Cover: Modeling the Impact of Research Investment on Down Syndrome–Associated Alzheimer's Disease

Modeling the Impact of Research Investment on Down Syndrome–Associated Alzheimer's Disease

Published Jul 24, 2023

by Margaret M. Weden, Zetianyu Wang, Lori Frank, Andrew W. Dick, Elizabeth Marsolais

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Research Questions

  1. What is the status of the cognitive health and longevity of the older adult DS population?
  2. What is the status of caregiving associated with DS-AD for the older adult DS population?
  3. How could research investment affect trends in cognitive health, longevity, and caregiving in the next 50 years?

Individuals with Down syndrome (DS) are living longer than they used to. This increase in life expectancy presents novel challenges, including increased prevalence of Alzheimer's disease (AD) among those with DS and related changes to caregiving needs. Information about the impacts of longer lives and increased DS-AD prevalence is lacking. This information is needed to inform both investment in research development programs for new treatments for DS-AD and policies related to health care and caregiving for aging adults with DS. To begin addressing the knowledge gap, the authors developed a multistate population simulation and projection model to study trends in DS-AD and the associated impact on caregiving.

The results of the study demonstrate the potential for investment in DS and DS-AD to increase years of life without DS-AD among those living with DS, with concomitant improvements in caregiving time investments. Specific projections depend on assumptions about DS longevity, which itself might improve with increased research investment. The magnitude of the caregiving impact is notable, given that, unlike in the general population, DS caregiving is ongoing for many individuals with DS whether or not the patients have AD.

Key Findings

  • Prevalence of AD among adults aged 65 and older is about six times higher among Americans with DS than in the general population (65 percent versus 11 percent).
  • Caregiving for the adult DS population aged 45 or older is currently estimated to require 35,000 full-time equivalent (FTE) hours per year and cost about $1 billion annually.
  • Over the past 50 years, the percentage of the DS population aged 50 and older quadrupled from about 5 percent to nearly 20 percent of the population by 2020.
  • Improvement in DS survival and four decades of declining births following the baby boom have dramatically increased the likelihood that individuals with DS survive to develop DS-AD.
  • Adults with DS are projected to have more than double the increase in the expected years of life with DS-AD than without DS-AD (respective increases of 40 percent versus 15 percent).
  • Treatment innovations reducing the onset of AD in the general population could improve health, survival, and caregiving outcomes by as much as 40 percent over the next 50 years if made available to the DS population.
  • Among the impacts are the following: (1) Years of life without DS-AD is expected to increase by five years, (2) prevalence of DS-AD is expected to decrease by 10 percentage points, and (3) caregiving for adults with DS-AD is expected to decline by 12,500 FTE hours.


  • AD treatment approvals should include DS-AD, which requires inclusion of individuals with DS-AD in clinical trials along with attention to adequacy of sample sizes.
  • Clinician education about these treatments should address guidance for use with patients with DS-AD.
  • Timely detection of AD among individuals with DS requires provider and caregiver education. Initiatives to improve early detection of treatable AD should include attention to those with DS-AD.

Research conducted by

The research described in this report was funded by the LuMind IDSC Foundation, the Alliance for Aging Research, BrightFocus Foundation, and the National Down Syndrome Society and conducted by the Social and Behavioral Policy Program within RAND Social and Economic Well-Being.

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