Title: Epidemiology of Dementia and Alzheimer’s Disease in Individuals with Down Syndrome
Legend: This figure displays the prevalence and incidence of dementia and Alzheimer’s disease among 2,968 Wisconsin Medicaid beneficiaries with Down syndrome. Dementia was prevalent in 4% of Medicaid beneficiaries with Down syndrome younger than 40 years of age, 40.3% of beneficiaries between 40 and 54 years of age, and 61% of beneficiaries aged 55 or older. The probability of an incident dementia claim was 40% (95% CI, 41%-47%) over 11 years of enrollment for adults with DS who were aged 40-54 years at cohort entry and 67% (95% CI, 60%- 74%) for those 55 years and older at cohort entry.
Citation: Rubenstein, E., Hartley, S., & Bishop, L. (2019). Epidemiology of Dementia and Alzheimer’s Disease in Individuals with Down Syndrome. JAMA Neurology
Abstract: We have seen a profound increase in lifespan for individuals with Down syndrome (DS) in the past few decades leading to a large and somewhat understudied population of middle- and older aged adults with DS. One health condition consistently seen in clinic-based DS samples is dementia (including Alzheimer’s disease). Chromosome 21, which is triplicated in DS, is where the amyloid precursor protein (APP) gene is located and that protein produces beta-amyloid which is hypothesized to increase risk for Alzheimer’s dementia. While clinic studies of dementia in DS are robust there had not yet been a population-based estimate of dementia and Alzheimer’s in the DS population. Our sample was adults (≥21) with DS enrolled in Medicaid (as identified by two ICD codes for DS on two separate days). To identify dementia and Alzheimer’s claims, we examined claims for Chronic Condition Data Warehouse codes for ‘Alzheimer’s disease, related disorders, or senile dementia.’ To be considered a ‘case’ in our data, a person had to be enrolled for three years and have at least two claims for any dementia. We assessed prevalence by age category at study entry using log-binomial regression and incidence by age category at study entry using log-Poisson regression with a 1-year washout. We created Kaplan Meier curves accounting for administrative censoring. We assessed whether dementia prevalence differed by sex using log-binomial regression. In the ≥55 category, 3 in 5 had dementia claims, 1 in 3 had AD claims, and incidence was 101.5 cases per 1000 person-years. In the 40-54 category, 2 in 5 had dementia claims and incidence was 49 per 1000 person-years. Probability of incident dementia claim was 0.4 over 11 years enrollment for adults with DS 40-54 at entry and 0.63 for those ≥55 years at entry (Figure 1). There were no sex differences for dementia in the <40 (Prevalence Ratio [PR]: 1.07 95% CI: 0.6, 1.8) or the ≥55 age category (PR 0.94 95% CI 0.7, 1.2). Dementia prevalence was higher in females than males in the 40-54 category (PR 1.23, 95% CI: 1.0, 1.5). Findings highlight the need to support the development of memory care programs for adult Medicaid beneficiaries with DS living in the community.
About the Lab: Dr. Bishop is interested in modifiable factors that improve health equity and reduce health disparities in adults with developmental disabilities as they age. Current research projects conducted by the Aging and Health Equity in Autism and Developmental Disabilities (AHEADD) Team aims to: (1) investigate heterogeneity in health and mental health conditions in adults with autism and other developmental disabilities as they age using Wisconsin Medicaid data; (2) characterize condition-based and neighborhood-level socioeconomic disparities in Medicare beneficiaries on the autism spectrum; and (3) adapt and pilot an intervention designed to reduce distress and improve health in middle aged and older adults on the autism spectrum. Dr. Bishop and the AHEADD Team are also broadly interested in education and training aimed at educating the workforce of practitioners who provide community-based services to people with developmental disabilities..