment was associated with progression. APOE4 may be a prognostic factor, a predictive factor for treatment efficacy and predicts an adverse response (ARIA). Elevated biomarkers (CSF/plasma p-tau, CSF t-tau, and plasma neurofilament light) were associated with disease progression. Conclusions: Age was the strongest risk factor for progression. Biomarkers were associated with progression, supporting their use in trial selection and aiding diagnosis. Baseline cognitive impairment was a prognostic factor. APOE4 predicted ARIA, aligning with emerging evidence and relevant to treatment initiation/monitoring.

Alzheimer Disease as a Clinical-Biological Construct-An International Working Group Recommendation.

Importance: Since 2018, a movement has emerged to define Alzheimer disease (AD) as a purely biological entity based on biomarker findings. The recent revision of the Alzheimer Association (AA) criteria for AD furthers this direction. However, concerns about a purely biological definition of AD being applied clinically, the understanding of AD by society at large, and the translation of blood-based biomarkers into clinical practice prompt these International Working Group (IWG) updated recommendations. Objective: To consider the revised AA criteria and to offer an alternative definitional view of AD as a clinical-biological construct for clinical use. The recommendations of the 2021 IWG diagnostic criteria are updated for further elaborating at-risk and presymptomatic states. Evidence Review: PubMed was searched for articles published between July 1, 2020, and March 1, 2024, using the terms "biomarker" OR "amyloid" OR "tau" OR "neurodegeneration" OR "preclinical" OR "CSF" OR "PET" OR "plasma" AND "Alzheimer's disease." The references of relevant articles were also searched. Findings: In the new AA diagnostic criteria, AD can be defined clinically as encompassing cognitively normal people having a core 1 AD biomarker. However, recent literature shows that the majority of biomarker-positive cognitively normal individuals will not become symptomatic along a proximate timeline. In the clinical setting, disclosing a diagnosis of AD to cognitively normal people with only core 1 AD biomarkers represents the most problematic implication of a purely biological definition of the disease. Conclusions and Relevance: The ultimate aim of the field was to foster effective AD treatments, including preventing symptoms and dementia. The approach of diagnosing AD without a clinical and biological construct would be unwarranted and potentially concerning without a clear knowledge of when or whether symptoms will ever develop. It is recommended that those who are amyloid-positive only and, more generally, most biomarker-positive cognitively normal individuals, should not be labeled as having AD. Rather, they should be considered as being at risk for AD. The expansion of presymptomatic AD is viewed as a better diagnostic construct for those with a specific pattern of biomarkers, indicating that they are proximate to the expression of symptoms in the near future.

Regional dynamics of amyloid-ß deposition in healthy elderly, mild cognitive impairment and Alzheimer's disease: a voxelwise PiB-PET longitudinal study.

Amyloid-ß deposition in Alzheimer's disease is thought to start while individuals are still cognitively unimpaired and it is hypothesized that after an early phase of fast accumulation, a plateau is reached by the time of cognitive decline. However, few longitudinal Pittsburgh compound B-positron emission tomography studies have tested this hypothesis, and with conflicting results. The purpose of this work is to further our understanding of the dynamics of amyloid-ß deposition in a large longitudinal cohort. A total of 32 patients with Alzheimer's disease, 49 subjects with mild cognitive impairment and 103 healthy controls underwent two Pittsburgh compound B-positron emission tomography scans 18 months apart. For each participant, a parametric map of Pittsburgh compound B-positron emission tomography rate of change was created [(follow-up scan - baseline scan)/follow-up duration] and entered in a voxelwise three-way analysis of covariance, with clinical status (healthy controls, mild cognitive impairment or Alzheimer's disease), disease progression (clinical conversion from healthy controls to mild cognitive impairment or Alzheimer's disease, or from mild cognitive impairment to Alzheimer's disease) and Pittsburgh compound B status (positive versus negative) as independent factors. Only a significant effect of the Pittsburgh compound B status was found: both Pittsburgh compound B-positive and -negative subjects showed a significant increase in amyloid-ß deposition, with this increase being significantly higher in Pittsburgh compound B-positive individuals. This finding suggests either that Pittsburgh compound B-negative individuals have slower rates of amyloid-ß accumulation than positive, or that the proportion of individuals showing significant increase in amyloid-ß deposition, termed 'Pittsburgh compound B accumulators', is higher within the Pittsburgh compound B-positive group than within the Pittsburgh compound B-negative group. The bimodal distribution of the individual rates of neocortical amyloid-ß accumulation observed support the existence of 'Pittsburgh compound B non-accumulators' and 'Pittsburgh compound B accumulators' and different clustering analyses led to a consistent threshold to separate these two subgroups (0.014-0.022 standardized uptake value ratio(pons)/year). The voxelwise three-way analysis of covariance was thus recomputed with the 'Pittsburgh compound B accumulators' only and the results were almost unchanged, with the Pittsburgh compound B-positive group showing higher accumulation than the Pittsburgh compound B-negative group. Finally, a significant negative correlation was found between Pittsburgh compound B rate of change and Pittsburgh compound B baseline burden, but only in the Pittsburgh compound B-positive group (r= -0.24; P=0.025). Higher rates of amyloid-ß deposition are associated with higher amyloid-ß burden suggesting that amyloid-ß deposition does not reach a plateau when cognitive impairments manifest but is instead an ongoing process present even at the Alzheimer's disease stage. amyloid-ß accumulation also seems to slow down at the latest stages of the process, i.e. in participants with the highest amyloid burden. Furthermore, this study identified the existence of Pittsburgh compound 'accumulators' and 'non-accumulators', notably within the Pittsburgh compound B-negative group, which may be a relevant concept for future studies.

