The Alzheimer's Association appropriate use recommendations for blood biomarkers in Alzheimer's disease

Comparison of ultrasensitive and mass spectrometry quantification of blood-based amyloid biomarkers for Alzheimer's disease diagnosis in a memory clinic cohort

BACKGROUND

Alzheimer's disease (AD) is a complex neurodegenerative disorder with β-amyloid pathology as a key underlying process. The relevance of cerebrospinal fluid (CSF) and brain imaging biomarkers is validated in clinical practice for early diagnosis. Yet, their cost and perceived invasiveness are a limitation for large-scale implementation. Based on positive amyloid profiles, blood-based biomarkers should allow to detect people at risk for AD and to monitor patients under therapeutics strategies. Thanks to the recent development of innovative proteomic tools, the sensibility and specificity of blood biomarkers have been considerably improved. However, their diagnosis and prognosis relevance for daily clinical practice is still incomplete.

METHODS

The Plasmaboost study included 184 participants from the Montpellier's hospital NeuroCognition Biobank with AD (n = 73), mild cognitive impairments (MCI) (n = 32), subjective cognitive impairments (SCI) (n = 12), other neurodegenerative diseases (NDD) (n = 31), and other neurological disorders (OND) (n = 36). Dosage of β-amyloid biomarkers was performed on plasma samples using immunoprecipitation-mass spectrometry (IPMS) developed by Shimadzu (IPMS-Shim Aβ₄₂, Aβ₄₀, APP_669-711) and Simoa Human Neurology 3-PLEX A assay (Aβ₄₂, Aβ₄₀, t-tau). Links between those biomarkers and demographical and clinical data and CSF AD biomarkers were investigated. Performances of the two technologies to discriminate clinically or biologically based (using the AT(N) framework) diagnosis of AD were compared using receiver operating characteristic (ROC) analyses.

RESULTS

The amyloid IPMS-Shim composite biomarker (combining APP_669-711/Aβ₄₂ and Aβ₄₀/Aβ₄₂ ratios) discriminated AD from SCI (AUC: 0.91), OND (0.89), and NDD (0.81). The IPMS-Shim Aβ_42/40 ratio also discriminated AD from MCI (0.78). IPMS-Shim biomarkers have similar relevance to discriminate between amyloid-positive and amyloid-negative individuals (0.73 and 0.76 respectively) and A-T-N-/A+T+N+ profiles (0.83 and 0.85). Performances of the Simoa 3-PLEX Aβ_42/40 ratio were more modest. Pilot longitudinal analysis on the progression of plasma biomarkers indicates that IPMS-Shim can detect the decrease in plasma Aβ₄₂ that is specific to AD patients.

CONCLUSIONS

Our study confirms the potential usefulness of amyloid plasma biomarkers, especially the IPMS-Shim technology, as a screening tool for early AD patients.

Clinical utility of cerebrospinal fluid biomarkers in the evaluation of cognitive impairment: a systematic review and meta-analysis

BACKGROUND

The analytical and clinical validity of cerebrospinal (CSF) biomarkers has been extensively researched in dementia. Further work is needed to assess the ability of these biomarkers to improve diagnosis, management and health outcomes in the clinical setting OBJECTIVES: To assess the added value and clinical utility of CSF biomarkers in the diagnostic assessment of cognitively impaired patients under evaluation for Alzheimer's disease (AD).

METHODS

Systematic literature searches of Medline, EMBASE, PsycINFO and Web of Science research databases were conducted on 17 December 2022. Data from relevant studies were extracted and independently screened for quality using a tool for bias. Clinical utility was measured by clinicians' changes in diagnosis, diagnostic confidence and patient management (when available), after their examination of patients' CSF biomarkers. Cost-effectiveness was assessed by consideration of additional cost per patient and quality-adjusted life years.

RESULTS

Searches identified 17 studies comprising 2090 patient participants and 593 clinicians. The meta-analysis revealed that clinicians' use of CSF biomarkers resulted in a pooled percentage change in diagnosis of 25% (95% CI 14 to 37), an increase in diagnostic confidence of 14% (95% CI 9 to 18) and a pooled proportion of patients whose management changed of 31% (95% CI 12 to 50). CSF biomarkers were deemed cost-effective, particularly in memory services, where pre-test AD prevalence is higher compared with a primary care setting.

