European intersocietal recommendations for the biomarker-based diagnosis of neurocognitive disorders

Correlation of early-phase β-amyloid positron-emission-tomography and neuropsychological testing in patients with Alzheimer's disease

PURPOSE

Clinical staging in individuals with Alzheimer's disease (AD) typically relies on neuropsychological testing. Recognizing the imperative for an objective measure of clinical AD staging, regional perfusion in early-phase β-amyloid-PET may aid as a cost-efficient index for the assessment of neurodegeneration severity in patients with Alzheimer's disease.

METHODS

Regional perfusion deficits in early-phase β-amyloid-PET as well as neuropsychological testing (max. 90 days delay) were evaluated in 82 patients with biologically defined AD according to the ATN classification. In reference to the Braak staging system patients were classified into the groups stage0, stageI-II+, stageI-IV+, stageI-VI+, and stageatypical+ according to regional perfusion deficits in regions of interest (ROIs) published by the Alzheimer's Disease Neuroimaging Initiative. Multiple regression analysis controlling for age, gender, and education was used to evaluate the association of regional z-scores on perfusion-phase PET with clinical scores for all patients and with annual decline of cognitive performance in 23 patients with follow-up data.

RESULTS

Patients classified as stage0 and stageI-II+ demonstrated significantly superior neuropsychological performance compared to those classified as stageI-IV+ and stageI-VI+. Lower cognitive performance was associated with decreased perfusion in early-phase β-amyloid-PET globally and regionally, with the most pronounced association identified in the left temporal lobe. Mean z-scores on early-phase PET in temporal and parietal regions offered a robust prediction of future annual decline in MMSE and sum scores of the CERAD-Plus (Consortium to Establish a Registry for Alzheimer's Disease) test battery.

CONCLUSION

Regional and global perfusion deficits in early-phase β-amyloid-PET can serve as an objective index of neurodegeneration severity and may act as prognostic markers of future cognitive decline in AD.

Development of a diagnostic checklist to identify functional cognitive disorder versus other neurocognitive disorders

Background

Functional cognitive disorder (FCD) poses a diagnostic challenge due to its resemblance to other neurocognitive disorders and limited biomarker accuracy. We aimed to develop a new diagnostic checklist to identify FCD versus other neurocognitive disorders.

Methods

The clinical checklist was developed through mixed methods: (1) a literature review, (2) a three-round Delphi study with 45 clinicians from 12 countries and (3) a pilot discriminative accuracy study in consecutive patients attending seven memory services across the UK. Items gathering consensus were incorporated into a pilot checklist. Item redundancy was evaluated with phi coefficients. A briefer checklist was produced by removing items with >10% missing data. Internal validity was tested using Cronbach's alpha. Optimal cut-off scores were determined using receiver operating characteristic curve analysis.

Results

A full 11-item checklist and a 7-item briefer checklist were produced. Overall, 239 patients (143 FCD, 96 non-FCD diagnoses) were included. The checklist scores were significantly different across subgroups (FCD and other neurocognitive disorders) (F(2, 236)=313.3, p<0.001). The area under the curve was excellent for both the full checklist (0.97, 95% CI 0.95 to 0.99) and its brief version (0.96, 95% CI 0.93 to 0.98). Optimal cut-off scores corresponded to a specificity of 97% and positive predictive value of 91% for identifying FCD. Both versions showed good internal validity (>0.80).

Conclusions

This pilot study shows that a brief clinical checklist may serve as a quick complementary tool to differentiate patients with neurodegeneration from those with FCD. Prospective blind large-scale validation in diverse populations is warranted.Cite Now.

Event-related potential markers of subjective cognitive decline and mild cognitive impairment during a sustained visuo-attentive task

Subjective cognitive decline (SCD), mild cognitive impairment (MCI), and Alzheimer's disease stages lack well-defined electrophysiological correlates, creating a critical gap in the identification of robust biomarkers for early diagnosis and intervention. In this study, we analysed event-related potentials (ERPs) recorded during a sustained visual attention task in a cohort of 178 individuals (119 SCD, 40 MCI, and 19 healthy subjects, HS) to investigate sensory and cognitive processing alterations associated with these conditions. SCD patients exhibited significant attenuation in both sensory (P1, N1, P2) and cognitive (P300, P600, P900) components compared to HS, with cognitive components showing performance-related gains. In contrast, MCI patients did not show a further decrease in any ERP component compared to SCD. Instead, they exhibited compensatory enhancements, reversing the downward trend observed in SCD. This compensation resulted in a non-monotonic pattern of ERP alterations across clinical conditions, suggesting that MCI patients engage neural mechanisms to counterbalance sensory and cognitive deficits. These findings support the use of electrophysiological markers in support of medical decision-making, enhancing personalized prognosis and guiding targeted interventions in cognitive decline.

Alpha rhythm and Alzheimer's disease: Has Hans Berger's dream come true?

