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

Improving community health-care systems' early detection of cognitive decline and dementia

Preliminary estimates suggest that current global health-care systems lack the resource capacity to provide persons with dementia timely access to diagnosis, treatment, and care. There is an increasing need to improve timely identification of individuals who will likely progress to Alzheimer's disease (AD) dementia particularly among under-represented, underserved, and vulnerable populations. The rapidly evolving area of bioinformatics of health system data and the emergence of fluid-based biomarkers for pre-symptomatic AD may provide an innovative strategic option for health system planners. A think-tank style meeting entitled "The Campaign to Prevent Alzheimer's Disease Work Group on Community-Based Detection and Assessment of Cognitive Decline" developed recommendations to guide future sustainability activities, public policy campaigns, and implementation pilots. The group identified and explored different pathways of community-based detection using electronic health records, from different international health-care systems, to detect and surveil individuals with early possible cognitive impairment.

Alzheimer’s disease – the journey of a healthy brain into organ failure

As the most common dementia, Alzheimer’s disease (AD) exacts an immense personal, societal, and economic toll. AD was first described at the neuropathological level in the early 1900s. Today, we have mechanistic insight into select aspects of AD pathogenesis and have the ability to clinically detect and diagnose AD and underlying AD pathologies in living patients. These insights demonstrate that AD is a complex, insidious, degenerative proteinopathy triggered by Aβ aggregate formation. Over time Aβ pathology drives neurofibrillary tangle (NFT) pathology, dysfunction of virtually all cell types in the brain, and ultimately, overt neurodegeneration. Yet, large gaps in our knowledge of AD pathophysiology and huge unmet medical need remain. Though we largely conceptualize AD as a disease of aging, heritable and non-heritable factors impact brain physiology, either continuously or at specific time points during the lifespan, and thereby alter risk for devolvement of AD. Herein, I describe the lifelong journey of a healthy brain from birth to death with AD, while acknowledging the many knowledge gaps that remain regarding our understanding of AD pathogenesis. To ensure the current lexicon surrounding AD changes from inevitable, incurable, and poorly manageable to a lexicon of preventable, curable, and manageable we must address these knowledge gaps, develop therapies that have a bigger impact on clinical symptoms or progression of disease and use these interventions at the appropriate stage of disease.

Disease-Modifying Therapies for Alzheimer's Disease: More Questions than Answers

Scientific advances over the last four decades have steadily infused the Alzheimer's disease (AD) field with great optimism that therapies targeting Aβ, amyloid, tau, and innate immune activation states in the brain would provide disease modification. Unfortunately, this optimistic scenario has not yet played out. Though a recent approval of the anti-Aβ aggregate binding antibody, Aduhelm (aducanumab), as a "disease-modifying therapy for AD" is viewed by some as a breakthrough, many remain unconvinced by the data underlying this approval. Collectively, we have not succeeded in changing AD from a largely untreatable, inevitable, and incurable disease to a treatable, preventable, and curable one. Here, I will review the major foci of the AD "disease-modifying" therapeutic pipeline and some of the "open questions" that remain in terms of these therapeutic approaches. I will conclude the review by discussing how we, as a field, might adjust our approach, learning from our past failures to ensure future success.

Alzheimer Disease Worries, Fears, and Stigma and Their Relationship to Genetic and Interventional Research Engagement

BACKGROUND

Alzheimer disease (AD) research increasingly requires healthy individuals willing to undergo genetic testing.

OBJECTIVE

This study seeks to: (1) describe older adults' beliefs about AD genetic testing, worry about AD, and fear of AD stigma, and (2) explore how these constructs relate to research participation.

METHODS

Surveys were sent to participants active in AD-observational research and those that were not. Three measures of research participation were explored: (1) being a current research participant, (2) self-report of clinical trial participation, and (3) expressing genetic registry interest.

RESULTS

The majority of the 502 respondents perceived greater benefit than the risk associated with AD genetic testing. AD worry and perceptions of AD stigma were low. Higher levels of AD worry and lower perceptions of AD stigma were associated with being a current AD research volunteer. AD worry and stigma were unrelated to clinical trial participation or genetic registry interest; these research participation measures were associated with AD genetic testing benefit.

CONCLUSIONS

Beliefs about AD genetic testing, AD worry, and AD stigma are related to research participation, but relationships vary based on the research participation investigated. Future work should identify how these findings can inform outreach and recruitment efforts.

