The Health and Retirement Study Harmonized Cognitive Assessment Protocol Project: Study Design and Methods

Ethnic Differences in the Association Between Cognitive Performance and Informant-rated Cognitive Decline

OBJECTIVES

It is unknown whether cognitive test scores are equivalently associated with informant-rated cognitive decline across culturally and linguistically diverse older adults. We examined the association between cognitive domain scores on the Harmonized Cognitive Assessment Protocol (HCAP) and informant-rated cognitive decline in a harmonized population-based sample of older adults.

DESIGN, SETTING, AND PARTICIPANTS

We combined data from the HCAP sub-study of the Health and Retirement Study (HRS; 2016) and the Brain Attack Surveillance in Corpus Christi-Cognitive (BASIC-C; 2018-2020) study. We included Hispanic/Latino-a-e-x (H/L; n = 566) and non-H/L white (NHW; n = 2,145) older adults.

MEASUREMENT

Both studies included the HCAP cognitive assessment with domain scores for memory, attention/executive function (EF), language, visuospatial, orientation, and general cognitive performance (GCP). Informants rated cognitive decline with the Informant Questionnaire of Cognitive Decline in the Elderly (IQCODE).

RESULTS

Cognitive domain scores were more strongly associated with IQCODE scores for NHW than H/L participants for four of six domains (GCP, EF, visuospatial, and orientation) after adjusting for demographics (age, sex/gender, education) and study membership. Informants generally rated greater cognitive decline in NHW than H/L respondents for a given cognitive domain score, and the magnitude of this difference was greater for lower cognitive test scores.

CONCLUSIONS

We found generally weaker associations between cognitive performance and informant-rated cognitive decline in H/L compared to NHW older adults. These findings suggest cognitive measurement differences across culturally and linguistically diverse older adult populations, which may result in underestimation of cognitive impairment in H/L populations.

Language, literacy, and sensory impairments and missing cognitive test scores in the Harmonized Cognitive Assessment Protocol of the China Health and Retirement Longitudinal Study

BACKGROUND

The potentially biasing impacts of low language fluency, illiteracy, and sensory impairments on cognitive test performance are unknown, which may have implications for understanding their roles in cognitive decline and dementia.

AIMS

We investigated effects of these features on cognitive test item completion and performance among older adults in China, a multilingual country with high prevalence of illiteracy and sensory impairment.

METHODS

We used cognitive test data from the Harmonized Cognitive Assessment Protocol of the China Health and Retirement Longitudinal Study conducted in 2018 (N = 9755, age 60 + years). We first tested associations of fluency in spoken Mandarin, literacy, and sensory impairment (hearing and vision) with missingness of cognitive items. We then tested for differential item functioning (DIF) in observed cognitive items by these features.

RESULTS

We observed high levels of missing data in most cognitive test items - on average 13% and as high as 65%. Low fluency in spoken Mandarin, illiteracy, and impairments in hearing and vision were each associated with greater odds of missingness on nearly all tests. Partly because of differential missingness, there was minimal evidence of DIF by these features in items in which we expected a priori to find DIF (e.g., repetition of a spoken phrase among those with hearing impairment). Several cognitive test items exhibited statistically significant DIF, however there was minimal evidence of meaningful DIF.

CONCLUSIONS

Differential missingness in cognitive items by spoken language, literacy, and sensory impairments is potentially more of an inferential threat than measurement differences in test items.

Cognitive assessment tools for Arabic-speaking older adults: A systematic review

This systematic review aims to identify available cognitive assessments for Arabic-speaking older adults and to assess their validity and performance. A comprehensive search was conducted using Medline, Embase, and APA PsycInfo up to November 2023, encompassing studies validating or using cognitive tools in Arabic for individuals aged ≥ 50. We identified 29 validation studies for 20 cognitive tools and 125 studies using cognitive tools. Three tools were validated in more than one study/setting. Cut-offs for dementia were validated for 16 tools (including two domain-specific tools) and for cognitive impairment for three tools. The Mini-Mental State Examination and Montreal Cognitive Assessment were the most frequently validated and used tools. The results highlight a large need for improved psychometric data for cognitive assessments for Arabic-speaking older adults and identify important gaps in knowledge regarding domain-specific tools, the detection of cognitive changes, and the suitability of assessments across different settings and subgroups. HIGHLIGHTS: We reviewed the availability and properties of cognitive assessments in Arabic. Psychometric data on cognitive tools for older Arabic-speaking adults are scarce. Only three tools are validated in more than one study/setting. Data are largely lacking for domain-specific tools and early cognitive changes. The review identifies important methodology, reporting, and reproducibility issues.

Validation of harmonized cognitive assessment protocol within the Egyptian context

This study addresses the urgent need for culturally sensitive cognitive assessments in Egypt by validating an adapted version of Harmonized Cognitive Assessment Protocol (HCAP) to the Egyptian context. This version is to be used as a part of the Egyptian Aging Survey (AL-SEHA). We enrolled 300 participants aged 55 + from diverse backgrounds and meticulously adapted the HCAP for Egypt's linguistic and cultural context. Demonstrating strong reliability and validity (sensitivity 87.6%, specificity 89.2%, accuracy 89.7%), the Egyptian HCAP effectively identified cognitive impairment. Integrated into the AL-SEHA, this validated HCAP offers valuable insights on cognitive function decline in Egypt's aging population. Our findings not only contribute to global understanding of cognitive health but also set a precedent for future cross-cultural HCAP validations, informing policies and early diagnosis for dementia care.

Dementia caregiving in India: New evidence from a National representative sample

INTRODUCTION

As India's population ages, the prevalence of dementia is increasing rapidly, inducing higher need for informal caregivers for a complex population. However, the effects of individuals' cognitive impairment on their caregivers' well-being in India have not been well studied.

METHODS

We analyzed data from 4196 informants of participants in the Longitudinal Aging Study in India-Diagnostic Assessment of Dementia (LASI-DAD). Informants' caregiving roles and well-being, including stress, mental health, positive affect, and spirituality, were assessed alongside the cognitive function and dementia status of LASI-DAD respondents.

RESULTS

Informants of individuals with cognitive impairment experienced significantly higher stress, poorer mental health, and lower levels of positive affect and spirituality. Greater caregiving responsibility intensified the negative impact on well-being.

DISCUSSION

These results demonstrate the significant emotional and psychological strain on dementia caregivers in India, underscoring the need for targeted interventions and support structures.

HIGHLIGHTS

We used a dual data collection approach in LASI-DAD to create a first-of-its-kind linked dataset on care recipients' and caregivers' outcomes, representative of Indian older adults. Using this dataset, we tested whether cognitive impairment in care recipients increased informants' stress and lowers well-being, with greater caregiving responsibility amplifying these effects. Informants of cognitively impaired individuals reported significantly higher stress, poorer mental health, and lower positive affect and spirituality, with stronger effects for those with greater caregiving roles. Non-primary caregivers also experienced well-being declines when assisting a cognitively impaired older adult, likely driven by family disruptions and added household responsibilities for co-residents and logistical challenges and reduced control for those living separately. Our findings highlight the widespread emotional and psychological strain of dementia caregiving in India, emphasizing the need for targeted support and interventions.

Regional disparities in cognitive life expectancy: The role of birth and current residence in the United States

Regional disparities in cognitive impairment are well-documented, but the combined impact of birth and current residence remains unclear. Prior studies examine geographic patterns, yet none estimate years spent in different cognitive states-key for understanding long-term health and policy implications. Using data from the 1998-2020 Health and Retirement Study (105,491 observations from 19,213 individuals), we employ a Bayesian multistate life table approach to estimate cognitively healthy and impaired life expectancies at age 50 across different combinations of birth and current regions. Our findings show that birth region plays a stronger role in cognitive impairment risk than current residence. At age 50, Southern-born individuals, regardless of where they live later, have fewer years without cognitive impairment (Men: 20.5-21.5; Women: 24.8-25.4) and more years with dementia (Men: 2.3-2.5; Women: 3.0-3.1) than those born elsewhere. Those both born and living in the South have the shortest cognitively healthy life expectancy. Regional differences based on current residence alone are minimal and only evident when considered alongside birthplace. Beyond the Southern birth disadvantage, we also identify a Western birth disadvantage, particularly in life expectancy with dementia and, for women, a higher percentage of life spent with cognitive impairment but not dementia. This suggests that Western-born individuals, especially women, may experience prolonged cognitive decline even if they avoid full-blown dementia. These findings provide new evidence of the lasting impact of early-life geographic exposures on cognitive impairment risk, underscoring that growing up in certain regions, particularly the South and, in some respects, the West, can shape cognitive health trajectories decades later.