CONCLUSIONS

CSF biomarkers can be a helpful additional diagnostic tool for clinicians assessing patients with cognitive impairment. In particular, CSF biomarkers consistently improved clinicians' confidence in diagnosing AD and influenced on diagnostic change and patient management. Further research is needed to study the clinical utility of blood-based biomarkers in the clinical setting.

The Costs of Dementia in Europe: An Updated Review and Meta-analysis

BACKGROUND AND OBJECTIVE

The prevalence of dementia is increasing, while new opportunities for diagnosing, treating and possibly preventing Alzheimer's disease and other dementia disorders are placing focus on the need for accurate estimates of costs in dementia. Considerable methodological heterogeneity creates challenges for synthesising the existing literature. This study aimed to estimate the costs for persons with dementia in Europe, disaggregated into cost components and informative patient subgroups.

METHODS

We conducted an updated literature review searching PubMed, Embase and Web of Science for studies published from 2008 to July 2021 reporting empirically based cost estimates for persons with dementia in European countries. We excluded highly selective or otherwise biased reports, and used a random-effects meta-analysis to produce estimates of mean costs of care across five European regions.

RESULTS

Based on 113 studies from 17 European countries, the estimated mean costs for all patients by region were highest in the British Isles (73,712 EUR), followed by the Nordics (43,767 EUR), Southern (35,866 EUR), Western (38,249 EUR), and Eastern Europe and Baltics (7938 EUR). Costs increased with disease severity, and the distribution of costs over informal and formal care followed a North-South gradient with Southern Europe being most reliant on informal care.

CONCLUSIONS

To our knowledge, this study represents the most extensive meta-analysis of the cost for persons with dementia in Europe to date. Though there is considerable heterogeneity across studies, much of this is explained by identifiable factors. Further standardisation of methodology for capturing resource utilisation data may further improve comparability of future studies. The cost estimates presented here may be of value for cost-of-illness studies and economic evaluations of novel diagnostic technologies and therapies for Alzheimer's disease.

Attitudes of Neurologists Toward the Use of Biomarkers in the Diagnosis of Early Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) biomarkers reflect key elements of pathophysiology and improve the diagnostic process. However, their use in routine clinical practice is still limited.

OBJECTIVE

We aimed to assess neurologists' barriers and enablers to early AD diagnosis using core AD biomarkers.

METHODS

We conducted an online study in collaboration with the Spanish Society of Neurology. Neurologists answered a survey exploring their attitudes towards AD diagnosis using biomarkers in mild cognitive impairment (MCI) or mild AD dementia. Multivariate logistic regression analyses were conducted to determine the association between neurologists' characteristics and diagnostic attitudes.

RESULTS

We included 188 neurologists with a mean age (SD) of 40.6 (11.3) years, 52.7% male. Most participants had access to AD biomarkers, mainly in cerebrospinal fluid (CSF) (89.9%,#x0025;, n = 169). The majority of participants (95.2%,#x0025;, n = 179) considered CSF biomarkers useful for an etiological diagnosis in MCI. However, 85.6% of respondents (n = 161) used them in less than 60% of their MCI patients in routine clinical practice. Facilitating patients and their families to plan for the future was the most frequent enabler for the use of biomarkers. Short consultation time and practicalities associated with the programming of a lumbar puncture were the most common barriers. A younger neurologist age (p = 0.010) and a higher number of patients managed weekly (p = 0.036) were positively associated with the use of biomarkers.

CONCLUSION

Most neurologists had a favorable attitude to the use of biomarkers, especially in MCI patients. Improvements in resources and consultation time may increase their use in routine clinical practice.

Dementia with Lewy bodies: Impact of co-pathologies and implications for clinical trial design

Dementia with Lewy bodies (DLB) is clinically defined by the presence of visual hallucinations, fluctuations, rapid eye movement (REM) sleep behavioral disorder, and parkinsonism. Neuropathologically, it is characterized by the presence of Lewy pathology. However, neuropathological studies have demonstrated the high prevalence of coexistent Alzheimer's disease, TAR DNA-binding protein 43 (TDP-43), and cerebrovascular pathologic cases. Due to their high prevalence and clinical impact on DLB individuals, clinical trials should account for these co-pathologies in their design and selection and the interpretation of biomarkers values and outcomes. Here we discuss the frequency of the different co-pathologies in DLB and their cross-sectional and longitudinal clinical impact. We then evaluate the utility and possible applications of disease-specific and disease-nonspecific biomarkers and how co-pathologies can impact these biomarkers. We propose a framework for integrating multi-modal biomarker fingerprints and step-wise selection and assessment of DLB individuals for clinical trials, monitoring target engagement, and interpreting outcomes in the setting of co-pathologies.

