The Bio-Hermes Study: Biomarker database developed to investigate blood-based and digital biomarkers in community-based, diverse populations clinically screened for Alzheimer's disease.

INTRODUCTION: Alzheimer's disease (AD) trial participants are often screened for eligibility by brain amyloid positron emission tomography/cerebrospinal fluid (PET/CSF), which is inefficient as many are not amyloid positive. Use of blood-based biomarkers may reduce screen failures. METHODS: We recruited 755 non-Hispanic White, 115 Hispanic, 112 non-Hispanic Black, and 19 other minority participants across groups of cognitively normal (n = 417), mild cognitive impairment (n = 312), or mild AD (n = 272) participants. Plasma amyloid beta (Aß)40, Aß42, Aß42/Aß40, total tau, phosphorylated tau (p-tau)181, and p-tau217 were measured; amyloid PET/CSF (n = 956) determined amyloid positivity. Clinical, blood biomarker, and ethnicity/race differences associated with amyloid status were evaluated. RESULTS: Greater impairment, older age, and carrying an apolipoprotein E (apoE) ε4 allele were associated with greater amyloid burden. Areas under the receiver operating characteristic curve for amyloid status of plasma Aß42/Aß40, p-tau181, and p-tau217 with amyloid positivity were ≥ 0.7117 for all ethnoracial groups (p-tau217, ≥0.8128). Age and apoE ε4 adjustments and imputation of biomarker values outside limit of quantitation provided small improvement in predictive power. DISCUSSION: Blood-based biomarkers are highly associated with amyloid PET/CSF results in diverse populations enrolled at clinical trial sites. HIGHLIGHTS: Amyloid beta (Aß)42/Aß40, phosphorylated tau (p-tau)181, and p-tau 217 blood-based biomarkers predicted brain amyloid positivity. P-tau 217 was the strongest predictor of brain amyloid positivity. Biomarkers from diverse ethnic, racial, and clinical cohorts predicted brain amyloid positivity. Community-based populations have similar Alzheimer's disease (AD) biomarker levels as other populations. A prescreen process with blood-based assays may reduce the number of AD trial screen failures.

Challenges and progress in research, diagnostics, and therapeutics in Alzheimer's disease and related dementias.

The health, well-being, and financial security of Americans are greatly impacted by Alzheimer's disease. The forecast paints an upward trajectory with the number of Americans suffering from Alzheimer's disease and related dementia. To discuss the Alzheimer's crisis, The Senate Committee on Finance, Subcommittee on Health Care, held a hearing titled, "The Alzheimer's Crisis: Examining, Testing, and Treatment Pipelines and Fiscal Implications," on December 16, 2020. Here, we summarize and expand on the discussion of the panel and its review of recent progress, ongoing challenges associated with Alzheimer's disease, and potential initiatives that promise to speed progress in developing treatments and improving care.

Value-Generating Exploratory Trials in Neurodegenerative Dementias.

Drug development for Alzheimer disease and other neurodegenerative dementias, including frontotemporal dementia, has experienced a long history of phase 2 and phase 3 clinical trials that failed to show efficacy of investigational drugs. Despite differences in clinical and behavioral characteristics, these disorders have shared pathologies and face common challenges in designing early-phase trials that are predictive of late-stage success. Here, we discuss exploratory clinical trials in neurodegenerative dementias. These are generally phase 1b or phase 2a trials that are designed to assess pharmacologic effects and rely on biomarker outcomes, with shorter treatment durations and fewer patients than traditional phase 2 studies. Exploratory trials can establish go/no-go decision points, support proof of concept and dose selection, and terminate drugs that fail to show target engagement with suitable exposure and acceptable safety profiles. Early failure saves valuable resources including opportunity costs. This is especially important for programs in academia and small biotechnology companies but may be applied to high-risk projects in large pharmaceutical companies to achieve proof of concept more rapidly at lower costs than traditional approaches. Exploratory studies in a staged clinical development program may provide promising data to warrant the substantial resources needed to advance compounds through late-stage development. To optimize the design and application of exploratory trials, the Alzheimer's Drug Discovery Foundation and the Association for Frontotemporal Degeneration convened an advisory panel to provide recommendations on outcome measures and statistical considerations for these types of studies and study designs that can improve efficiency in clinical development.

Drug discovery and development: Role of basic biological research.

