The Return of Biomarker Results in Research: Balancing Complexity, Precision, and Ethical Responsibility

Recent research aimed at the discovery, integration, and communication of health outcome measures (or "biomarkers") in Alzheimer's disease has raised challenging questions related to whether, how and when results from these investigations should be disclosed to research participants. Reflecting the apparent heterogeneity of many neurodegenerative diseases, biomarker or other risk factor results are often probabilistic, interactive, multi-modal, and selective. Such characteristics make it very complex to summarize and communicate to clinicians, researchers, and research participants. Whereas the format and content of academic literature is well-managed by the peer-review process, reporting individualized results to participants involves complex, sensitive, and ethical considerations. This paper describes three key factors to consider in decisions about the return of results to research participants: complexity, precision, and responsibility. The paper also presents six practical recommendations for implementing meaningful and ethical communication with research participants.

Clinical research in dementia: A perspective on implementing innovation

The increasing global prevalence of dementia demands concrete actions that are aimed strategically at optimizing processes that drive clinical innovation. The first step in this direction requires outlining hurdles in the transition from research to practice. The different parties needed to support translational processes have communication mismatches; methodological gaps hamper evidence-based decision-making; and data are insufficient to provide reliable estimates of long-term health benefits and costs in decisional models. Pilot projects are tackling some of these gaps, but appropriate methods often still need to be devised or adapted to the dementia field. A consistent implementation perspective along the whole translational continuum, explicitly defined and shared among the relevant stakeholders, should overcome the "research-versus-adoption" dichotomy, and tackle the implementation cliff early on. Concrete next steps may consist of providing tools that support the effective participation of heterogeneous stakeholders and agreeing on a definition of clinical significance that facilitates the selection of proper outcome measures.

Revisiting the Cholinergic Hypothesis in Alzheimer's Disease: Emerging Evidence from Translational and Clinical Research

Scientific evidence collected over the past 4 decades suggests that a loss of cholinergic innervation in the cerebral cortex of patients with Alzheimer's disease is an early pathogenic event correlated with cognitive impairment. This evidence led to the formulation of the "Cholinergic Hypothesis of AD" and the development of cholinesterase inhibitor therapies. Although approved only as symptomatic therapies, recent studies suggest that long-term use of these drugs may also have disease-modifying benefits. A Cholinergic System Workgroup reassessed the role of the cholinergic system on AD pathogenesis in light of recent data, including neuroimaging data charting the progression of neurodegeneration in the cholinergic system and suggesting that cholinergic therapy may slow brain atrophy. Other pathways that contribute to cholinergic synaptic loss and their effect on cognitive impairment in AD were also reviewed. These studies indicate that the cholinergic system as one of several interacting systems failures that contribute to AD pathogenesis.

A roadmap to advance delirium research: Recommendations from the NIDUS Scientific Think Tank

Delirium is an acute disorder of attention and cognition. It occurs across the life span, yet it is particularly common among older adults, and is closely linked with underlying neurocognitive disorders. Evidence is mounting that intervening on delirium may represent an important opportunity for delaying the onset or progression of dementia. To accelerate the current understanding of delirium, the Network for Investigation of Delirium: Unifying Scientists (NIDUS) held a conference “Advancing Delirium Research: A Scientific Think Tank” in June 2019. This White Paper encompasses the major knowledge and research gaps identified at the conference: advancing delirium definition and measurement, understanding delirium pathophysiology, and prevention and treatment of delirium. A roadmap of research priorities is proposed to advance the field in a systematic, interdisciplinary, and coordinated fashion. A call is made for an international consortium and biobank targeted to delirium, as well as a public health campaign to advance the field.

The cholinergic system in the pathophysiology and treatment of Alzheimer's disease

Cholinergic synapses are ubiquitous in the human central nervous system. Their high density in the thalamus, striatum, limbic system, and neocortex suggest that cholinergic transmission is likely to be critically important for memory, learning, attention and other higher brain functions. Several lines of research suggest additional roles for cholinergic systems in overall brain homeostasis and plasticity. As such, the brain's cholinergic system occupies a central role in ongoing research related to normal cognition and age-related cognitive decline, including dementias such as Alzheimer's disease. The cholinergic hypothesis of Alzheimer's disease centres on the progressive loss of limbic and neocortical cholinergic innervation. Neurofibrillary degeneration in the basal forebrain is believed to be the primary cause for the dysfunction and death of forebrain cholinergic neurons, giving rise to a widespread presynaptic cholinergic denervation. Cholinesterase inhibitors increase the availability of acetylcholine at synapses in the brain and are one of the few drug therapies that have been proven clinically useful in the treatment of Alzheimer's disease dementia, thus validating the cholinergic system as an important therapeutic target in the disease. This review includes an overview of the role of the cholinergic system in cognition and an updated understanding of how cholinergic deficits in Alzheimer's disease interact with other aspects of disease pathophysiology, including plaques composed of amyloid-β proteins. This review also documents the benefits of cholinergic therapies at various stages of Alzheimer's disease and during long-term follow-up as visualized in novel imaging studies. The weight of the evidence supports the continued value of cholinergic drugs as a standard, cornerstone pharmacological approach in Alzheimer's disease, particularly as we look ahead to future combination therapies that address symptoms as well as disease progression.