Plasma Amyloid-β, Total Tau, and Neurofilament Light Chain Across the Alzheimer's Disease Clinical Spectrum: A Population-Based Study

BACKGROUND

Plasma biomarkers have emerged as a promising approach for characterizing pathophysiology in mild cognitive impairment (MCI) and Alzheimer's disease (AD).

OBJECTIVE

We aimed to characterize plasma biomarkers for AD and neurodegeneration across the AD clinical continuum, and to assess their ability to differentiate between AD, MCI, and normal cognition.

METHODS

This population-based study engaged 1,446 rural-dwelling older adults (age ≥60 years, 61.0% women) derived from MIND-China; of these, 402 were defined with MCI and 142 with AD. Plasma amyloid-β (Aβ), total tau (t-tau), and neurofilament light chain (NfL) concentrations were analyzed using the Simoa platform. Data were analyzed using linear and logistic regression models, and receiver operating characteristic (ROC) analysis.

RESULTS

Across the AD clinical spectrum, plasma Aβ40 and NfL increased, whereas Aβ42/Aβ40 ratio decreased. Plasma t-tau was higher in people with AD dementia than those with MCI or normal cognition. Plasma NfL outperformed other biomarkers in differentiating AD from normal cognition (area under the ROC curve [AUC] = 0.75), but all plasma biomarkers performed poorly to distinguish MCI from normal cognition (AUC <0.60). Plasma NfL in combination with age, sex, education, and APOE genotype yielded the AUC of 0.87 for differentiating between AD and normal cognition, 0.79 between AD and MCI, and 0.64 between MCI and normal cognition.

CONCLUSIONS

In this Chinese population, AD plasma biomarkers vary by age, sex, and APOE genotype. Plasma Aβ, t-tau, and NfL differ across the AD clinical spectrum, and plasma NfL appears to be superior to plasma Aβ and t-tau for defining the clinical spectrum.

Advancing Diagnostic Certainty in Alzheimer's Disease: A Synthesis of the Diagnostic Process

Changes in diagnostic certainty can be evaluated by assessing the impact of a diagnostic test in driving decision making. Diagnostic tests can be appraised using validated measures of accuracy, i.e., sensitivity, specificity, and positive or negative predictive values against a known reference standard. However, other less well formalized factors affect diagnostic certainty. These inputs are under-researched and more difficult to quantify. Clinicians assess the significance of available data in the context of their expertise, pre-diagnostic confidence, and background knowledge of populations and disease. Inherent qualities of the diagnostic test and an individual clinician's interpretation of the meaning of test results will also affect the subsequent level of diagnostic certainty. These factors are only infrequently considered alongside the diagnostic accuracy of a test. In this paper, we present a model of the different processes which can affect diagnostic certainty in Alzheimer's disease (AD). This model builds upon existing understanding and provides further insights into the complexity of diagnostic certainty in AD and how we might improve this.

Association of neurofilament light chain with renal function: mechanisms and clinical implications

BACKGROUND

Blood-based neurofilament light chain (NfL) is a promising biomarker of neurodegeneration across multiple neurodegenerative diseases. However, blood-based NfL is highly associated with renal function in older adults, which leads to the concern that blood-based NfL levels may be influenced by renal function, rather than neurodegeneration alone. Despite growing interest in using blood-based NfL as a biomarker of neurodegeneration in research and clinical practices, whether renal function should always be accounted for in these settings remains unclear. Moreover, the mechanisms underlying this association between blood-based measures of NfL and renal function remain elusive. In this study, we first evaluated the effect of renal function on the associations of plasma NfL with other measures of neurodegeneration. We then examined the extent of genetic and environmental contributions to the association between plasma NfL and renal function.