In this "centenary" paper, an expert panel revisited Hans Berger's groundbreaking discovery of human restingstate electroencephalographic (rsEEG) alpha rhythms (8-12 Hz) in 1924, his foresight of substantial clinical applications in patients with "senile dementia," and new developments in the field, focusing on Alzheimer's disease (AD), the most prevalent cause of dementia in pathological aging. Clinical guidelines issued in 2024 by the US National Institute on Aging-Alzheimer's Association (NIA-AA) and the European Neuroscience Societies did not endorse routine use of rsEEG biomarkers in the clinical workup of older adults with cognitive impairment. Nevertheless, the expert panel highlighted decades of research from independent workgroups and different techniques showing consistent evidence that abnormalities in rsEEG delta, theta, and alpha rhythms (< 30 Hz) observed in AD patients correlate with wellestablished AD biomarkers of neuropathology, neurodegeneration, and cognitive decline. We posit that these abnormalities may reflect alterations in oscillatory synchronization within subcortical and cortical circuits, inducing cortical inhibitory-excitatory imbalance (in some cases leading to epileptiform activity) and vigilance dysfunctions (e.g., mental fatigue and drowsiness), which may impact AD patients' quality of life. Berger's vision of using EEG to understand and manage dementia in pathological aging is still actual.

Clinical and metabolic profiles in behavioural frontotemporal dementia: Impact of age at onset

AIM

Frontotemporal dementia (FTD) is a heterogeneous neurodegenerative disorder, with considerable variability of age-at-onset. We explored clinical and metabolic differences between early- and late-onset behavioural FTD (bvFTD), assuming that they might represent different disease phenotypes.

MATERIALS AND METHODS

We retrospectively studied consecutive patients diagnosed with prodromal or overt bvFTD with [18F]FDG PET scan, neuropsychological assessment (NPS), and Neuropsychiatric Inventory (NPI) available at baseline. Patients were divided into three groups based on age-at-onset: early onset-bvFTD (EO-bvFTD, age<70), late onset-bvFTD (LO-bvFTD, age 70-75) and very late onset-bvFTD (vLO-bvFTD, age>75). NPS and NPI were compared between groups and in the subset of prodromal patients, to study different syndromic phenotypes. Voxel-based analysis compared brain [18F]FDG PET of EO-bvFTD, LO-bvFTD and vLO-bvFTD independently, with respect to healthy controls, to explore metabolic differences. An inter-regional metabolic covariance analysis was performed in frontal lobe subregions, to explore differences in brain connectivity. Moreover, we supported our result using a correlation-based approach on clinical and metabolic variables.

RESULTS

101 bvFTD (62 prodromal bvFTD) were enrolled (EO-bvFTD: n = 36, prodromal n = 21; LO-bvFTD: n = 36, prodromal: n = 22; vLO-bvFTD: n = 29, prodromal: n = 19). Greater verbal memory deficit was evident in LO-bvFTD and vLO-bvFTD compared to EO-bvFTD (immediate recall: p = .018; p = .024; delayed recall: both p = .001, respectively), with similar results in the subset of prodromal patients. EO-bvFTD and LO-bvFTD had a higher behavioural severity than vLO-bvFTD. LO-bvFTD and vLO-bvFTD showed more widespread relative hypometabolism, with a greater involvement of posterior, subcortical and temporo-limbic regions compared with EO-bvFTD. Moreover, vLO-bvFTD showed a different pattern of intrafrontal metabolic covariance compared to EO-bvFTD and LO-bvFTD.

DISCUSSION

The cognitive-behavioural profile of bvFTD differs between early- and late-onset, already from the prodromal stage of the disease. Both metabolic pattern and functional connectivity vary based on age-at-onset. Understanding these differences could contribute to improve diagnostic accuracy and understanding the underling pathological heterogeneity.

A new paradigm for neurodegenerative diseases classification: A clinical perspective

A vast progress has been made in the understanding of neurodegenerative diseases during the past few years. However, clinical diagnostic accuracy continues to be very low, despite the introduction of various diagnostic tools and repeated revisions of diagnostic criteria. For instance, patients with Alzheimer's disease (AD) may present with symptoms that overlap with other neurodegenerative conditions like dementia with Lewy bodies (DLB), making accurate diagnosis challenging. This diagnostic uncertainty can lead to delayed or incorrect treatment, significantly impacting patients' quality of life and prognosis. Thus, the definite diagnosis still relies on post-mortem pathological findings, placing a significant burden on both clinicians and researchers. As a growing body of evidence indicates, co-pathology seems to be the rule among neurodegenerative diseases. Additionally, a single pathological diagnosis, such as AD, can manifest in various clinical presentations, ranging from predominantly cognitive impairment to significant motor symptoms. Each of these presentations currently requires its own set of complicated diagnostic criteria. Perhaps, the time has come for a much-needed radical revision of existing clinical diagnostic criteria. Inclusion of patients do not neatly fit into existing diagnostic categories for neurodegenerative diseases, in future large-scale, longitudinal studies and/or clinical trials, and systematic assessment of their clinical features and disease progression using machine learning could generate valuable data on patients with mixed pathologies and improve our understanding of how to effectively treat these complex cases.

Introduction to the DETeCD-ADRD special issue

HIGHLIGHT

This special issue contains multiple articles related to the DETeCD-ADRD guideline.