Harmonized prevalence estimates of dementia in Europe vary strongly with childhood education

Up-to-date, strictly cross-nationally comparable and nationally representative data on cognitive health are essential for our understanding of the dementia-related challenges in healthcare, to detect shortcomings in healthcare systems and to design effective prevention strategies. Such data have been missing in Europe. We use the most recent 2022 wave of the strictly harmonized Survey of Health, Ageing and Retirement in Europe (SHARE, 47,773 individuals age 65 and older) to obtain prevalence estimates of mild cognitive impairment and dementia for 27 European countries and Israel in 2022. The novelty of the paper is to validate these estimates using the Harmonized Cognitive Assessment Protocol (HCAP) as a validation tool. These new data exhibit much higher prevalence rates of dementia in the Mediterranean and Southeastern European countries and a much larger variation of cognitive impairment across Europe and Israel than previously known. Dementia prevalence ranges from 4.5% in Switzerland to 22.7% in Spain, MCI prevalence from 17.2% in Sweden to 31.1% in Portugal. Most of this variation can be explained by differences in education when respondents were young. Prevalence rates vary plausibly with other risk factors such as age and comorbidities associated with dementia.

Assessing Cognitive Impairment in the Health and Retirement Study Harmonized Cognitive Assessment Protocol Project: Comparing a Diagnostic Algorithm With a Diagnostic Consensus Panel

BackgroundAccurate classification of cognitive impairment in population studies is challenging.ObjectiveTo compare the performance of a diagnostic algorithm with a clinical consensus panel.SampleIn 2016, the Health and Retirement Study (HRS) implemented the Harmonized Cognitive Assessment Protocol Project (HRS-HCAP) to streamline cognitive assessments for select HRS participants.MethodsThe Manly-Jones HCAP diagnostic classification was used to classify cognitive status as normal, mild cognitive impairment (MCI), or dementia. For this analysis, a consensus panel of five clinicians reviewed 50 cases with high diagnostic uncertainty, each reviewing 30 cases, blinded to the algorithm's classifications.AnalysisDiagnostic concordance was assessed using unweighted and weighted Cohen's kappa (κ).ResultsUnweighted concordance was 70% (35/50), with discordance mostly among MCI cases. Weighted concordance was 84%. Unweighted κ was 0.56 (95% CI 0.30-0.81) and weighted κ was 0.75 (95% CI 0.49-0.91), indicating moderate to substantial agreement between the two methods.

Cognitive Performance and Long-term Exposure to Outdoor Air Pollution: Findings From the Harmonized Cognitive Assessment Protocol Substudy of the English Longitudinal Study of Ageing (ELSA-HCAP)

BACKGROUND

Although air pollution is associated with worse cognitive performance, whether these relationships differ by cognitive domain and which sources of air pollution are particularly detrimental to cognition remains understudied. This study examined associations between cognitive scores across 3 domains in older adults and 8-10 years of exposure to air pollutants (NO2, total PM2.5, and PM2.5 from different emission sources).

METHODS

We used data from the 2018 Harmonized Cognitive Assessment Protocol substudy of the English Longitudinal Study of Ageing (N = 1 127). Outdoor concentrations of each pollutant were estimated for 2008/2010-2017 and summarized using means and group-based trajectories. Linear regression models were used to assess long-term air pollution exposure relationships with memory, executive function, language, and global cognitive function after adjustment for key individual and neighborhood-level confounders.

RESULTS

Associations between air pollution trajectories and cognition are mostly inverted j-shaped, with respondents exposed to the highest residential levels of NO2 and total PM2.5 having worse performance for global cognition (β = -.241; 95% CI = [-0.46, -0.02] and β = -.334; 95% CI = [-0.55, -0.12], respectively) than those exposed to average levels of pollution. Similar associations were also found for executive function and memory (PM2.5 only), whereas more compelling dose-response evidence was found for language. Higher emissions from industry and residential combustion, as well as biofuel, coal, and oil and natural gas combustion, were associated with worse language scores.

CONCLUSIONS

Air pollution and its sources have domain-specific associations with cognitive performance, with most consistent evidence observed for language. Continued efforts to reduce air pollution, particularly where levels are the highest, might benefit cognitive performance.

Depression, Subjective Health, Obesity, and Multimorbidity are Associated with Epigenetic Age Acceleration

Background

Epigenetic aging, measured through various DNA methylation-based clocks, may have implications for predicting disease risk. However, the sensitivity of different epigenetic clocks that have emerged as biomarkers for biological aging and in predicting physical and mental health outcomes remains uncertain. This study examines the age and sex-adjusted associations between multiple epigenetic age acceleration measures and three key health indicators, including self-rated health, depressive symptoms, and body mass index (BMI), in a nationally representative sample of U.S. middle-aged and older adults.

Methods

We analyzed data from 4,018 adults in the 2016 wave of the Health and Retirement Study (HRS), which included several epigenetic age acceleration measures: HORVATH, HANNUM, LEVINE, HORVATHSKIN, LIN, WEIDNER, VIDALBRALO, YANG, ZHANG, BOCKLANDT, GARAGNANI, and GRIMAGE. Linear regression models were used to assess the associations between epigenetic age acceleration and self-rated health (poor health), depressive symptoms, and BMI, adjusting for age and sex.

Results

We found significant positive associations between epigenetic age acceleration and worse self-rated health, higher depressive symptoms, and increased BMI. However, these associations varied across different epigenetic clocks, with some measures potentially having more consistent utility for specific health outcomes than others.

Conclusion

Epigenetic age acceleration is linked to poorer self-rated health, greater depressive symptoms, and higher BMI, but choosing which epigenetic clock(s) to use is also important. These findings underscore the need to consider multiple epigenetic aging markers when assessing health risks and highlight the potential for particular clocks to serve as more sensitive indicators of physical and mental health outcomes.

Factors associated with non-participation in the Healthy Cognitive Ageing Project

BACKGROUND

Understanding cognitive decline trajectories is crucial for dementia prevention, as many cases go undetected. Identifying participation biases in such studies is essential for data validity.

METHODS

We examined non-participation correlates in the Healthy Cognitive Ageing Project (HCAP), a sub-study of the English Longitudinal Study of Ageing (ELSA). We compared sociodemographic and health characteristics of invited, interviewed, and non-interviewed individuals, and assessed the impact of sample weights.

RESULTS

Of 1778 ELSA members invited in 2018, 1273 (72%) participated. Participants were similar to the invited sample in sociodemographics but were younger, had fewer daily living difficulties, and had better cognition. Non-participation was linked to difficulties in daily living (odds ratio 1.78), dementia (1.55), and psychiatric conditions (1.34). Weighted analyses highlighted differences in disability and cognition.

DISCUSSION

Non-participation in cognitive studies is not random, lowering response and retention rates, and requiring adjustments to data analysis beyond the use of weights.

HIGHLIGHTS

We compared the sociodemographics of invited, interviewed, and non-interviewed individuals. We used sample weights to assess differences in participants' characteristics. We found non-participation linked to daily living difficulties, dementia, and psychiatric conditions.

The Impact of Later-Life Learning on Trajectories of Cognitive Function Among U.S. Older Adults

Background and Objectives

Low education in early life is a major risk factor for dementia. However, little is known about how education in later life is related to cognitive function in older adults. We assessed whether later-life learning was associated with better cognitive function over time and whether the associations differed by sex, race/ethnicity, and prior education.

Research Design and Methods

We used data from the 2008-2018 Health and Retirement Study, including participants aged 65+ without baseline dementia and followed for up to 6 years. Global cognition was measured using a summary score. Later-life learning was measured at every wave at least once a month or more, not in the last month, or never.

Results

Of 12 099 participants, 10.2% attended an educational or training course "at least once a month or more," 45.5% reported "not in the last month," and 43.3% reported "never" at each wave of the study. Results from adjusted mixed-effects models showed that engaging in any later-life learning, either at least once a month (0.56 points higher, 95% confidence interval [CI] = 0.40-0.73) or not in the last month (0.55 points higher, 95% CI = 0.45-0.65) was associated with better cognitive function compared to never engaging in these activities. The association remained consistent as people aged. The benefits of later-life learning on cognitive function were greater in women than in men-at least once a month versus never was 0.30 points greater in women than men (95% CI = -0.03 to 0.63, p = .0760); not in the last month versus never was 0.24 points greater in women than men (95% CI = 0.04-0.43, p = .016). There were no significant differences by race/ethnicity or prior education.

Discussion and Implications

Later-life learning was associated with better cognitive function over time. These findings underscore the importance of continued learning among older adults.

Cross-national statistical harmonization of the Center for Epidemiologic Studies Depression (CES-D) scale among older adults in China, England, India, Mexico, South Africa, and the United States

OBJECTIVES

We examined differential item functioning (DIF) of the Center for Epidemiologic Studies Depression Scale (CES-D) items by country and statistically harmonized common cross-national factor scores for the CES-D to aid further cross-national research.

STUDY DESIGN AND SETTING

Data were from Harmonized Cognitive Assessment Protocol (HCAP) studies in China (N = 9639), England (N = 1262), India (N = 4048), Mexico (N = 1918), South Africa (N = 631), and the United States (N = 3321). Multiple indicators, multiple causes models were estimated to test DIF in the CES-D items by country. DIF items were defined as having an odds ratio (OR) outside the range of 0.75-1.25 in multiple indicators, multiple causes models. We evaluated DIF impact and identified salient DIF by examining whether the difference between DIF-adjusted factor scores and non-DIF-adjusted factor scores exceeded a threshold of 0.30 standard deviation (SD) units. Confirmatory factor analysis was used to create DIF-adjusted, cross-nationally harmonized CES-D factor scores.