METHODS

In a sample of 393 adults (mean age=75.22 years, range=54-90), we examined the associations of plasma NfL with cerebrospinal fluid (CSF) NfL and brain volumetric measures before and after adjusting for levels of serum creatinine (an index of renal function). In an independent sample of 969 men (mean age=67.57 years, range=61-73) that include monozygotic and dizygotic twin pairs, we replicated the same analyses and leveraged biometrical twin modeling to examine the genetic and environmental influences on the plasma NfL and creatinine association.

RESULTS

Plasma NfL's associations with cerebrospinal fluid NfL and brain volumetric measures did not meaningfully change after adjusting for creatinine levels. Both plasma NfL and creatinine were significantly heritable (h2=0.54 and 0.60, respectively). Their phenotypic correlation (r=0.38) was moderately explained by shared genetic influences (genetic correlation=0.46) and unique environmental influences (unique environmental correlation=0.27).

CONCLUSIONS

Adjusting for renal function is unnecessary when assessing associations between plasma NfL and other measures of neurodegeneration but is necessary if plasma NfL is compared to a cutoff for classifying neurodegeneration-positive versus neurodegeneration-negative individuals. Blood-based measures of NfL and renal function are heritable and share common genetic influences.

A framework for addressing Alzheimer's disease: Without a frame, the work has no aim

Confronting Alzheimer's disease (AD) involves patients, healthcare professionals, supportive services, caregivers, and government agencies interacting along a continuum from initial awareness to diagnosis, treatment, support, and care. This complex scope presents a challenge for health system transformation supporting individuals at risk for, or diagnosed with, AD. The AD systems preparedness framework was developed to help health systems identify specific opportunities to implement and evaluate focused improvement programs. The framework is purposely flexible to permit local adaptation across different health systems and countries. Health systems can develop solutions tailored to system-specific priorities considered within the context of the overall framework. Example metric concepts and initiatives are provided for each of ten areas of focus. Examples of funded projects focusing on screening and early detection are provided. It is our hope that stakeholders utilize the common framework to generate and share additional implementation evidence to benefit individuals with AD.

Differential roles of Aβ42/40, p-tau231 and p-tau217 for Alzheimer's trial selection and disease monitoring

Blood biomarkers indicative of Alzheimer's disease (AD) pathology are altered in both preclinical and symptomatic stages of the disease. Distinctive biomarkers may be optimal for the identification of AD pathology or monitoring of disease progression. Blood biomarkers that correlate with changes in cognition and atrophy during the course of the disease could be used in clinical trials to identify successful interventions and thereby accelerate the development of efficient therapies. When disease-modifying treatments become approved for use, efficient blood-based biomarkers might also inform on treatment implementation and management in clinical practice. In the BioFINDER-1 cohort, plasma phosphorylated (p)-tau231 and amyloid-β42/40 ratio were more changed at lower thresholds of amyloid pathology. Longitudinally, however, only p-tau217 demonstrated marked amyloid-dependent changes over 4-6 years in both preclinical and symptomatic stages of the disease, with no such changes observed in p-tau231, p-tau181, amyloid-β42/40, glial acidic fibrillary protein or neurofilament light. Only longitudinal increases of p-tau217 were also associated with clinical deterioration and brain atrophy in preclinical AD. The selective longitudinal increase of p-tau217 and its associations with cognitive decline and atrophy was confirmed in an independent cohort (Wisconsin Registry for Alzheimer's Prevention). These findings support the differential association of plasma biomarkers with disease development and strongly highlight p-tau217 as a surrogate marker of disease progression in preclinical and prodromal AD, with impact for the development of new disease-modifying treatments.

Performance of a fully-automated Lumipulse plasma phospho-tau181 assay for Alzheimer's disease

BACKGROUND

The recent promise of disease-modifying therapies for Alzheimer's disease (AD) has reinforced the need for accurate biomarkers for early disease detection, diagnosis and treatment monitoring. Advances in the development of novel blood-based biomarkers for AD have revealed that plasma levels of tau phosphorylated at various residues are specific and sensitive to AD dementia. However, the currently available tests have shortcomings in access, throughput, and scalability that limit widespread implementation.

