The Aging, Demographics, and Memory Study: Study Design and Methods

Verbal memory is associated with adherence to COVID-19 protective behaviors in community dwelling older adults

Background

Adherence to protective behaviors is central to limiting the spread of COVID-19 and associated risk of serious illness and mortality in older populations. Whether cognition predicts adherence to protective behaviors has not been examined in older adults.

Aims

To examine whether specific cognitive abilities predict adherence to COVID-19 protective behaviors in older adults, independent of other relevant factors.

Methods

Data from 431 older adults (i.e., ≥ 65 years) who took part in the COVID-19 module of the Health and Retirement Study were included in the present study. Separate binary logistic regression models were used to examine whether performance on measures of immediate and delayed recall and working memory predicted adherence to COVID-19 protective behaviors, controlling for demographics, level of COVID-19 concern, depressive symptoms, and medical conditions.

Results

For every unit increase in immediate and delayed recall, the probability of adhering to COVID-19 protective behaviors increased by 47% and 69%, respectively. There was no association between the measure of working memory and adherence.

Discussion

It is of public interest to understand the factors that reduce adherence to protective behaviors so that we can better protect those most vulnerable and limit community spread. Our findings demonstrate that reduced memory predicts non-adherence to COVID-19 protective behaviors, independent of virus concern, and other relevant demographic and health factors.

Conclusions

Public health strategies aimed at increasing adherence to COVID-19 protective behaviors in community dwelling older adults, should account for the role of reduced cognitive function in limiting adherence.

Does postponing retirement affect cognitive function? A counterfactual experiment to disentangle life course risk factors

Evidence suggests that contemporaneous labor force participation affects cognitive function; however, it is unclear whether it is employment itself or endogenous factors related to individuals’ likelihood of employment that protects against cognitive decline. We exploit innovations in counterfactual causal inference to disentangle the effect of postponing retirement on later-life cognitive function from the effects of other life-course factors. With the U.S. Health and Retirement Study (1996–2014, n = 20,469), we use the parametric g-formula to estimate the effect of postponing retirement to age 67. We also study whether the benefit of postponing retirement is affected by gender, education, and/or occupation, and whether retirement affects cognitive function through depressive symptoms or comorbidities. We find that postponing retirement is protective against cognitive decline, accounting for other life-course factors (population: 0.34, 95% confidence interval (CI): 0.20,0.47; individual: 0.43, 95% CI: 0.26,0.60). The extent of the protective effect depends on subgroup, with the highest educated experiencing the greatest mitigation of cognitive decline (individual: 50%, 95% CI: 32%,71%). By using innovative models that better reflect the empirical reality of interconnected life-course processes, this work makes progress in understanding how retirement affects cognitive function.

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Research is inconclusive as to employments' protection against cognitive decline.

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Causal inference models can better reflect interconnected life-course processes.

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The parametric g-formula shows a substantial protective effect of ongoing employment.

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Protective effect holds for all subgroups, but is greatest for the highest educated.

Depression and executive functioning bidirectionally impair one another across 9 years: Evidence from within-person latent change and cross-lagged models

BACKGROUND

Scar and vulnerability models assert that increased psychopathology may predict subsequent executive functioning (EF) deficits (and vice versa) over protracted timescales, yet most prior work on this topic has been cross-sectional. Thus, we tested the within- and between-person relations between EF, depression, and anxiety.

METHODS

Older adult participants (n = 856) were assessed across four waves, approximately 2 years apart. Performance-based EF and caregiver-rated symptom measures were administered. Bivariate latent change score and random-intercept cross-lagged panel models were conducted.

RESULTS

Within persons, random-intercept cross-lagged panel models revealed that prior greater depression forecasted lower subsequent EF, and vice versa (d = -0.292 vs. -0.292). Bivariate dual latent change score models showed that within-person rise in depression predicted EF decreases, and vice versa (d = -0.245 vs. -0.245). No within-person, cross-lagged, EF-anxiety relations emerged. Further, significant negative between-person EF-symptom relations were observed (d = -0.264 to -0.395).

CONCLUSION

Prospective, within-person findings offer some evidence for developmental scar and vulnerability models.

Cognitive Impairment and the Trajectory of Loneliness in Older Adulthood: Evidence from the Health and Retirement Study

Objective: To examine whether the trajectory of facets of loneliness-emotional and social-varied by cognitive impairment status in older adulthood. Methods: Data came from the Health and Retirement Study 2008-2018 waves (N = 15,352). Cognitive impairment was assessed using standard cutoffs for cognitive impairment no dementia (CIND) and dementia. The 11-item UCLA loneliness scale was used to measure emotional and social loneliness. Results: Using multilevel modeling, we found that CIND and dementia status were associated with higher overall, emotional, and social loneliness, controlling for physical health, social contact, and depressive symptoms. The trajectory of loneliness did not vary by cognitive status. There were modest variations by sociodemographic factors. Discussion: Persons with CIND and dementia experience heightened emotional and social loneliness, but cognitive impairment does not contribute to the worsening of loneliness. Older adults' social integration may be maintained early in cognitive impairment.

Long-Term Care Market Trend and Patterns of Caregiving in the U.S

Informal care is a major source of long-term services and supports (LTSS) for older adults in the U.S. However, the increasing gap between available family caregivers and those needing LTSS in coming years warrants better understanding of the balance between informal and formal home or community-based LTSS to meet the growing demand. The current study aimed to 1) identify patterns of informal and formal LTSS use among community-dwelling individuals, and 2) examine if the supply of formal LTSS predicts the use of informal care. These aims were investigated by linking the market supply of formal LTSS at the state-level to the Health and Retirement Survey data (N = 7,781). Results provide important empirical evidence that patterns of informal and formal LTSS use among older adults are heterogeneous and market supply of formal home and community-based services (HCBS) significantly predicts the use of informal care. Most older adults rely on informal care in combination with some formal supports, suggesting that the two systems work in tandem to meet the growing needs of LTSS. This offers important implications for states allocating resources to meet the LTSS needs of older adults and individuals with disabilities since states play key roles in U.S. long-term care policies.

Association of Coronary Artery Bypass Grafting vs Percutaneous Coronary Intervention With Memory Decline in Older Adults Undergoing Coronary Revascularization

IMPORTANCE

It is uncertain whether coronary artery bypass grafting (CABG) is associated with cognitive decline in older adults compared with a nonsurgical method of coronary revascularization (percutaneous coronary intervention [PCI]).

OBJECTIVE

To compare the change in the rate of memory decline after CABG vs PCI.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study of community-dwelling participants in the Health and Retirement Study, who underwent CABG or PCI between 1998 and 2015 at age 65 years or older. Data were modeled for up to 5 years preceding and 10 years following revascularization or until death, drop out, or the 2016-2017 interview wave. The date of final follow-up was November 2017.

EXPOSURES

CABG (including on and off pump) or PCI, ascertained from Medicare fee-for-service billing records.

MAIN OUTCOMES AND MEASURES

The primary outcome was a summary measure of cognitive test scores and proxy cognition reports that were performed biennially in the Health and Retirement Study, referred to as memory score, normalized as a z score (ie, mean of 0, SD of 1 in a reference population of adults aged ≥72 years). Memory score was analyzed using multivariable linear mixed-effects models, with a prespecified subgroup analysis of on-pump and off-pump CABG. The minimum clinically important difference was a change of 1 SD of the population-level rate of memory decline (0.048 memory units/y).

RESULTS

Of 1680 participants (mean age at procedure, 75 years; 41% female), 665 underwent CABG (168 off pump) and 1015 underwent PCI. In the PCI group, the mean rate of memory decline was 0.064 memory units/y (95% CI, 0.052 to 0.078) before the procedure and 0.060 memory units/y (95% CI, 0.048 to 0.071) after the procedure (within-group change, 0.004 memory units/y [95% CI, -0.010 to 0.018]). In the CABG group, the mean rate of memory decline was 0.049 memory units/y (95% CI, 0.033 to 0.065) before the procedure and 0.059 memory units/y (95% CI, 0.047 to 0.072) after the procedure (within-group change, -0.011 memory units/y [95% CI, -0.029 to 0.008]). The between-group difference-in-differences estimate for memory decline for PCI vs CABG was 0.015 memory units/y (95% CI, -0.008 to 0.038; P = .21). There was statistically significant increase in the rate of memory decline after off-pump CABG compared with after PCI (difference-in-differences: mean increase in the rate of decline of 0.046 memory units/y [95% CI, 0.008 to 0.084] after off-pump CABG), but not after on-pump CABG compared with PCI (difference-in-differences: mean slowing of decline of 0.003 memory units/y [95% CI, -0.024 to 0.031] after on-pump CABG).

CONCLUSIONS AND RELEVANCE

Among older adults undergoing coronary revascularization with CABG or PCI, the type of revascularization procedure was not significantly associated with differences in the change of rate of memory decline.

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.

