Anemia, hemoglobin concentration and cognitive function in the Longitudinal Ageing Study in India-Harmonized Diagnostic Assessment of Dementia (LASI-DAD) and the Health and Retirement Study.

Background: In India, anemia is widely researched in children and women of reproductive age, however, studies in older populations are lacking. Given the adverse effect of anemia on cognitive function and dementia this older population group warrants further study. The Longitudinal Ageing Study in India - Harmonized Diagnostic Assessment of Dementia (LASI-DAD) dataset contains detailed measures to allow a better understanding of anaemia as a potential risk factor for dementia. Method: 2,758 respondents from the LASI-DAD cohort, aged 60 or older, had a complete blood count measured from venous blood as well as cognitive function tests including episodic memory, executive function and verbal fluency. Linear regression was used to test the associations between blood measures (including anemia and hemoglobin concentration (g/dL)) with 11 cognitive domains. All models were adjusted for age and gender with the full model containing adjustments for rural location, years of education, smoking, region, BMI and population weights.Results from LASI-DAD were validated using the USA-based Health and Retirement Study (HRS) cohort (n=5720) to replicate associations between blood cell measures and global cognition. Results: In LASI-DAD, we showed an association between anemia and poor memory (p=0.0054). We found a positive association between hemoglobin concentration and ten cognitive domains tested (ß=0.041-0.071, p<0.05). The strongest association with hemoglobin was identified for memory-based tests (immediate episodic, delayed episodic and broad domain memory, ß=0.061-0.071, p<0.005). Positive associations were also shown between the general cognitive score and the other red blood count tests including mean corpuscular hemoglobin concentration (MCHC, ß=0.06, p=0.0001) and red cell distribution width (RDW, ß =-0.11, p<0.0001). In the HRS cohort, positive associations were replicated between general cognitive score and other blood count tests (Red Blood Cell, MCHC and RDW, p<0.05). Conclusion: We have established in a large South Asian population that low hemoglobin and anaemia are associated with low cognitive function, therefore indicating that anaemia could be an important modifiable risk factor. We have validated this result in an external cohort demonstrating both the variability of this risk factor cross-nationally and its generalizable association with cognitive outcomes.

Cohort Profile: Real-Time Insights of COVID-19 in India (RTI COVID-India).

BACKGROUND: The coronavirus disease (COVID) pandemic caused disruption globally and was particularly distressing in low- and middle-income countries such as India. This study aimed to provide population representative estimates of COVID-related outcomes in India over time and characterize how COVID-related changes and impacts differ by key socioeconomic groups across the life course. METHODS: The sample was leveraged from an existing nationally representative study on cognition and dementia in India: Harmonized Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India (LASI-DAD). The wave-1 of LASI-DAD enrolled 4096 older adults aged 60 years and older in 3316 households from 18 states and union territories of India. Out of the 3316 LASI-DAD households, 2704 with valid phone numbers were contacted and invited to participate in the Real-Time Insights COVID-19 in India (RTI COVID-India) study. RTI COVID-India was a bi-monthly phone survey that provided insight into the individual's knowledge, attitudes, and behaviour towards COVID-19 and changes in the household's economic and health conditions throughout the pandemic. The survey was started in May 2020 and 9 rounds of data have been collected. FINDINGS TILL DATE: Out of the 2704 LASI-DAD households with valid phone numbers, 1766 households participated in the RTI COVID-India survey at least once. Participants were in the age range of 18-102 years, 49% were female, 66% resided in rural area. Across all rounds, there was a higher report of infection among respondents aged 60-69 years. There was a greater prevalence of COVID-19 diagnosis reported in urban (23.0%) compared to rural areas (9.8%). Respondents with higher education had a greater prevalence of COVID-19 diagnosis compared to those with lower or no formal education. Highest prevalence of COVID-19 diagnosis was reported from high economic status compared to middle and low economic status households. Comparing education gradients in experiencing COVID-19 symptoms and being diagnosed, we observe an opposite pattern: respondents with no formal schooling reported the highest level of experiencing COVID-19 symptoms, whereas the greatest proportion of the respondents with secondary school or higher education reported being diagnosed with COVID-19. FUTURE PLANS: The study group will analyse the data collected showing the real-time changes throughout the pandemic and will make the data widely available for researchers to conduct further studies.

Deep phenotyping and genomic data from a nationally representative study on dementia in India.