METHODS

We evaluated the diagnostic and prognostic performance of a high-throughput and fully-automated Lumipulse plasma p-tau181 assay for the detection of AD. Plasma from older clinically unimpaired individuals (CU, n = 463) and patients with mild cognitive impairment (MCI, n = 107) or AD dementia (n = 78) were obtained from the longitudinal Stanford University Alzheimer's Disease Research Center (ADRC) and the Stanford Aging and Memory Study (SAMS) cohorts. We evaluated the discriminative accuracy of plasma p-tau181 for clinical AD diagnosis, association with amyloid β peptides and p-tau181 concentrations in CSF, association with amyloid positron emission tomography (PET), and ability to predict longitudinal cognitive and functional change.

RESULTS

The assay showed robust performance in differentiating AD from control participants (AUC 0.959, CI: 0.912 to 0.990), and was strongly associated with CSF p-tau181, CSF Aβ42/Aβ40 ratio, and amyloid-PET global SUVRs. Associations between plasma p-tau181 with CSF biomarkers were significant when examined separately in Aβ+ and Aβ- groups. Plasma p-tau181 significantly increased over time in CU and AD diagnostic groups. After controlling for clinical diagnosis, age, sex, and education, baseline plasma p-tau181 predicted change in MoCA overall and change in CDR Sum of Boxes in the AD group over follow-up of up to 5 years.

CONCLUSIONS

This fully-automated and available blood-based biomarker assay therefore may be useful for early detection, diagnosis, prognosis, and treatment monitoring of AD.

Linking the Amyloid, Tau, and Mitochondrial Hypotheses of Alzheimer's Disease and Identifying Promising Drug Targets

Damage or loss of brain cells and impaired neurochemistry, neurogenesis, and synaptic and nonsynaptic plasticity of the brain lead to dementia in neurodegenerative diseases, such as Alzheimer's disease (AD). Injury to synapses and neurons and accumulation of extracellular amyloid plaques and intracellular neurofibrillary tangles are considered the main morphological and neuropathological features of AD. Age, genetic and epigenetic factors, environmental stressors, and lifestyle contribute to the risk of AD onset and progression. These risk factors are associated with structural and functional changes in the brain, leading to cognitive decline. Biomarkers of AD reflect or cause specific changes in brain function, especially changes in pathways associated with neurotransmission, neuroinflammation, bioenergetics, apoptosis, and oxidative and nitrosative stress. Even in the initial stages, AD is associated with Aβ neurotoxicity, mitochondrial dysfunction, and tau neurotoxicity. The integrative amyloid-tau-mitochondrial hypothesis assumes that the primary cause of AD is the neurotoxicity of Aβ oligomers and tau oligomers, mitochondrial dysfunction, and their mutual synergy. For the development of new efficient AD drugs, targeting the elimination of neurotoxicity, mutual potentiation of effects, and unwanted protein interactions of risk factors and biomarkers (mainly Aβ oligomers, tau oligomers, and mitochondrial dysfunction) in the early stage of the disease seems promising.

Developments in scalable strategies for detecting early markers of cognitive decline

Effective strategies for early detection of cognitive decline, if deployed on a large scale, would have individual and societal benefits. However, current detection methods are invasive or time-consuming and therefore not suitable for longitudinal monitoring of asymptomatic individuals. For example, biological markers of neuropathology associated with cognitive decline are typically collected via cerebral spinal fluid, cognitive functioning is evaluated from face-to-face assessments by experts and brain measures are obtained using expensive, non-portable equipment. Here, we describe scalable, repeatable, relatively non-invasive and comparatively inexpensive strategies for detecting the earliest markers of cognitive decline. These approaches are characterized by simple data collection protocols conducted in locations outside the laboratory: measurements are collected passively, by the participants themselves or by non-experts. The analysis of these data is, in contrast, often performed in a centralized location using sophisticated techniques. Recent developments allow neuropathology associated with potential cognitive decline to be accurately detected from peripheral blood samples. Advances in smartphone technology facilitate unobtrusive passive measurements of speech, fine motor movement and gait, that can be used to predict cognitive decline. Specific cognitive processes can be assayed using 'gamified' versions of standard laboratory cognitive tasks, which keep users engaged across multiple test sessions. High quality brain data can be regularly obtained, collected at-home by users themselves, using portable electroencephalography. Although these methods have great potential for addressing an important health challenge, there are barriers to be overcome. Technical obstacles include the need for standardization and interoperability across hardware and software. Societal challenges involve ensuring equity in access to new technologies, the cost of implementation and of any follow-up care, plus ethical issues.

