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We are pleased to announce the launch of the Gateway to Global Aging Harmonized Cognitive Assessment Protocol (HCAP) website. The Gateway HCAP website provides a centralized, research-focused hub for accessing harmonized cognitive data designed to support rigorous, cross-national research on cognitive aging and dementia.

Developed in collaboration with the Health and Retirement Study (HRS) and its International Network of Studies (HRS-INS), the HCAP protocol is designed to support the measurement of cognition across diverse populations and settings. The new website is intended to make these data, and the methodological work underlying them, more transparent, accessible, and usable for the research community.

Why HCAP Matters for Researchers

Comparative research on cognitive aging and dementia has long been constrained by differences in measurement and study design. A lack of documentation across studies and differences in data cleaning and preparation have also created barriers to high-quality research. HCAP and the Gateway suite of HCAP resources directly address these challenges by providing a standardized cognitive assessment framework that is implemented across multiple studies and by further ensuring consistency in data cleaning and processing pipelines.

By using harmonized instruments and carefully aligned protocols, HCAP enables researchers to:

• Conduct cross-national comparisons of cognitive functioning and impairment
• Study population-level patterns of cognitive aging across social, economic, and cultural contexts
• Investigate risk and protective factors for dementia using comparable cognitive outcomes
• Integrate cognitive measures into broader longitudinal analyses of health, aging, and inequality

Importantly, harmonized HCAP data is designed to complement existing harmonized data products available through the Gateway, allowing researchers to combine these in-depth cognitive assessments with rich longitudinal information on demographics, health, family structure, and socioeconomic conditions.

A Closer Look at the Gateway to Global Aging HCAP Website

The Gateway HCAP website serves as a dedicated entry point for discovering studies, understanding data structure, and accessing documentation needed for reproducible research. Key sections include:

Getting started
The Getting Started page offers practical guidance for researchers who are new to HCAP, including introductory materials and links to related Gateway tools. These resources are particularly useful for early-career researchers or those transitioning into comparative cognitive aging research.

HCAP Study Overviews
This section provides Study Overviews of the individual studies that have implemented HCAP, including geographic coverage and study-specific context. Researchers can quickly identify which countries and populations are represented. If an HCAP study is conducted on a sub-sample of one of the larger HRS-INS, information on how HCAP fits within the broader survey is also included.

HCAP Question Concordance
The Question Concordance allows users to explore cognitive assessment instruments and informant questionnaires across studies in a structured format. This tool enables researchers to examine availability and comparability of individual questionnaire items across countries and studies. The question concordance is particularly valuable for evaluating measurement comparability, selecting subsets of cognitive items for analysis, and understanding the content underlying harmonized variables.

Harmonized HCAP Data
Gateway data harmonization processes seek to generate research-ready variables that can be used in harmonized, cross-national analyses. Variable Concordance tables illustrate the availability of these harmonized variables across contexts, and the Search Tool makes it easy to identify existing variables in harmonized HCAP data. The codebooks available alongside the harmonized data provide further information on variable definitions, harmonization decisions, and dataset structure. The clear documentation of these data elements supports transparent and efficient use of the data.

Additional HCAP Resources (Including Methodological Documentation)
A key strength of the Gateway HCAP website is its emphasis on methodological transparency. Under Additional HCAP Resources, researchers will find detailed methodological documentation, including information on the imputation of cognitive data, the development of summary cognitive measures using psychometric modeling approaches, and best practices for cross-national analysis of HCAP data. These materials are essential for understanding the data processing pipelines that result in summary measures of cognition across studies and can help researchers use these data appropriately. Information posted in Webinars & Presentations further addresses common analytic and conceptual questions.

Looking Ahead

The release of the Gateway HCAP website represents an important step forward in supporting high-quality, comparative research on cognitive aging and dementia. As additional studies, waves, and documentation are incorporated, the website will continue to evolve as a core resource for researchers conducting cross-national research on cognition, aging, and population health. We invite researchers to explore the Gateway HCAP website, review the available data and documentation, and consider how our HCAP resources can enhance their work.