WITHDRAWN: Revisiting the cholinergic hypothesis in Alzheimer's disease: Emerging evidence from translational and clinical research

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Politics of science: Progress toward prevention of the dementia-Alzheimer's syndrome

There exist many challenges hampering the discovery and development of effective interventions to prevent dementia. Three major trends have now intersected to influence the emerging interest in disease modifying therapies that may delay or halt dementia. The three crucial factors shaping this current focus are: (1) the emergence of the longevity revolution and the impact of a aging society, (2) the effects of the US Federal investment in research in advancing knowledge about the neurobiology of aging and dementia, and (3) the problem of US legislators and health policy makers to balance the allocation of evermore scarce research funding resources. The purpose of this essay is to provide a survey of the politics of science and to describe efforts to correctly manage the high level of expectations of both the patient and research communities. The perspective offered reviews the history and evolution of the ideas to treat or prevent dementia and Alzheimer's disease as a national strategic goal. The aim is to evaluate the interplay between science and formulation of public policy for setting research priority. We use the history of developing US National Institute of Aging's extramural research programs on brain aging and Alzheimer's disease (Khachaturian, 2006; 2007) as an initial case study.

Health economic evaluation of treatments for Alzheimer's disease: impact of new diagnostic criteria

The socio-economic impact of Alzheimer's disease (AD) and other dementias is enormous, and the potential economic challenges ahead are clear given the projected future numbers of individuals with these conditions. Because of the high prevalence and cost of dementia, it is very important to assess any intervention from a cost-effectiveness viewpoint. The diagnostic criteria for preclinical AD suggested by the National Institute on Aging and Alzheimer's Association workgroups in combination with the goal of effective disease-modifying treatment (DMT) are, however, a challenge for clinical practice and for the design of clinical trials. Key issues for future cost-effectiveness studies include the following: (i) the consequences for patients if diagnosis is shifted from AD-dementia to predementia states, (ii) bridging the gap between clinical trial populations and patients treated in clinical practice, (iii) translation of clinical trial end-points into measures that are meaningful to patients and policymakers/payers and (iv) how to measure long-term effects. To improve cost-effectiveness studies, long-term population-based data on disease progression, costs and outcomes in clinical practice are needed not only in dementia but also in predementia states. Reliable surrogate end-points in clinical trials that are sensitive to detect effects even in predementia states are also essential as well as robust and validated modelling methods from predementia states that also take into account comorbidities and age. Finally, the ethical consequences of early diagnosis should be considered.

Advances in the prevention of Alzheimer's disease and dementia

BACKGROUND

Definitions and diagnostic criteria for all medical conditions are regularly subjected to reviews and revisions as knowledge advances. In the field of Alzheimer's disease (AD) research, it has taken almost three decades for diagnostic nomenclature to undergo major re-examination. The shift towards presymptomatic and pre-dementia stages of AD has brought prevention and treatment trials much closer to each other than before.

METHODS

Here we discuss: (i) the impact of diagnostic reliability on the possibilities for developing preventive strategies for AD; (ii) the scientific evidence to support moving from observation to action; (iii) ongoing intervention studies; and (iv) the methodological issues and prospects for balancing strategies for high-risk individuals with those for broad population-based prevention.

RESULTS

The associations between neuropathology and cognition are still not entirely clear. In addition, the risk factors for AD dementia and the neuropathological hallmarks of AD may not necessarily be the same. Cognitive impairment has a clearer clinical significance and should therefore remain the main focus of prevention. Risk/protective factors for dementia/AD need to be studied from a life-course perspective. New approaches in prevention trials include enrichment strategies based on genetic risk factors or beta-amyloid biomarkers (at least four ongoing pharmacological trials), and multidomain interventions simultaneously targeting various vascular and lifestyle-related risk factors (at least three ongoing trials). Experience from prevention programmes in other chronic diseases can provide additional methodological improvements.

CONCLUSIONS

Building infrastructures for international collaborations is necessary for managing the worldwide public health problem of AD and dementia. The International Database on Aging and Dementia (IDAD) and the European Dementia Prevention Initiative (EDPI) are examples of ongoing international efforts aiming to improve the methodology of preventive studies and provide the basis for larger intervention trials.