Blood biomarkers for Alzheimer's disease with the Lumipulse automated platform: Age-effect and clinical value interpretation

BACKGROUND

Advances in analytical methods have recently paved the way to Alzheimer's disease (AD) biomarkers testing in blood along with the more established CSF testing. To ensure a forthcoming application of this low-invasive diagnostic that might allow to recognize early onset of dementia, appropriate pathological cut-points need to be defined.

METHODS

In this cross-sectional study we measured blood and CSF neurofilament light chain (NFL), phosphorylated tau (pTau 181), Amyloid-β1-42 (AB 1-42) and Amyloid-β1-40 (AB 1-40) on a fully automated chemiluminescent platform (Lumipulse, Fujirebio) in 80 cognitively impaired patients and 55 cognitively unimpaired subjects. Clinical cut points were calculated with receiver-operator characteristic (ROC) curve analysis and a head-to-head comparison of blood and CSF testing was performed.

RESULTS

Blood NFL best discriminant thresholds to distinguish neurodegenerative diseases from controls varied age-dependently, being 19 and 33 pg/mL in subjects 50-65 years and > 65 years respectively. AD was best framed by AB 1-42/1-40 ratio < 0.079 and ptau181 > 1 pg/mL. Though a strong correlation for all biomarkers, only blood AB ratio was equal to CSF testing for AD diagnosis.

CONCLUSIONS

The specific context of use might be considered to define the cut-offs of blood biomarkers of neurodegenerative diseases. Future efforts towards reference materials for each AD blood biomarker will improve clinical cut-offs.

Cutting through the noise: A narrative review of Alzheimer's disease plasma biomarkers for routine clinical use

As novel, anti-amyloid therapies have become more widely available, access to timely and accurate diagnosis has become integral to ensuring optimal treatment of patients with early-stage Alzheimer's disease (AD). Plasma biomarkers are a promising tool for identifying AD pathology; however, several technical and clinical factors need to be considered prior to their implementation in routine clinical use. Given the rapid pace of advancements in the field and the wide array of available biomarkers and tests, this review aims to summarize these considerations, evaluate available platforms, and discuss the steps needed to bring plasma biomarker testing to the clinic. We focus on plasma phosphorylated(p)-tau, specifically plasma p-tau217, as a robust candidate across both primary and secondary care settings. Despite the high performance and robustness demonstrated in research, plasma p-tau217, like all plasma biomarkers, can be affected by analytical and pre-analytical variability as well as patient comorbidities, sex, ethnicity, and race. This review also discusses the advantages of the two-point cut-off approach to mitigating these factors, and the challenges raised by the resulting intermediate range measurements, where clinical guidance is still unclear. Further validation of plasma p-tau217 in heterogeneous, real-world cohorts will help to increase confidence in testing and support establishing a standardized approach. Plasma biomarkers are poised to become a more affordable and less invasive alternative to PET and CSF testing. However, understanding the factors that impact plasma biomarker measurement and interpretation is critical prior to their implementation in routine clinical use.

The Alzheimer's Association clinical practice guideline for the Diagnostic Evaluation, Testing, Counseling, and Disclosure of Suspected Alzheimer's Disease and Related Disorders (DETeCD-ADRD): Executive summary of recommendations for specialty care

US clinical practice guidelines for the diagnostic evaluation of cognitive impairment due to Alzheimer's disease (AD) or a related dementia (ADRD) are two decades old. This evidence-based guideline was developed to empower all clinicians to implement a structured approach for evaluating a patient with symptoms that may represent clinical AD/ADRD. An expert workgroup conducted a review of 7374 publications (133 met inclusion criteria) and developed recommendations as steps in an evaluation process. This summary briefly reviews core recommendations and details specialist recommendations of a high-quality, evidence-supported evaluation process aimed at characterizing, diagnosing, and disclosing the patient's cognitive functional status, cognitive-behavioral syndrome, and likely underlying brain disease so that optimal care plans to maximize patient/care partner dyad quality of life can be developed; a companion article summarizes primary care recommendations. If clinicians use the recommendations in this guideline and health-care systems provide adequate resources, outcomes should improve in most patients in most practice settings. HIGHLIGHTS: US clinical practice guidelines for the diagnostic evaluation of cognitive impairment due to Alzheimer's disease (AD) or related dementias (ADRD) are decades old and aimed at specialists. This evidence-based guideline was developed to empower all-including primary care-clinicians to implement a structured approach for evaluating a patient with symptoms that may represent clinical AD/ADRD. This summary focuses on recommendations appropriate for specialty practice settings, forming key elements of a high-quality, evidence-supported evaluation process aimed at characterizing, diagnosing, and disclosing the patient's cognitive functional status, cognitive-behavioral syndrome, and likely underlying brain disease so that optimal care plans to maximize patient/care partner dyad quality of life can be developed; a companion article summarizes primary care recommendations. If clinicians use this guideline and health-care systems provide adequate resources, outcomes should improve in most patients in most practice settings.

Perspectives on the diagnosis and management of functional cognitive disorder: An international Delphi study

BACKGROUND

Current proposed criteria for functional cognitive disorder (FCD) have not been externally validated. We sought to analyse the current perspectives of cognitive specialists in the diagnosis and management of FCD in comparison with neurodegenerative conditions.