This article provides a brief overview of the processes of drug discovery and development. Our aim is to help scientists whose research may be relevant to drug discovery and/or development to frame their research report in a way that appropriately places their findings within the drug discovery and development process and thereby support effective translation of preclinical research to humans. One overall theme of our article is that the process is sufficiently long, complex, and expensive so that many biological targets must be considered for every new medicine eventually approved for clinical use and new research tools may be needed to investigate each new target. Studies that contribute to solving any of the many scientific and operational issues involved in the development process can improve the efficiency of the process. An awareness of these issues allows the early implementation of measures to increase the opportunity for success. As editors of the journal, we encourage submission of research reports that provide data relevant to the issues presented.

Randomized controlled trials in mild cognitive impairment: Sources of variability.

OBJECTIVE: To examine the variability in performance among placebo groups in randomized controlled trials for mild cognitive impairment (MCI). METHODS: Placebo group data were obtained from 2 National Institute on Aging (NIA) MCI randomized controlled trials, the Alzheimer's Disease Cooperative Study (ADCS) MCI trial and the Alzheimer's Disease Neuroimaging Initiative (ADNI), which is a simulated clinical trial, in addition to industry-sponsored clinical trials involving rivastigmine, galantamine, rofecoxib, and donepezil. The data were collated for common measurement instruments. The performance of the placebo participants from these studies was tracked on the Alzheimer's Disease Assessment Scale-cognitive subscale, Mini-Mental State Examination, and Clinical Dementia Rating-sum of boxes, and for progression on these measures to prespecified clinical study endpoints. APOE status, where available, was also analyzed for its effects. RESULTS: The progression to clinical endpoints varied a great deal among the trials. The expected performances were seen for the participants in the 2 NIA trials, ADCS and ADNI, with generally worsening of performance over time; however, the industry-sponsored trials largely showed stable or improved performance in their placebo participants. APOE4 carrier status influenced results in an expected fashion on the study outcomes, including rates of progression and cognitive subscales. CONCLUSIONS: In spite of apparently similar criteria for MCI being adopted by the 7 studies, the implementation of the criteria varied a great deal. Several explanations including instruments used to characterize participants and variability among study populations contributed to the findings.

Standardizing the use of the Continuous Performance Test in schizophrenia research: a validation study.

BACKGROUND: The Continuous Performance Test (CPT) has emerged as the most commonly administered measure of sustained attention, but use of discrepant versions reduces the ability of researchers and clinicians to accurately draw cross-study conclusions. In an effort to standardize use of the CPT, this study compared four versions of the Identical Pairs CPT for their reliability and ability to discriminate between patients with schizophrenia and healthy volunteers. The relationship of performance on the different versions of the CPT with measures of psychopathology, functioning, and other aspects of cognition was also examined. METHODS: Performance on the 2-digit, 3-digit, 4-digit, and Shapes Identical Pairs CPT was assessed at three test sessions over five weeks, during which subjects also completed the Brief Assessment of Cognition in Schizophrenia (BACS) and questionnaires assessing psychopathology and functioning. RESULTS: All four CPTs discriminated between patients with schizophrenia and healthy volunteers, but there were no statistical differences in sensitivity among the versions. The 3-digit CPT showed non-statistical advantages in that it had high test-retest reliability, low potential for a ceiling effect, and a very low rate of false alarms. There were also moderate correlations between CPT performance and performance of the BACS subtests, but no significant correlations between CPT performance and measures of psychopathology and functioning. CONCLUSIONS: While all versions of the CPT tested here had good psychometric characteristics, the 3-digit CPT-IP has some advantages in repeated measures studies such as clinical trials.

The diagnosis of dementia due to Alzheimer's disease: recommendations from the National Institute on Aging-Alzheimer's Association workgroups on diagnostic guidelines for Alzheimer's disease.

The National Institute on Aging and the Alzheimer's Association charged a workgroup with the task of revising the 1984 criteria for Alzheimer's disease (AD) dementia. The workgroup sought to ensure that the revised criteria would be flexible enough to be used by both general healthcare providers without access to neuropsychological testing, advanced imaging, and cerebrospinal fluid measures, and specialized investigators involved in research or in clinical trial studies who would have these tools available. We present criteria for all-cause dementia and for AD dementia. We retained the general framework of probable AD dementia from the 1984 criteria. On the basis of the past 27 years of experience, we made several changes in the clinical criteria for the diagnosis. We also retained the term possible AD dementia, but redefined it in a manner more focused than before. Biomarker evidence was also integrated into the diagnostic formulations for probable and possible AD dementia for use in research settings. The core clinical criteria for AD dementia will continue to be the cornerstone of the diagnosis in clinical practice, but biomarker evidence is expected to enhance the pathophysiological specificity of the diagnosis of AD dementia. Much work lies ahead for validating the biomarker diagnosis of AD dementia.

