Functional Decline in Three Dementia Types

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DESCRIPTION (provided by applicant): Decline in ability to carry out normal activities of daily living is a highly salient end-point to examine the course of dementia. This project seeks to inform research and clinical care as to expected rates of functional decline in Alzheimer's disease (AD), vascular dementia (VaD) and dementia with Lewy bodies (DLB), and differences among these dementia types. The specific aims are: 1) Determine the extent to which the rate of functional decline differs among persons with AD, VaD, and DLB; 2) Evaluate whether the relationship of dementia type and functional decline varies by age or sex; and 3) Determine the extent to which certain dementia types are at increased risk for decline in specific activities. The data source will be the Uniform Data Set (UDS), developed and maintained by the National Alzheimer's Coordinating Center since 2005, and consisting of data collected from 29 Alzheimer's Disease Centers (ADCs). In this longitudinal, nation-wide database, each participant has an initial visit and is re-evaluated annually. Published diagnostic criteria were adopted as part of the UDS and data are collected using standard forms. The analytic sample will be drawn from all UDS enrollees who: 1) made at least 2 visits where diagnostic criteria were met at visit 1 (clinical diagnosis of dementia and primary diagnosis of probable AD, probable VaD, or DLB); 2) age 60+ years (visit 1); 3) Clinical Dementia Rating-Sum of Boxes (CDR-SOB) score <16 (visit 1); and 4) time between successive visits restricted to 0.5-1.5 years. Currently, there are 2846 participants meeting these criteria (2610 AD, 174 DLB, 62 VaD). All participants have 2+ visits, 1339 have 3+ visits, 442 have 4+ visits and 10 have 5 visits. These numbers will increase as the UDS continues to enroll new participants and follow existing ones. For aim 1, two continuous outcomes, measured at each visit, will be examined: a total score from the Functional Activities Questionnaire (FAQ) and the CDR-SOB score from the CDR scale. Linear mixed effects models will be used to examine the effect of dementia type on rate of functional decline while accounting for within-subject and within-center correlations in outcomes and potential confounding variables (age, sex, race, marital status, education, co-morbidities, time since symptom onset, baseline cognitive impairment). To evaluate the degree to which age and sex alter the effect of dementia type on functional decline (aim 2), interaction terms will be tested for inclusion in models. In aim 3, we will examine four specific activities from the FAQ (and two corresponding items from the CDR), selected a priori based on hypotheses that these activities involve cognitive domains known to be more impaired in DLB and VaD, relative to AD. For each activity, binary outcomes of decline/no decline (over the past year) will be derived and generalized linear mixed models will be used to examine the association between odds of decline and dementia type. The results of this study may assist clinicians and family caregivers to anticipate and plan for a demented individual's need for help with activities of daily living. PUBLIC HEALTH RELEVANCE: The ability to carry out normal activities of daily living becomes impaired with dementia and progression of these impairments can lead to decreased quality of life for those living with dementia and increased burden on caregivers, families, and the health-care system. Different dementias may have different sequences or patterns of impairment in activities of daily living. The results of this study will provide guidance to families, caregivers, and health care providers on how everyday abilities will be impacted by Alzheimer's disease, vascular dementia, and dementia with Lewy bodies, so that appropriate care strategies can be planned.