METHODS

International experts in cognitive disorders were invited to assess seven illustrative clinical vignettes containing history and bedside characteristics alone. Participants assigned a probable diagnosis and selected the appropriate investigation and treatment. Qualitative, quantitative and inter-rater agreement analyses were undertaken.

RESULTS

Eighteen diagnostic terminologies were assigned by 45 cognitive experts from 12 countries with a median of 13 years of experience, across the seven scenarios. Accurate discrimination between FCD and neurodegeneration was observed, independently of background and years of experience: 100% of the neurodegenerative vignettes were correctly classified and 75%-88% of the FCD diagnoses were attributed to non-neurodegenerative causes. There was <50% agreement in the terminology used for FCD, in comparison with 87%-92% agreement for neurodegenerative syndromes. Blood tests and neuropsychological evaluation were the leading diagnostic modalities for FCD. Diagnostic communication, psychotherapy and psychiatry referral were the main suggested management strategies in FCD.

CONCLUSIONS

Our study demonstrates the feasibility of distinguishing between FCD and neurodegeneration based on relevant patient characteristics and history details. These characteristics need further validation and operationalisation. Heterogeneous labelling and framing pose clinical and research challenges reflecting a lack of agreement in the field. Careful consideration of FCD diagnosis is advised, particularly in the presence of comorbidities. This study informs future research on diagnostic tools and evidence-based interventions.

Clinical performance of the fully automated Lumipulse plasma p-tau217 assay in mild cognitive impairment and mild dementia

Introduction

Plasma phosphorylated tau (p-tau)217 is a leading blood-biomarker for the detection of amyloid beta (Aβ) pathology. We assessed the performance of a fully automated plasma p-tau217 immunoassay to detect Aβ pathology in mild cognitive impairment (MCI)/mild dementia.

Methods

Paired plasma and cerebrospinal fluid (CSF) samples were obtained at time of diagnostic lumbar puncture (LP) in a specialist memory service. Plasma p-tau217 was measured using the Lumipulse immunoassay platform and ability to detect CSF-defined Aβ positivity assessed.

Results

Of 148 participants (69.4 ± 6.5 years; 54.1% female), 101 had MCI and 47 mild dementia. Median plasma p-tau217 was > 4-fold higher in Aβ+ vs Aβ- individuals with an area under the curve of 0.92 (0.87-0.97). Application of 90%, 95%, and 97.5% sensitivity/specificity thresholds for plasma p-tau217 may have obviated the need for more than half of LPs.

Discussion

Our real-world data support the clinical use of fully automated plasma p-tau217 immunoassays, although further studies in more diverse cohorts are required.

HIGHLIGHTS

Plasma phosphorylated tau (p-tau)217 was measured using a fully automated immunoassay (Lumipulse).P-tau217 was > 4-fold higher in amyloid beta (Aβ)+ versus Aβ- individuals.Plasma p-tau217 had an area under the curve of 0.92 for detection of Aβ status.Using a previously proposed two-threshold approach may avoid more than half of lumbar punctures.

Alzheimer's Association clinical practice guideline for the Diagnostic Evaluation, Testing, Counseling, and Disclosure of Suspected Alzheimer's Disease and Related Disorders (DETeCD-ADRD): Executive summary of recommendations for primary care

US clinical practice guidelines for the diagnostic evaluation of cognitive impairment due to Alzheimer's disease (AD) or AD and related dementias (ADRD) are decades old and aimed at specialists. This evidence-based guideline was developed to empower all-including primary care-clinicians to implement a structured approach for evaluating a patient with symptoms that may represent clinical AD/ADRD. Through a modified-Delphi approach and guideline-development process (7374 publications were reviewed; 133 met inclusion criteria) an expert workgroup developed recommendations as steps in a patient-centered evaluation process. This summary focuses on recommendations, appropriate for any practice setting, forming core elements of a high-quality, evidence-supported evaluation process aimed at characterizing, diagnosing, and disclosing the patient's cognitive functional status, cognitive-behavioral syndrome, and likely underlying brain disease so that optimal care plans to maximize patient/care partner dyad quality of life can be developed; a companion article summarizes specialist recommendations. If clinicians use this guideline and health-care systems provide adequate resources, outcomes should improve in most patients in most practice settings. Highlights US clinical practice guidelines for the diagnostic evaluation of cognitive impairment due to Alzheimer's disease (AD) or AD and related dementias (ADRD) are decades old and aimed at specialists. This evidence-based guideline was developed to empower all-including primary care-clinicians to implement a structured approach for evaluating a patient with symptoms that may represent clinical AD/ADRD. This summary focuses on recommendations, appropriate for any practice setting, forming core elements of a high-quality, evidence-supported evaluation process aimed at characterizing, diagnosing, and disclosing the patient's cognitive functional status, cognitive-behavioral syndrome, and likely underlying brain disease so that optimal care plans to maximize patient/care partner dyad quality of life can be developed; a companion article summarizes specialist recommendations. If clinicians use this guideline and health-care systems provide adequate resources, outcomes should improve in most patients in most practice settings.