Revision of the criteria for Alzheimer's disease: A symposium.

The current criteria for classification of Alzheimer's disease (AD) have deficiencies that limit drug development, research, and practice. The current standard for the clinical diagnosis of AD, the National Institute of Neurological and Communicative Disorders and Stroke (now known as the National Institute of Neurological Disorders and Stroke), and the Alzheimer's Disease and Related Disorders Association (now known as the Alzheimer's Association) criteria, are nearly 25 years old and have not been revised to incorporate advances in the epidemiology and genetics of AD, studies of clinicopathologic correlations and recent studies of potential diagnostic biomarkers. In a very real sense our ability to diagnose AD with a very high level of certainty has outpaced our current diagnostic criteria. The Alzheimer's Association Research Roundtable convened a meeting in April 2009 to discuss new data and technologies that could, with further development, enable improvements in the clinical diagnosis of AD, especially in its earliest and mildest stages. This meeting reviewed the current standards for detecting and defining the clinical presentation of AD and discussed areas that could contribute to earlier and more accurate definitive clinical diagnosis. These included clinical, neuropsychological, and other performance-based assessments, genetic contributions, and biochemical and neuroimaging biomarkers that could reflect AD pathology and lead to better ascertainment of AD, mild cognitive impairment, and presymptomatic AD.

Developing a national strategy to prevent dementia: Leon Thal Symposium 2009.

Among the major impediments to the design of clinical trials for the prevention of Alzheimer's disease (AD), the most critical is the lack of validated biomarkers, assessment tools, and algorithms that would facilitate identification of asymptomatic individuals with elevated risk who might be recruited as study volunteers. Thus, the Leon Thal Symposium 2009 (LTS'09), on October 27-28, 2009 in Las Vegas, Nevada, was convened to explore strategies to surmount the barriers in designing a multisite, comparative study to evaluate and validate various approaches for detecting and selecting asymptomatic people at risk for cognitive disorders/dementia. The deliberations of LTS'09 included presentations and reviews of different approaches (algorithms, biomarkers, or measures) for identifying asymptomatic individuals at elevated risk for AD who would be candidates for longitudinal or prevention studies. The key nested recommendations of LTS'09 included: (1) establishment of a National Database for Longitudinal Studies as a shared research core resource; (2) launch of a large collaborative study that will compare multiple screening approaches and biomarkers to determine the best method for identifying asymptomatic people at risk for AD; (3) initiation of a Global Database that extends the concept of the National Database for Longitudinal Studies for longitudinal studies beyond the United States; and (4) development of an educational campaign that will address public misconceptions about AD and promote healthy brain aging.

Atomoxetine augmentation of cholinesterase inhibitor therapy in patients with Alzheimer disease: 6-month, randomized, double-blind, placebo-controlled, parallel-trial study.

OBJECTIVES: To examine the efficacy and tolerability of atomoxetine (ATX) in improving cognitive performance of patients with Alzheimer dementia. DESIGN: A randomized, double-blind, placebo (PLA)-controlled, parallel-groups study, starting with a 5-33-day screening and evaluation period, followed by a 6-month treatment period. SETTING: Eight independent or academic outpatient clinics in the United States. PARTICIPANTS: Male or female patients, aged 55 years and older, with mild-to-moderate Alzheimer disease (Mini-Mental State Examination score between 10 and 26) at baseline. INTERVENTION: ATX (25-80 mg/day) or PLA for up to 6 months, added to ongoing cholinesterase-inhibitor therapy. MEASUREMENTS: Alzheimer Disease Assessment Scale-Cognitive Portion (ADAS-Cog, primary measure), Clinician's Interview-Based Impression of Change score at end point, Neuropsychiatric Inventory, and Alzheimer's Disease Cooperative Study Inventory-Activities of Daily Living Inventory total score, safety measures (secondary measures). RESULTS: Patients' (N = 92) scores on assessments of cognitive function, global clinical impression, and neuropsychiatric symptoms were not significantly different between treatment groups. Neither group showed significant changes from baseline on the primary measure of efficacy, the ADAS-Cog. The ATX group showed a significantly greater increase of heart rate, and the mean increase in diastolic blood pressure and decrease in weight differed significantly from the decrease in pressure and weight increase in the PLA group. No other clinically meaningful safety results were obtained. CONCLUSIONS: Addition of ATX to ongoing cholinesterase-inhibitor therapy was generally well tolerated but did not significantly improve cognitive function.