2021 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including incidence and prevalence, mortality and morbidity, use and costs of care, and the overall impact on caregivers and society. The Special Report discusses the challenges of providing equitable health care for people with dementia in the United States. An estimated 6.2 million Americans age 65 and older are living with Alzheimer's dementia today. This number could grow to 13.8 million by 2060 barring the development of medical breakthroughs to prevent, slow or cure AD. Official death certificates recorded 121,499 deaths from AD in 2019, the latest year for which data are available, making Alzheimer's the sixth-leading cause of death in the United States and the fifth-leading cause of death among Americans age 65 and older. Between 2000 and 2019, deaths from stroke, heart disease and HIV decreased, whereas reported deaths from AD increased more than 145%. This trajectory of deaths from AD was likely exacerbated in 2020 by the COVID-19 pandemic. More than 11 million family members and other unpaid caregivers provided an estimated 15.3 billion hours of care to people with Alzheimer's or other dementias in 2020. These figures reflect a decline in the number of caregivers compared with a decade earlier, as well as an increase in the amount of care provided by each remaining caregiver. Unpaid dementia caregiving was valued at $256.7 billion in 2020. Its costs, however, extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes - costs that have been aggravated by COVID-19. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are more than three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 23 times as great. Total payments in 2021 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $355 billion. Despite years of efforts to make health care more equitable in the United States, racial and ethnic disparities remain - both in terms of health disparities, which involve differences in the burden of illness, and health care disparities, which involve differences in the ability to use health care services. Blacks, Hispanics, Asian Americans and Native Americans continue to have a higher burden of illness and lower access to health care compared with Whites. Such disparities, which have become more apparent during COVID-19, extend to dementia care. Surveys commissioned by the Alzheimer's Association recently shed new light on the role of discrimination in dementia care, the varying levels of trust between racial and ethnic groups in medical research, and the differences between groups in their levels of concern about and awareness of Alzheimer's disease. These findings emphasize the need to increase racial and ethnic diversity in both the dementia care workforce and in Alzheimer's clinical trials.

Association of CSF Alzheimer's disease biomarkers with postoperative delirium in older adults

INTRODUCTION

The interaction between delirium and dementia is complex. We examined if Alzheimer's disease (AD) biomarkers in patients without clinical dementia are associated with increased risk of postoperative delirium, and whether AD biomarkers demonstrate a graded association with delirium severity.

METHODS

Participants (n = 59) were free of clinical dementia, age ≥ 70 years, and scheduled for elective total knee or hip arthroplasties. Cerebrospinal fluid (CSF) was collected at the time of induction for spinal anesthesia. CSF AD biomarkers were measured by enzyme-linked immunosorbent assay (ELISA) (ADX/Euroimmun); cut points for amyloid, tau, and neurodegeneration (ATN) biomarker status were A = amyloid beta (Aβ)42 <175 pg/mL or Aβ42/40 ratio <0.07; T = p-tau >80 pg/mL; and N = t-tau >700 pg/mL. Confusion Assessment Method (CAM) and CAM-Severity (CAM-S) were rated daily post-operatively for delirium and delirium severity, respectively.

RESULTS

Aβ42, tau, and p-tau mean pg/mL (SD) were 361.5 (326.1), 618.3 (237.1), and 97.1 (66.1), respectively, for those with delirium, and 550.4 (291.6), 518.3 (213.5), and 54.6 (34.5), respectively, for those without delirium. Thirteen participants (22%) were ATN positive. Delirium severity by peak CAM-S [mean difference (95% confidence interval)] was 1.48 points higher (0.29-2.67), P = 0.02 among the ATN positive. Delirium in the ATN-positive group trended toward but did not reach statistical significance (23% vs. 7%, p = 0.10). Peak CAM-S [mean (SD)] in the delirium group was 7 (2.8) compared to no delirium group 2.5 (1.3), but when groups were further classified by ATN status, an incremental effect on delirium severity was observed, such that patients who were both ATN and delirium negative had the lowest mean (SD) peak CAM-S scores of 2.5 (1.3) points, whereas those who were ATN and delirium positive had CAM-S scores of 8.7 (2.3) points; other groups (either ATN or delirium positive) had intermediate CAM-S scores.

DISCUSSION

The presence of AD biomarkers adds important information in predicting delirium severity. Future studies are needed to confirm this relationship and to better understand the role of AD biomarkers, even in pre-clinical phase, in delirium.

Temporal Trends in Stroke-Related Memory Change: Results From a US National Cohort 1998-2016

BACKGROUND AND PURPOSE

Findings from the Framingham Heart Study suggest that declines in dementia incidence rates over recent decades are partially due to decreases in stroke incidence and mortality; however, whether trends of declining dementia rates extend to survivors of incident stroke remains unclear. We investigated evidence for temporal trends in memory change related to incident stroke in a nationally representative cohort.

METHODS

Adults age 50+ in the HRS (Health and Retirement Study) were followed across three successive 6-year epochs (epoch 1: 1998-2004, n=16 781; epoch 2: 2004-2010, n=15 345; and epoch 3: 2010-2016; n=15 949). Participants were included in an epoch if they were stroke-free at the start of that epoch. Annual rates of change in a composite z-standardized memory score were compared using demographic-adjusted linear regression models for stroke-free participants, those who survived after stroke, and those who died after stroke, considering memory change before stroke, at the time of stroke, and for years following stroke.

RESULTS

Crude stroke incidence rates decreased from 8.5 per 1000 person-years in epoch 1 to 6.8 per 1000 person-years in epoch 3. Rates of memory change before and following stroke onset were similar across epochs. Memory decrement immediately after stroke onset attenuated from -0.37 points (95% CI, -0.44 to -0.29) in epoch 1 to -0.26 (95% CI, -0.33 to -0.18) points in epoch 2 and -0.25 (95% CI, -0.33 to -0.17) points in epoch 3 (P value for linear trend=0.02).

CONCLUSIONS

Decreases in stroke-related dementia in recent years may be partially attributable to smaller memory decrements immediately after stroke onset. Findings suggest reductions in stroke incidence and improvements in stroke care may also reduce population burden of dementia. Further investigations into whether temporal trends are attributable to improvements in stroke care are needed.

Evaluation of Selective Survival and Sex/Gender Differences in Dementia Incidence Using a Simulation Model

IMPORTANCE

Dementia research is susceptible to bias arising from selective survival, a process that results in individuals with certain characteristics disproportionately surviving to old age. Spurious associations between risk factors and dementia may be induced when factors associated with longer survival also influence dementia incidence.

OBJECTIVE

To assess the role of selective survival in explaining reported sex/gender differences in dementia incidence.

DESIGN, SETTING, AND PARTICIPANTS

This decision analytical model used a simulated cohort of US participants aged 50 years and without dementia at baseline followed up for incident dementia through age 95 years. Selective survival was induced by a selection characteristic (eg, childhood social disadvantage or Alzheimer genetic risk) that influenced both mortality and dementia incidence at varying magnitudes. Data analysis was performed from April 2018 to May 2020.

EXPOSURE

Sex/gender, conceptualized as the combination of biological sex and social consequences of gender.

MAIN OUTCOMES AND MEASURES

Dementia incidence rate ratios (IRRs) for women compared with men. In all simulations, it was assumed that there would be no true effect of sex/gender on dementia incidence; all observed sex/gender differences were due to selective survival.

RESULTS

At baseline, the simulation included 100 000 participants aged 50 years (51 000 [51%] women, mirroring the 1919-1921 US birth cohort of non-Latino White individuals at age 50 years); distributions of the selection characteristic were standard normal (mean [SD], 0.0 [1.0]). Observed sex/gender differences in dementia incidence in individuals aged 85 years or older ranged from insignificant (IRR, 1.00; 95% CI, 0.91-1.11) to consistent with sex/gender differences (20% higher risk for women [IRR, 1.20; 95% CI, 1.08-1.32]) reported in an extant study. Simulations in which bias was large enough to explain prior findings required moderate to large differential effects of selective survival (eg, hazard ratio for selection characteristic on mortality at least 2.0 among men, no effect among women).

CONCLUSIONS AND RELEVANCE

These results suggest that selective survival may contribute to observed sex/gender differences in dementia incidence but do not preclude potential contributions of sex/gender-specific mechanisms. Further research on plausibility of selection characteristics with outcomes of the magnitude required for selective survival to explain sex/gender differences in dementia incidence and sex/gender-specific mechanisms represent an opportunity to understand prevention and treatment of dementia.

Personality, Retirement, and Cognitive Impairment: Moderating and Mediating Associations

Objectives: Five-factor model (FFM) personality traits, including higher conscientiousness and lower neuroticism, are associated with lower risk of dementia and cognitive impairment. In this research, we test whether retirement status moderates and/or mediates the relation between personality and cognitive impairment. Method: We used data from the Health and Retirement Study (N = 9899), a longitudinal study of Americans over the age of 50 years, to examine moderating and mediating associations between personality traits and retirement status on risk of dementia and cognitive impairment not dementia (CIND) over an 8-10 year follow-up. Results: Personality and retirement each had strong, independent associations with risk of dementia and CIND. There were not, however, strong or consistent, moderating or mediating associations between personality and retirement predicting impairment risk. Discussion: Overall, these results indicate that personality and retirement are independent risk factors for incident cognitive impairment. Mechanisms other than retirement are likely to explain this association.