The Italian INTERCEPTOR Project: From the Early Identification of Patients Eligible for Prescription of Antidementia Drugs to a Nationwide Organizational Model for Early Alzheimer's Disease Diagnosis

Alzheimer's disease is the most common age-related neurodegenerative disorder and its burden on patients, families, and society grows significantly with lifespan. Early modifications of risk-enhancing lifestyles and treatment initiation expand personal autonomy and reduce management costs. Many clinical trials with potentially disease-modifying drugs are devoted to mild cognitive impairment (MCI) prodromal-to-Alzheimer's disease. The identification of biomarkers for early diagnosis may thus be crucial for early intervention and identification of high-risk subjects, the most appropriate target of new drugs as soon as they will be discovered. INTERCEPTOR is a strategic project by the Italian Ministry of Health and the Italian Medicines Agency (AIFA), aiming to validate the best combination (highly accurate, non-invasive, available on the whole national territory and financially sustainable) of biomarkers and organizational model for early diagnosis. 500 MCI subjects will be enrolled at baseline and followed-up for 3 years for at least 400 of them in order to define a "hub & spoke" nationwide model with recruiting (spokes) centers for MCI identification and expert (hubs) centers for risk diagnosis.

Predicting Cognitive Decline and Dementia with the Newly Normed SKT Short Cognitive Performance Test

Objective

The aim of this article was to determine the criterion-related validity of the newly normed SKT (Syndrom-Kurztest) Short Cognitive Performance Test with the onset of dementia as the predicted criterion.

Methods

The cognitive ability was tested with the SKT in a sample of 546 cognitively healthy adults aged 65-85 years. New cases of mild cognitive impairment (MCI) or dementia were determined in 3 follow-up investigations at 1-year intervals. Each participant's cognitive status was rated on the Clinical Dementia Rating Scale. The cognitive status according to the SKT is presented in terms of a traffic light system.

Results

Based on Kaplan-Meier estimators, the trajectories of the different SKT traffic light labels were investigated over 3 years. The trajectories were significantly different, representing differential risks for dementia onset. In comparison to the green group, the hazard ratio (HR) for the development of dementia and MCI amounted to HR 6.63 (95% CI 2.75-15.96) and HR 2.34 (95% CI 1.37-3.99), respectively, in the yellow group, and to HR 25.40 (95% CI 10.73-60.14) and HR 3.83 (95% CI 1.86-7.86), respectively, in the red group.

Conclusions

The newly normed SKT showed a high predictive validity for the onset of dementia.

A Late Life Risk Index for Severe Cognitive Impairment in Mexico

BACKGROUND

Several dementia risk indices have been developed for older adults in high-income countries. However, no index has been developed for populations in low- or middle-income countries.

OBJECTIVE

To create a risk index for predicting severe cognitive impairment among adults aged ≥60 in Mexico and to compare the accuracy of this index to the Dementia Screening Indicator (DSI).

METHODS

This study included 3,002 participants from the Mexican Health and Aging Study (MHAS) interviewed in 2001 and 2012. The MHAS risk index included sociodemographic, health, and functional characteristics collected in 2001. A point value based on the beta coefficients from a multivariable logistic regression model was assigned to each risk factor and the total score was calculated.

RESULTS

The MHAS risk index (AUC = 0.74 95% CI = 0.70-0.77) and DSI (AUC = 0.72 95% CI = 0.69-0.77) had similar accuracy for discriminating between participants who developed severe cognitive impairment from those who did not. A score of ≥16 on the MHAS risk index had a sensitivity of 0.69 (95% CI = 0.64-0.70) and specificity of 0.67 (95% CI = 0.66-0.69). A score of ≥23 on the DSI had a sensitivity of 0.56 (95% CI = 0.50-0.63) and specificity of 0.78 (95% CI = 0.76-0.79).

DISCUSSION

The MHAS risk index and DSI have moderate accuracy for predicting severe cognitive impairment among older adults in Mexico. This provides evidence that existing dementia risk indices may be applicable in low- and middle-income countries such as Mexico. Future research should seek to identify additional risk factors that can improve the accuracy of the MHAS risk index.