A roadmap for the prevention of dementia II: Leon Thal Symposium 2008.

This document proposes an array of recommendations for a National Plan of Action to accelerate the discovery and development of therapies to delay or prevent the onset of disabling symptoms of Alzheimer's disease. A number of key scientific and public-policy needs identified in this document will be incorporated by the Alzheimer Study Group into a broader National Alzheimer's Strategic Plan, which will be presented to the 111th Congress and the Obama administration in March 2009. The Alzheimer's Strategic Plan is expected to include additional recommendations for governance, family support, healthcare, and delivery of social services.

Consortium to Establish a Registry for Alzheimer's Disease (CERAD): the first twenty years.

The Consortium to Establish a Registry for Alzheimer's Disease (CERAD) was funded by the National Institute on Aging in 1986 to develop standardized, validated measures for the assessment of Alzheimer's disease (AD). The present report describes the measures that CERAD developed during its first decade and their continued use in their original and translated forms. These measures include clinical, neuropsychological, neuropathologic, and behavioral assessments of AD and also assessment of family history and parkinsonism in AD. An approach to evaluating neuroimages did not meet the standards desired. Further evaluations that could not be completed because of lack of funding (but where some materials are available) include evaluation of very severe AD and of service use and need by patient and caregiver. The information that was developed in the U.S. and abroad permits standardized assessment of AD in clinical practice, facilitates epidemiologic studies, and provides information valuable for individual and public health planning. CERAD materials and data remain available for those wishing to use them.

A perspective on risks that impede development of drugs to modify the course of Alzheimer's disease: can they be reduced?

Discovery, development, and testing of new drugs with novel mechanisms and new indications are extremely risky. The number of new drugs introduced into clinical practice with new mechanisms and novel indications has not increased during recent years in spite of advances in biologic science. The sources of uncertainty leading to failure in drug development are discussed in three categories: biologic or target risk, clinical development uncertainty, and market uncertainty. Efforts to develop drugs that modify the course of Alzheimer's disease and/or delay the initial clinical manifestations of disease are subject to all three types of risk. Opportunities for government, academic researchers, advocacy groups, and the pharmaceutical industry to mitigate some of these risks and possibly speed the introduction of new therapies are mentioned.

Efficacy of duloxetine on cognition, depression, and pain in elderly patients with major depressive disorder: an 8-week, double-blind, placebo-controlled trial.

OBJECTIVE: This study compared the effects of duloxetine, 60 mg/day, versus placebo on cognition, depression, and pain in elderly patients with recurrent major depressive disorder. METHOD: Patients were randomly assigned (2:1) to duloxetine, 60 mg/day (N=207), or placebo (N=104) for 8 weeks in a double-blind study. The primary outcome measure was a prespecified composite cognitive score composed of four individual tests. Secondary measures included the Geriatric Depression Scale, the Hamilton Depression Rating Scale, the Visual Analogue Scale assessing pain, and standard safety and tolerability assessments. RESULTS: Patients had a median age of 72 years (range=65-90). Duloxetine demonstrated significantly greater improvement in the composite cognitive score versus placebo (least-squares mean change from baseline to endpoint: 1.95 versus 0.76), driven by improved verbal learning and memory. Duloxetine treatment showed significantly greater baseline-to-endpoint reductions in both Hamilton depression scale (-6.49 versus -3.72) and Geriatric Depression Scale (-4.07 versus -1.34) total scores compared with placebo. Hamilton depression scale response (37.3% versus 18.6%) and remission (27.4% versus 14.7%) rates at endpoint were significantly higher for duloxetine than for placebo. Duloxetine significantly improved Visual Analogue Scale scores for back pain and time in pain while awake versus placebo. Significantly fewer patients receiving duloxetine withdrew from the study because of lack of efficacy (2.9% versus 9.6%); the incidences of discontinuation due to adverse events were similar for duloxetine and placebo (9.7% versus 8.7%). CONCLUSIONS: Duloxetine improved cognition, depression, and some pain measures and was safe and well tolerated in elderly patients with recurrent major depressive disorder.