[How to deal with memory complaints]. / Conduite à tenir devant une plainte mnésique.

HOW TO DEAL WITH MEMORY COMPLAINTS. Memory complaint is a common condition in the general population and can indicate normal brain aging as well as incurable neurodegenerative disease or curable disorders. Therefore, the role of any primary care physician is crucial for the referral to further investigations. Furthermore, the pitfall of underdiagnosis, often related to the current incurability of the suspected cause, is contrary to all current guidelines. When facing a memory complaint, the primary care consultation has four objectives: to identify the possible red flags amongst the memory complaint and the memory complaint severity, to objectify a neurocognitive disorder associated with the memory complaint using cognitive tests, to search for associated signs, and to screen for obvious, frequent, and curable causes of memory complaint. The article is intended to be a practical tool aligned with the 2018 French multidisciplinary recommendations regarding the graded and personalized strategy for diagnosing neurocognitive disorders. It details the possibly worrisome elements to be collected in the history, the elements that need special attention or assessment, and finally, the course of action to be taken after a primary care consultation.

CONDUITE À TENIR DEVANT UNE PLAINTE MNÉSIQUE. La plainte mnésique est une affection répandue en population générale qui peut relever aussi bien d'un vieillissement cérébral normal que d'une maladie neurodégénérative incurable ou d'une affection curable. Aussi, le rôle du médecin généraliste est-il capital pour l'orientation vers d'éventuelles explorations complémentaires. L'écueil du sous-diagnostic, notamment en raison de l'incurabilité fréquente de la cause suspectée, est contraire à toutes les recommandations actuelles. Face à une plainte mnésique, la consultation de soins primaires a quatre objectifs : reconnaître les signes de gravité (drapeaux rouges) et sa sévérité, objectiver un trouble cognitif associé à l'aide de tests cognitifs, rechercher des signes associés, et dépister des causes évidentes, fréquentes et curables. Cet article se veut un outil pratique, conforme aux recommandations de 2018 concernant la stratégie graduée et personnalisée de diag nostic des troubles neurocognitifs. Il détaille les éléments inquiétants à rechercher à l'anamnèse, les éléments qui doivent faire l'objet d'une attention ou d'une évaluation particulière et enfin la conduite à tenir à l'issue d'une consultation de soins primaires.

Key questions for the evaluation of anti-amyloid immunotherapies for Alzheimer's disease.

The clinical benefit associated with anti-amyloid immunotherapies, a new class of drugs for the treatment of Alzheimer's disease, is predicated on their ability to modify disease course by lowering brain amyloid levels. At the time of writing, two amyloid-lowering antibodies, aducanumab and lecanemab, have obtained United States Food and Drug Administration accelerated approval, with further agents of this class in the Alzheimer's disease treatment pipeline. Based on limited published clinical trial data to date, regulators, payors and physicians will need to assess their efficacy, clinical effectiveness and safety, as well as cost and accessibility. We propose that attention to three important questions related to treatment efficacy, clinical effectiveness and safety should guide evidence-based consideration of this important class of drugs. These are: (1) Were trial statistical analyses appropriate and did they convincingly support claims of efficacy? (2) Do reported treatment effects outweigh safety concerns and are they generalizable to a representative clinical population of people with Alzheimer's disease? and (3) Do the data convincingly demonstrate disease course modification, suggesting that increasing clinical benefits beyond the duration of the trials are likely? We suggest specific approaches to interpreting trial results for these drugs and highlight important areas of uncertainty where additional data and a cautious interpretation of existing results is warranted. Safe, effective and accessible treatments for Alzheimer's disease are eagerly awaited by millions of patients and their caregivers worldwide. While amyloid-targeting immunotherapies may be promising disease-modifying Alzheimer's disease treatments, rigorous and unbiased assessment of clinical trial data is critical to regulatory decision-making and subsequently determining their provision and utility in routine clinical practice. Our recommendations provide a framework for evidence-based appraisal of these drugs by regulators, payors, physicians and patients.

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.

Can a failure in the error-monitoring system explain unawareness of memory deficits in Alzheimer's disease?