Cerebrospinal Fluid Classical Biomarker Levels in Mixed vs. Pure A+T+ (A+T1+) Alzheimer's Disease

Background: Alzheimer's disease (AD) may present with pure (typical or atypical) and mixed phenotypes, sometimes causing difficulties in (differential) diagnosis. In order to achieve a diagnostic accuracy as high as possible, the diagnosis of AD during life depends on various biomarkers, including the cerebrospinal fluid (CSF) biomarkers. Methods: Classical CSF AD biomarkers were determined in a total of 61 patients, classified as both beta amyloid- and tau-positive A+T+ (or A+T1+ according to the recently revised Alzheimer Association criteria for diagnosis and staging of AD). Twenty one of these patients fulfilled the criteria for mixed AD (mixed with Lewy bodies, cerebrovascular disease, or normal pressure hydrocephalus), whilst 40 had pure AD. Results: Patients did not differ with respect to gender, education, disease duration, and cognitive status. After controlling for confounding factors, no difference was observed between mixed and pure AD groups in Aβ42 or Aβ42/Aβ40 levels. Although by definition, patients of both groups had abnormal (increased) levels of phospho-tau181, the mixed AD group presented with lower (less abnormal) levels of phospho-tau181 and total tau as compared to the pure group. Conclusions: In patients with AD of comparable cognitive status, mixed AD cases may present with lower levels of tau proteins and, if close to the cut-off values, diagnostic uncertainty may be increased.

Physiopathological mechanisms underlying Alzheimer's disease: a narrative review

The neuropathological signature of Alzheimer's disease (AD) comprises mainly amyloid plaques, and neurofibrillary tangles, resulting in synaptic and neuronal loss. These pathological structures stem from amyloid dysfunctional metabolism according to the amyloid cascade hypothesis, leading to the formation of plaques, and apparently inducing the initiation of the abnormal tau pathway, with phosphorylation and aggregation of these proteins, ultimately causing the formation of tangles. In this narrative review, the existing hypothesis related to the pathophysiology of AD were compiled, and biological pathways were highlighted in order to identify the molecules that could represent biological markers of the disease, necessary to establish early diagnosis, as well as the selection of patients for therapeutical interventional strategies.

Computerized decision support to optimally funnel patients through the diagnostic pathway for dementia

BACKGROUND

The increasing prevalence of dementia and the introduction of disease-modifying therapies (DMTs) highlight the need for efficient diagnostic pathways in memory clinics. We present a data-driven approach to efficiently guide stepwise diagnostic testing for three clinical scenarios: 1) syndrome diagnosis, 2) etiological diagnosis, and 3) eligibility for DMT.

METHODS

We used data from two memory clinic cohorts (ADC, PredictND), including 504 patients with dementia (302 Alzheimer's disease, 107 frontotemporal dementia, 35 vascular dementia, 60 dementia with Lewy bodies), 191 patients with mild cognitive impairment, and 188 cognitively normal controls (CN). Tests included digital cognitive screening (cCOG), neuropsychological and functional assessment (NP), MRI with automated quantification, and CSF biomarkers. Sequential testing followed a predetermined order, guided by diagnostic certainty. Diagnostic certainty was determined using a clinical decision support system (CDSS) that generates a disease state index (DSI, 0-1), indicating the probability of the syndrome diagnosis or underlying etiology. Diagnosis was confirmed if the DSI exceeded a predefined threshold based on sensitivity/specificity cutoffs relevant to each clinical scenario. Diagnostic accuracy and the need for additional testing were assessed at each step.

RESULTS

Using cCOG as a prescreener for 1) syndrome diagnosis has the potential to accurately reduce the need for extensive NP (42%), resulting in syndrome diagnosis in all patients, with a diagnostic accuracy of 0.71, which was comparable to using NP alone. For 2) etiological diagnosis, stepwise testing resulted in an etiological diagnosis in 80% of patients with a diagnostic accuracy of 0.77, with MRI needed in 77%, and CSF in 37%. When 3) determining DMT eligibility, stepwise testing (100% cCOG, 83% NP, 75% MRI) selected 60% of the patients for confirmatory CSF testing and eventually identified 90% of the potentially eligible patients with AD dementia.

CONCLUSIONS

Different diagnostic pathways are accurate and efficient depending on the setting. As such, a data-driven tool holds promise for assisting clinicians in selecting tests of added value across different clinical contexts. This becomes especially important with DMT availability, where the need for more efficient diagnostic pathways is crucial to maintain the accessibility and affordability of dementia diagnoses.

Guidelines for the use and interpretation of Alzheimer's disease biomarkers in clinical practice in Brazil: recommendations from the Scientific Department of Cognitive Neurology and Aging of the Brazilian Academy of Neurology

In recent years, the diagnostic accuracy of Alzheimer's disease has been enhanced by the development of different types of biomarkers that indicate the presence of neuropathological processes. In addition to improving patient selection for clinical trials, biomarkers can assess the effects of new treatments on pathological processes. However, there is concern about the indiscriminate and poorly supported use of biomarkers, especially in asymptomatic individuals or those with subjective cognitive decline. Difficulties interpreting these tests, high costs, and unequal access make this scenario even more challenging in healthcare. This article presents the recommendations from the Scientific Department of Cognitive Neurology and Aging of the Brazilian Academy of Neurology (Departamento Científico de Neurologia Cognitiva e Envelhecimento da Academia Brasileira de Neurologia) regarding the rational use and interpretation of Alzheimer's disease biomarkers in clinical practice. The clinical diagnosis of cognitive-behavioral syndrome is recommended as the initial step to guide the request for biomarkers.