Sex, Race, and Age Differences in Prevalence of Dementia in Medicare Claims and Survey Data

OBJECTIVES

This study provides the first comparison of trends in dementia prevalence in the U.S. population using 3 different dementia ascertainments/data sources: neuropsychological assessment, cognitive tests, and diagnosis codes from Medicare claims.

METHODS

We used data from the nationally representative Health and Retirement Study and Aging, Demographics, and Memory Study, and a 20% random sample of Medicare beneficiaries. We compared dementia prevalence across the 3 sources by race, gender, and age. We estimated trends in dementia prevalence from 2006 to 2013 based on cognitive tests and diagnosis codes utilizing logistic regression.

RESULTS

Dementia prevalence among older adults aged 70 and older in 2004 was 16.6% (neuropsychological assessment), 15.8% (cognitive tests), and 12.2% (diagnosis codes). The difference between dementia prevalence based on cognitive tests and diagnosis codes diminished in 2012 (12.4% and 12.9%, respectively), driven by decreasing rates of cognitive test-based and increasing diagnosis codes-based dementia prevalence. This difference in dementia prevalence between the 2 sources by sex and for age groups 75-79 and 90 and older vanished over time. However, there remained substantial differences across measures in dementia prevalence among blacks and Hispanics (10.9 and 9.8 percentage points, respectively) in 2012.

DISCUSSION

Our results imply that ascertainment of dementia through diagnosis may be improving over time, but gaps across measures among racial/ethnic minorities highlight the need for improved measurement of dementia prevalence in these populations.

Cognitively Intact and Happy Life Expectancy in the United States

OBJECTIVES

We examined the number of years to be lived with and without cognitive impairment and with high self-assessed quality of life (i.e., happiness) among a nationally representative sample of Americans aged 65 years and older. Two key questions are addressed: Can people have a high quality of life despite being cognitively impaired? Which is longer: happy life expectancy or cognitively intact life expectancy?

METHOD

Data from nine waves of the Health and Retirement Study (1998-2014) were used to estimate transition probabilities into and out of cognitively intact/impaired-un/happy states, as well as to death. Recently extended Bayesian multistate life table methods were used to estimate age-specific cognitively intact and happy life expectancy net of sex, race/ethnicity, education, and birth cohort.

RESULTS

Happiness and cognitive impairment were shown to coexist in both the gross cross-tabulated data and in the life tables. Happy life expectancy is approximately 25% longer than cognitively intact life expectancy at age 65 years, and by age 85, happy life expectancy is roughly double cognitively intact life expectancy, on average.

DISCUSSION

Lack of cognitive impairment is not a necessary condition for happiness. In other words, people can have a high quality of life despite being cognitively impaired.

Personality and Dementia Risk in England and Australia

Evidence for the relation between personality and dementia risk comes mainly from American samples. We tested whether personality-dementia links extend to populations from England and Australia. Data from the English Longitudinal Study of Ageing (ELSA; N = 6,887; Follow-up mean: 5.64 years) and the Household, Income and Labour Dynamics in Australia (HILDA; N = 2,778; Follow-up mean: 10.96 years) were analyzed using Cox PH models. In both samples, higher neuroticism was associated with increased dementia risk. In ELSA, lower conscientiousness was related to increased risk. In HILDA, conscientiousness had a similar effect but did not reach statistical significance. The present work found a consistent association for neuroticism and suggests similar personality-dementia links across demographic groups and high-income countries.

Estimates of the Association of Dementia With US Mortality Levels Using Linked Survey and Mortality Records

Importance

Vital statistics are the primary source of data used to understand the mortality burden of dementia in the US, despite evidence that dementia is underreported on death certificates. Alternative estimates, drawing on population-based samples, are needed.

Objective

To estimate the percentage of deaths attributable to dementia in the US.

Design, Setting, and Participants

A prospective cohort study of the Health and Retirement Study of noninstitutionalized US individuals with baseline exposure assessment in 2000 and follow-up through 2009 was conducted. Data were analyzed from November 2018 to May 2020. The sample was drawn from 7489 adults aged 70 to 99 years interviewed directly or by proxy. Ninety participants with missing covariates or sample weights and 57 participants lost to follow-up were excluded. The final analytic sample included 7342 adults.

Exposure

Dementia and cognitive impairment without dementia (CIND) were identified at baseline using Health and Retirement Study self- or proxy-reported cognitive measures and the validated Langa-Weir score cutoff.

Main Outcomes and Measures

Hazard ratios relating dementia and CIND status to all-cause mortality were estimated using Cox proportional hazards regression models, accounting for covariates, and were used to calculate population-attributable fractions. Results were compared with information on cause of death from death certificates.

Results

Of the 7342 total sample, 4348 participants (60.3%) were women. At baseline, 4533 individuals (64.0%) were between ages 70 and 79 years, 2393 individuals (31.0%) were between 80 and 89 years, and 416 individuals (5.0%) were between 90 and 99 years; percentages were weighted. The percentage of deaths attributable to dementia was 13.6% (95% CI, 12.2%-15.0%) between 2000 and 2009. The mortality burden of dementia was significantly higher among non-Hispanic Black participants (24.7%; 95% CI, 17.3-31.4) than non-Hispanic White participants (12.2%; 95% CI, 10.7-13.6) and among adults with less than a high school education (16.2%; 95% CI, 13.2%-19.0%) compared with those with a college education (9.8%; 95% CI, 7.0%-12.5%). Underlying cause of death recorded on death certificates (5.0%; 95% CI, 4.3%-5.8%) underestimated the contribution of dementia to US mortality by a factor of 2.7. Incorporating deaths attributable to CIND revealed an even greater underestimation.

Conclusions and Relevance

The findings of this study suggest that the mortality burden associated with dementia is underestimated using vital statistics, especially when considering CIND in addition to dementia.

Considering the APOE locus in Alzheimer's disease polygenic scores in the Health and Retirement Study: a longitudinal panel study

Background

Polygenic scores are a strategy to aggregate the small, additive effects of single nucleotide polymorphisms across the genome. With phenotypes like Alzheimer’s disease, which have a strong and well-established genomic locus (APOE), the cumulative effect of genetic variants outside of this area has not been well established in a population-representative sample.

Methods

Here we examine the association between polygenic scores for Alzheimer’s disease both with and without the APOE region (chr19: 45,384,477 to 45,432,606, build 37/hg 19) at different P value thresholds and dementia. We also investigate the addition of APOE-ε4 carrier status and its effect on the polygenic score—dementia association in the Health and Retirement Study using generalized linear models accounting for repeated measures by individual and use a binomial distribution, logit link, and unstructured correlation structure.

Results

In a large sample of European ancestry participants of the Health and Retirement Study (n = 9872) with an average of 5.2 (standard deviation 1.8) visit spaced two years apart, we found that including the APOE region through weighted variants in a polygenic score was insufficient to capture the large amount of risk attributed to this region. We also found that a polygenic score with a P value threshold of 0.01 had the strongest association with the odds of dementia in this sample (odds ratio = 1.10 95%CI 1.0 to 1.2).

Conclusion

We recommend removing the APOE region from polygenic score calculation and treating the APOE locus as an independent covariate when modeling dementia. We also recommend using a moderately conservative P value threshold (e.g. 0.01) when creating polygenic scores for Alzheimer’s disease on dementia. These recommendations may help elucidate relationships between polygenic scores and regions of strong significance for phenotypes similar to Alzheimer’s disease.

Implications of the Use of Algorithmic Diagnoses or Medicare Claims to Ascertain Dementia

INTRODUCTION

Formal dementia ascertainment with research criteria is resource-intensive, prompting the growing use of alternative approaches. Our objective was to illustrate the potential bias and implications for study conclusions introduced through the use of alternate dementia ascertainment approaches.

METHODS

We compared dementia prevalence and risk factor associations obtained using criterion-standard dementia diagnoses to those obtained using algorithmic or Medicare-based dementia ascertainment in participants of the baseline visit of the Aging, Demographics, and Memory Study (ADAMS), a Health and Retirement Study (HRS) sub-study.

RESULTS

Estimates of dementia prevalence derived using algorithmic or Medicare-based ascertainment differ substantially from those obtained using criterion-standard ascertainment. Use of algorithmic or Medicare-based dementia ascertainment can, but does not always, lead to risk factor associations that substantially differ from those obtained using criterion-standard ascertainment.

DISCUSSION/CONCLUSIONS

Absolute estimates of dementia prevalence should rely on samples with formal dementia ascertainment. The use of multiple algorithms is recommended for risk factor studies when formal dementia ascertainment is not available.