RESULTS

Controlling for underlying depressive symptoms, HCAP participants in India had higher odds of reporting being not hopeful about future (OR = 1.38, 95% confidence interval [CI]: 1.34-1.42), not enjoying life (OR = 1.43, 95% CI: 1.38-1.48), and being unhappy (OR = 1.29, 95% CI: 1.25-1.34), compared to HCAP participants in the United States. These identified DIF items artificially increased mean harmonized CES-D factor scores by 0.48 SD units in the India HCAP, with over 50% of the factor scores increased by over 0.30 SD units, indicating salient DIF in the India HCAP.

CONCLUSION

Our findings demonstrate cross-national heterogeneity in the expression of depressive symptoms. We provide DIF-adjusted CES-D factor scores to improve the quality of cross-national comparisons in aging research.

The association between adult child education and cognitive functioning among older parents: A cross-national comparison of diverse contexts

INTRODUCTION

The association between adult child educational attainment and older parent's cognitive health may vary across diverse contexts but cross-national comparisons have been limited by differences in outcome assessment, study design, and analytic choices.

METHODS

We used harmonized data with comprehensive cognitive assessments from the United States (N = 3088), India (N = 3828), and Mexico (N = 1875) to estimate associations between adult child education and older adults' cognitive functioning using linear regression models adjusted for respondent and family-level socio-economic status (SES) in each study.

RESULTS

Each additional year of offspring education was associated with 0.02 (Longitudinal Aging Study in India - Diagnostic Assessment of Dementia [LASI-DAD]) to 0.04 (Health and Retirement Study Harmonized Cognitive Assessment Protocol Survey [HRS-HCAP], Mexican Health and Aging Study Cognitive Aging Ancillary Study [Mex-Cog]) standard deviation (SD) units higher cognitive score (pooled estimate: 0.032 [95% confidence interval [CI]: 0.018-0.046]), comparable to about 1/3-1/4 of the association with respondents' own years of education. Differences by respondent gender were heterogeneous across contexts.

DISCUSSION

Consistent overall estimates despite differences in context and potential confounding structures underscore the importance of offspring education for cognitive outcomes among older adults.

HIGHLIGHTS

The harmonized study design allows for fair comparisons across diverse contexts. Effect sizes were largely consistent across the United States, India, and Mexico, despite differences in confounding structures. The pooled association between adult child education and parental cognitive functioning was about 1/3-1/4 of the association with respondent's own years of education. Heterogeneity in gender differences point to the potential effects of local culture and context.

The added value of metadata on test completion time for the quantification of cognitive functioning in survey research

OBJECTIVE

Information on the time spent completing cognitive testing is often collected, but such data are not typically considered when quantifying cognition in large-scale community-based surveys. We sought to evaluate the added value of timing data over and above traditional cognitive scores for the measurement of cognition in older adults.

METHOD

We used data from the Longitudinal Aging Study in India-Diagnostic Assessment of Dementia (LASI-DAD) study (N = 4,091), to assess the added value of timing data over and above traditional cognitive scores, using item-specific regression models for 36 cognitive test items. Models were adjusted for age, gender, interviewer, and item score.

RESULTS

Compared to Quintile 3 (median time), taking longer to complete specific items was associated (p < 0.05) with lower cognitive performance for 67% (Quintile 5) and 28% (Quintile 4) of items. Responding quickly (Quintile 1) was associated with higher cognitive performance for 25% of simpler items (e.g., orientation for year), but with lower cognitive functioning for 63% of items requiring higher-order processing (e.g., digit span test). Results were consistent in a range of different analyses adjusting for factors including education, hearing impairment, and language of administration and in models using splines rather than quintiles.

CONCLUSIONS

Response times from cognitive testing may contain important information on cognition not captured in traditional scoring. Incorporation of this information has the potential to improve existing estimates of cognitive functioning.

Differences in setting of initial dementia diagnosis among fee-for-service Medicare beneficiaries

BACKGROUND

Accurate and timely diagnosis of dementia is necessary to allow affected individuals to make informed decisions and access appropriate resources. When dementia goes undetected until a hospitalization or nursing home stay, this could reflect delayed diagnosis or misdiagnosis, and may reflect underlying disparities in healthcare access.

METHODS

In this retrospective cohort study, we used 2012-2020 Medicare claims and other administrative data to examine variation in setting of dementia diagnosis among fee-for-service Medicare beneficiaries with an initial claims-based dementia diagnosis in 2016. We used multinomial logistic regression to evaluate the association of person and geographic factors with diagnosis location, and Cox proportional hazards regression to examine 4-year survival relative to diagnosis location.

RESULTS

Among 754,204 Medicare beneficiaries newly diagnosed with dementia in 2016, 60.3% were diagnosed in the community, 17.2% in hospitals, and 22.5% in nursing homes. Adjusted 4-year survival rates were significantly lower among those diagnosed in hospitals [-16.1 percentage points (95% CI: -17.0, -15.1)] and nursing homes [-16.8 percentage points (95% CI: -17.7, -15.9)], compared to those diagnosed in the community. Community-diagnosed beneficiaries were more often female, younger, Asian or Pacific Islander, Native American or Alaskan Native, Hispanic, had fewer baseline hospitalizations and higher homecare use, and resided in wealthier ZIP codes. Rural beneficiaries were more likely to be diagnosed in hospitals.

CONCLUSIONS

Many older adults are diagnosed with dementia in a hospital or nursing home. These individuals have significantly lower survival than those diagnosed in the community, which may indicate diagnosis during an acute illness or care transition, or at a later disease stage, all of which are suboptimal. These results highlight the need for improved dementia screening in the general population, particularly for individuals in rural areas and communities with higher social deprivation.

Measuring visual ability in linguistically diverse populations

Measurement of object recognition (OR) ability could predict learning and success in real-world settings, and there is hope that it may reduce bias often observed in cognitive tests. Although the measurement of visual OR is not expected to be influenced by the language of participants or the language of instructions, these assumptions remain largely untested. Here, we address the challenges of measuring OR abilities across linguistically diverse populations. In Study 1, we find that English-Spanish bilinguals, when randomly assigned to the English or Spanish version of the novel object memory test (NOMT), exhibit a highly similar overall performance. Study 2 extends this by assessing psychometric equivalence using an approach grounded in item response theory (IRT). We examined whether groups fluent in English or Spanish differed in (a) latent OR ability as assessed by a three-parameter logistic IRT model, and (2) the mapping of observed item responses on the latent OR construct, as assessed by differential item functioning (DIF) analyses. Spanish speakers performed better than English speakers, a difference we suggest is due to motivational differences between groups of vastly different size on the Prolific platform. That we found no substantial DIF between the groups tested in English or Spanish on the NOMT indicates measurement invariance. The feasibility of increasing diversity by combining groups tested in different languages remains unexplored. Adopting this approach could enable visual scientists to enhance diversity, equity, and inclusion in their research, and potentially in the broader application of their work in society.

A study evaluation framework for measuring cognition. Lessons learned in cross-national contexts from four English-speaking aging cohorts

The Harmonized Cognitive Assessment Protocol (HCAP) is a detailed battery assessing cognition among older people used by studies across the world. Data harmonization is a key priority for HCAP studies. We used a mixed-methods approach using established theories from the existing literature detailing the methodologies of longitudinal studies and from the implementation of HCAP in four English-speaking studies adopting the same protocol. Through a detailed investigation involving the English Longitudinal Study of Ageing (ELSA), the Health and Retirement Study (HRS), The Irish Longitudinal Study on Ageing (TILDA), and the Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA), we identified 60 factors contributing to the development of a conceptual framework for the evaluation and implementation of HCAP. We present this framework and a prototype checklist as a tool for providing a transparent and structured approach to improve data quality, cross-country comparability and for identifying, mitigating, and monitoring sources of bias. The framework consisting of four broad headings: (1) Organisation and design, (2) Competency of personnel and systems, (3) Implementation and outputs, and (4) Feedback and communication. Studies seeking to harmonize results in cross-national contexts should give operational aspects of fieldwork careful consideration as part of the harmonization process.

Mexican Health and Aging Study Biomarker and Genetic Data Profile

The Mexican Health and Aging Study (MHAS) is one of the largest ongoing longitudinal studies of aging in Latin America, with six waves over 20 years. MHAS includes sociodemographic, economic, and health data from a nationally representative sample of adults 50 years and older in urban and rural Mexico. MHAS is designed to study the impact of diseases on adults' health, function, and mortality. As Mexico is experiencing rapid population aging, providing adequate information to study this phenomenon is vital for designing and implementing public policies. The availability of biomarker and genetic data and longitudinal survey data elevates opportunities for research on aging in a low-middle-income country. This manuscript describes the profile of biomarkers and genetic data available in the MHAS study, including sample sizes and sociodemographic characteristics of participants who provided biospecimens for biomarker analyses, emphasizing recent genetic data. The sample size of individuals with anthropometric biomarkers was 2 707 (Wave 1-2001), 2 361 (Wave 2-2003), 2 086 (Wave 3-2012), and 2 051 (2016). Capillary blood samples were collected from 2 063 participants in 2012 (Wave 3) and 1 141 in 2016. Venous blood samples for blood-based biomarkers were collected from 2 003 participants in 2012 (Wave 3) and 752 in 2016. Venous blood samples were also collected for genetic data from 2 010 participants in 2012 (Wave 3) and 750 in 2016. A total of 7 821 participants provided saliva in 2018, and 2 671 provided hair in 2018. From these samples, a total of 7 204 have genome-wide genetic data, 8 600 have apolipoprotein-E genotype data, and 7 156 have genetic ancestry data.