The Harmonized Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India (LASI-DAD) is a nationally representative in-depth study of cognitive aging and dementia. We present a publicly available dataset of harmonized cognitive measures of 4,096 adults 60 years of age and older in India, collected across 18 states and union territories. Blood samples were obtained to carry out whole blood and serum-based assays. Results are included in a venous blood specimen datafile that can be linked to the Harmonized LASI-DAD dataset. A global screening array of 960 LASI-DAD respondents is also publicly available for download, in addition to neuroimaging data on 137 LASI-DAD participants. Altogether, these datasets provide comprehensive information on older adults in India that allow researchers to further understand risk factors associated with cognitive impairment and dementia.

Adherence to COVID-19 protective behaviours in India from May to December 2020: evidence from a nationally representative longitudinal survey.

OBJECTIVES: Since the onset of the COVID-19 pandemic, behavioural interventions to reduce disease transmission have been central to public health policy worldwide. Sustaining individual protective behaviour is especially important in low-income and middle-income settings, where health systems have fewer resources and access to vaccination is limited. This study seeks to assess time trends in COVID-19 protective behaviour in India. DESIGN: Nationally representative, panel-based, longitudinal study. SETTING: We conducted a panel survey of Indian households to understand how the adoption of COVID-19 protective behaviours has changed over time. Our data span peaks and valleys of disease transmission over May-December 2020. PARTICIPANTS: Respondents included 3719 adults from 1766 Indian households enrolled in the Harmonised Diagnostic Assessment of Dementia for the Longitudinal Ageing Study in India. ANALYSIS: We used ordinary least squares regression analysis to quantify time trends in protective behaviours. RESULTS: We find a 30.6 percentage point (95% CI (26.7 to 34.5); p<0.01) decline in protective behaviours related to social distancing over the observation period. Mask wearing and handwashing, in contrast, decreased by only 4.3 percentage points (95% CI (0.97 to 7.6); p<0.05) from a high base. Our conclusions are unchanged after adjusting for recorded COVID-19 caseload and nationwide COVID-19 containment policy; we also observe significant declines across socioeconomic strata spanning age, gender, education and urbanicity. CONCLUSION: We argue that these changes reflect, at least in part, 'COVID-19 fatigue,' where adherence to social distancing becomes more difficult over time irrespective of the surrounding disease environment.

Learning From Clinical Consensus Diagnosis in India to Facilitate Automatic Classification of Dementia: Machine Learning Study.

BACKGROUND: The Harmonized Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India (LASI-DAD) is the first and only nationally representative study on late-life cognition and dementia in India (n=4096). LASI-DAD obtained clinical consensus diagnosis of dementia for a subsample of 2528 respondents. OBJECTIVE: This study develops a machine learning model that uses data from the clinical consensus diagnosis in LASI-DAD to support the classification of dementia status. METHODS: Clinicians were presented with the extensive data collected from LASI-DAD, including sociodemographic information and health history of respondents, results from the screening tests of cognitive status, and information obtained from informant interviews. Based on the Clinical Dementia Rating (CDR) and using an online platform, clinicians individually evaluated each case and then reached a consensus diagnosis. A 2-step procedure was implemented to train several candidate machine learning models, which were evaluated using a separate test set for predictive accuracy measurement, including the area under receiver operating curve (AUROC), accuracy, sensitivity, specificity, precision, F1 score, and kappa statistic. The ultimate model was selected based on overall agreement as measured by kappa. We further examined the overall accuracy and agreement with the final consensus diagnoses between the selected machine learning model and individual clinicians who participated in the clinical consensus diagnostic process. Finally, we applied the selected model to a subgroup of LASI-DAD participants for whom the clinical consensus diagnosis was not obtained to predict their dementia status. RESULTS: Among the 2528 individuals who received clinical consensus diagnosis, 192 (6.7% after adjusting for sampling weight) were diagnosed with dementia. All candidate machine learning models achieved outstanding discriminative ability, as indicated by AUROC >.90, and had similar accuracy and specificity (both around 0.95). The support vector machine model outperformed other models with the highest sensitivity (0.81), F1 score (0.72), and kappa (.70, indicating substantial agreement) and the second highest precision (0.65). As a result, the support vector machine was selected as the ultimate model. Further examination revealed that overall accuracy and agreement were similar between the selected model and individual clinicians. Application of the prediction model on 1568 individuals without clinical consensus diagnosis classified 127 individuals as living with dementia. After applying sampling weight, we can estimate the prevalence of dementia in the population as 7.4%. CONCLUSIONS: The selected machine learning model has outstanding discriminative ability and substantial agreement with a clinical consensus diagnosis of dementia. The model can serve as a computer model of the clinical knowledge and experience encoded in the clinical consensus diagnostic process and has many potential applications, including predicting missed dementia diagnoses and serving as a clinical decision support tool or virtual rater to assist diagnosis of dementia.