A data-driven prospective study of dementia among older adults in the United States

Background

Studies examining risk factors for dementia have typically focused on testing a priori hypotheses within specific risk factor domains, leaving unanswered the question of what risk factors across broad and diverse research fields may be most important to predicting dementia. We examined the relative importance of 65 sociodemographic, early-life, economic, health and behavioral, social, and genetic risk factors across the life course in predicting incident dementia and how these rankings may vary across racial/ethnic (non-Hispanic white and black) and gender (men and women) groups.

Methods and findings

We conducted a prospective analysis of dementia and its association with 65 risk factors in a sample of 7,908 adults aged 51 years and older from the nationally representative US-based Health and Retirement Study. We used traditional survival analysis methods (Fine and Gray models) and a data-driven approach (random survival forests for competing risks) which allowed us to account for the semi-competing risk of death with up to 14 years of follow-up. Overall, the top five predictors across all groups were lower education, loneliness, lower wealth and income, and lower self-reported health. However, we observed variation in the leading predictors of dementia across racial/ethnic and gender groups such that at most four risk factors were consistently observed in the top ten predictors across the four demographic strata (non-Hispanic white men, non-Hispanic white women, non-Hispanic black men, non-Hispanic black women).

Conclusions

We identified leading risk factors across racial/ethnic and gender groups that predict incident dementia over a 14-year period among a nationally representative sample of US aged 51 years and older. Our ranked lists may be useful for guiding future observational and quasi-experimental research that investigates understudied domains of risk and emphasizes life course economic and health conditions as well as disparities therein.

Association of Plasma Neurofilament Light with Postoperative Delirium

OBJECTIVE

To examine the association of the plasma neuroaxonal injury markers neurofilament light (NfL), total tau, glial fibrillary acid protein, and ubiquitin carboxyl-terminal hydrolase L1 with delirium, delirium severity, and cognitive performance.

METHODS

Delirium case-no delirium control (n = 108) pairs were matched by age, sex, surgery type, cognition, and vascular comorbidities. Biomarkers were measured in plasma collected preoperatively (PREOP), and 2 days (POD2) and 30 days postoperatively (PO1MO) using Simoa technology (Quanterix, Lexington, MA). The Confusion Assessment Method (CAM) and CAM-S (Severity) were used to measure delirium and delirium severity, respectively. Cognitive function was measured with General Cognitive Performance (GCP) scores.

RESULTS

Delirium cases had higher NfL on POD2 and PO1MO (median matched pair difference = 16.2pg/ml and 13.6pg/ml, respectively; p < 0.05). Patients with PREOP and POD2 NfL in the highest quartile (Q4) had increased risk for incident delirium (adjusted odds ratio [OR] = 3.7 [95% confidence interval (CI) = 1.1-12.6] and 4.6 [95% CI = 1.2-18.2], respectively) and experienced more severe delirium, with sum CAM-S scores 7.8 points (95% CI = 1.6-14.0) and 9.3 points higher (95% CI = 3.2-15.5). At PO1MO, delirium cases had continued high NfL (adjusted OR = 9.7, 95% CI = 2.3-41.4), and those with Q4 NfL values showed a -2.3 point decline in GCP score (-2.3 points, 95% CI = -4.7 to -0.9).

INTERPRETATION

Patients with the highest PREOP or POD2 NfL levels were more likely to develop delirium. Elevated NfL at PO1MO was associated with delirium and greater cognitive decline. These findings suggest NfL may be useful as a predictive biomarker for delirium risk and long-term cognitive decline, and once confirmed would provide pathophysiological evidence for neuroaxonal injury following delirium. ANN NEUROL 2020;88:984-994.

Approximating dementia prevalence in population-based surveys of aging worldwide: An unsupervised machine learning approach

INTRODUCTION

Ability to determine dementia prevalence in low- and middle-income countries (LMIC) remains challenging because of frequent lack of data and large discrepancies in dementia case ascertainment.

METHODS

High likelihood of dementia was determined with hierarchical clustering after principal component analysis applied in 10 population surveys of aging: HRS (USA, 2014), SHARE (Europe and Israel, 2015), MHAS (Mexico, 2015), ELSI (Brazil, 2016), CHARLS (China, 2015), IFLS (Indonesia, 2014-2015), LASI (India, 2016), SAGE-Ghana (2007), SAGE-South Africa (2007), SAGE-Russia (2007-2010). We approximated dementia prevalence using weighting methods.

RESULTS

Estimated numbers of dementia cases were: China, 40.2 million; India, 18.0 million; Russia, 5.2 million; Europe and Israel, 5.0 million; United States, 4.4 million; Brazil, 2.2 million; Mexico, 1.6 million; Indonesia, 1.3 million; South Africa, 1.0 million; Ghana, 319,000.

DISCUSSION

Our estimations were similar to prior ones in high-income countries but much higher in LMIC. Extrapolating these results globally, we suggest that almost 130 million people worldwide were living with dementia in 2015.

Loneliness and Risk of Dementia

OBJECTIVE

The present study tests whether loneliness is associated with risk of dementia in the largest sample to date and further examines whether the association is independent of social isolation, a related but independent component of social integration, and whether it varies by demographic factors and genetic vulnerability.

METHOD

Participants from the Health and Retirement Study (N = 12,030) reported on their loneliness, social isolation, and had information on clinical, behavioral, and genetic risk factors. Cognitive status was assessed at baseline and every 2 years over a 10-year follow-up with the modified Telephone Interview for Cognitive Status (TICSm). A TICSm score of 6 or less was indicative of dementia.

RESULTS

Cox proportional hazards regression indicated that loneliness was associated with a 40% increased risk of dementia. This association held controlling for social isolation, and clinical, behavioral, and genetic risk factors. The association was similar across gender, race, ethnicity, education, and genetic risk.

DISCUSSION

Loneliness is associated with increased risk of dementia. It is one modifiable factor that can be intervened on to reduce dementia risk.

Mild cognitive impairment and receipt of procedures for acute ischemic stroke in older adults

BACKGROUND AND PURPOSE

Older patients with pre-existing mild cognitive impairment (MCI) receive less evidence-based care after acute myocardial infarction, however, whether they receive less care after acute ischemic stroke (AIS) is unknown. We compared receipt of guideline-concordant procedures after AIS between older adults with pre-existing MCI and normal cognition.

METHODS

Prospective study of 591 adults ≥65 hospitalized for AIS between 2000 and 2014, and followed through 2015 using data from the nationally representative Health and Retirement Study, Medicare and American Hospital Association. We assessed pre-existing MCI (modified Telephone Interview for Cognitive Status score of 7-11) and normal cognition (score of 12-27). Primary outcome was a composite quality measure representing the number of 4 procedures (carotid imaging, cardiac monitoring, echocardiogram, and rehabilitation assessment) received within 30 days after AIS (ordinal scale with values of 0, 1, 2, 3-4).

RESULTS

Among survivors of AIS, 26.9% had pre-existing MCI (62.9% were women, with a mean [SD] age of 82.4 [7.7] years), and 73.1% had normal cognition (51.4% were women, with a mean age of 78.4 [7.2] years). Patients with pre-existing MCI, compared to cognitively normal patients, had 39% lower cumulative odds of receiving the composite quality measure (unadjusted cumulative odds ratio, OR, 0.61 [95% CI, 0.43-0.87]; P=0.006). However, this association became non-significant after adjusting for patient and hospital factors (adjusted cumulative OR, 0.83 [95% CI, 0.56-1.24]; P=0.37). Lower cumulative odds of receiving the composite quality measure were associated with older patient age (adjusted cumulative OR per 1-year older age, 0.97 [95% CI, 0.95-0.99]; P=0.01) and Southern hospitals (adjusted cumulative OR for South vs North, 0.54 [95% CI, 0.31-0.94]; P=0.03).

CONCLUSIONS

Differences in receipt of guideline-concordant procedures after AIS exist between patients with pre-existing MCI and normal cognition. These differences were largely explained by patient and regional factors associated with receiving less AIS care.

Cognitive impairment in the U.S.: Lifetime risk, age at onset, and years impaired

Prior studies have analyzed the burden of cognitive impairment, but often use potentially biased prevalence-based methods or measure only years lived with impairment, without estimating other relevant metrics. We use the Health and Retirement Study (1998-2014; n = 29,304) and the preferred incidence-based Markov-chain models to assess three key measures of the burden of cognitive impairment: lifetime risk, mean age at onset, and number of years lived impaired. We analyze both mild and severe cognitive impairment (dementia) and gender, racial/ethnic, and educational variation in impairment. Our results paint a multi-dimensional picture of cognitive health, presenting the first comprehensive analysis of the burden of cognitive impairment for the U.S. population age 50 and older. Approximately two out of three Americans experience some level of cognitive impairment at an average age of approximately 70 years. For dementia, lifetime risk for women (men) is 37% (24%) and mean age at onset 83 (79) years. Women can expect to live 4.2 years with mild impairment and 3.2 with dementia, men 3.5 and 1.8 years. A critical finding is that for the most advantaged groups (i.e., White and/or higher educated), cognitive impairment is both delayed and compressed toward the very end of life. In contrast, despite the shorter lives of disadvantaged subgroups (Black and/or lower educated), they experience a younger age of onset, higher lifetime risk, and more years cognitively impaired. For example, men with at least an Associate degree have 21% lifetime dementia risk, compared to 35% among men with less than high school education. White women have 6 years of cognitively-impaired life expectancy, compared to 12 and 13 years among Black women and Latinas. These educational and racial/ethnic gradients highlight the very uneven burden of cognitive impairment. Further research is required to identify the mechanisms driving these disparities in cognitive impairment.

