The Healthy Cognitive Aging Project: A major data resource for cognitive epidemiology
Anybody who has ever loved, lived with, or cared for a person with Alzheimer's disease or its related dementias knows that its effects are multifaceted, complex, and often difficult to predict. That’s why NIA's longitudinal aging studies are so important—they can provide prospective data on these as-yet incompletely understood points. This week, we are proud to announce the first public release of data from the Healthy Cognitive Aging Project (HCAP), a nationally representative study that will help shed light on how and when cognitive decline progresses in older adults.
The history of HCAP
Five years ago, NIA decided to support a bold effort to take its largest, widest ranging, and most representative cohort study and collect much richer cognitive data on a random subsample of U.S. adults at greatest risk for dementia (those over the age of 65). The idea was that this expansion could, in principle, provide us with population-level information about not only the prevalence of Alzheimer’s disease and related dementias, but also the relationship between cognitive impairment and thousands of other observations, including clinical, behavioral, social, and healthcare factors collected on the same individual over the course of decades.
The study we chose to enrich with additional cognitive data was the Health and Retirement Study (HRS), a population-representative longitudinal survey of more than 20,000 older adults admitted to the study in their early 50s and followed up every 2 years until the end of their lives. It’s worth noting that the majority of HRS participants have consented to be genotyped, given us blood samples from which a vast array of biomarkers can be measured, and consented to Medicare claims records linkages.
To collect the new data on a subset of HRS participants, we designed a testing battery called the Harmonized Cognitive Assessment Protocol, which included key neuropsychological measures that are widely used in other studies of dementia. Because of the extensive cross-referencing between these studies and longitudinal cognitive data already collected in the HRS, the protocol can and will be used to better understand a huge variety of risk factors for Alzheimer’s disease and related dementias as well as the behavioral, social, and medical consequences of dementia in a representative U.S. population.
HCAP goes global
In recent years, a growing number of international studies (in countries including Mexico, England, China, and India) that parallel the form and content of the HRS have administered a translated and adapted version of the Harmonized Cognitive Assessment Protocol. This now-global consortium of studies has been dubbed the Healthy Cognitive Aging Project, or HCAP for short.
We are honored to have the participants in these studies enrich our knowledge of Alzheimer’s and related dementias, and we’re excited to begin making more meaningful international comparisons of variables and outcomes related to these diseases. When field work is complete, data from more than 20,000 participants, from countries including over half of the world's population, will be freely available to researchers.
Data are available now!
The first public data releases of HCAP for the United States and Mexico have been made, with data releases for all other funded international HCAP studies to follow during the next 3 years. Be aware that use of sensitive data linked to respondents, including biomarker and genotype data, requires registering for an additional license (Data Access Use Agreement).
We are quite pleased to see this expansion and evolution of HCAP and hope the data is a valuable resource for your research. Please comment below with your thoughts or questions and stay tuned for a future blog post on how to start using the public, sensitive, and restricted data from HRS and HCAP.