Cognition, function, and prevalent dementia in centenarians and near-centenarians: An individual participant data (IPD) meta-analysis of 18 studies.

INTRODUCTION: There are limited data on prevalence of dementia in centenarians and near-centenarians (C/NC), its determinants, and whether the risk of dementia continues to rise beyond 100. METHODS: Participant-level data were obtained from 18 community-based studies (N = 4427) in 11 countries that included individuals ≥95 years. A harmonization protocol was applied to cognitive and functional impairments, and a meta-analysis was performed. RESULTS: The mean age was 98.3 years (SD = 2.67); 79% were women. After adjusting for age, sex, and education, dementia prevalence was 53.2% in women and 45.5% in men, with risk continuing to increase with age. Education (OR 0.95;0.92-0.98) was protective, as was hypertension (odds ratio [OR] 0.51;0.35-0.74) in five studies. Dementia was not associated with diabetes, vision and hearing impairments, smoking, and body mass index (BMI). DISCUSSION: Among the exceptional old, dementia prevalence remains higher in the older participants. Education was protective against dementia, but other factors for dementia-free survival in C/NC remain to be understood.

Retention of Alzheimer Disease Research Participants.

INTRODUCTION: Participant retention is important to maintaining statistical power, minimizing bias, and preventing scientific error in Alzheimer disease and related dementias research. METHODS: We surveyed representative investigators from NIH-funded Alzheimer's Disease Research Centers (ADRC), querying their use of retention tactics across 12 strategies. We compared survey results to data from the National Alzheimer's Coordinating Center for each center. We used a generalized estimating equation with independent working covariance model and empirical standard errors to assess relationships between survey results and rates of retention, controlling for participant characteristics. RESULTS: Twenty-five (83%) responding ADRCs employed an average 42 (SD=7) retention tactics. In a multivariable model that accounted for participant characteristics, the number of retention tactics used by a center was associated with participant retention (odds ratio=1.68, 95% confidence interval: 1.42, 1.98; P<0.001 for the middle compared with the lowest tertile survey scores; odds ratio=1.59, 95% confidence interval: 1.30, 1.94; P<0.001 for the highest compared with the lowest tertile survey scores) at the first follow-up visit. Participant characteristics such as normal cognition diagnosis, older age, higher education, and Caucasian race were also associated with higher retention. CONCLUSIONS: Retention in clinical research is more likely to be achieved by employing a variety of tactics.

Use of nonintrusive sensor-based information and communication technology for real-world evidence for clinical trials in dementia.

Cognitive function is an important end point of treatments in dementia clinical trials. Measuring cognitive function by standardized tests, however, is biased toward highly constrained environments (such as hospitals) in selected samples. Patient-powered real-world evidence using information and communication technology devices, including environmental and wearable sensors, may help to overcome these limitations. This position paper describes current and novel information and communication technology devices and algorithms to monitor behavior and function in people with prodromal and manifest stages of dementia continuously, and discusses clinical, technological, ethical, regulatory, and user-centered requirements for collecting real-world evidence in future randomized controlled trials. Challenges of data safety, quality, and privacy and regulatory requirements need to be addressed by future smart sensor technologies. When these requirements are satisfied, these technologies will provide access to truly user relevant outcomes and broader cohorts of participants than currently sampled in clinical trials.

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.

Sex differences in the association of alcohol with cognitive decline and brain pathology in a cohort of octogenarians.

RATIONALE: The beneficial effects of moderate alcohol may differ in aging men versus women. OBJECTIVES: Cognitive and functional decline and neuropathology were investigated in a cohort of aging men and women with diverse alcohol histories. METHODS: Non-demented (Clinical Dementia Rating (CDR) of ≤ 0.5 and a Mini-Mental State Examination (MMSE) score of > 24), autonomously living participants were tracked in longitudinal aging studies to examine self-report and objective tests of rates of decline in a cohort (n = 486) of octogenarians. Neurofibrillary tangles (NFTs; Braak stage) and neuritic plaques (NPs) were staged at autopsy in a subset of participants (n = 149) using current standard neuropathologic diagnostic criteria. RESULTS: Moderate drinking men had an attenuated rate of decline compared to rare/never drinkers and women on the MMSE and CDR sum of boxes. In contrast, moderate drinking women had a reduced rate of decline only in the Logical Memory Delayed Recall Test (LMDR) compared to rare/never drinkers and men. Moderate alcohol consumption was associated with a reduction in the incidence of advanced (stages 5-6) Braak NFT stage in men (p < 0.05), with no effect in women. CONCLUSIONS: In this cohort, men experienced a broader range of beneficial effects associated with alcohol. Alcohol's effects may differ in men and women in important ways that suggest a narrower beneficial window.