Dementia

Dementia, or major neurocognitive disorder, is defined as a decline in 1 or more cognitive domains that causes impairment in everyday function. Alzheimer disease is the most common type of dementia in the United States, with an estimated 6.9 million adults who have Alzheimer disease and are 65 years or older. This article discusses the latest findings in preventing cognitive decline. It also discusses dementia screening, diagnosis, treatment, and the quality of life for persons with dementia and their caregivers.

Clinical and diagnostic implications of Alzheimer's disease copathology in Lewy body disease

Concomitant Alzheimer's disease (AD) pathology is a frequent event in the context of Lewy body disease (LBD), occurring in approximately half of all cases. Evidence shows that LBD patients with AD copathology show an accelerated disease course, a greater risk of cognitive decline and an overall poorer prognosis. However, LBD-AD cases may show heterogeneous motor and non-motor phenotypes with a higher risk of dementia and, consequently, be not rarely misdiagnosed. In this review, we summarize the current understanding of LBD-AD by discussing the synergistic effects of AD neuropathological changes and Lewy pathology and their clinical relevance. Furthermore, we provide an extensive overview of neuroimaging and fluid biomarkers under assessment for use in LBD-AD and their possible diagnostic and prognostic values. AD pathology can be predicted in vivo by means of CSF, MRI and PET markers, whereas the most promising technique to date for identifying Lewy pathology in different biological tissues is the α-synuclein seed amplification assay. Pathological imaging and CSF AD biomarkers are associated with a higher likelihood of cognitive decline in LBD but do not always mirror the neuropathological severity as in pure AD. Implementing the use of blood-based AD biomarkers might allow faster screening of LBD patients for AD copathology, thus improving the overall diagnostic sensitivity for LBD-AD. Finally, we discuss the literature on novel candidate biomarkers being exploited in LBD-AD to investigate other aspects of neurodegeneration, such as neuroaxonal injury, glial activation and synaptic dysfunction. The thorough characterization of AD copathology in LBD should be taken into account when considering differential diagnoses of dementia syndromes, to allow prognostic evaluation on an individual level, and to guide symptomatic and disease-modifying therapies.

Aβ status assessment in a hypothetical scenario prior to treatment with disease-modifying therapies: Evidence from 10-year real-world experience at university memory clinics

INTRODUCTION

With the advent of disease-modifying therapies, accurate assessment of biomarkers indicating the presence of disease-associated amyloid beta (Aβ) pathology becomes crucial in patients with clinically suspected Alzheimer's disease (AD). We evaluated Aβ levels in cerebrospinal fluid (Aβ CSF) and Aβ levels in positron emission tomography (Aβ PET) biomarkers in a real-world memory-clinic setting to develop an efficient algorithm for clinical use.

METHODS

Patients were evaluated for AD-related Aβ pathology from two independent cohorts (Ludwig Maximilian University [LMU], n = 402, and Medical University of Vienna [MUV], n = 144). Optimal thresholds of CSF biomarkers were deduced from receiver operating characteristic curves and validated against Aβ PET positivity.

RESULTS

In both cohorts, a CSF Aβ42/40 ratio ≥ 7.1% was associated with a low risk of a positive Aβ PET scan (negative predictive value: 94.3%). Implementing two cutoffs revealed 14% to 16% of patients with intermediate results (CSF Aβ42/40 ratio: 5.5%-7.1%), which had a strong benefit from Aβ PET imaging (44%-52% Aβ PET positivity).

DISCUSSION

A two-cutoff approach for CSF Aβ42/40 including Aβ PET imaging at intermediate results provides an effective assessment of Aβ pathology in real-world settings.

Highlights

We evaluated cerebrospinal fluid (CSF) and positron emission tomography (PET) amyloid beta (Aβ) biomarkers for Alzheimer's disease in real-world cohorts.A CSF Aβ 42/40 ratio between 5.5% and 7.1% defines patients at borderline levels.Patients at borderline levels strongly benefit from additional Aβ PET imaging.Two-cutoff CSF Aβ 42/40 and PET will allow effective treatment stratification.

Plasma Biomarkers of Brain Injury and Their Association With Brain MRI and Cognition in Type 1 Diabetes

OBJECTIVE

To evaluate associations between plasma biomarkers of brain injury and MRI and cognitive measures in participants with type 1 diabetes (T1D) from the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study.

RESEARCH DESIGN AND METHODS

Plasma amyloid-β-40, amyloid-β-42, neurofilament light chain (NfL), phosphorylated Tau-181 (pTau-181), and glial fibrillary acidic protein (GFAP) were measured in 373 adults who participated in the DCCT/EDIC study. MRI assessments included total brain and white matter hyperintensity volumes, white matter mean fractional anisotropy, and indices of Alzheimer disease (AD)-like atrophy and predicted brain age. Cognitive measures included memory and psychomotor and mental efficiency tests and assessments of cognitive impairment.