The Association of Cognitive and Visual Function in a Nationally Representative Study of Older Adults in India.

INTRODUCTION: Due to population aging, India is poised to experience a large increase in the burden of both dementia and vision impairment (VI). Prior studies from other settings suggest that VI may be a modifiable risk factor for cognitive decline and dementia. However, to date, no studies have examined the association of impaired visual acuity and cognition in India. METHODS: A total of 3,784 participants in wave 1 of the population-based Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India underwent visual acuity testing and a cognitive test battery. Multivariable linear regression was used to model the cross-sectional associations of mild (<6/12-6/16), moderate (<6/18-6/60), and severe visual acuity impairment/blindness (<6/60) with cognitive performance scores corresponding to total cognition, orientation, memory, language/fluency, executive function, and informant-reported cognitive status. Models were adjusted for demographic, socioeconomic, and health characteristics. RESULTS: The weighted percentage of participants with any VI was 52.6%. VI was independently associated with lower cognitive scores across all domains, even after adjustment for known dementia risk factors. In fully adjusted models of total cognition (mean score: 130.7), mild, moderate, and severe VI/blindness were associated with a significant change of -3.5 (95% CI: -6.3, -0.6), -8.2 (95% CI -10.5, -5.6), and -16.8 (95% CI -22.3, -11.3) units, respectively. A dose-response association between level of VI and cognitive function was observed for all cognitive outcomes except for language/fluency domain scores. Associations were robust when cognitive tests dependent on visual function were excluded. Across each fully adjusted model of total, domain-specific, and informant-reported cognitive performance, moderate VI was equivalent to 5-9 years of cognitive aging. DISCUSSION/CONCLUSION: This study illustrates that VI is cross-sectionally associated with lower cognitive performance, largely in a dose-response pattern, across various cognitive domains in the Indian population. These findings are important for informing future longitudinal and interventional studies.

Design and Methodology of the Longitudinal Aging Study in India-Diagnostic Assessment of Dementia (LASI-DAD).

BACKGROUND/OBJECTIVES: To provide high-quality data on older adults in India that will enable an in-depth study of late-life cognition and dementia in India and cross-country analysis of risk factors for cognitive aging and dementia. DESIGN: The Longitudinal Aging Study in India (LASI) is a nationally representative survey of health, economic, and social well-being of the Indian population aged 45 and older. Its large sample of more than 70,000 older adults represents not only the country as a whole but also each state. LASI-Diagnostic Assessment of Dementia (DAD) is an in-depth study of late-life cognition and dementia, drawing a subsample of over 3,000 LASI respondents aged 60 and older. SETTING: Participants were interviewed at home or in a participating hospital according to their preferences. PARTICIPANTS: Adults aged 60 and older (N = 3,224), along with 3,191 informants. MEASUREMENTS: Respondents underwent a battery of cognitive tests, and informants were interviewed about their cognitive and health conditions. A common set of cognitive tests was selected to enable international comparisons, and additional cognitive tests suitable for illiterate and innumerate populations were also selected. Rich data on risk factors of dementia were collected through health examination, venous blood assays, and genotyping. RESULTS: The response rate was 82.9%, varying across sex, education, and urbanicity. Data are available to other researchers. CONCLUSION: LASI-DAD provides an opportunity to study late-life cognition and dementia and their risk factors in the older population in India and to gain further insights through cross-country analysis by pooling data from its international sister studies. J Am Geriatr Soc 68:S5-S10, 2020.

Online Clinical Consensus Diagnosis of Dementia: Development and Validation.

OBJECTIVES: To introduce cost-effective expert clinical diagnoses of dementia into population-based research using an online platform and to demonstrate their validity against in-person clinical assessment and diagnosis. DESIGN: The online platform provides standardized data necessary for clinicians to rate participants on the Clinical Dementia Rating (CDR® ). Using this platform, clinicians diagnosed 60 patients at a range of CDR levels at two clinical sites. The online consensus diagnosis was compared with in-person clinical consensus diagnosis. SETTING: All India Institute of Medical Sciences (AIIMS), Delhi, and National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India. PARTICIPANTS: Thirty patients each at AIIMS and NIMHANS with equal numbers of patients previously independently rated in person by experts as CDR is 0 (cognitively normal), CDR is 0.5 (mild cognitive impairment), and CDR is 1 or greater (dementia). MEASUREMENTS: Multiple clinicians independently rate each participant on each CDR domain using standardized data and expert clinical judgment. The overall summary CDR is calculated by algorithm. When there are discrepancies among clinician ratings, clinicians discuss the case through a virtual consensus conference and arrive at a consensus overall rating. RESULTS: Online clinical consensus diagnosis based on standardized interview data provides consistent clinical diagnosis with in-person clinical assessment and consensus diagnosis (κ coefficient = 0.76). CONCLUSION: A web-based clinical consensus platform built on the Harmonized Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India interview data is a cost-effective way to obtain reliable expert clinical judgments. A similar approach can be used for other epidemiological studies of dementia. J Am Geriatr Soc 68:S54-S59, 2020.