Can we prevent Alzheimer's disease? Secondary "prevention" trials in Alzheimer's disease

Current research including the basic biology of Alzheimer's disease (AD) provides a foundation to explore whether our current state of knowledge is sufficient to initiate prevention studies and allow us to believe prevention of AD is possible. Current research and recently revised criteria for the diagnosis of AD by the National Institutes on Aging and the Alzheimer's Association suggest a continuum of disease from preclinical asymptomatic to symptomatic Alzheimer's dementia. In light of these revised criteria, the possibility of secondary prevention and even primary prevention is under discussion. The Alzheimer's Association Research Roundtable convened a meeting to discuss the rationale and feasibility of conducting secondary prevention trials in AD.

Advancing Alzheimer's disease diagnosis, treatment, and care: recommendations from the Ware Invitational Summit

To address the pending public health crisis due to Alzheimer's disease (AD) and related neurodegenerative disorders, the Marian S. Ware Alzheimer Program at the University of Pennsylvania held a meeting entitled "State of the Science Conference on the Advancement of Alzheimer's Diagnosis, Treatment and Care," on June 21-22, 2012. The meeting comprised four workgroups focusing on Biomarkers; Clinical Care and Health Services Research; Drug Development; and Health Economics, Policy, and Ethics. The workgroups shared, discussed, and compiled an integrated set of priorities, recommendations, and action plans, which are presented in this article.

The epidemiology of Alzheimer's disease: laying the foundation for drug design, conduct, and analysis of clinical trials

Epidemiological studies increasingly inform Alzheimer's disease (AD) public health impact, prevention strategies, drug targets, therapeutic interventions, and clinical trial design. For this reason, the Alzheimer's Association Research Roundtable convened an international group of AD experts with experience in conducting both observational and clinical trials for a meeting on October 19 and 20, 2010, in Washington, DC, to discuss the role of epidemiologic studies in AD research and therapeutic advances. Topics included wellness markers and risk factors, with a focus on special populations such as those at elevated risk, super agers, and underserved populations. Discussions also highlighted lessons learned from observational studies of aging, cardiovascular disease, and other disease areas, as well as how new technologies have enabled the gathering of data relevant to drug development and clinical trial conduct.

The draft "National Plan" to address Alzheimer's disease - National Alzheimer's Project Act (NAPA)

This perspective updates the status of the "National Plan to Address Alzheimer's Disease" and the recommendations of the NAPA Advisory Council's Sub-committee on Research. Here, we identify some of the critical issues the future reiterations of the National Plan should consider during implementation phase of the plan. The Journal invites the scientific community to contribute additional ideas and suggestions towards a national research initiative.

Neuropsychiatric symptoms in Alzheimer's disease

Neuropsychiatric symptoms (NPS) are core features of Alzheimer's disease and related dementias. Once thought to emerge primarily in people with late-stage disease, these symptoms are currently known to manifest commonly in very early disease and in prodromal phases, such as mild cognitive impairment. Despite decades of research, reliable treatments for dementia-associated NPS have not been found, and those that are in widespread use present notable risks for people using these medications. An Alzheimer's Association Research Roundtable was convened in the spring of 2010 to review what is known about NPS in Alzheimer's disease, to discuss classification and underlying neuropathogenesis and vulnerabilities, and to formulate recommendations for new approaches to tailored therapeutics.

Neuropsychiatric symptoms in Alzheimer's disease

Neuropsychiatric symptoms (NPS) are core features of Alzheimer's disease and related dementias. Once thought to emerge primarily in people with late-stage disease, these symptoms are currently known to manifest commonly in very early disease and in prodromal phases, such as mild cognitive impairment. Despite decades of research, reliable treatments for dementia-associated NPS have not been found, and those that are in widespread use present notable risks for people using these medications. An Alzheimer's Association Research Roundtable was convened in the spring of 2010 to review what is known about NPS in Alzheimer's disease, to discuss classification and underlying neuropathogenesis and vulnerabilities, and to formulate recommendations for new approaches to tailored therapeutics.

Countrywide strategic plans on Alzheimer's disease: developing the framework for the international battle against Alzheimer's disease

As the world's population ages, countries must prepare for the significant impact Alzheimer's disease will have on their health systems, their economies, and their citizens. In anticipation of major global demographic changes, many countries in the G-20 since 2000 have begun to develop and enact plans to address Alzheimer's disease as a national priority. However, even with nearly half of these participating countries having plans in place, there has been little research done to quantify the value of enacting a countrywide plan on this disease. In this review, we summarize recent national plans (from the year 2000 and beyond) and any results stemming from their respective recommendations and activities.

Global issues in drug development for Alzheimer's disease

The number of clinical trials for Alzheimer's disease conducted outside the United States in a broad array of countries is increasing. As the number of compounds ready for clinical testing increases, and as trials become longer and more complex, this trend is expected to grow. The cultural and ethical context of global clinical trials, potential benefits for those involved, and practical approaches to obstacles generated by these global trials were discussed at a meeting of the Alzheimer's Association Research Roundtable. Regulatory issues, including regional differences in study registration procedures, rules for collecting and reporting serious adverse events, requirements for national identity of study populations, and regulatory audits were also discussed by individuals who are knowledgeable about global clinical trials for Alzheimer's disease.