The Mexican Cognitive Aging Ancillary Study (Mex-Cog): Study Design and Methods

OBJECTIVE

Describe the protocol sample and instruments of the Cognitive Aging Ancillary Study in Mexico (Mex-Cog). The study performs an in-depth cognitive assessment in a subsample of older adults of the ongoing Mexican Health and Aging Study (MHAS). The Mex-Cog is part of the Harmonized Cognitive Assessment Protocol (HCAP) design to facilitate cross-national comparisons of the prevalence and trends of dementia in aging populations around the world, funded by the National Institute on Aging (NIA).

METHODS

The study protocol consists of a cognitive assessment instrument for the target subject and an informant questionnaire. All cognitive measures were selected and adapted by a team of experts from different ongoing studies following criteria to warrant reliable and comparable cognitive instruments. The informant questionnaire is from the 10/66 Dementia Study in Mexico.

RESULTS

A total of 2,265 subjects aged 55-104 years participated, representing a 70% response rate. Validity analyses showed the adequacy of the content validity, proper quality-control procedures that sustained data integrity, high reliability, and internal structure.

CONCLUSIONS

The Mex-Cog study provides in-depth cognitive data that enhances the study of cognitive aging in two ways. First, linking to MHAS longitudinal data on cognition, health, genetics, biomarkers, economic resources, health care, family arrangements, and psychosocial factors expands the scope of information on cognitive impairment and dementia among Mexican adults. Second, harmonization with other similar studies around the globe promotes cross-national studies on cognition with comparable data. Mex-Cog data is publicly available at no cost to researchers.

Sleep Difficulties and Cognition for 10 Years in a National Sample of U.S. Older Adults

Background and Objectives

Sleep difficulties are common among older adults and are associated with cognitive decline. We used data from a large, nationally representative longitudinal survey of adults aged older than 50 in the United States to examine the relationship between specific sleep difficulties and cognitive function over time.

Research Design and Methods

Longitudinal data from the 2004–2014 waves of the Health and Retirement Study were used in the current study. We examined sleep difficulties and cognitive function within participants and across time (n = 16 201). Sleep difficulty measures included difficulty initiating sleep, nocturnal awakenings, early morning awakenings, and waking up feeling rested from rarely/never (1) to most nights (3). The modified Telephone Interview for Cognitive Status was used to measure cognitive function. Generalized linear mixed models were used with time-varying covariates to examine the relationship between sleep difficulties and cognitive function over time.

Results

In covariate-adjusted models, compared to “never” reporting sleep difficulty, difficulty initiating sleep “most nights” was associated with worse cognitive function over time (Year 2014: b = −0.40, 95% CI: −0.63 to −0.16, p < .01) as was difficulty waking up too early “most nights” (Year 2014: b = −0.31, 95% CI: −0.56 to −0.07, p < .05). In covariate-adjusted analyses, compared to “never” reporting waking up feeling rested, cognitive function was higher among those who reported waking up feeling rested “some nights” (Year 2010: b = 0.21, 95% CI: 0.02 to 0.40, p < .05).

Discussion and Implications

Our findings highlight an association between early morning awakenings and worse cognitive function, but also an association between waking up feeling rested and better cognitive function over time.

Racial and Ethnic Differences in Knowledge About One's Dementia Status

OBJECTIVES

To examine racial and ethnic differences in knowledge about one's dementia status.

DESIGN

Prospective cohort study.

SETTING

The 2000 to 2014 Health and Retirement Study.

PARTICIPANTS

Our sample included 8,686 person-wave observations representing 4,065 unique survey participants, aged 70 years or older, with dementia, as identified by a well-validated statistical prediction model based on individual demographic and clinical characteristics.

MEASUREMENTS

Primary outcome measure was knowledge of one's dementia status, as reported in the survey. Patient characteristics included race/ethnicity, age, sex, survey year, cognition, function, comorbidity, and whether living in a nursing home.

RESULTS

Among subjects identified as having dementia by the prediction model, 43.5% to 50.2%, depending on the survey year, reported that they were informed of the dementia status by their physician. This proportion was lower among Hispanics (25.9%-42.2%) and non-Hispanic blacks (31.4%-50.5%) than among non-Hispanic whites (47.7%-52.9%). Our fully adjusted regression model indicated lower dementia awareness among non-Hispanic blacks (odds ratio [OR] = 0.74; 95% confidence interval [CI] = 0.58-0.94) and Hispanics (OR = 0.60; 95% CI = 0.43-0.85), compared to non-Hispanic whites. Having more instrumental activity of daily living limitations (OR = 1.65; 95% CI = 1.56-1.75) and living in a nursing home (OR = 2.78; 95% CI = 2.32-3.32) were associated with increased odds of subjects reporting being told about dementia by a physician.

CONCLUSION

Less than half of individuals with dementia reported being told by a physician about the condition. A higher proportion of non-Hispanic blacks and Hispanics with dementia may be unaware of their condition, despite higher dementia prevalence in these groups, compared to non-Hispanic whites. Dementia outreach programs should target diverse communities with disproportionately high disease prevalence and low awareness. J Am Geriatr Soc 68:1763-1770, 2020.

Alternative causal inference methods in population health research: Evaluating tradeoffs and triangulating evidence

Population health researchers from different fields often address similar substantive questions but rely on different study designs, reflecting their home disciplines. This is especially true in studies involving causal inference, for which semantic and substantive differences inhibit interdisciplinary dialogue and collaboration. In this paper, we group nonrandomized study designs into two categories: those that use confounder-control (such as regression adjustment or propensity score matching) and those that rely on an instrument (such as instrumental variables, regression discontinuity, or differences-in-differences approaches). Using the Shadish, Cook, and Campbell framework for evaluating threats to validity, we contrast the assumptions, strengths, and limitations of these two approaches and illustrate differences with examples from the literature on education and health. Across disciplines, all methods to test a hypothesized causal relationship involve unverifiable assumptions, and rarely is there clear justification for exclusive reliance on one method. Each method entails trade-offs between statistical power, internal validity, measurement quality, and generalizability. The choice between confounder-control and instrument-based methods should be guided by these tradeoffs and consideration of the most important limitations of previous work in the area. Our goals are to foster common understanding of the methods available for causal inference in population health research and the tradeoffs between them; to encourage researchers to objectively evaluate what can be learned from methods outside one's home discipline; and to facilitate the selection of methods that best answer the investigator's scientific questions.

Residential Setting and the Cumulative Financial Burden of Dementia in the 7 Years Before Death

OBJECTIVES

Care for older adults with dementia during the final years of life is costly, and families shoulder much of this burden. We aimed to assess the financial burden of care for those with and without dementia, and to explore differences across residential settings.

DESIGN

Using the Health and Retirement Study (HRS) and linked claims, we examined total healthcare spending and proportion by payer-Medicare, Medicaid, out-of-pocket, and calculated costs of informal caregiving-over the last 7 years of life, comparing those with and without dementia and stratifying by residential setting.

SETTING

The HRS is a nationally representative longitudinal study of older adults in the United States.

PARTICIPANTS

We sampled HRS decedents from 2004 to 2015. To ensure complete data, we limited the sample to those 72 years or older at death who had continuous fee-for-service Medicare Parts A and B coverage during the 7-year period (n = 2909).

MEASUREMENTS

We compared decedents with dementia at last HRS assessment with those without dementia across annual and cumulative 7-year spending measures, and personal characteristics. We present annual and cumulative spending by payer, and the changing proportion of spending by payer over time, comparing those with and without dementia and stratifying results by residential setting.

RESULTS

We found that, consistent with prior studies, people with dementia experience significantly higher costs, with a disproportionate share falling on patients and families. This pattern is most striking among community residents with dementia, whose families shoulder 64% of total expenditures (including $176,180 informal caregiving costs and $55,550 out-of-pocket costs), compared with 43% for people with dementia residing in nursing homes ($60,320 informal caregiving costs and $105,590 out-of-pocket costs).

CONCLUSION

These findings demonstrate disparities in financial burden shouldered by families of those with dementia, particularly among those residing in the community. They highlight the importance of considering the residential setting in research, programs, and policies. J Am Geriatr Soc 68:1319-1324, 2020.