Unawareness of memory deficits is an early manifestation in patients with Alzheimer's disease (AD), which often delays diagnosis. This intriguing behavior constitutes a form of anosognosia, whose neural mechanisms remain largely unknown. We hypothesized that anosognosia may depend on a critical synaptic failure in the error-monitoring system, which would prevent AD patients from being aware of their own memory impairment. To investigate, we measured event-related potentials (ERPs) evoked by erroneous responses during a word memory recognition task in two groups of amyloid positive individuals with only subjective memory complaints at study entry: those who progressed to AD within the five-year study period (PROG group), and those who remained cognitively normal (CTRL group). A significant reduction in the amplitude of the positivity error (Pe), an ERP related to error awareness, was observed in the PROG group at the time of AD diagnosis (vs study entry) in intra-group analysis, as well as when compared with the CTRL group in inter-group analysis, based on the last EEG acquisition for all subjects. Importantly, at the time of AD diagnosis, the PROG group exhibited clinical signs of anosognosia, overestimating their cognitive abilities, as evidenced by the discrepancy scores obtained from caregiver/informant vs participant reports on the cognitive subscale of the Healthy Aging Brain Care Monitor. To our knowledge, this is the first study to reveal the emergence of a failure in the error-monitoring system during a word memory recognition task at the early stages of AD. This finding, along with the decline of awareness for cognitive impairment observed in the PROG group, strongly suggests that a synaptic dysfunction in the error-monitoring system may be the critical neural mechanism at the origin of unawareness of deficits in AD.

Dementia prevention in memory clinics: recommendations from the European task force for brain health services.

Observational population studies indicate that prevention of dementia and cognitive decline is being accomplished, possibly as an unintended result of better vascular prevention and healthier lifestyles. Population aging in the coming decades requires deliberate efforts to further decrease its prevalence and societal burden. Increasing evidence supports the efficacy of preventive interventions on persons with intact cognition and high dementia risk. We report recommendations for the deployment of second-generation memory clinics (Brain Health Services) whose mission is evidence-based and ethical dementia prevention in at-risk individuals. The cornerstone interventions consist of (i) assessment of genetic and potentially modifiable risk factors including brain pathology, and risk stratification, (ii) risk communication with ad-hoc protocols, (iii) risk reduction with multi-domain interventions, and (iv) cognitive enhancement with cognitive and physical training. A roadmap is proposed for concept validation and ensuing clinical deployment.

Therapeutic news in Alzheimer's disease: soon a disease-modifying therapy? / Actualités thérapeutiques dans la maladie d'Alzheimer : bientôt un traitement de fond ?

Research on disease-modifying treatments for Alzheimer's disease has resulted in a series of failures over the past 20 years. However, in the last 4 years, five molecules have shown significant effects in phase II or III trials on clinical endpoints (i.e., slowing of cognitive decline). Among these five molecules, three are anti-amyloid immunotherapies: aducanumab, donanemab, and lecanemab responsible for a significant clearance of cerebral amyloid deposits. These results are still awaiting confirmation in order to put an end to the controversy surrounding the Food and Drug Administration's decision to give conditional approval to aducanumab, which is considered premature by many specialists. Confirmation is also necessary to assess the benefit (magnitude of the slowing of decline) and risk (edema and cerebral hemorrhage induced by these treatments) balance of these molecules, which appears to be so far questionable after 18 months. Masitinib, a treatment whose probable mechanism of action is neuroinflammation, has also shown positive effects that need to be confirmed. Treatments targeting the tau protein are less advanced but weak signals are emerging from immunotherapies in the moderate stages of the disease (semorinemab). There is renewed hope for patients since it may not be unreasonable that these disease-modifying therapies will be part of the French therapeutic arsenal within the next five years.

La recherche de traitements de fond (disease modifiers) de la maladie d'Alzheimer s'est soldée depuis 20 ans par une série d'échecs. Ces quatre dernières années, cinq molécules ont néanmoins présenté, lors d'essais de phase II ou III, des effets significatifs sur des critères cliniques (c'est-à-dire sur le ralentissement du déclin cognitif). Parmi ces cinq molécules, trois sont des immunothérapies anti-amyloïdes (l'aducanumab, le donanemab et le lecanemab) entraînant une clairance majeure des dépôts amyloïdes cérébraux. Néanmoins, ces résultats attendent encore confirmation afin de mettre fin à la controverse quant à la décision de la Food and Drug Administration de donner d'ores et déjà une autorisation conditionnelle à l'aducanumab, jugée prématurée par de nombreux spécialistes, et de pouvoir juger de la balance bénéfice (amplitude du ralentissement du déclin cognitif)-risque (œdèmes et hémorragies cérébrales induites par ces traitements) de ces molécules qui semble pour le moment discutable. Le masitinib, un traitement dont le mécanisme d'action probable est celui de la neuroinflammation, a aussi montré des effets positifs à confirmer. Quant aux traitements ciblant la protéine tau, leur développement est moins avancé mais des signaux faibles émergent d'immunothérapies aux stades modérés de la maladie (semorinemab). L'espoir renaît donc pour les patients avec la possibilité non déraisonnable de voir apparaître des traitements de fond de maladie d'Alzheimer au sein de l'arsenal thérapeutique français dans les 5 années à venir.