Recent developments in longitudinal studies of aging in the United States

Congressional Symmetry: Years Remaining Mirror Years Served in the U.S. House and Senate

Our overarching goal in this paper was to both test and identify applications for a fundamental theorem of replacement-level populations known as the Stationary Population Identity (SPI), a mathematical model that equates the fraction of a population age x and the fraction with x years to live. Since true stationarity is virtually non-existent in human populations as well as in populations of non-human species, we used historical data on the memberships in both chambers of the U.S. Congress as population proxies. We conceived their fixed numbers (e.g., 100 Senators; 435 Representatives) as stationary populations, and their years served and years remaining as the equivalent of life lived and life remaining. Our main result was the affirmation of the mathematical prediction-i.e., the robust symmetry of years served and years remaining in Congress over the approximately 230 years of its existence (1789-2022). A number of applications emerged from this regularity and the distributional patterns therein including (1) new metrics such as Congressional half-life and other quantiles (e.g., 95% turnover); (2) predictability of the distribution of member's years remaining; (3) the extraordinary information content of a single number-the mean number of years served [i.e., derive birth (b) and death (d) rates; use of d as exponential rate parameter for model life tables]; (4) the concept of and metrics associated with period-specific populations (Congress); (5) Congressional life cycle concept with Formation, Growth, Senescence and Extinction Phases; and (6) longitudinal party transition rates for 100% Life Cycle turnover (Democrat/Republican) i.e., each seat from predecessor party-to-incumbent party and from incumbent party-to-successor party. Although our focus is on the use of historical data for Congressional members, we believe that most of the results are general and thus both relevant and applicable to most types of stationary or quasi-stationary populations including to the future world of zero population growth (ZPG).

A prospective cohort study of racial/ethnic variation in the association between change in cystatin C and dietary quality in older Americans

Using a sample of US adults aged 65 years and older, we examined the role of dietary quality in cystatin C change over 4 years and whether this association varied by race/ethnicity. The Health and Retirement Study provided observations with biomarkers collected in 2012 and 2016, participant attributes measured in 2012, and dietary intake assessed in 2013. The sample was restricted to respondents who were non-Hispanic/Latino White (n 789), non-Hispanic/Latino Black (n 108) or Hispanic/Latino (n 61). Serum cystatin C was constructed to be equivalent to the 1999-2002 National Health and Nutrition Examination Survey (NHANES) scale. Dietary intake was assessed by a semi-quantitative FFQ with diet quality measured using an energy-adjusted form of the Alternative Healthy Eating Index-2010 (AHEI-2010). Statistical analyses were conducted using autoregressive linear modelling adjusting for covariates and complex sampling design. Cystatin C slightly increased from 1·2 mg/l to 1·3 mg/l over the observational period. Greater energy-adjusted AHEI-2010 scores were associated with slower increase in cystatin C from 2012 to 2016. Among respondents reporting moderately low to low dietary quality, Hispanic/Latinos had significantly slower increases in cystatin C than their non-Hispanic/Latino White counterparts. Our results speak to the importance of considering racial/ethnic determinants of dietary intake and subsequent changes in health in ageing populations. Further work is needed to address measurement issues including further validation of dietary intake questionnaires in diverse samples of older adults.

Has demography witnessed a data revolution? Promises and pitfalls of a changing data ecosystem

Over the past 25 years, technological improvements that have made the collection, transmission, storage, and analysis of data significantly easier and more cost efficient have ushered in what has been described as the 'big data' era or the 'data revolution'. In the social sciences context, the data revolution has often been characterized in terms of increased volume and variety of data, and much excitement has focused on the growing opportunity to repurpose data that are the by-products of the digitalization of social life for research. However, many features of the data revolution are not new for demographers, who have long used large-scale population data and been accustomed to repurposing imperfect data not originally collected for research. Nevertheless, I argue that demography, too, has been affected by the data revolution, and the data ecosystem for demographic research has been significantly enriched. These developments have occurred across two dimensions. The first involves the augmented granularity, variety, and opportunities for linkage that have bolstered the capabilities of 'old' big population data sources, such as censuses, administrative data, and surveys. The second involves the growing interest in and use of 'new' big data sources, such as 'digital traces' generated through internet and mobile phone use, and related to this, the emergence of 'digital demography'. These developments have enabled new opportunities and offer much promise moving forward, but they also raise important ethical, technical, and conceptual challenges for the field.