RESULTS

Participants were 60 (range 44-74) years old with 38 (30-51) years' T1D duration. Higher NfL was associated with an increase in predicted brain age (0.51 years per 20% increase in NfL; P < 0.001) and a 19.5% increase in the odds of impaired cognition (P < 0.01). Higher NfL and pTau-181 were associated with lower psychomotor and mental efficiency (P < 0.001) but not poorer memory. Amyloid-β measures were not associated with study measures. A 1% increase in mean HbA1c was associated with a 14.6% higher NfL and 12.8% higher pTau-181 (P < 0.0001).

CONCLUSIONS

In this aging T1D cohort, biomarkers of brain injury did not demonstrate an AD-like profile. NfL emerged as a biomarker of interest in T1D because of its association with higher HbA1c, accelerated brain aging on MRI, and cognitive dysfunction. Our study suggests that early neurodegeneration in adults with T1D is likely due to non-AD/nonamyloid mechanisms.

The Bayesian approach for real-world implementation of plasma p-tau217 in tertiary care memory clinics in Thailand

INTRODUCTION

Plasma phosphorylated tau (p-tau)217 is a promising biomarker for Alzheimer's disease (AD) diagnosis, but its clinical implementation remains challenging. We propose a strategy based on Bayes' theorem and test it in real-life memory clinics.

METHODS

Memory clinic patients were evaluated by neurocognitive specialists for prespecified diagnosis and subsequently underwent blood collection for p-tau217, cerebrospinal fluid, or amyloid positron emission tomography. Using cross-validation, the Bayesian approach (pretest probability × individualized likelihood ratio) was compared to other models for AD diagnosis.

RESULTS

The Bayesian strategy demonstrated an area under the receiver operating characteristic curve (AUC) of 0.98 (95% confidence interval [CI]: 0.96-1.0), significantly outperforming multivariable logistic regression (p-tau217, age, apolipoprotein E; AUC 0.95, p = 0.024) and p-tau217 alone (AUC = 0.94, p = 0.007). When applying the two-threshold approach, the Bayesian strategy yielded an accuracy of 0.94 (95% CI: 0.88-1.0) without requiring confirmatory tests in 62.9% of the iterations.

DISCUSSION

The Bayesian strategy offers an effective and flexible approach to address the limitations of plasma p-tau217 in clinical practice.

HIGHLIGHTS

Incorporating pretest probability into the interpretation of plasma phosphorylated tau (p-tau)217 improves the diagnostic performance significantly. The strategy could obviate the need for confirmatory testing in most of the patients. Plasma p-tau217 proves useful as a biomarker for Alzheimer's disease in low- and middle-income country such as Thailand.

Single-domain magnetic particles with motion behavior under electromagnetic AC and DC fields are a fatal cargo in Metropolitan Mexico City pediatric and young adult early Alzheimer, Parkinson, frontotemporal lobar degeneration and amyotrophic lateral sclerosis and in ALS patients

Metropolitan Mexico City (MMC) children and young adults exhibit overlapping Alzheimer and Parkinsons' diseases (AD, PD) and TAR DNA-binding protein 43 pathology with magnetic ultrafine particulate matter (UFPM) and industrial nanoparticles (NPs). We studied magnetophoresis, electron microscopy and energy-dispersive X-ray spectrometry in 203 brain samples from 14 children, 27 adults, and 27 ALS cases/controls. Saturation isothermal remanent magnetization (SIRM), capturing magnetically unstable FeNPs ~ 20nm, was higher in caudate, thalamus, hippocampus, putamen, and motor regions with subcortical vs. cortical higher SIRM in MMC ≤ 40y. Motion behavior was associated with magnetic exposures 25-100 mT and children exhibited IRM saturated curves at 50-300 mT associated to change in NPs position and/or orientation in situ. Targeted magnetic profiles moving under AC/AD magnetic fields could distinguish ALS vs. controls. Motor neuron magnetic NPs accumulation potentially interferes with action potentials, ion channels, nuclear pores and enhances the membrane insertion process when coated with lipopolysaccharides. TEM and EDX showed 7-20 nm NP Fe, Ti, Co, Ni, V, Hg, W, Al, Zn, Ag, Si, S, Br, Ce, La, and Pr in abnormal neural and vascular organelles. Brain accumulation of magnetic unstable particles start in childhood and cytotoxic, hyperthermia, free radical formation, and NPs motion associated to 30-50 μT (DC magnetic fields) are critical given ubiquitous electric and magnetic fields exposures could induce motion behavior and neural damage. Magnetic UFPM/NPs are a fatal brain cargo in children's brains, and a preventable AD, PD, FTLD, ALS environmental threat. Billions of people are at risk. We are clearly poisoning ourselves.

Performance of plasma p-tau217 for the detection of amyloid-β positivity in a memory clinic cohort using an electrochemiluminescence immunoassay

BACKGROUND

Plasma p-tau217 has emerged as the most promising blood-based marker (BBM) for the detection of Alzheimer Disease (AD) pathology, yet few studies have evaluated plasma p-tau217 performance in memory clinic settings. We examined the performance of plasma p-tau217 for the detection of AD using a high-sensitivity immunoassay in individuals undergoing diagnostic lumbar puncture (LP).