Integrating accelerometry, GPS, GIS and molecular data to investigate mechanistic pathways of the urban environmental exposome and cognitive outcomes in older adults: a longitudinal study protocol

INTRODUCTION

Maintaining cognitive health in later life is a global priority. Encouraging individuals to make health behaviour changes, such as regular physical activity, and providing supportive urban environments can help maintain cognitive health, thereby preventing or delaying the progress of dementia and cognitive decline. However, the mechanistic pathways by which the urban environmental exposome influences cognitive health outcomes are poorly understood. The aim of this study is to use granular measures of the urban environment exposome (encompassing the built, natural and social environment) and physical activity to explore how these interact with a person's biology to ultimately influence cognitive health outcomes.

METHODS AND ANALYSIS

This ongoing study uses a cohort design, recruiting participants from the Northern Ireland Cohort for the Longitudinal study of Ageing and the Harmonised Cognitive Assessment Protocol study. Participants (n=400 at each wave) will be aged ≥65 years and have the capacity to provide written informed consent. Measures include device-measured physical activity (Actigraph wGT3XP-BT), environmental location data (Global Positioning System, Qstarz BT-Q1000XT), linked to a battery of neuropsychological tests, including the Mini Mental State Examination and the Centre for Epidemiological Studies Depression Scale. Blood-derived biochemical, genetic and epigenetic data will be included in multimodal analyses. These data will be integrated with urban environment Geographic Information System data and analysed using causal inference and mediation methods to investigate plausible mechanistic pathways.

ETHICS AND DISSEMINATION

This study has been approved by the Queen's University Belfast, Faculty of Medicine, Health and Life Sciences Research Ethics Committee (MHLS 21_72). Alongside peer-reviewed publications in high-ranking international journals, dissemination activities include conference presentations, project videos, working papers, policy briefing papers, newsletters, summaries and case study stories.

How to assess cognitive decline when test administration changes across study waves? Harmonizing cognitive scores across waves in the China Health and Retirement Longitudinal Study

Background

Conducting longitudinal cognitive analyses is an essential part of understanding the underlying mechanism of Alzheimer's disease, especially for social and health behavior determinants. However, the cognitive test administration is highly likely to change across time and thus complicate the longitudinal analyses. The China Health and Retirement Longitudinal Study assessed memory through word recall tests across five study waves from 2011 to 2020. Since 2018, changes in the test stimuli and administration posed challenges for longitudinal cognitive analyses.

Objective

To address differences in administration and to preserve differences attributed to characteristics such as age and education and to derive equated scores for use in longitudinal analyses in CHARLS.

Methods

To ensure consistent underlying test ability across waves in the full sample (N = 19,364), we derived a calibration sample (N = 11,148) balancing age, gender, and education. Within this sample, we used weighted equipercentile equating to crosswalk percentile ranks between 2015 and 2018/2020 scores, then applied the algorithm to the full sample.

Results

Mean original delayed word recall was higher in 2018 (4.3 words) and 2020 (5.1 words) versus 2015 (3.2 words). Following equating, scores in 2018 and 2020 aligned better with previous waves (2015, 2018, 2020 immediate means: 4.1, 3.6, 4.0; delayed: 3.2, 2.4, 2.9 words).

Conclusions

Equipercentile equating enables the derivation of comparable scores, facilitating longitudinal analysis when cognitive test administration procedures change over time. We recommended the use of equated scores for longitudinal analyses using CHARLS cognitive data.

Relationship between cognitive function and sleep quality in middle-aged and older adults for minimizing disparities and achieving equity in health: Evidence from multiple nationwide cohorts

BACKGROUND

Cognitive decline, a heavy burden on middle-aged and older adults as global aging is aggravated, was found to be associated with sleep quality. However, the country-between heterogeneity of the association prevented us from quantifying underlying relationship and identifying potential effect modifiers for vulnerable populations and targeted interventions.

METHODS

We collected data from 79,922 eligible adults in five nationwide cohorts, examined the respective relationships between cognitive function and sleep quality, synthesized underlying average relationships by meta-analysis, and explored effect modifiers by meta-regressions. Additionally, we conducted subgroup and interaction analyses to identify vulnerable populations and to determine their disparities in vulnerability.

RESULTS

Although country-between disparities exist, cognitive function is robustly associated with sleep quality in middle-aged and older adults worldwide, with an effect (β) of 0.015 [0.003, 0.027]. Executive function is the subdomain most relevant to sleep quality. Disparities in the effects of sleep quality on subdomains exist in populations with different sexes (orientation: βfemale/βmale = 1.615, P = 0.020), marital statuses (orientation: βunmarried/βmarried = 2.074, P < 0.001), education levels (orientation:βuneducated/βeducated = 2.074, P < 0.001) and chronic disease statuses (memory: βunhealthy/βhealthy = 1.560, P = 0.005).

CONCLUSIONS

Cognitive function decreases with worsening sleep quality in middle-aged and older adults. Vulnerability to poor sleep generally persists in singles, females, the uneducated and people with chronic diseases. To minimize disparities and achieve health equity, we advocate for targeted interventions, i.e., encouraging socialization in singles, confirming effectiveness of hormone replacement therapy in females, employing compulsory education in middle-aged and older adults.

The Association Between Bilingual Animal Naming and Memory Among Bilingual Mexican American Older Adults

BACKGROUND

Monolingual cognitive assessments are standard for bilinguals; the value of bilingual assessment is unknown. Since declines in animal naming accompany memory declines in dementia, we examined the association between bilingual animal naming and memory among bilingual Mexican American (MA) older adults.

METHODS

Bilingual MA (n = 155) completed the Harmonized Cognitive Assessment Protocol (HCAP) in a Texas community study. Regressions included HCAP memory score (English) as the outcome and English and Spanish animal naming trials as independent variables; demographics and language dominance were covariates.

RESULTS

English animal naming (b = 0.06, P = 0.004) was more reliably associated with memory than Spanish (b = 0.05, P = 0.06). Considered together, only English (b = 0.05, P = 0.02) was associated with memory, not Spanish (b = 0.01, P = 0.63). Conclusions: Spanish animal naming did not uniquely add to English animal naming in its association with memory among bilingual older MA.

Type II diabetes and cognitive function among older adults in India and China-results from Harmonized Cognitive Assessment Protocol studies

Objective

Type II diabetes is a recognized risk factor of declining cognitive function in high-income countries. However, there is limited research on this association across low- and middle-income countries. We aimed to examine and compare the relationship between type II diabetes and cognition amongst adults aged 60 years and older for two of the largest LMICs: India and China.

Methods

Cross-sectional data was analyzed from population-based Harmonized Cognitive Assessment Protocols studies in India (n = 4,062) and China (n = 9,741). Multivariable-adjusted linear regression models examined the relationship between diabetes (self-reported or biomarker HbA1c ≥6.5%) and general cognition. Interaction testing assessed effect modification based on urban versus rural residence and educational attainment.

Results

Type II diabetes was not associated with general cognitive scores in India or China in fully adjusted models. Interaction testing revealed a positive association in rural but not urban residences in India, however this was not seen in China. Both countries showed effect modification by education attainment. In India, diabetes was associated with higher average cognitive scores among those with none or early childhood education, while the relationship was null among those with at least an upper secondary education. In China, diabetes was inversely related to average cognitive scores among those with less than lower secondary education, while the relationship was null among the remainder of the study sample.

Conclusion

The type II diabetes and cognitive function association in India and China differs from that observed in high-income countries. These findings suggest epidemiologic and nutrition transition variations. In India, health care access, urbanization and social differences between urban and rural areas may influence this relationship. In both countries, epidemiologic and nutrition patterns may adversely impact individuals from socially and financially vulnerable populations with less than lower secondary education. Longitudinal research using harmonized cognitive scores is encouraged to further investigate these findings.

From Reactive to Proactive - The Future Life Design to Promote Health and Extend the Human Lifespan

Disease treatment and prevention have improved the human lifespan. Current studies on aging, such as the biological clock and senolytic drugs have focused on the medical treatments of various disorders and health maintenance. However, to efficiently extend the human lifespan to its theoretical maximum, medicine can take a further proactive approach and identify the inapparent disorders that affect the gestation, body growth, and reproductive stages of the so-called "healthy" population. The goal is to upgrade the standard health status to a new level by targeting the inapparent disorders. Thus, future research can shift from reaction, response, and prevention to proactive, quality promotion and vigor prolonging; from single disease-oriented to multiple dimension protocol for a healthy body; from treatment of symptom onset to keep away from disorders; and from the healthy aging management to a healthy promotion design beginning at the birth.