A framework for harmonizing sensor data to support embedded health assessment.

The use of in-home and mobile sensing is likely to be a key component of future care and has recently been studied by many research groups world-wide. Researchers have shown that embedded sensors can be used for health assessment such as early illness detection and the management of chronic health conditions. However, research collaboration and data sharing have been hampered by disparate sets of sensors and data collection methods. To date, there have been no studies to investigate common measures that can be used across multiple sites with different types of sensors, which would facilitate large scale studies and reuse of existing datasets. In this paper, we propose a framework for harmonizing heterogeneous sensor data through an intermediate layer, the Conceptual Sensor, which maps physical measures to clinical space. Examples are included for sleep quality and ambulatory physical function.

Aging, the central nervous system, and mobility.

BACKGROUND: Mobility limitations are common and hazardous in community-dwelling older adults but are largely understudied, particularly regarding the role of the central nervous system (CNS). This has limited development of clearly defined pathophysiology, clinical terminology, and effective treatments. Understanding how changes in the CNS contribute to mobility limitations has the potential to inform future intervention studies. METHODS: A conference series was launched at the 2012 conference of the Gerontological Society of America in collaboration with the National Institute on Aging and the University of Pittsburgh. The overarching goal of the conference series is to facilitate the translation of research results into interventions that improve mobility for older adults. RESULTS: Evidence from basic, clinical, and epidemiological studies supports the CNS as an important contributor to mobility limitations in older adults without overt neurologic disease. Three main goals for future work that emerged were as follows: (a) develop models of mobility limitations in older adults that differentiate aging from disease-related processes and that fully integrate CNS with musculoskeletal contributors; (b) quantify the contribution of the CNS to mobility loss in older adults in the absence of overt neurologic diseases; (c) promote cross-disciplinary collaboration to generate new ideas and address current methodological issues and barriers, including real-world mobility measures and life-course approaches. CONCLUSIONS: In addition to greater cross-disciplinary research, there is a need for new approaches to training clinicians and investigators, which integrate concepts and methodologies from individual disciplines, focus on emerging methodologies, and prepare investigators to assess complex, multisystem associations.

Model-based inference of cognitive processes from unobtrusive gait velocity measurements.

In this paper we describe a preliminary modeling and analysis of a unique data set comprising unobtrusive and continuous measurements of gait velocity in the elder participants' residences. The data have been collected as a part of a longitudinal study aimed at early detection of cognitive decline. We motivate these analyses by first presenting evidence that suggests significant relationship between gait parameters and cognitive functions. We then describe a simple, model-based approach to the analysis of gait velocity using a weighted correlation function estimates. One of the main challenges is due to the fact that the daily estimates of the gait parameters vary with the number of walks. We illustrate the importance of using weighted as opposed to unweighted estimates on a sample of different houses. The correlation functions appear to capture behavioral differences that can be related to the cognitive functioning of the participants.

ADCS Prevention Instrument Project: assessment of instrumental activities of daily living for community-dwelling elderly individuals in dementia prevention clinical trials.

BACKGROUND: In primary prevention trials for Alzheimer disease, the inception cohort typically has normal or minimally impaired complex activities of daily living (ADL). ADL change during a trial could trigger detailed evaluation or serve as an outcome measure. A brief, easily administered, and reliable ADL rating scale would assist prevention studies. OBJECTIVES: To develop an ADL scale for prevention trials that allows self-rating or completion by informants. METHODS: The Activities of Daily Living-Prevention Instrument (ADL-PI) was developed, comprising 15 ADL and 5 physical function questions. Six hundred forty-four elderly subjects participating in the Prevention Instrument Project completed a self-rated version of the ADL-PI, and informants for 632 subjects completed an informant version. Informants also completed a Mild Cognitive Impairment (MCI) ADL questionnaire to allow comparisons. RESULTS: Subjects performed well on all ADL scales at baseline. Completion of the ADL-PI questionnaires at home or in-clinic yielded comparable information. Scores from baseline to 3 months had good reliability. The ADL-PI, obtained from either self-report or informants, discriminated between subjects rated as CDR 0 and CDR 0.5. Subjects with worse baseline cognitive performance also had slightly worse ADL-PI scores. Preliminary analysis indicates that subjects who triggered cognitive evaluations had slightly lower baseline ADL-PI scores by both self and informant reports. CONCLUSIONS: The ADL-PI can be completed at home or in clinic, and has adequate reliability. The utility of self-administered and informant versions and predictive value of reported deficits requires further follow-up.