Optimal design of clinical trials for drugs designed to slow the course of Alzheimer's disease.

Compounds now in clinical development are hypothesized to slow the clinical progression and pathogenesis of Alzheimer's disease (AD) by their effects to diminish production, increase clearance, or decrease aggregation of amyloid beta protein. Options for investigating the effects of these and other drugs on clinical progression and pathogenesis of AD were examined at a conference that included: (1) a review of experimental methods used to investigate disease-modifying drugs for multiple sclerosis, rheumatoid arthritis, cardiovascular disease, and osteoporosis; (2) discussion of possible study designs and outcome measures for trials in patients with AD; and (3) discussion of biomarkers available for AD. There is no uniformly best way to investigate a drug's impact on AD progression but characteristics of studies supportive of a disease-slowing effect can be specified. Relevant clinical outcomes in drug-treated patients versus placebo-treated patients should be compared over at least 1 and possibly as long as 2 years with biomarkers reflective of pathogenesis and of the drug's mechanistic effects measured concurrently.

Type 2 diabetes is negatively associated with Alzheimer's disease neuropathology.

BACKGROUND: In cross-sectional and longitudinal studies, type 2 diabetes has been positively associated with the risk of Alzheimer's disease (AD). The present descriptive study compared diabetic and nondiabetic subjects on the severity of neuritic plaques and neurofibrillary tangles (NFTs) in the cerebral cortex and in the hippocampus. METHODS: The study included specimens from 385 consecutive autopsies of residents of a nursing home (15.8% diabetics). Mean age at death = 84 years [standard deviation (SD) = 10], 66% were female, Clinical Dementia Rating mean = 3.0 (SD = 1.6), and 32.5% had an APOE4 allele. Additional analyses limited the sample to 268 subjects (14.1% diabetics) without neuropathology other than AD. RESULTS: Analyses of covariance controlling for age at death, dementia severity (Clinical Dementia Rating score), and APOE4 allele indicated that diabetics had significantly fewer neuritic plaques (p =.008) and NFTs (p =.047) in the cerebral cortex than did nondiabetics. In the hippocampus, diabetics had significantly lower plaque ratings than did nondiabetics (p =.019), but the lower ratings of NFTs did not achieve statistical significance (p =.082). In the entire sample, diabetics had significantly less AD-associated neuropathology in all four analyses. CONCLUSIONS: These results raise the possibility that the varied associations observed between diabetes and AD may be specific to as yet ill-defined subgroups of dementia and diabetic patients or may be more characteristic of younger patients than of those who survive to a mean age of 84 years. Future studies are encouraged to examine a variety of other characteristics such as age that may interact with diabetes affecting the incidence of AD.

Neuropsychological test performance in healthy volunteers before and after donepezil administration.

Participants in early Phase I clinical trials for drugs designed to enhance cognition are typically healthy volunteers. If improvement can be detected with a battery of cognitive tests in healthy volunteers, such a battery could be a pharmacodynamic marker in the future development of the compound for treatment of cognitive disorders. In the present exploratory study, a battery of neuropsychological (NP) tests was used to determine if changes in cognition from a pharmacological intervention could be detected in healthy volunteers. A drug with known cognitive-enhancing effects in Alzheimer's disease, donepezil, was compared with placebo and no treatment arms. Carry-over effects of repeated test administration were also assessed. In this double-blind study, 27 healthy adults were randomized into one of three arms (eight donepezil, nine placebo and 10 no treatment) and completed 14 days of donepezil (5 mg q.h.s.) or placebo (q.h.s.). A battery of NP tests was administered on days 0, 7, 14 (randomization), 21, 28 (end of treatment) and 42 (washout). There were no differences in performance between the placebo and the no treatment arms. However, on day 21, subjects in the donepezil group performed slightly but significantly worse on some tests of speed, attention and memory (p < 0.05) compared to the pooled control group (placebo and no treatment arms). No improvement in performance was present while on donepezil at days 21 or 28. While the results are counter to expectations, some tests in the battery did detect a cognitive change (transient mild worsening during drug administration) in healthy volunteers.