Development and assessment of analytic methods to improve the measurement of cognition in longitudinal studies of aging through the use of substudies with comprehensive neuropsychological testing

INTRODUCTION

The Health and Retirement Study International Partner Surveys (HRS IPS) have rich longitudinal data, but the brevity of cognitive batteries is a limitation.

METHODS

We used data from a substudy of the English Longitudinal Study of Ageing (ELSA) administering detailed cognitive assessments with the Harmonized Cognitive Assessment Protocol (ELSA-HCAP) (N = 1273) to inform approaches for estimating cognition in ELSA (N = 11,213). We compared two novel approaches: confirmatory factor analysis (CFA)- and regression-based prediction.

RESULTS

Compared to estimates from the full HCAP battery, estimated cognitive functioning derived using regression models or CFA had high correlations (regression: r = 0.85 [95% confidence interval [CI]: 0.83 to 0.87]; CFA: r = 0.83 [95% CI: 0.81 to 0.85]) and reasonable mean squared error (regression: 0.25 [0.22 to 0.27]; CFA: 0.29 [0.26 to 0.32]) in held-out data. The use of additional items from waves 7 to 9 improved performance.

DISCUSSION

Both approaches are recommended for future research; the similarity in approaches may be due to the brevity of available cognitive assessments in ELSA.

HIGHLIGHTS

Estimates of cognitive functioning informed by English Longitudinal Study of Ageing-Harmonized Cognitive Assessment Protocol (ELSA-HCAP) data had an adequate performance. Standard errors were smaller for associations with example risks when using measures informed by ELSA-HCAP. Performance was better when including additional cognitive measures available in waves 7 to 9. Conceptual advantages to the confirmatory factor analysis (CFA) approach were not important in practice due to the brevity of the ELSA cognitive battery.

Place of Birth and Cognitive Function Among Older Americans: Findings From the Harmonized Cognitive Assessment Protocol

OBJECTIVES

Growing evidence suggests that place of birth (PoB) and related circumstances may have long-lasting and multiplicative contributions to various later-life outcomes. However, the specific contributions to different domains of cognitive function in late life remain less understood. This study investigated the extent to which state of birth contributes to a wide range of domains of later-life cognitive function.

METHODS

A nationally representative sample of Americans aged 65 and older (N = 3,333) from the Health and Retirement Study (HRS) Harmonized Cognitive Assessment Protocol (HCAP) was utilized. Cognitive function was assessed in HCAP and linked to HRS state of birth data to explore the contribution of PoB to later-life cognitive disparities. Regression-based Shapley decompositions were employed to quantify this contribution.

RESULTS

PoB significantly contributed to all assessed cognitive domains including memory, executive function, language and fluency, visuospatial function, orientation, and general cognitive function. Geographic disparities in cognitive function were evident across PoB, with individuals born in U.S. southern states and foreign-born individuals performing worse than those born in other states. Overall, state of birth accounted for 2.2%-9.7% of the total variance in cognition after adjusting for age, sex, and race/ethnicity. This contribution declined to 2.0%-7.0% after further adjusting for comprehensive socioeconomic and health factors over the life course, and was robust to the control of current state of residence.

DISCUSSION

PoB has lasting contributions to later-life cognition, with significant geographic disparities observed. Addressing these disparities requires more equalized place-based policies, resources, and early-life environments to promote health equity over the life course.

Considerations for the use of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) in cross-country comparisons of cognitive aging and dementia

INTRODUCTION

Informant reports are a critical component of dementia diagnoses, but the comparability of informant reports across countries is not well understood.

METHODS

We compared the performance of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) using population-representative surveys in the United States (N = 3183), England (N = 1050), and India (N = 4047).

RESULTS

Analyses of regression splines and comparisons of model fit showed strong associations between IQCODE and objective cognition at low cognitive functioning in the United States and England; in India, the association was weaker but consistent over the range of cognition. Associations between IQCODE score and informant generation (analysis of variance [ANOVA] p = 0.001), caregiver status (p < 0.001), and years known by the informant (p = 0.015) were different across countries after adjusting for objective cognition.

DISCUSSION

In India, the IQCODE was less sensitive to impairments at the lowest levels of cognitive functioning. Country-specific adjustments to IQCODE scoring based on informant characteristics may improve cross-national comparisons.

HIGHLIGHTS

Associations between IQCODE and cognitive testing were similar in the United States and England but differed in India. In India, the IQCODE may be less sensitive to impairments among those with low cognition and no education. Informant characteristics may differentially impact informant reports of decline across countries. Adjustments or culturally sensitive adaptations may improve cross-national comparability.

Modifiable risk factors for dementia in India: A cross-sectional study revisiting estimates and reassessing prevention potential and priorities

Background

About 16% of worldwide dementia cases are in India. Evaluating the prospects for dementia prevention in India requires knowledge of context-specific risk factors, as relationships between risk factors and dementia observed in high-income countries (HICs) may not apply.

Methods

We computed population attributable fractions (PAFs) for dementia in India by estimating associations between risk factors and dementia, their prevalence and communality, within the same nationally representative sample of 4,096 Indians aged 60 and older, surveyed through the Harmonized Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India (LASI-DAD).

Results

The risk factor with the largest PAF (>20%) was no education, followed by vision impairment (14%), physical inactivity (12%), and social isolation (8%). According to our estimates, eliminating exposure to risk factors significantly associated with dementia would potentially prevent up to 70% of dementia cases in India.

Discussion

Previous estimates, based on samples limited to specific geographic areas and using risk factors' definitions and relative risks from HICs, may not correctly estimate the real opportunities for preventing dementia in India or identify the most critical areas for intervention.

Associations Between Hydration Status and Executive Function in Middle-Aged and Older Adults: Findings from the Nationally Representative Health and Retirement Study

The purpose of the current study is to examine the association between hydration status and cognitive function in middle-aged and older adults, drawing from a large, nationally representative sample in the United States and using a comprehensive set of executive function performance measures. We utilized data from the Health and Retirement Study to conduct twelve, three-stage hierarchical regressions on hydration status and executive function performance of older adults. Cognitive performance scores on the Trail Making A, Symbol Digit Modalities, and Letter Cancellation tests significantly differed by hydration status, and these outcomes follow a curvilinear pattern, such that performance scores are lower for those who are hyper-hydrated or dehydrated relative to those who are euhydrated or near-dehydration. Our study's findings are consistent with prior studies examining the impact of serum osmolarity on cognitive performance. Specifically, a curvilinear pattern was associated with speed of processing tests of executive function. Overall, hydration status is associated with curvilinear patterns of performance on executive function measures, specifically Trail Making A, Symbol Digit Modalities, and Letter Cancellation Tests.

A Community-Based Study of Cognitive Impairment Caregiving Outcomes Pre- and During the COVID-19 Pandemic

The impact of the COVID-19 pandemic on informal caregiving was examined in a Mexican American (MA) and Non-Hispanic White (NHW) population-based cohort. 395 participants age > 65 years were recruited via door-to-door and phone recruitment as part of the Brain Attack Surveillance in Corpus Christi-Cognitive (BASIC-C) project. Both recipients and caregivers answered questions regarding the recipient's health and the COVID-19 pandemic. 15% of caregivers saw their caregiving recipient less than before the pandemic and 18% saw their recipient more than before. 55% of caregivers reported a slight to severe impact of the pandemic on their caregiving, and 45% reported no impact. For most caregivers, their caregiving role did not change markedly during the pandemic. MA and NHW caregivers had similar survey responses.

Mental-somatic multimorbidity in trajectories of cognitive function for middle-aged and older adults

INTRODUCTION

Multimorbidity may confer higher risk for cognitive decline than any single constituent disease. This study aims to identify distinct trajectories of cognitive impairment probability among middle-aged and older adults, and to assess the effect of changes in mental-somatic multimorbidity on these distinct trajectories.

METHODS

Data from the Health and Retirement Study (1998-2016) were employed to estimate group-based trajectory models identifying distinct trajectories of cognitive impairment probability. Four time-varying mental-somatic multimorbidity combinations (somatic, stroke, depressive, stroke and depressive) were examined for their association with observed trajectories of cognitive impairment probability with age. Multinomial logistic regression analysis was conducted to quantify the association of sociodemographic and health-related factors with trajectory group membership.