Methodological considerations in designing and implementing the harmonized diagnostic assessment of dementia for longitudinal aging study in India (LASI-DAD).

The Harmonized Diagnostic Assessment of Dementia for Longitudinal Aging Study in India (LASI-DAD) is a population-representative, prospective cohort study of late-life cognition and dementia. It is part of an ongoing international research collaboration that aims to measure and understand cognitive impairment and dementia risk by collecting a set of cognitive and neuropsychological assessments and informant reports, referred to as the Harmonized Cognitive Assessment Protocol (HCAP). LASI-DAD provides nationally representative data drawn from a subsample of the ongoing Longitudinal Aging Study in India (LASI). One of LASI-DAD's distinctive features is its rich geriatric assessment, including the collection of venous blood samples and brain imaging data for a subsample of respondents. In this paper, we discuss the methodological considerations of developing and implementing the HCAP protocol in India. The lessons we learned from translating and applying the HCAP protocol in an environment where illiteracy and innumeracy are high will provide important insights to researchers interested in measuring and collecting data on late-life cognition and dementia in developing countries. We further developed an innovative blood management system that enables us to follow the collection, transportation, assay, and storage of samples. Such innovation can benefit other population surveys collecting biomarker data.

Cross-Country Comparisons of Disability and Morbidity: Evidence from the Gateway to Global Aging Data.

Background: International comparisons of disease prevalence have been useful in understanding what proportion of disease might be preventable and in informing potential policy interventions in different cultural and economic contexts. Using newly available, harmonized data from 20 countries, we compare disability and morbidity of older adults between the ages of 55 and 74. Methods: The Gateway to Global Aging Data, a data and information portal, provides access to easy-to-use individual-level longitudinal data from 10 surveys covering over 30 countries. Exploiting harmonized measures available from the Gateway, we descriptively examine how disability and morbidity differ across countries. Results: Significant cross-country differences are observed for several health indicators. Comparing countries with the highest and lowest prevalence rates, we observe that hypertension rates vary twofold and stroke rates vary threefold, while disability and arthritis rates vary more than fivefold. Among women, higher gross domestic product and life expectancy are related to lower diabetes, heart disease, and better functioning. Among men, national indicators of economic conditions are not significantly associated with reported disease prevalence. Conclusions: We document substantial heterogeneity in disability and morbidity across countries, separately for men and women and after controlling for population age composition and education. Rich data from various surveys across the world offers remarkable opportunities for cross-country analyses, calling for further investigation of what drives observed differences. The Gateway to Global Aging Data provides easy-to-use harmonized data files and tools to facilitate this type of research.

Measurement of adolescent drug use.

There is widespread agreement that estimates of adolescent drug use prevalence from the National Household Survey of Drug Abuse (NHSDA) and Monitoring the Future (MTF) are subject to considerable measurement error. Nevertheless, some have suggested that trends over time in these prevalence estimates probably reflect true trends in drug use, since underreporting may be assumed to be constant over time. A recent National Research Council report criticizes this assumption on logical grounds. The present study examines adolescent drug use responses on the NHSDA and MTF for evidence of "drug omission," "jargon confusion" and "conceptual confusion," three types of misreporting expected to vary in magnitude with changes in drug use practices and changes in survey items. Results demonstrate that adolescent drug users are significantly more likely than adults to report use of drugs not listed in the NHSDA. Among adolescents who wrote in the "other" drugs they used, 66% and 86% of hallucinogen and inhalant responses showed confusion over the meaning of the pharmacological terms used in the NHSDA. Almost 20% of MTF respondents who report lifetime use of Rohypnol or ecstasy, when specifically queried about these drugs, deny lifetime use of any substances in the drug classes intended to assess use of Rohypnol and ecstasy. MTF respondents reporting lifetime use of PCP underreport use of hallucinogens at rates that vary substantially over time, from a high of 45% (in 1986), to a low of just 8% (in 1998). The implications of these findings for adolescent drug use prevalence estimation and survey design are discussed.