2020 Alzheimer's disease facts and figures

This article describes the public health impact of Alzheimer's disease (AD), including incidence and prevalence, mortality and morbidity, use and costs of care, and the overall impact on caregivers and society. The Special Report discusses the future challenges of meeting care demands for the growing number of people living with Alzheimer's dementia in the United States with a particular emphasis on primary care. By mid-century, the number of Americans age 65 and older with Alzheimer's dementia may grow to 13.8 million. This represents a steep increase from the estimated 5.8 million Americans age 65 and older who have Alzheimer's dementia today. Official death certificates recorded 122,019 deaths from AD in 2018, the latest year for which data are available, making Alzheimer's the sixth leading cause of death in the United States and the fifth leading cause of death among Americans age 65 and older. Between 2000 and 2018, deaths resulting from stroke, HIV and heart disease decreased, whereas reported deaths from Alzheimer's increased 146.2%. In 2019, more than 16 million family members and other unpaid caregivers provided an estimated 18.6 billion hours of care to people with Alzheimer's or other dementias. This care is valued at nearly $244 billion, but its costs extend to family caregivers' increased risk for emotional distress and negative mental and physical health outcomes. Average per-person Medicare payments for services to beneficiaries age 65 and older with AD or other dementias are more than three times as great as payments for beneficiaries without these conditions, and Medicaid payments are more than 23 times as great. Total payments in 2020 for health care, long-term care and hospice services for people age 65 and older with dementia are estimated to be $305 billion. As the population of Americans living with Alzheimer's dementia increases, the burden of caring for that population also increases. These challenges are exacerbated by a shortage of dementia care specialists, which places an increasing burden on primary care physicians (PCPs) to provide care for people living with dementia. Many PCPs feel underprepared and inadequately trained to handle dementia care responsibilities effectively. This report includes recommendations for maximizing quality care in the face of the shortage of specialists and training challenges in primary care.

Prevalence and Multivariable Factors Associated With Preoperative Cognitive Impairment in Outpatient Surgery in the United States

Preoperative cognitive impairment increases the risk of adverse events after surgery but its prevalence in outpatient surgery has not been defined. We aimed to determine the prevalence and multivariable factors associated with cognitive impairment in individuals who present for outpatient surgery. We used data from the Health and Retirement Study, a longitudinal panel survey of older Americans. Of 1836 participants who reported having outpatient surgery, we found that 16.1% had evidence of cognitive impairment. Significant multivariable factors associated with preoperative cognitive impairment included non-Hispanic African American race, prior stroke, preoperative functional dependence, and lower socioeconomic status and education level.

Mild Cognitive Impairment and Receipt of Treatments for Acute Myocardial Infarction in Older Adults

BACKGROUND

Older adults with mild cognitive impairment (MCI) should receive evidence-based treatments when indicated. Providers and patients may overestimate the risk of dementia in patients with MCI leading to potential under-treatment. However, the association between pre-existing MCI and receipt of evidence-based treatments is uncertain.

OBJECTIVE

To compare receipt of treatments for acute myocardial infarction (AMI) between older adults with pre-existing MCI and cognitively normal patients.

DESIGN

Prospective study using data from the nationally representative Health and Retirement Study, Medicare, and American Hospital Association.

PARTICIPANTS

Six hundred nine adults aged 65 or older hospitalized for AMI between 2000 and 2011 and followed through 2012 with pre-existing MCI (defined as modified Telephone Interview for Cognitive Status score of 7-11) and normal cognition (score of 12-27).

MAIN MEASURES

Receipt of cardiac catheterization and coronary revascularization within 30 days and cardiac rehabilitation within 1 year of AMI hospitalization.

KEY RESULTS

Among the survivors of AMI, 19.2% had pre-existing MCI (55.6% were women and 44.4% were male, with a mean [SD] age of 82.3 [7.5] years), and 80.8% had normal cognition (45.7% were women and 54.3% were male, with a mean age of 77.1 [7.1] years). Survivors of AMI with pre-existing MCI were significantly less likely than those with normal cognition to receive cardiac catheterization (50% vs 77%; P < 0.001), coronary revascularization (29% vs 63%; P < 0.001), and cardiac rehabilitation (9% vs 22%; P = 0.001) after AMI. After adjusting for patient and hospital factors, pre-existing MCI remained associated with lower use of cardiac catheterization (adjusted hazard ratio (aHR), 0.65; 95% CI, 0.48-0.89; P = 0.007) and coronary revascularization (aHR, 0.55; 95% CI, 0.37-0.81; P = .003), but not cardiac rehabilitation (aHR, 1.01; 95% CI, 0.49-2.07; P = 0.98).

CONCLUSIONS

Pre-existing MCI is associated with lower use of cardiac catheterization and coronary revascularization but not cardiac rehabilitation after AMI.

Neuropsychiatric Symptoms as Risk Factors for Cognitive Decline in Clinically Normal Older Adults: The Cache County Study

INTRODUCTION

There has been considerable progress in identifying early cognitive and biomarker predictors of Alzheimer's disease (AD). Neuropsychiatric symptoms (NPS) are common in AD and appear to predict progression after the onset of mild cognitive impairment or dementia.

OBJECTIVES

The objective of the study is to examine the relationship between NPS in clinically normal older adults and subsequent cognitive decline in a population-based sample.

METHODS

The Cache County Study on Memory in Aging consists of a population-based sample of 5,092 older adults. We identified 470 clinically normal adults who were followed for an average period of 5.73 years. NPS were evaluated at the baseline clinical assessment using the Neuropsychiatric Inventory (NPI). NPI domain scores were quantified as the product of frequency X severity in individual NPI domains, and then summed for the NPI-Total. Neuropsychological measures were collected at baseline and at each subsequent follow-up wave. Linear mixed-effects models assessed the association of NPI-Total, NPI-Depression, and NPI-Anxiety scores (obtained at baseline) on longitudinal change in neuropsychological performance, controlling for age, sex, and education.

RESULTS

Baseline NPI-Total score was associated with a more rapid rate of decline in word list memory, praxis recall, and animal fluency. Baseline NPI-Depression was not associated with later decline on any of the cognitive tests, while baseline NPI-Anxiety was associated with decline in Symbol Digit Modality.

CONCLUSION

In conclusion, among clinically normal older adults derived from this population-based study, total burden of NPS was associated with longitudinal cognitive decline. These results add to the evidence that NPS are risk factors for or clinical indicators of preclinical dementia syndrome. Our study was an exploratory study and we did not control for multiple comparisons.

Long-term Functional Decline After High-Risk Elective Colorectal Surgery in Older Adults

BACKGROUND

Although most surgical outcomes research focuses on clinical end points and complications, older adult patients may value functional outcomes more. However, little is known about the risk of long-term functional disability after colorectal procedures.

OBJECTIVE

The purpose of this research was to understand the incidence and likelihood of functional decline after high-risk (ie, ≥1% inpatient mortality) colorectal operations both without and with complications.

DESIGN

This was a retrospective matched cohort study.

SETTINGS

The Health and Retirement Study, a nationally representative, longitudinal survey of adults >50 years of age, collects data on functional status, cognition, and demographics, among other topics. The survey was linked with Medicare claims and National Death Index data from 1992 to 2012.

PATIENTS

Patients ≥65 years of age who underwent elective high-risk colorectal surgery with functional status measured before and after surgery were included. These patients were matched 1:3 to survey respondents who did not undergo major surgery, based on propensity scores.

MAIN OUTCOME MEASURES

Functional decline, the primary outcome, was defined as an increase in the number of activities of daily living and instrumental activities of daily living requiring assistance before and after surgery. Using logistic regression, we examined whether surgery without or with complications was associated with functional decline.

RESULTS

We identified 289 patients who underwent high-risk colorectal surgery and 867 matched control subjects. Of the surgery patients, 90 (31%) experienced a complication. Compared with the control subjects, surgery patients experienced greater likelihood of functional decline (without complications: OR = 1.82 (95% CI, 1.22-2.71), and with complications: OR = 2.96 (95% CI, 1.70-5.14)). Increasing age also predicted greater odds of functional decline (OR = 2.09, per decade (95% CI, 1.57-2.80)).

LIMITATIONS

The functional measures were self-reported by survey participants.