RESULTS

Respondents (N = 20,070) had a mean age of 61.0 years (SD = 8.7) at baseline. Three distinct cognitive trajectories were identified using group-based trajectory modelling: (1) Low risk with late-life increase (62.6%), (2) Low initial risk with rapid increase (25.7%), and (3) High risk (11.7%). For adults following along Low risk with late-life increase, the odds of cognitive impairment for stroke and depressive multimorbidity (OR:3.92, 95%CI:2.91,5.28) were nearly two times higher than either stroke multimorbidity (OR:2.06, 95%CI:1.75,2.43) or depressive multimorbidity (OR:2.03, 95%CI:1.71,2.41). The odds of cognitive impairment for stroke and depressive multimorbidity in Low initial risk with rapid increase or High risk (OR:4.31, 95%CI:3.50,5.31; OR:3.43, 95%CI:2.07,5.66, respectively) were moderately higher than stroke multimorbidity (OR:2.71, 95%CI:2.35, 3.13; OR: 3.23, 95%CI:2.16, 4.81, respectively). In the multinomial logistic regression model, non-Hispanic Black and Hispanic respondents had higher odds of being in Low initial risk with rapid increase and High risk relative to non-Hispanic White adults.

CONCLUSIONS

These findings show that depressive and stroke multimorbidity combinations have the greatest association with rapid cognitive declines and their prevention may postpone these declines, especially in socially disadvantaged and minoritized groups.

Educational Attainment and Later-Life Cognitive Function in High- and Middle-Income Countries: Evidence From the Harmonized Cognitive Assessment Protocol

OBJECTIVES

Identifying social policies that can promote cognitive health is crucial for reducing the global burden of dementia. We evaluated the importance of educational attainment for later-life cognitive function in various social and geographic settings.

METHODS

Using harmonized data for individuals aged ≥65 years from the United States Health and Retirement Study (HRS) and its international partner studies in England, Mexico, China, and India, and each study's respective Harmonized Cognitive Assessment Protocol (HCAP), we conducted a cross-national comparative study to examine the role of educational attainment in later-life cognitive function across countries (n = 14,980, 2016-2019). We used multivariable-adjusted regression to estimate associations between educational attainment and harmonized global cognitive function scores.

RESULTS

In Mexico, China, and India, the general cognitive function scores on average are approximately one standard deviation of the HRS-HCAP cognitive function score distribution lower compared to the United States and England, paralleling patterns of educational attainment across countries. In all countries, higher educational attainment was associated with progressively higher later-life cognitive function scores. Population-level differences in educational attainment explained about 50%-90% of the observed differences in cognitive function scores across countries.

DISCUSSION

The relationship between education and later-life cognitive function across social and geographic contexts underscores the crucial role of education to promote cognitive health and reduce dementia risk. Continual improvement of educational attainment in low- and middle-income settings may yield a significant pay-off in later-life cognitive health.

Racial Disparities in Occupational Distribution Among Black and White Adults with Similar Educational Levels: Analysis of Middle-Aged and Older Individuals in the Health and Retirement Study

Background

Occupational classes play a significant role in influencing both individual and population health, serving as a vital conduit through which higher education can lead to better health outcomes. However, the pathway from education to corresponding occupational classes does not apply uniformly across different racial and ethnic groups, hindered by factors such as social stratification, labor market discrimination, and job segregation.

Aims

This study seeks to investigate the relationship between educational attainment and occupational classes among Black, Latino, and White middle-aged and older adults, with a focus on their transition into retirement.

Methods

Using cross-sectional data from the Health and Retirement Study (HRS), this research examines the impact of race/ethnicity, educational attainment, occupational classes, and timing of retirement among middle-aged and older adults. The analysis includes a sample of 7,096 individuals identified as White, Black, or Latino. Through logistic regression, we assess the additive and multiplicative effects of race/ethnicity and education on six defined occupational classes: 1. Managerial and specialty operations, 2. Professional Specialty, 3. Sales, 4. Clerical/administrative support, 5. Services, and 6. Manual labor.

Results

Participants were Black (n = 1,143) or White (n =5,953). This included Latino (N =459) or non-Latino (n = 6,634). Our analysis reveals a skewed distribution of Black and Latino adults in manual and service occupations, in stark contrast to White adults who were more commonly found in clerical/administrative and managerial positions. Educational attainment did not equate to similar occupational outcomes across racial groups. Key findings include: Firstly, Black individuals with a college degree or higher were less likely to occupy clerical and administrative positions compared to their White counterparts. Secondly, holding a General Educational Development (GED) credential or some college education was generally linked to reduced likelihood of being in managerial roles; however, this inverse relationship was less evident among Black middle-aged and older adults than White ones. Thirdly, having a GED reduced the chances of working in sales roles, while having a college degree increased such chances. An interaction between race and some college education revealed that the impact of some college education on sales roles was more significant for Black adults than for White ones. We did not observe any interaction between ethnicity (Latino) and educational attainment on occupational classes. Given the stability of occupational classes, these findings could also apply to the last occupation held prior to retirement.

Conclusion

This study highlights significant racial disparities in occupational classes among individuals with comparable levels of education, underscoring the profound implications for health and wellbeing disparities. Future research should explore strategies to alleviate labor market discrimination and job segregation as ways to close these occupational gaps. Additionally, the influence of social stratification, job segregation, and historical legacies, such as the repercussions of the Jim Crow era, on these disparities merits further investigation. Addressing these issues is crucial for enhancing the health and wellbeing of all populations.

Performance of the Informant Questionnaire on Cognitive Decline for the Elderly (IQCODE) in a nationally representative study in India: the LASI-DAD study

BACKGROUND

Low and middle-income countries like India anticipate rapid population aging and increases in dementia burden. In India, dementia screening scales originally developed in other contexts need to be assessed for feasibility and validity, given the number of different languages and varying levels of literacy and education.

METHOD

Using data from the Longitudinal Aging Study in India-Diagnostic Assessment of Dementia (N = 4,028), we characterize the performance of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). We described patterns and correlates of missingness, evaluated the psychometric properties of the scale, and assessed criterion validity against the Hindi Mental State Examination (HMSE) using linear regression.

RESULTS

Several IQCODE items had high levels of missingness, which was associated with urbanicity, respondent's gender, and informant's generation (same vs. younger generation). Full IQCODE scores showed strong criterion validity against the HMSE; each 1-point increase in IQCODE score was associated with a 3.03-point lower score on the HMSE, controlling for age, gender, and urbanicity. The statistically significant association between IQCODE and HMSE was stronger in urban than rural settings (p-value for interaction = 0.04). Associations between IQCODE and HMSE remained unchanged after removing the three items with the highest levels of differential missingness (remembering addresses and telephone numbers, ability to work with familiar machines, ability to learn to use new gadget or machine).

CONCLUSION

Findings raise questions about the value of including items with high proportions of missingness, which may signal cultural irrelevance, while removing them did not affect criterion validity.

Purpose in life and cognitive performance and informant ratings of cognitive decline, affect, and activities

OBJECTIVE

To examine (1) the association between purpose in life and multiple domains of cognitive function and informant-rated cognitive decline, affect, and activities; (2) whether these associations are moderated by sociodemographic factors, cognitive impairment, or depression; (3) whether the associations are independent of other aspects of well-being and depressive symptoms.

METHOD

As part of the 2016 Harmonized Cognitive Assessment Protocol from the Health and Retirement Study, participants completed a battery of cognitive tests and nominated a knowledgeable informant to rate their cognitive decline, affect, and activities. Participants with information available on their purpose in life from the 2014/2016 Leave Behind Questionnaire were included in the analytic sample (N = 2,812).

RESULTS

Purpose in life was associated with better performance in every cognitive domain examined (episodic memory, speed-attention, visuospatial skills, language, numeric reasoning; median β =.10, p <.001; median d =.53). Purpose was likewise associated with informant-rated cognitive decline and informant-rated affective and activity profiles beneficial for cognitive health (median β =.18, p < .001; median d =.55). There was little evidence of moderation by sociodemographic or other factors (e.g., depression). Life satisfaction, optimism, positive affect, and mastery were generally associated with cognition. When tested simultaneously with each other and depressive symptoms, most dimensions were reduced to non-significance; purpose remained a significant predictor.

CONCLUSIONS

Purpose in life is associated with better performance across numerous domains of cognition and with emotional and behavioral patterns beneficial for cognitive health that are observable by knowledgeable others. These associations largely generalize across demographic and clinical groups and are independent of other aspects of well-being.

Lifetime occupational skill and later-life cognitive function among older adults in the United States, Mexico, India, and South Africa

INTRODUCTION

We conducted a cross-national comparison of the association between main lifetime occupational skills and later-life cognitive function across four economically and socially distinct countries.

METHODS

Data were from population-based studies of aging and their Harmonized Cognitive Assessment Protocols (HCAPs) in the US, South Africa, India, and Mexico (N = 10,037; Age range: 50 to 105 years; 2016 to 2020). Main lifetime occupational skill was classified according to the International Standard Classification of Occupations. Weighted, adjusted regression models estimated pooled and country-specific associations between main lifetime occupational skill and later-life general cognitive function in men and women.

RESULTS

We observed positive gradients between occupational skill and later-life cognitive function for men and women in the US and Mexico, a positive gradient for women but not men in India, and no association for men or women in South Africa.

DISCUSSION

Main lifetime occupations may be a source of later-life cognitive reserve, with cross-national heterogeneity in this association.

HIGHLIGHTS

No studies have examined cross-national differences in the association of occupational skill with cognition. We used data from Harmonized Cognitive Assessment Protocols in the US, Mexico, India, and South Africa. The association of occupational skill with cognitive function varies by country and gender.