Clinical utility of cerebrospinal fluid biomarkers measured by LUMIPULSE® system

OBJECTIVES

Cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD) are well-established in research settings, but their use in routine clinical practice remains a largely unexploited potential. Here, we examined the relationship between CSF biomarkers, measured by a fully automated immunoassay platform, and brain β-amyloid (Aβ) deposition status confirmed by amyloid positron emission tomography (PET).

METHODS

One hundred ninety-nine CSF samples from clinically diagnosed AD patients enrolled in a clinical study and who underwent amyloid PET were used for the measurement of CSF biomarkers Aβ 1-40 (Aβ40), Aβ 1-42 (Aβ42), total tau (t-Tau), and phosphorylated tau-181 (p-Tau181) using the LUMIPULSE system. These biomarkers and their combinations were compared to amyloid PET classification (negative or positive) using visual read assessments. Several combinations were also analyzed with a multivariable logistic regression model.

RESULTS

Aβ42, t-Tau, and p-Tau181, and the ratios of Aβ42 with other biomarkers had a good diagnostic agreement with amyloid PET imaging. The multivariable logistic regression analysis showed that amyloid PET status was associated with Aβ40 and Aβ42, but other factors, such as MMSE, sex, t-Tau, and p-Tau181, did not significantly add information to the model.

CONCLUSIONS

CSF biomarkers measured with the LUMIPULSE system showed good agreement with amyloid PET imaging. The ratio of Aβ42 with the other analyzed biomarkers showed a higher correlation with amyloid PET than Aβ42 alone, suggesting that the combinations of biomarkers could be useful in the diagnostic assessment in clinical research and potentially in routine clinical practice.

Blood Analytes as Biomarkers of Mechanisms Involved in Alzheimer’s Disease Progression

Alzheimer’s disease (AD) is the leading cause of dementia, but the pathogenetic factors are not yet well known, and the relationships between brain and systemic biochemical derangements and disease onset and progression are unclear. We aim to focus on blood biomarkers for an accurate prognosis of the disease. We used a dataset characterized by longitudinal findings collected over the past 10 years from 90 AD patients. The dataset included 277 observations (both clinical and biochemical ones, encompassing blood analytes encompassing routine profiles for different organs, together with immunoinflammatory and oxidative markers). Subjects were grouped into four severity classes according to the Clinical Dementia Rating (CDR) Scale: mild (CDR = 0.5 and CDR = 1), moderate (CDR = 2), severe (CDR = 3) and very severe (CDR = 4 and CDR = 5). Statistical models were used for the identification of potential blood markers of AD progression. Moreover, we employed the Pathfinder tool of the Reactome database to investigate the biological pathways in which the analytes of interest could be involved. Statistical results reveal an inverse significant relation between four analytes (high-density cholesterol, total cholesterol, iron and ferritin) with AD severity. In addition, the Reactome database suggests that such analytes could be involved in pathways that are altered in AD progression. Indeed, the identified blood markers include molecules that reflect the heterogeneous pathogenetic mechanisms of AD. The combination of such blood analytes might be an early indicator of AD progression and constitute useful therapeutic targets.

Disclosing Individual Results in Dementia Research: A Proposed Study Participant’s Bill of Rights

This Study Participant’s Bill of Rights is a call to action for researchers in Alzheimer’s disease and related dementias (ADRD) to proactively design clinical studies that provide the option for research participants to learn their individual research results if they choose, and in a manner that ensures study integrity. This Bill of Rights was crafted by a committee of study participants, care partners, representatives of dementia advocacy organizations, and other stakeholders in dementia research for the Advisory Group on Risk Education for Dementia (AGREEDementia). The framework developed by the Multi-Regional Clinical Trials (MRCT) Return of Individual Research Results provides a useful context for researchers to plan their studies and disclosure.

Elevation of plasma phosphorylated tau181 during neurological illnesses affecting consciousness and kidney dysfunction

Introduction

Phosphorylated tau (p-tau)181 has become a promising blood-based Alzheimer's disease (AD) biomarker. We studied the agreement of plasma p-tau181 and cerebrospinal fluid (CSF) markers in patients with alteration of consciousness (AOC).