Marital Transitions, Change in Depressive Symptomology, and Quality of Social Relationships in Midlife and Older U.S. Adults: An Analysis of the Health and Retirement Study

Preventing negative health outcomes following marital transitions can promote personal recovery and well-being. We used the Health and Retirement Study (HRS) (2012, 2014) to test whether social relationship quality moderated the association between marital transition and change in depressive symptomology among U.S. adults aged 50 and older (n = 3,705). Marital status transitions between 2012 and 2014 included remained married/partnered, divorced/separated, and widowed. Depressive symptomology was measured using the Center for Epidemiological Studies Depression Scale 8 Short Form (CES-D 8). Social support, social contact, and social strain were indicators of social relationship quality. Change in depressive symptomology was modeled using autoregressive multiple regression. Social relationship quality appeared to influence depressive symptomatology for those experiencing divorce/separation. Compared to individuals who remained married/partnered, depressive symptomatology in those experiencing separation/divorce decreased among those reporting low social support, increased among those reporting high social support, and increased among those who reported low social strain. Limitations and clinical implications are discussed.

Dietary quality modifies the association between multimorbidity and change in mobility limitations among older Americans

To identify potentially modifiable risk-factors in the age-related disablement process, we examined the association between change in mobility limitations and multimorbidity and how dietary quality moderates this association. Information from 3320 adults aged 65 and older in 2012 was drawn from the Health and Retirement Study and the Health Care and Nutrition Study. Mobility limitations reported in 2012 and change in mobility limitations from 2012 to 2014 were regressed on multimorbidity measured as number of chronic conditions in 2012, dietary quality measured in 2013 using the Alternative Healthy Eating Index-2010 (AHEI-2010), and their interaction term using Poisson regression. Respondents reported an average of 2.9 (SD, 2.9) mobility limitations in 2012 and 3.1 (SD, 3.0) mobility limitations in 2014, an average of 2.64 (SD, 1.4) chronic conditions in 2012, and mean AHEI-2010 score in 2013 of 57.1 (SD, 10.9). Greater AHEI-2010 scores were associated with fewer mobility limitations at baseline (p < .001) and slower progression of mobility limitations over the two-year observational window (p < .001). For those with AHEI-2010 scores ≥48.4, dietary quality appeared to moderate the association between multimorbidity and change in mobility limitations. These results suggest that improving dietary quality may be an effective means of reducing the progression of mobility limitations among older adults and that dietary quality may modify the effect of multimorbidity on progressive disablement. Our work adds to research supporting dietary quality as a potentially intervenable factor in the reduction of disablement in aging populations.

Latent profile analysis of dietary intake in a community-dwelling sample of older Americans

Objective:

To estimate latent dietary profiles in a community-dwelling sample of older Americans and identify associations between dietary profile membership and individual demographic, socio-economic and health characteristics.

Design:

Secondary analysis of the 2012 Health and Retirement Study (HRS) and linked 2013 Health Care and Nutrition Study (HCNS). Latent profile analysis identified mutually exclusive subgroups of dietary intake and bivariate analyses examined associations between dietary profile membership, participant characteristics and nutrient intakes.

Setting:

USA.

Participants:

An analytic sample of 3558 adults aged 65 years or older.

Results:

Four dietary profiles were identified with 15·5 % of the sample having a ‘Healthy’ diet, 42·0 % consuming a ‘Western’ diet, 29·7 % having a diet consisting of high intake of all food groups and 12·7 % reporting relatively low intake of all food groups. Members of the ‘Healthy’ profile reported the greatest socio-economic resources and health, and members of the ‘Low Intake’ profile had the fewest resources and worst health outcomes. Macronutrient and micronutrient intakes varied across profile although inadequate and excessive intakes of selected nutrients were observed for all profiles.