Cross-national comparisons of later-life cognitive function using data from the Harmonized Cognitive Assessment Protocol (HCAP): Considerations and recommended best practices

The Harmonized Cognitive Assessment Protocol (HCAP) is a major innovation that provides, for the first time, harmonized data for cross-national comparisons of later-life cognitive functions that are sensitive to linguistic, cultural, and educational differences across countries. However, cognitive function does not lend itself to direct comparison across diverse populations without careful consideration of the best practices for such comparisons. This perspective discusses theoretical and methodological considerations and offers a set of recommended best practices for conducting cross-national comparisons of risk factor associations using HCAP data. Because existing and planned HCAP studies provide cognition data representing an estimated 75% of the global population ≥65 years of age, these recommended best practices will support high-quality comparative analyses of cognitive aging around the world. The principles described in this perspective are applicable to any researcher aiming to integrate or compare harmonized data on cognitive outcomes and their risk and protective factors across diverse populations.

Prevalence of DSM-5 mild and major neurocognitive disorder in India: Results from the LASI-DAD

INTRODUCTION

India, with its rapidly aging population, faces an alarming burden of dementia. We implemented DSM-5 criteria in large-scale, nationally representative survey data in India to characterize the prevalence of mild and major Neurocognitive disorder.

METHODS

The Harmonized Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India (LASI-DAD) (N = 4,096) is a nationally representative cohort study in India using multistage area probability sampling methods. Using neuropsychological testing and informant reports, we defined DSM-5 mild and major neurocognitive disorder, reported its prevalence, and evaluated criterion and construct validity of the algorithm using clinician-adjudicated Clinical Dementia Ratings (CDR)®.

RESULTS

The prevalence of mild and major neurocognitive disorder, weighted to the population, is 17.6% and 7.2%. Demographic gradients with respect to age and education conform to hypothesized patterns. Among N = 2,390 participants with a clinician-adjudicated CDR, CDR ratings and DSM-5 classification agreed for N = 2,139 (89.5%) participants.

DISCUSSION

The prevalence of dementia in India is higher than previously recognized. These findings, coupled with a growing number of older adults in the coming decades in India, have important implications for society, public health, and families. We are aware of no previous Indian population-representative estimates of mild cognitive impairment, a group which will be increasingly important in coming years to identify for potential therapeutic treatment.

Time-lagged associations between two adverse childhood experiences and later-life cognitive function through educational attainment and stroke

OBJECTIVE

Adverse childhood experiences (ACEs) have been associated with worse cognitive health in older adulthood. This study aimed to extend findings on the specificity, persistence, and pathways of associations between two ACEs and cognition by using a comprehensive neuropsychological battery and a time-lagged mediation design.

METHOD

Participants were 3304 older adults in the Health and Retirement Study Harmonized Cognitive Assessment Protocol. Participants retrospectively reported whether they were exposed to parental substance abuse or experienced parental physical abuse before age 18. Factor scores derived from a battery of 13 neuropsychological tests indexed cognitive domains of episodic memory, executive functioning, processing speed, language, and visuospatial function. Structural equation models examined self-reported years of education and stroke as mediators, controlling for sociodemographics and childhood socioeconomic status.

RESULTS

Parental substance abuse in childhood was associated with worse later-life cognitive function across all domains, in part via pathways involving educational attainment and stroke. Parental physical abuse was associated with worse cognitive outcomes via stroke independent of education.

CONCLUSIONS

This national longitudinal study in the United States provides evidence for broad and persistent indirect associations between two ACEs and cognitive aging via differential pathways involving educational attainment and stroke. Future research should examine additional ACEs and mechanisms as well as moderators of these associations to better understand points of intervention.

Investigating the prevalence of cognitive impairment and dementia in the Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA): the Harmonised Cognitive Assessment Protocol (HCAP) cross-sectional substudy

INTRODUCTION

The Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA) study is the largest study of ageing in Northern Ireland (NI). The Harmonised Cognitive Assessment Protocol (HCAP) is a substudy of NICOLA designed to assess cognitive impairment and dementia in individuals aged 65 and over. The NICOLA-HCAP substudy is funded by the National Institute on Aging as part of a network for enhancing cross-national research within a worldwide group of population-based, longitudinal studies of ageing, all of which are centred around the US-based Health and Retirement Study.

METHODS AND ANALYSIS

The NICOLA-HCAP study will draw on the main NICOLA cohort (of 8283 participants) and randomly sample 1000 participants aged 65 and over to take part in the substudy. Participants will complete a series of cognitive tests (n=19) via a computer-assisted personal interview administered in their home (or alternatively within the research centre) and will be asked to nominate a family member or friend to complete an additional interview of validated instruments to provide information on respondent's prior and current cognitive and physical functioning and whether the individual requires help with daily activities. The objectives of the study are: to investigate the prevalence of dementia and cognitive impairment in NICOLA; harmonise scoring of the NICOLA-HCAP data to the HCAP studies conducted in Ireland, the USA and England; to explore the validity of dementia estimates; and investigate the risk factors for dementia and cognitive impairment.

ETHICS AND DISSEMINATION

The study received ethical approval from the Faculty of Medicine, Health and Life Sciences Research Ethics Committee, Queen's University Belfast. We will provide data from the Northern Irish HCAP to the research community via data repositories such as the Dementias Platform UK and Gateway to Global Aging to complement existing public data resources and support epidemiological research by others. Findings will also be disseminated through peer-reviewed publications and at international conferences.

The Association of Allergy-Related and Non-Allergy-Related Olfactory Impairment with Cognitive Function in Older Adults: Two Cross- Sectional Studies

BACKGROUND

Evidence on the association of Olfactory Impairment (OI) with age-related cognitive decline is inconclusive, and the potential influence of allergy remains unclear.

OBJECTIVE

We aimed to evaluate the cross-sectional associations of allergy-related and non-allergy- related OI to cognitive function.

METHODS

We included 2,499 participants from the Health and Retirement Study (HRS)-Harmonized Cognitive Assessment Protocol (HCAP) sub-study and 1,086 participants from the English Longitudinal Study of Ageing (ELSA)-HCAP. The Olfactory Function Field Exam (OFFE) using Sniffin' Stick odor pens was used to objectively assess olfactory function and an olfactory score <6/11 indicated OI. Mini-Mental Status Examination (MMSE) was used to assess global cognitive function and define cognitive impairment (<24/30). A neuropsychologic battery was used to assess five cognitive domains.

RESULTS

Compared to non-OI participants, individuals with OI had lower MMSE z-score [βHRS = -0.33, 95% Confidence Interval (CI): -0.41 to -0.24; βELSA = -0.31, -0.43 to -0.18] and higher prevalence of cognitive impairment (Prevalence Ratio (PR)HRS = 1.46, 1.06 to 2.01; PRELSA = 1.63, 1.26 to 2.11). The associations were stronger for non-allergy-related OI (βHRS = -0.36; βELSA = -0.34) than for allergy-related OI (βHRS = -0.26; βELSA = 0.13). Similar associations were observed with domain- specific cognitive function measures.

CONCLUSION

OI, particularly non-allergy-related OI, was related to poorer cognitive function in older adults. Although the current cross-sectional study is subject to several limitations, such as reverse causality and residual confounding, the findings will provide insights into the OI-cognition association and enlighten future attention to non-allergy-related OI for the prevention of potential cognitive impairment.

Factor structure of the Harmonized Cognitive Assessment Protocol neuropsychological battery in the Health and Retirement Study

OBJECTIVE

The Harmonized Cognitive Assessment Protocol (HCAP) describes an assessment battery and a family of population-representative studies measuring neuropsychological performance. We describe the factorial structure of the HCAP battery in the US Health and Retirement Study (HRS).

METHOD

The HCAP battery was compiled from existing measures by a cross-disciplinary and international panel of researchers. The HCAP battery was used in the 2016 wave of the HRS. We used factor analysis methods to assess and refine a theoretically driven single and multiple domain factor structure for tests included in the HCAP battery among 3,347 participants with evaluable performance data.

RESULTS

For the eight domains of cognitive functioning identified (orientation, memory [immediate, delayed, and recognition], set shifting, attention/speed, language/fluency, and visuospatial), all single factor models fit reasonably well, although four of these domains had either 2 or 3 indicators where fit must be perfect and is not informative. Multidimensional models suggested the eight-domain model was overly complex. A five-domain model (orientation, memory delayed and recognition, executive functioning, language/fluency, visuospatial) was identified as a reasonable model for summarizing performance in this sample (standardized root mean square residual = 0.05, root mean square error of approximation = 0.05, confirmatory fit index = 0.94).

CONCLUSIONS

The HCAP battery conforms adequately to a multidimensional structure of neuropsychological performance. The derived measurement models can be used to operationalize notions of neurocognitive impairment, and as a starting point for prioritizing pre-statistical harmonization and evaluating configural invariance in cross-national research.

A Community-Based Study of Dementia in Mexican American and Non-Hispanic White Individuals

BACKGROUND

Little information is available on the prevalence of cognitive impairment in Mexican American persons.