CONCLUSIONS

High-risk colorectal surgery, without or with complications, is associated with increased likelihood of functional decline in older adults. Patient-centered decision-making should include discussion of expected functional outcomes and long-term disability. See Video Abstract at http://links.lww.com/DCR/B78. PÉRDIDA DE LA FUNCIONALIDAD A LARGO PLAZO LUEGO DE CIRUGÍA ELECTIVA COLORRECTAL DE ALTO RIESGO EN EL PACIENTE AÑOSO: Aunque en la mayoría de las investigaciones los resultados quirúrgicos se centran en los puntos finales clínicos y las complicaciones, actualmente se pueden valorar los resultados funcionales en el paciente añoso. Sin embargo, se sabe poco sobre el riesgo de la discapacidad funcional a largo plazo después de un procedimiento colorrectal.Comprender la incidencia y la probabilidad del deterioro funcional después de operaciones colorrectales de alto riesgo (es decir, ≥1% de mortalidad hospitalaria) con y sin complicaciones.Estudio de cohorte emparejado retrospectivo.El seguimiento longitudinal representativo a nivel nacional en adultos de >50 años y que recopila datos sobre su estado funcional, su estado cognitivo y su demografía, entre otros temas es el llamado "Estudio de Salud en jubilados." La encuesta se vinculó con los reclamos de Medicare y los datos del Índice Nacional de Defunciones entre 1992 y 2012.Aquellos de ≥65 años que se sometieron a cirugía colorrectal electiva de alto riesgo con un estado funcional medido antes y después de la cirugía. Estos pacientes se compararon 1: 3 con los encuestados que no se sometieron a cirugía mayor, según puntajes de propensión.La disminución functional como resultado primario, se definió como un aumento en el número de actividades de la vida diaria y actividades instrumentales de la vida diaria que requieren asistencia antes y después de la cirugía. Mediante la regresión logística, evaluamos si la cirugía sin complicaciones y/o con complicaciones se asoció con un deterioro funcional.Identificamos 289 pacientes que se sometieron a cirugía colorrectal de alto riesgo y 867 controles pareados. De los pacientes de cirugía, 90 (31%) experimentaron algun tipo de complicación. En comparación con los controles, los pacientes de cirugía experimentaron una mayor probabilidad de deterioro funcional (sin complicaciones: OR 1.82, IC 95% 1.22-2.71, y con complicaciones: OR 2.96, IC 95% 1.70-5.14). El aumento de la edad también predijo mayores probabilidades en el deterioro funcional (OR 2.09, por década, IC 95% 1.57-2.80).Las medidas funcionales fueron autoinformadas por los participantes de la encuesta.La cirugía colorrectal de alto riesgo, con o sin complicaciones, se asocia con una mayor probabilidad de deterioro funcional en adultos mayores. La toma de decisiones centradas en el paciente deben incluir la discusión de los resultados funcionales esperados y la discapacidad a largo plazo. Vea el resumen del video en http://links.lww.com/DCR/B78.

Development of Algorithmic Dementia Ascertainment for Racial/Ethnic Disparities Research in the US Health and Retirement Study

BACKGROUND

Disparities research in dementia is limited by lack of large, diverse, and representative samples with systematic dementia ascertainment. Algorithmic diagnosis of dementia offers a cost-effective alternate approach. Prior work in the nationally representative Health and Retirement Study has demonstrated that existing algorithms are ill-suited for racial/ethnic disparities work given differences in sensitivity and specificity by race/ethnicity.

METHODS

We implemented traditional and machine learning methods to identify an improved algorithm that: (1) had ≤5 percentage point difference in sensitivity and specificity across racial/ethnic groups; (2) achieved ≥80% overall accuracy across racial/ethnic groups; and (3) achieved ≥75% sensitivity and ≥90% specificity overall. Final recommendations were based on robustness, accuracy of estimated race/ethnicity-specific prevalence and prevalence ratios compared to those using in-person diagnoses, and ease of use.

RESULTS

We identified six algorithms that met our prespecified criteria. Our three recommended algorithms achieved ≤3 percentage point difference in sensitivity and ≤5 percentage point difference in specificity across racial/ethnic groups, as well as 77%-83% sensitivity, 92%-94% specificity, and 90%-92% accuracy overall in analyses designed to emulate out-of-sample performance. Pairwise prevalence ratios between non-Hispanic whites, non-Hispanic blacks, and Hispanics estimated by application of these algorithms are within 1%-10% of prevalence ratios estimated based on in-person diagnoses.

CONCLUSIONS

We believe these algorithms will be of immense value to dementia researchers interested in racial/ethnic disparities. Our process can be replicated to allow minimally biasing algorithmic classification of dementia for other purposes.

Racial disparities and temporal trends in dementia misdiagnosis risk in the United States

Introduction

Systematic disparities in misdiagnosis of dementia across racial/ethnic groups have implications for health disparities. We compared the risk of dementia under- and overdiagnosis in clinical settings across racial/ethnic groups from 2000 to 2010.

Methods

We linked fee-for-service Medicare claims to participants aged ≥70 from the nationally representative Health and Retirement Study. We classified dementia status using an algorithm with similar sensitivity and specificity across racial/ethnic groups and assigned clinical dementia diagnosis status using ICD-9-CM codes from Medicare claims. Multinomial logit models were used to estimate relative risks of clinical under- and overdiagnosis between groups and over time.

Results

Non-Hispanic blacks had roughly double the risk of underdiagnosis as non-Hispanic whites. While primary analyses suggested a shrinking disparity over time, this was not robust to sensitivity analyses or adjustment for covariates. Risk of overdiagnosis increased over time in both groups.

Discussion

Our results suggest that efforts to reduce racial disparities in underdiagnosis are warranted.

Reduced Prevalence and Incidence of Cognitive Impairment Among Centenarian Offspring

Background

Centenarian offspring have better health and lower mortality in comparison to referent cohorts, however it is unknown whether they have preserved cognition at older ages.

Methods

This prospective study of 491 centenarian offspring and 270 referent participants without familial longevity (mean baseline age 75.5 years) from the New England Centenarian Study analyzed longitudinal cognitive assessments performed using the Telephone Interview for Cognitive Status. Logistic regression was used for cognitive impairment at baseline and Cox proportional hazards regression for risk of incident cognitive impairment.

Results

After adjustment for age, sex, education, stroke, and diabetes, offspring were 46% less likely to have baseline cognitive impairment (adjusted odds ratio 0.54, 95% CI 0.35-0.82) and were 27% less likely to become cognitively impaired over a median follow-up of 7.8 years (adjusted hazard ratio 0.73, 95% CI 0.53-0.99). Female gender was also independently associated with lower odds of baseline cognitive impairment and lower risk of incident cognitive impairment.

Conclusions

Familial longevity may confer exposure to genetic and environmental factors that predispose centenarian offspring to preservation of cognitive function at older ages. Centenarian offspring cohorts may provide an opportunity to study cognitive resilience associated with familial longevity.

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

INTRODUCTION

The Harmonized Cognitive Assessment Protocol (HCAP) Project is a substudy within the Health and Retirement Study (HRS), an ongoing nationally representative panel study of about 20,000 adults aged 51 or older in the United States. The HCAP is part of an international research collaboration funded by the National Institute on Aging to better measure and identify cognitive impairment and dementia in representative population-based samples of older adults, in the context of ongoing longitudinal studies of aging in high-, middle-, and low-income countries around the world.

METHODS

The HCAP cognitive test battery was designed to measure a range of key cognitive domains affected by cognitive aging (including attention, memory, executive function, language, and visuospatial function) and to allow harmonization and comparisons to other studies in the United States and around the world. The HCAP included a pair of in-person interviews, one with the target HRS respondent (a randomly selected HRS sample member, aged 65+) that lasted approximately 1 h and one with an informant nominated by the respondent that lasted approximately 20 min. The final HRS HCAP sample included 3,496 study subjects, representing a 79% response rate among those invited to participate.

CONCLUSION

Linking detailed HCAP cognitive assessments to the wealth of available longitudinal HRS data on cognition, health, biomarkers, genetics, health care utilization, informal care, and economic resources and behavior will provide unique and expanded opportunities to study cognitive impairment and dementia in a nationally representative US population-based sample. The fielding of similar HCAP projects in multiple countries around the world will provide additional opportunities to study international differences in the prevalence, incidence, and outcomes of dementia globally with comparable data. Like all HRS data, HCAP data are publicly available at no cost to researchers.

Before Hospice: Symptom Burden, Dementia, and Social Participation in the Last Year of Life

Background: Little is known about clinical symptom burden, dementia, and social isolation in the last year of life among older adults. Objective: To describe and contrast the type and severity of symptom burden for older decedents with and without dementia, and whether specific symptoms and presence of dementia are associated with limitations in social participation in the last year of life. Design: Cross-sectional logistic regression analysis of a population-based study. Setting/Subjects: A total of 1270 community-dwelling adults of age ≥65 years in the United States participated in the 2011 National Health and Aging Trends Study and died by 2015. Measurements: Dementia status, 13 clinical symptoms, and limitations in 6 social activities were drawn from the interview preceding death. Severity of sensory, physical, and psychiatric symptom burden was examined in tertiles. Results: Decedents with dementia (37.3%) had higher prevalence of all symptoms (p's < 0.05), except insomnia and breathing problems. Dementia was associated with greater likelihood of high versus low burden of sensory (odds ratio [OR] 4.52 [95% confidence interval {CI} 3.08-6.63]), physical (OR 3.49 [95% CI 2.48-4.91]), and psychiatric (OR 2.80 [95% CI 1.98-3.95]) symptoms. Dementia and physical symptoms (problems with speaking, leg strength/movement, and balance) were independently associated with limitations in at least three social activities (p's < 0.05 for adjusted ORs). Conclusion: Symptom burden is higher in patients with dementia. Dementia and physical symptoms are associated with social activity limitations. Older patients with dementia or physical symptoms may benefit from earlier emphasis on palliative care and quality of life.

