This exciting new research will focus on adults aged 90 and older, a rapidly growing population that remains understudied in Alzheimer’s disease and related dementias (AD/ADRD) research. Drawing on four large studies, Elizabeth Rose's team will investigate how potentially modifiable factors, including social connection, physical activity, vision and hearing, and chronic conditions, may influence cognitive decline and dementia risk among the “oldest-old.” By bringing rigorous epidemiologic methods to this important and often overlooked population, the study aims to identify opportunities to preserve cognitive health and prevent dementia among people living into their 90s and beyond. Congratulations, Elizabeth Rose!
Project Abstract
By 2050, 1 in 10 US adults aged 65+ will be 90 or older,1 a group that already accounts for 1 in 5 Alzheimer’s disease and Alzheimer’s disease related dementias (AD/ADRD) cases.2 However, there is limited evidence on how to preserve cognitive function and prevent AD/ADRD in individuals aged 90 and older (referred to as the "oldest-old"). The available evidence suggests that risk and protective factors for AD/ADRD may differ among the oldest-old compared to other age groups. Research on determinants of AD/ADRD among the oldest-old faces several critical challenges. The overall objective of the proposed research is to provide high-quality evidence on modifiable determinants of AD/ADRD among the oldest-old. We will achieve this by carefully triangulating evidence across four data sources using methods to address methodological challenges for research on determinants of AD/ADRD in this age group. The LifeAfter90 (LA90) study (n=1,397, all aged ≥90) and The 90+ Study (n=1,630, all aged ≥90) were designed to maximize data quality for AD/ADRD research in the oldest-old. They involve shorter, more frequent study assessments (every 6 months) to capture changes in cognitive and daily functioning. The Health and Retirement Study (HRS) (total n=45,234; n=3,359 aged ≥90) and the National Health and Aging Trends Study (NHATS) (total n=18,439; n=3,132 aged ≥90) are nationally representative US studies. For all aims, we will draw on the strengths of these four data sources to correct biases found in the others. We will use rigorous methods to deliver valid estimates in settings where conventional methods may be biased and employ quantitative bias analysis to estimate potential magnitude of biases. These methods have not yet been comprehensively applied to the study of AD/ADRD risk among the oldest-old. We focus on social, behavioral, and clinical factors that are particularly relevant to the oldest-old, either due to their greater prevalence or the distinctive physiology of the oldest-old. Our specific aims are to: (1) estimate the effects of social contact, including structure (network size, mode, frequency), support received (emotional support, instrumental support), and participation in social activities, on cognitive decline and dementia risk among US adults aged 90 and older; (2) estimate the effects of physical activity (exertion level, type, frequency) on cognitive decline and dementia risk among US adults aged 90 and older; (3) estimate the effects of under-corrected vision impairments and under-corrected hearing impairments on cognitive decline and dementia risk among US adults aged 90 and older; and (4) estimate the effects of chronic conditions and their management, including hypertension, diabetes, and depression, on cognitive decline and dementia, considering current conditions and conditions at ages 65-89 years. The proposed study will provide high- quality evidence on modifiable determinants of AD/ADRD among the oldest-old, contributing insights into AD/ADRD risk at all ages.