OBJECTIVE

To determine the prevalence of mild cognitive impairment (MCI) and dementia in those 65 years and older among Mexican American and non-Hispanic white individuals in a community.

METHODS

This was a population-based cohort study in Nueces County, Texas, USA. Participants were recruited using a random housing sample. The Harmonized Cognitive Assessment (HCAP) participant and informant protocol was performed after Montreal Cognitive Assessment (MoCA) screening. An algorithm was used to sort participants into diagnostic categories: no cognitive impairment, MCI, or dementia. Logistic regression determined the association of ethnicity with MCI and dementia controlling for age, gender, and education.

RESULTS

1,901 participants completed the MoCA and 547 the HCAP. Mexican Americans were younger and had less educational attainment than non-Hispanic whites. Overall, dementia prevalence was 11.6% (95% CI 9.2-14.0) and MCI prevalence was 21.2% (95% CI 17.5-24.8). After adjusting for age, gender, and education level, there was no significant ethnic difference in the odds of dementia or MCI. Those with ≤11 compared with ≥16 years of education had much higher dementia [OR = 4.9 (95% CI 2.2-11.1)] and MCI risk [OR = 3.5 (95% CI 1.6-7.5)].

CONCLUSIONS

Dementia and MCI prevalence were high in both Mexican American and non-Hispanic white populations. Mexican American persons had double the odds of mild cognitive impairment and this was attenuated when age and educational attainment were considered. Educational attainment was a potent predictor of cognitive impairment.

Does education moderate gender disparities in later-life memory function? A cross-national comparison of harmonized cognitive assessment protocols in the United States and India

INTRODUCTION

We compared gender disparities in later-life memory, overall and by education, in India and the United States (US).

METHODS

Data (N = 7443) were from harmonized cognitive assessment protocols (HCAPs) in the Longitudinal Aging Study of India-Diagnostic Assessment of Dementia (LASI-DAD; N = 4096; 2017-19) and US Health and Retirement Study HCAP (HRS-HCAP; N = 3347; 2016-17). We derived harmonized memory factors from each study using confirmatory factor analysis. We used multivariable-adjusted linear regression to compare gender disparities in memory function between countries, overall and by education.

RESULTS

In the United States, older women had better memory than older men (0.28 SD-unit difference; 95% CI: 0.22, 0.35). In India, older women had worse memory than older men (-0.15 SD-unit difference; 95% CI: -0.20, -0.10), which attenuated with increasing education and literacy.

CONCLUSION

We observed gender disparities in memory in India that were not present in the United States, and which dissipated with education and literacy.

Longitudinal trajectory of amplitude of low-frequency fluctuation changes in breast cancer patients during neoadjuvant chemotherapy-A preliminary prospective study

There is growing evidence that the amplitude of low-frequency fluctuation (ALFF) changes in breast cancer patients after chemotherapy. However, longitudinal changes in ALFF during chemotherapy are unclear. To assess the trajectory of ALFF changes during chemotherapy, 36 breast cancer patients underwent both resting-state functional magnetic resonance imaging and neuropsychological testing at three time points, including before neoadjuvant chemotherapy (NAC) (time point 0, TP0), after one cycle of NAC (before the second cycle of NAC, TP1), and upon completion of NAC (pre-operation, TP2). Healthy controls (HC) received the same assessments at matching time points. We compared the longitudinal changes of ALFF in the NAC and two HC groups. In the NAC group, compared with TP0, ALFF values in the right orbital part of the inferior frontal gyrus, left medial orbital part of the superior frontal gyrus, right insula, left medial part of the superior frontal gyrus, and right middle frontal gyrus declined significantly at TP1 and TP2. Compared with TP1, there were no significant changes in ALFF values at TP2. In the two HC groups, there were no significant changes in ALFF at corresponding intervals. We concluded that for breast cancer patients receiving NAC, ALFF values declined significantly in some brain regions after one cycle of NAC and then remained stable until the completion of NAC, and most of the brain regions with ALFF changes were located in the frontal lobe.

The Add Health Parent Study: A Biosocial Resource for the Study of Multigenerational Racial/Ethnic Disparities in Alzheimer's Disease and Alzheimer's Disease-Related Dementias

Background

Alzheimer's disease and Alzheimer's disease related dementias (AD/ADRD) have increased in prevalence.

Objective

This article describes the Add Health Parent Study (AHPS) Phase 2, a study of social, behavioral, and biological factors influencing healthy aging and risk for AD/ADRD, in a national sample of adults aged 58-90.

Methods

Sample members are parents of the National Longitudinal Study of Adolescent to Adult Health (Add Health) cohort, initially interviewed in Add Health in midlife (1994-95). AHPS Phase 1 (2015-17) collected longitudinal data on a random subsample of parents and their spouse/partners, who were mostly Non-Hispanic (NH) White. AHPS Phase 2 will collect the same longitudinal socio-behavioral, and health survey data on all remaining NH Black and Hispanic parents (Black and Hispanic Supplement, BHS). Additionally, Phase 2 will collect cognitive and DNA data from AHPS Phase 1 and BHS sample parents and their current spouse/partners.

Results

Funded by the National Institute on Aging, recruitment will occur between June 2025 and May 2026, producing an expected total AHPS sample of 5506 parents and their spouse/partners.

Conclusions

The AHPS will be the first longitudinal cohort study powered to address multigenerational racial/ethnic disparities in AD/ADRD risk and protective factors across race/ethnic groups and socioeconomic strata.

Association between perceived risk of Alzheimer's disease and related dementias and cognitive function among U.S. older adults

INTRODUCTION

The aim of the study was to assess factors associated with the perceived risk of developing Alzheimer's disease and related dementias (ADRD) and how the perceived risk of ADRD was related to cognitive function.

METHODS

We conducted a retrospective cohort study using 5 waves of data from the Health and Retirement Study (2012-2022) that included adults aged 65 years or older with no previous diagnosis of ADRD at baseline. Cognitive function was measured at baseline and over time using a summary score that included immediate/delayed word recall, serial 7's test, objective naming test, backwards counting, recall of the current date, and naming the president/vice-president (range = 0-35). Perceived risk of developing ADRD was categorized at baseline as "definitely not" (0% probability), "unlikely" (1-49%), "uncertain" (50%), and "more than likely" (>50-100%). Additional baseline measures included participants' sociodemographic background, psychosocial resources, health behaviors, physiological status, and healthcare utilization.

RESULTS

Of 1457 respondents (median age 74 [IQR = 69-80] and 59.8% women), individuals who perceived that they were "more than likely" to develop ADRD had more depressive symptoms and were more likely to be hospitalized in the past two years than individuals who indicated that it was "unlikely" they would develop ADRD. Alternatively, respondnets who perceived that they would "definitely not" develop ADRD were more likely to be non-Hispanic Black, less educated, and have lower income than individuals who indicated it was "unlikely" they would develop ADRD. Respondents who reported their risks of developing ADRD as "more than likely" (β = -2.10, P < 0.001) and "definitely not" (β = -1.50, P < 0.001) had the lowest levels of cognitive function; and the associations were explained in part by their socioeconomic, psychosocial, and health status.

CONCLUSIONS

Perceived risk of developing ADRD is associated with cognitive function. The (dis)concordance between individuals' perceived risk of ADRD and their cognitive function has important implications for increasing public awareness and developing interventions to prevent ADRD.

Identification of high likelihood of dementia in population-based surveys using unsupervised clustering: a longitudinal analysis

BACKGROUND

Dementia is defined as a cognitive decline that affects functional status. Longitudinal ageing surveys often lack a clinical diagnosis of dementia though measure cognition and daily function over time. We used unsupervised machine learning and longitudinal data to identify transition to probable dementia.

METHODS

Multiple Factor Analysis was applied to longitudinal function and cognitive data of 15,278 baseline participants (aged 50 years and more) from the Survey of Health, Ageing, and Retirement in Europe (SHARE) (waves 1, 2 and 4-7, between 2004 and 2017). Hierarchical Clustering on Principal Components discriminated three clusters at each wave. We estimated probable or "Likely Dementia" prevalence by sex and age, and assessed whether dementia risk factors increased the risk of being assigned probable dementia status using multistate models. Next, we compared the "Likely Dementia" cluster with self-reported dementia status and replicated our findings in the English Longitudinal Study of Ageing (ELSA) cohort (waves 1-9, between 2002 and 2019, 7840 participants at baseline).

RESULTS

Our algorithm identified a higher number of probable dementia cases compared with self-reported cases and showed good discriminative power across all waves (AUC ranged from 0.754 [0.722-0.787] to 0.830 [0.800-0.861]). "Likely Dementia" status was more prevalent in older people, displayed a 2:1 female/male ratio, and was associated with nine factors that increased risk of transition to dementia: low education, hearing loss, hypertension, drinking, smoking, depression, social isolation, physical inactivity, diabetes, and obesity. Results were replicated in ELSA cohort with good accuracy.

CONCLUSIONS

Machine learning clustering can be used to study dementia determinants and outcomes in longitudinal population ageing surveys in which dementia clinical diagnosis is lacking.