Psychological Distress, Self-Beliefs, and Risk of Cognitive Impairment and Dementia

Depressive symptoms and a history of mental disorders are associated with increased risk for dementia. Less is known about whether other aspects of psychological distress and negative self-beliefs also increase risk. The purpose of this research is to examine 1) whether eight aspects of psychological distress and self-beliefs (anxiety, negative affect, hostility, anger-in, anger-out, hopelessness, pessimism, perceived constraints) are associated with risk of incident dementia and cognitive impairment not dementia (CIND), 2) whether the associations are independent of depressive symptoms and history of a mental health diagnosis, and 3) whether the associations are also independent of behavioral, clinical, and genetic risk factors. A total of 9,913 participants (60% female) from the Health and Retirement Study completed the baseline measures, scored in the non-impaired range of cognition at baseline, and had cognitive status assessed across the 6-8-year follow-up. Baseline measures included eight aspects of psychological distress and self-beliefs, cognitive performance, depressive symptoms, and genetic, clinical, and behavioral risk factors. Participants who scored higher on anxiety, negative affect, hostility, pessimism, hopelessness, and perceived constraints were at a 20-30% increased risk of dementia and a 10-20% increased risk of CIND. The associations held controlling for baseline depressive symptoms, history of a mental health diagnosis, clinical and behavioral risk factors, and genetic risk. Anger-in and anger-out were unrelated to risk of either dementia or CIND. Independent of the core experience of depressed affect, other aspects of negative emotionality and self-beliefs increase risk of mild and severe cognitive impairment, which suggests additional targets of intervention.

The Impact of Changes in Population Health and Mortality on Future Prevalence of Alzheimer's Disease and Other Dementias in the United States

Objectives

We assessed potential benefits for older Americans of reducing risk factors associated with dementia.

Methods

A dynamic simulation model tracked a national cohort of persons 51 and 52 years of age to project dementia onset and mortality in risk reduction scenarios for diabetes, hypertension, and dementia.

Results

We found reducing incidence of diabetes by 50% did not reduce number of years a person ages 51 or 52 lived with dementia and increased the population ages 65 and older in 2040 with dementia by about 115,000. Eliminating hypertension at middle and older ages increased life expectancy conditional on survival to age 65 by almost 1 year, however, it increased years living with dementia. Innovation in treatments that delay onset of dementia by 2 years increased longevity, reduced years with dementia, and decreased the population ages 65 and older in 2040 with dementia by 2.2 million.

Conclusions

Prevention of chronic disease may generate health and longevity benefits but does not reduce burden of dementia. A focus on treatments that provide even short delays in onset of dementia can have immediate impacts on longevity and quality of life and reduce the number of Americans with dementia over the next decades.

Optimism and Healthy Aging in Women and Men

Mounting evidence indicates that there are specific associations between higher levels of optimism and healthier behaviors, reduced risk of chronic diseases, and lower mortality. Yet, for public health purposes, it is critical to consider how optimism might be related to a full scope of health conditions in aging-from cognitive to physical health. Using prospective data from the Health and Retirement Study (n = 5,698), we examined whether higher baseline optimism was associated with subsequent increased likelihood of maintaining healthy aging over 6-8 years of follow-up. Optimism was assessed at study baseline (2006 or 2008), and components of healthy aging were assessed every 2 years, defined as: 1) remaining free of major chronic diseases; 2) having no cognitive impairment; and 3) good physical functioning. Hazard ratios were obtained using Cox proportional hazards models, and a range of relevant covariates were considered (sociodemographic factors, depressive symptoms, and health behaviors). After adjusting for sociodemographic factors and depression, the most (top quartile) versus least (bottom quartile) optimistic participants had a 24% increased likelihood of maintaining healthy aging (95% CI: 1.11, 1.38). Further adjustment for health behaviors did not meaningfully change the findings. Optimism, a potentially modifiable health asset, merits further research for its potential to improve likelihood of health in aging.

Verbal fluency and risk of dementia

OBJECTIVE

Verbal fluency is a common neuropsychological test that is impaired in dementia. We test whether verbal fluency is a prospective risk factor for incident dementia, cognitive impairment not dementia (CIND), and conversion from CIND to dementia.

METHODS

Participants (N = 18 189) from the Health and Retirement Study were administered a standard test of verbal fluency and were assessed for cognitive status every 2 years between baseline and 6 years' follow-up.

RESULTS

Every standard deviation increase in verbal fluency was associated with an approximately 60% reduced risk of incident dementia, an approximately 25% reduced risk of incident CIND, and an approximately 25% reduced risk of conversion from CIND to dementia. These associations were independent of age, gender, education, race, ethnicity, and APOE risk status. The associations were slightly weaker (but still significant) for African Americans and individuals with lower education. There was no interaction between verbal fluency and APOE risk status.

CONCLUSION

Verbal fluency is an easily administered task that is predictive of incident cognitive impairment.

Comparison of Methods for Algorithmic Classification of Dementia Status in the Health and Retirement Study

Supplemental Digital Content is available in the text.

Background:

Dementia ascertainment is time-consuming and costly. Several algorithms use existing data from the US-representative Health and Retirement Study (HRS) to algorithmically identify dementia. However, relative performance of these algorithms remains unknown.

Methods:

We compared performance across five algorithms (Herzog–Wallace, Langa–Kabeto–Weir, Crimmins, Hurd, Wu) overall and within sociodemographic subgroups in participants in HRS and Wave A of the Aging, Demographics, and Memory Study (ADAMS, 2000–2002), an HRS substudy including in-person dementia ascertainment. We then compared algorithmic performance in an internal (time-split) validation dataset including participants of HRS and ADAMS Waves B, C, and/or D (2002–2009).

Results:

In the unweighted training data, sensitivity ranged from 53% to 90%, specificity ranged from 79% to 97%, and overall accuracy ranged from 81% to 87%. Though sensitivity was lower in the unweighted validation data (range: 18%–62%), overall accuracy was similar (range: 79%–88%) due to higher specificities (range: 82%–98%). In analyses weighted to represent the age-eligible US population, accuracy ranged from 91% to 94% in the training data and 87% to 94% in the validation data. Using a 0.5 probability cutoff, Crimmins maximized sensitivity, Herzog–Wallace maximized specificity, and Wu and Hurd maximized accuracy. Accuracy was higher among younger, highly-educated, and non-Hispanic white participants versus their complements in both weighted and unweighted analyses.

Conclusion:

Algorithmic diagnoses provide a cost-effective way to conduct dementia research. However, naïve use of existing algorithms in disparities or risk factor research may induce nonconservative bias. Algorithms with more comparable performance across relevant subgroups are needed.

Predictors of dementia misclassification when using brief cognitive assessments

BACKGROUND

Brief cognitive assessments can result in false-positive and false-negative dementia misclassification. We aimed to identify predictors of misclassification by 3 brief cognitive assessments; the Mini-Mental State Examination (MMSE), Memory Impairment Screen (MIS) and animal naming (AN).

METHODS

Participants were 824 older adults in the population-based US Aging, Demographics and Memory Study with adjudicated dementia diagnosis (DSM-III-R and DSM-IV criteria) as the reference standard. Predictors of false-negative, false-positive and overall misclassification by the MMSE (cut-point <24), MIS (cut-point <5) and AN (cut-point <9) were analysed separately in multivariate bootstrapped fractional polynomial regression models. Twenty-two candidate predictors included sociodemographics, dementia risk factors and potential sources of test bias.

RESULTS

Misclassification by at least one assessment occurred in 301 (35.7%) participants, whereas only 14 (1.7%) were misclassified by all 3 assessments. There were different patterns of predictors for misclassification by each assessment. Years of education predicts higher false-negatives (odds ratio [OR] 1.23, 95% confidence interval [95% CI] 1.07-1.40) and lower false-positives (OR 0.77, 95% CI 0.70-0.83) by the MMSE. Nursing home residency predicts lower false-negatives (OR 0.15, 95% CI 0.03-0.63) and higher false-positives (OR 4.85, 95% CI 1.27-18.45) by AN. Across the assessments, false-negatives were most consistently predicted by absence of informant-rated poor memory. False-positives were most consistently predicted by age, nursing home residency and non-Caucasian ethnicity (all p < 0.05 in at least 2 models). The only consistent predictor of overall misclassification across all assessments was absence of informant-rated poor memory.

CONCLUSIONS

Dementia is often misclassified when using brief cognitive assessments, largely due to test specific biases.