Alzheimer disease research in the 21st century: past and current failures, new perspectives and funding priorities

Much of Alzheimer disease (AD) research has been traditionally based on the use of animals, which have been extensively applied in an effort to both improve our understanding of the pathophysiological mechanisms of the disease and to test novel therapeutic approaches. However, decades of such research have not effectively translated into substantial therapeutic success for human patients. Here we critically discuss these issues in order to determine how existing human-based methods can be applied to study AD pathology and develop novel therapeutics. These methods, which include patient-derived cells, computational analysis and models, together with large-scale epidemiological studies represent novel and exciting tools to enhance and forward AD research. In particular, these methods are helping advance AD research by contributing multifactorial and multidimensional perspectives, especially considering the crucial role played by lifestyle risk factors in the determination of AD risk. In addition to research techniques, we also consider related pitfalls and flaws in the current research funding system. Conversely, we identify encouraging new trends in research and government policy. In light of these new research directions, we provide recommendations regarding prioritization of research funding. The goal of this document is to stimulate scientific and public discussion on the need to explore new avenues in AD research, considering outcome and ethics as core principles to reliably judge traditional research efforts and eventually undertake new research strategies.

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.

Pre-clinical cognitive phenotypes for Alzheimer disease: a latent profile approach

BACKGROUND

Cognitive profiles for pre-clinical Alzheimer disease (AD) can be used to identify groups of individuals at risk for disease and better characterize pre-clinical disease. Profiles or patterns of performance as pre-clinical phenotypes may be more useful than individual test scores or measures of global decline.

OBJECTIVE

To evaluate patterns of cognitive performance in cognitively normal individuals to derive latent profiles associated with later onset of disease using a combination of factor analysis and latent profile analysis.

METHODS

The National Alzheimer Coordinating Centers collect data, including a battery of neuropsychological tests, from participants at 29 National Institute on Aging-funded Alzheimer Disease Centers across the United States. Prior factor analyses of this battery demonstrated a four-factor structure comprising memory, attention, language, and executive function. Factor scores from these analyses were used in a latent profile approach to characterize cognition among a group of cognitively normal participants (N = 3,911). Associations between latent profiles and disease outcomes an average of 3 years later were evaluated with multinomial regression models. Similar analyses were used to determine predictors of profile membership.

RESULTS

Four groups were identified; each with distinct characteristics and significantly associated with later disease outcomes. Two groups were significantly associated with development of cognitive impairment. In post hoc analyses, both the Trail Making Test Part B, and a contrast score (Delayed Recall - Trails B), significantly predicted group membership and later cognitive impairment.

CONCLUSIONS

Latent profile analysis is a useful method to evaluate patterns of cognition in large samples for the identification of preclinical AD phenotypes; comparable results, however, can be achieved with very sensitive tests and contrast scores.

Community engagement in diverse populations for Alzheimer disease prevention trials

The recruitment of asymptomatic volunteers has been identified as a critical factor that is delaying the development and validation of preventive therapies for Alzheimer disease (AD). Typical recruitment strategies involve the use of convenience samples or soliciting participation of older adults with a family history of AD from clinics and outreach efforts. However, high-risk groups, such as ethnic/racial minorities, are traditionally less likely to be recruited for AD prevention studies, thus limiting the ability to generalize findings for a significant proportion of the aging population. A community-engagement approach was used to create a registry of 2311 research-ready, healthy adult volunteers who reflect the ethnically diverse local community. Furthermore, the registry's actual commitment to research was examined, through demonstrated participation rates in a clinical study. The approach had varying levels of success in establishing a large, diverse pool of individuals who are interested in participating in pharmacological prevention trials and meet the criteria for primary prevention research trials designed to delay the onset of AD. Our efforts suggest that entry criteria for the clinical trials need to be carefully considered to be inclusive of African Americans, and that sustained effort is needed to engage African Americans in pharmacological prevention approaches.

Was phenserine a failure or were investigators mislead by methods?

Over 200 Alzheimer's disease (AD) drug candidates have failed in development, and other neuropsychiatric trials have had their validity compromised. Studies suggest that methodological errors can be a source for these compromises and failures. We gained access to documentation for phenserine, an experimental AD drug that reached phase III clinical trials. The 06 Phase III trial was cited by the developers as grounds for their abandonment of the development. We compared evidence for interventions to control methodological errors and grounds for moving through phases of drug development to 40 other randomly selected AD developments we had studied. We analyzed methods and conditions of the 06 phenserine clinical trial, for biases able to account for its abandonment during development. The phenserine development failed to control error sources able to affect the outcomes. There are statistically significant relationships in the 06 clinical trial between outcomes at research sites and levels of variance, placebo group improvements and other factors. We conclude that phenserine was abandoned, at least in part, due to a clinical trial invalidated by relationships among its methods and outcomes.

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 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.