Methods

Plasma and CSF were simultaneously collected in participants presenting with AOC. Plasma p-tau181 was measured using the single-molecule array. CSF biomarkers were classified according to the amyloid/tau/neurodegeneration (AT[N]) framework.

Results

Among participants enrolled, the median (interquartile range) age was 57 (28.5-75) years and 5.8% had AD. Plasma p-tau181 yielded area under the curve of 0.85 and showed moderate correlation with CSF p-tau181 (Rho = 0.42, P < .001). Using the historical cut-point, many non-AD participants had elevated plasma p-tau181 resulting in a specificity of 0.57. Plasma p-tau181 correlated with the glomerular filtration rate (Rho = -0.52, P < .001). Among A- participants with elevated plasma p-tau181, 42% had kidney dysfunction.

Discussion

Plasma p-tau181 showed inadequate specificity in patients with AOC partially attributable to concomitant kidney dysfunction.

Considerations for clinical trial design and conduct in the evaluation of novel advanced therapeutics in neurodegenerative disease

The recent advances in the development of potentially disease modifying cell and gene therapies for neurodegenerative disease has resulted in the production of a number of promising novel therapies which are now moving forward to clinical evaluation. The robust evaluation of these therapies pose a significant number of challenges when compared to more traditional evaluations of pharmacotherapy, which is the current mainstay of neurodegenerative disease symptom management. Indeed, there is an inherent complexity in the design and conduct of these trials at multiple levels. Here we discuss specific aspects requiring consideration in the context of investigating novel cell and gene therapies for neurodegenerative disease. This extends to overarching trial designs that could be employed and the factors that underpin design choices such outcome assessments, participant selection and methods for delivery of cell and gene therapies. We explore methods of data collection that may improve efficiency in trials of cell and gene therapy to maximize data sharing and collaboration. Lastly, we explore some of the additional context beyond efficacy evaluations that should be considered to ensure implementation across relevant healthcare settings.

Alzheimer Disease Biomarkers in Clinical Practice: A Blood-Based Diagnostic Revolution

An estimated 6.1 million Americans live with cognitive impairment-a number that is expected to triple by 2050. Alzheimer disease (AD) is the most common cause of impairment. The development of blood-based biomarkers capable of detecting pathological changes of AD in living patients has the potential to revolutionize the diagnostic approach to cognitive impairment by enabling screening for AD using accessible, non-invasive measures of amyloid and tau neuropathology, with accuracy that increasingly approaches that seen with "gold standard" positron emission tomography and cerebrospinal fluid measures. Demand for biomarker testing is expected to intensify with the emergence of effective treatments for AD and related dementias. Clinicians in all fields must prepare to meet this demand. Primary care practitioners are well positioned to support dementia diagnosis and management, including the application and interpretation of biomarkers. This article reviews the current uses of AD biomarkers and the potential applications of emerging blood-based AD biomarkers in clinical practice.

Communicating and Using Dementia Risk Evidence

Advances in biomarkers, genetics, and other data used as dementia risk evidence (DRE) are increasingly informing clinical diagnosis and management. The purpose of this Mini-Forum is to provide a solutions-based discussion of the ethical and legal gaps and practical questions about how to use and communicate these data. Investigators often use DRE in research. When participants ask for their personal results, investigators have concerns. Will data that was intended to study groups be valid for individuals? Will sharing data cause distress? Debates around sharing DRE became heated when blood-based amyloid tests and amyloid reducing drugs appeared poised to enable clinicians easily to identify people with elevated brain amyloid and reduce it with a drug. Such an approach would transform the traditional role of DRE from investigational to foundational; however, then the high costs, uncertain clinical benefits and risks of the therapy led to an urgent need for education to support clinical decision making. Further complicating DRE use are direct to consumer genetic testing and increasingly available biomarker testing. Withholding DRE becomes less feasible and public education around responsible use and understanding become vital. A critical answer to these legal and ethical issues is supporting education that clearly delineates known risks, benefits, and gaps in knowledge, and communication to promote understanding among researchers, clinicians, patients, and all stakeholders. This paper provides an overview and identifies general concepts and resource documents that support more informed discussions for individuals and interdisciplinary groups.