Developing a global strategy to prevent Alzheimer's disease: Leon Thal Symposium 2010

The fourth Leon Thal Symposium (LTS2010) was convened in Toulouse, France, on November 3, 2010. This symposium reviewed design parameters that are necessary to develop comprehensive national databases on healthy aging. Such datasets offer the potential to serve as the foundation for a systems-approach to solve the dual public health problems of: (1) early detection of people who are at elevated risk for Alzheimer's disease, and (2) the development of interventions to delay onset of, or prevent, late-life dementia. The symposium considered three interrelated components of a National Database for Longitudinal Studies on Healthy Aging as follows: (a) a registry of healthy aging adults; (b) refined computer-based assessments for data gathering, including assessments of behavioral/memory changes associated with aging that are appropriate for broad use in nonexpert settings; and (c) high performance computing/supercomputer-based approaches for health data modeling and mining.

Assessment of cognition in mild cognitive impairment: a comparative study

The demand for rapidly administered, sensitive, and reliable cognitive assessments that are specifically designed for identifying individuals in the earliest stages of cognitive decline (and to measure subtle change over time) has escalated as the emphasis in Alzheimer's disease clinical research has shifted from clinical diagnosis and treatment toward the goal of developing presymptomatic neuroprotective therapies. To meet these changing clinical requirements, cognitive measures or tailored batteries of tests must be validated and determined to be fit-for-use for the discrimination between cognitively healthy individuals and persons who are experiencing very subtle cognitive changes that likely signal the emergence of early mild cognitive impairment. We sought to collect and review data systematically from a wide variety of (mostly computer-administered) cognitive measures, all of which are currently marketed or distributed with the claims that these instruments are sensitive and reliable for the early identification of disease or, if untested for this purpose, are promising tools based on other variables. The survey responses for 16 measures/batteries are presented in brief in this review; full survey responses and summary tables are archived and publicly available on the Campaign to Prevent Alzheimer's Disease by 2020 Web site (http://pad2020.org). A decision tree diagram highlighting critical decision points for selecting measures to meet varying clinical trials requirements has also been provided. Ultimately, the survey questionnaire, framework, and decision guidelines provided in this review should remain as useful aids for the evaluation of any new or updated sets of instruments in the years to come.

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.

Comparison of clinical and neuropathologic diagnoses of Alzheimer's disease in 3 epidemiologic samples

BACKGROUND

Studies of dementia in populations avoid many of the selection biases in clinical samples but require special evaluation and diagnostic methods to obtain high participation rates. To address this issue, we developed a unique in-home dementia assessment. We assessed validity of these assessments using neuropathologic confirmation of the clinical diagnosis in 3 epidemiologic samples.

METHODS

Subjects were 175 participants in 3 ongoing studies of dementia. Two were population based and identified dementia by cognitive screening. The third study sought volunteers via advertisements. Dementia evaluations were then conducted at the participants' residences by specially trained nurses and psychometricians. Evaluation results were interpreted, and preliminary diagnoses were assigned by a geropsychiatrist or neurologist and a psychologist. Final diagnoses were assigned by a consensus panel of neurologists, geropsychiatrists, and psychologists. We compared the clinical diagnoses with the gold-standard neuropathologic diagnoses for those participants who subsequently underwent autopsy.

RESULTS

Among the demented, the sensitivity of a clinical diagnosis of probable or possible Alzheimer's disease (AD) was 93% across the 3 studies. The rate of overall diagnostic agreement was 81%. Measures of agreement did not differ meaningfully across varying levels of dementia severity.

CONCLUSIONS

Rates of neuropathologic confirmation for clinical AD diagnoses in these studies were similar to those reported from clinic-based samples. These results support the validity of clinical diagnoses of AD from a structured in-home assessment of community dwelling and institutionalized individuals using relatively economical methods of dementia screening and assessment.

Creating a transatlantic research enterprise for preventing Alzheimer's disease

In recognition of the global problem posed by Alzheimer's disease and other dementias, an international think-tank meeting was convened by Biocat, the Pasqual Maragall Foundation, and the Lou Ruvo Brain Institute in February 2009. The meeting initiated the planning of a European Union-North American collaborative research enterprise to expedite the delay and ultimate prevention of dementing disorders. The key aim is to build parallel and complementary research infrastructure that will support international standardization and inter-operability among researchers in both continents. The meeting identified major challenges, opportunities for research resources and support, integration with ongoing efforts, and identification of key domains to influence the design and administration of the enterprise.

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.