Structural imaging in early pre-states of dementia

In this review focus is on structural imaging in the Alzheimer's disease (AD) pre-states, particularly cognitively normal (CN) persons at future dementia risk. Findings in mild cognitive impairment (MCI) are described here only for comparison with CN. Cited literature evidence and commentary address issues of structural imaging alterations in CN that precede MCI and AD, regional patterns of such alterations, and the time relationship between structural imaging alterations and the appearance of symptoms of AD, issues relevant to the conduct of future AD prevention trials. This article is part of a Special Issue entitled: Imaging Brain Aging and Neurodegenerative disease.

Prospects for designating Alzheimer's disease research a national priority

This editorial evaluates the prospects of the National Alzheimer's Project Act (NAPA) succeeding to shape public policies that would substantially increase national expenditures for research on Alzheimer's disease. The essay identifies, in the context of 30-year history, some of the difficult challenges the NAPA Advisory Council must address and offers specific recommendations for an action plan by the Secretary, Department of Health and Human Services (DHHS).

Alzheimer's Prevention Initiative: a plan to accelerate the evaluation of presymptomatic treatments

There is an urgent need to find effective presymptomatic Alzheimer's disease (AD) treatments that reduce the risk of AD symptoms or prevent them completely. It currently takes too many healthy people, too much money and too many years to evaluate the range of promising presymptomatic treatments using clinical endpoints. We have used brain imaging and other measurements to track some of the earliest changes associated with the predisposition to AD. We have proposed the Alzheimer's Prevention Initiative (API) to evaluate investigational amyloid-modifying treatments in healthy people who, based on their age and genetic background, are at the highest imminent risk of developing symptomatic AD using brain imaging, cerebrospinal fluid (CSF), and cognitive endpoints. In one trial, we propose to study AD-causing presenilin 1 [PS1] mutation carriers from the world's largest early-onset AD kindred in Antioquia, Colombia, close to their estimated average age at clinical onset. In another trial, we propose to study apolipoprotein E (APOE) ε4 homozygotes (and possibly heterozygotes) close to their estimated average age at clinical onset. The API has several goals: 1) to evaluate investigational AD-modifying treatments sooner than otherwise possible; 2) to determine the extent to which the treatment's brain imaging and other biomarker effects predict a clinical benefit-information needed to help qualify biomarker endpoints for use in pivotal prevention trials; 3) to provide a better test of the amyloid hypothesis than clinical trials in symptomatic patients, when these treatments may be too little too late to exert their most profound effect; 4) to establish AD prevention registries needed to support these and other presymptomatic AD trials; and 5) to give those individuals at highest imminent risk of AD symptoms access to the most promising investigational treatments in clinical trials.

A multi-state model for the analysis of changes in cognitive scores over a fixed time interval

In this article, we present the novel approach of using a multi-state model to describe longitudinal changes in cognitive test scores. Scores are modelled according to a truncated Poisson distribution, conditional on survival to a fixed endpoint, with the Poisson mean dependent upon the baseline score and covariates. The model provides a unified treatment of the distribution of cognitive scores, taking into account baseline scores and survival. It offers a simple framework for the simultaneous estimation of the effect of covariates modulating these distributions, over different baseline scores. A distinguishing feature is that this approach permits estimation of the probabilities of transitions in different directions: improvements, declines and death. The basic model is characterised by four parameters, two of which represent cognitive transitions in survivors, both for individuals with no cognitive errors at baseline and for those with non-zero errors, within the range of test scores. The two other parameters represent corresponding likelihoods of death. The model is applied to an analysis of data from the Canadian Study of Health and Aging (1991-2001) to identify the risk of death, and of changes in cognitive function as assessed by errors in the Modified Mini-Mental State Examination. The model performance is compared with more conventional approaches, such as multivariate linear and polytomous regressions. This model can also be readily applied to a wide variety of other cognitive test scores and phenomena which change with age.

Addressing the challenges to successful recruitment and retention in Alzheimer's disease clinical trials

Among the key challenges in Alzheimer's disease drug development is the timely completion of clinical trials. Unfortunately, clinical trials often suffer from slow or insufficient enrollment. Successful clinical trial recruitment describes a balance between expeditiously achieving full enrollment and ensuring an appropriate study sample. Investigators face a number of challenges to the successful negotiation of this balance. The failure to address these challenges means that drug development may take more time and money and that trial results may not adequately represent drug efficacy or may not be applicable beyond the study. We review the challenges to recruitment and retention in Alzheimer's disease clinical trials and present a framework to address them.