METHODS

Paired plasma and cerebrospinal fluid (CSF) samples were analysed from the TIMC-BRAiN cohort. Amyloid (Aβ) and Tau (T) pathology were classified based on established cut-offs for CSF Aβ42 and CSF p-tau181 respectively. High-sensitivity electrochemiluminescence (ECL) immunoassays were performed on paired plasma/CSF samples for p-tau217, p-tau181, Glial Fibrillary Acidic Protein (GFAP), Neurofilament Light (NfL) and total tau (t-tau). Biomarker performance was evaluated using Receiver-Operating Curve (ROC) and Area-Under-the-Curve (AUC) analysis.

RESULTS

Of 108 participants (age: 69 ± 6.5 years; 54.6% female) with paired samples obtained at time of LP, 64.8% (n = 70/108) had Aβ pathology detected (35 with Mild Cognitive Impairment and 35 with mild dementia). Plasma p-tau217 was over three-fold higher in Aβ + (12.4 pg/mL; 7.3-19.2 pg/mL) vs. Aβ- participants (3.7 pg/mL; 2.8-4.1 pg/mL; Mann-Whitney U = 230, p < 0.001). Plasma p-tau217 exhibited excellent performance for the detection of Aβ pathology (AUC: 0.91; 95% Confidence Interval [95% CI]: 0.86-0.97)-greater than for T pathology (AUC: 0.83; 95% CI: 0.75-0.90; z = 1.75, p = 0.04). Plasma p-tau217 outperformed plasma p-tau181 for the detection of Aβ pathology (z = 3.24, p < 0.001). Of the other BBMs, only plasma GFAP significantly differed by Aβ status which significantly correlated with plasma p-tau217 in Aβ + (but not in Aβ-) individuals. Application of a two-point threshold at 95% and 97.5% sensitivities & specificities may have enabled avoidance of LP in 58-68% of cases.

CONCLUSIONS

Plasma p-tau217 measured using a high-sensitivity ECL immunoassay demonstrated excellent performance for detection of Aβ pathology in a real-world memory clinic cohort. Moving forward, clinical use of plasma p-tau217 to detect AD pathology may substantially reduce need for confirmatory diagnostic testing for AD pathology with diagnostic LP in specialist memory services.

The Role of Genomic-Informed Risk Assessments in Predicting Dementia Outcomes

Importance

By integrating genetic and clinical risk factors into genomic-informed dementia risk reports, healthcare providers can offer patients detailed risk profiles to facilitate understanding of individual risk and support the implementation of personalized strategies for promoting brain health.

Objective

To develop a genomic-informed risk assessment composed of family history, genetic, and clinical risk factors and, in turn, evaluate how the risk assessment predicted incident dementia.

Design

This longitudinal study included data from two clinical case-control cohorts with an average of 6.6 visits. Secondary analyses were conducted from July 2023 - March 2024.

Setting

Data were previously collected across multiple US locations from 1994 to 2023.

Participants

Older adults aged 55+ with whole-genome sequencing and dementia-free at baseline.

Exposures

An additive score comprising the modified Cardiovascular Risk Factors, Aging, and Incidence of Dementia Risk Score (mCAIDE), family history of dementia, APOE genotype, and an AD polygenic risk score.

Main Outcomes and Measures

The risk of progression to all-cause dementia was evaluated using Cox-proportional hazard models (hazard ratios with 95% confidence intervals [OR 9%CI]).

Results

A total of 3,429 older adults were included (aged 75 ± 7 years; 59% female; 75% non-Latino White, 15% Black, 5.2% Latino, 3.6% other, and 0.4% Asian; 27% MCI), with 751 participants progressing to dementia. The most common high-risk indicator was a family history of dementia (56%), followed by APOE*ε4 genotype (36%), high mCAIDE score (34%), and high AD-PRS (11%). Most participants had at least one high-risk indicator, with 39% having one, 32% two, 9.8% three, and 1% four. The presence of 1, 2, 3, or 4 risk indicators was associated with a doubling (HR = 1.72, CI: 1.34-2.22, p = 2.5e-05), tripling (HR = 3.09, CI: 2.41-3.95, p = 4.4e-19), quadrupling (HR = 4.46, CI: 3.34-5.94, p = 2.2e-24), and a twelvefold increase (HR = 12.15, CI: 7.33-20.14, p = 3.2e-22) in dementia risk.

Conclusion & Relevance

We found that most participants in memory and aging clinics had at least one high-risk indicator for dementia. Furthermore, we observed a dose-response relationship where a greater number of risk indicators was associated with an increased risk of incident dementia.

Diagnosis of Alzheimer's Disease in Clinical Practice: Time to Incorporate Biomarkers?

Hippocampal dysfunction is associated with early clinical signs of Alzheimer's disease (AD). Due to the limited availability or invasiveness of current biomarkers, the AD diagnosis is usually based on cognitive assessment and structural brain imaging. The recent study by Lalive and colleagues examined the specificity of brain morphometry for the AD diagnosis in a memory clinic cohort with hippocampal-type amnestic syndrome. The results indicate that memory deficits and hippocampal atrophy are similar in AD and non-AD patients, highlighting their low diagnostic specificity. These findings challenge the traditional AD diagnosis and underscore the need for biomarkers to differentiate specific neuropathological entities.