Conclusions:

We identified dietary patterns among older Americans typified by either selective intake of foods or overall quantity of foods consumed, with those described as ‘Low Intake’ reporting the fewest socio-economic resources, greatest risk of food insecurity and the worst health outcomes. Limitations including the presence of measurement error in dietary questionnaires are discussed. The causes and consequences of limited dietary intake among older Americans require further study and can be facilitated by the HRS and HCNS.

Food insecurity, comorbidity, and mobility limitations among older U.S. adults: Findings from the Health and Retirement Study and Health Care and Nutrition Study

Both food insecurity and comorbidity have been identified as precursors to functional limitation in older adults, yet whether food insecurity modifies the progression from chronic disease to disability has not been assessed. We examined 5986 respondents age 50 and older drawn from the 2012-2014 Health and Retirement Study (HRS) and 2013 Health Care and Nutrition Study (HCNS). Mobility limitations reported in 2014 and change in mobility limitations from 2012 to 2014 were regressed on measures of food insecurity, number of chronic conditions, and their interaction terms using Poisson regression. Around 17.3% of the sample was identified as food insecure. In 2012, respondents reported an average of 1.9 (SD = 1.5) chronic conditions and 2.4 mobility limitations (SD = 3.0). In 2014, individuals reported an average of 2.5 (SD = 3.1) mobility limitations. Food insecurity was associated with a greater number of mobility limitations (IRR = 1.20, 95% CI: 1.11-1.29, p < .001) and more rapid increase in mobility limitations over the two-year observational period (IRR = 1.06, 95% CI: 1.00-1.11, p = .047). Food security status also modified the association between comorbidity and both mobility limitation outcomes, with the food secure exhibiting a stronger positive association between chronic conditions and mobility limitations than the food insecure. The food insecure tended to have more mobility limitations than the food secure when few chronic conditions were reported. Our results suggest that food insecurity is associated with prevalence and change in mobility limitations among older adults.

Latent Profiles of Macronutrient Density and their Association with Mobility Limitations in an Observational Longitudinal Study of Older U.S. Adults

OBJECTIVES

Our first objective was to estimate empirically-derived subgroups (latent profiles) of observed carbohydrate, protein, and fat intake density in a nationally representative sample of older U.S. adults. Our second objective was to determine whether membership in these groups was associated with levels of, and short term change in, physical mobility limitations.

DESIGN AND SETTING

Measures of macronutrient density were taken from the 2013 Health Care and Nutrition Study, an off-year supplement to the Health and Retirement Study, which provided indicators of physical mobility limitations and sociodemographic and health-related covariates.

PARTICIPANTS

3,914 community-dwelling adults age 65 years and older.

MEASUREMENTS

Percent of daily calories from carbohydrate, protein, and fat were calculated based on responses to a modified Harvard food frequency questionnaire. Latent profile analysis was used to describe unobserved heterogeneity in measures of carbohydrate, protein, and fat density. Mobility limitation counts were based on responses to 11 items indicating physical limitations. Poisson regression models with autoregressive controls were used to identify associations between macronutrient density profile membership and mobility limitations. Sociodemographic and health-related covariates were included in all Poisson regression models.

RESULTS

Four latent subgroups of macronutrient density were identified: "High Carbohydrate", "Moderate with Fat", "Moderate", and "Low Carbohydrate/High Fat". Older adults with the lowest percentage of daily calories coming from carbohydrate and the greatest percentage coming from fat ("Low Carbohydrate/High Fat") were found to have greater reported mobility limitations in 2014 than those identified as having moderate macronutrient density, and more rapid two-year increases in mobility limitations than those identified as "Moderate with Fat" or "Moderate".

CONCLUSION

Older adults identified as having the lowest carbohydrate and highest fat energy density were more likely to report a greater number of mobility limitations and experience greater increases in these limitations than those identified as having moderate macronutrient density. These results suggest that the interrelation of macronutrients must be considered by those seeking to reduce functional limitations among older adults through dietary interventions.

Recent cancer treatment and memory decline in older adults: An analysis of the 2002-2012 Health and Retirement Study

OBJECTIVE

Few studies have examined the impact of cancer treatment on cognitive trajectories in the growing population of older adults diagnosed with and surviving cancer. This study examined whether recent cancer and its treatment accelerated memory decline in older adults.

MATERIALS AND METHODS

We conducted a secondary analysis of observations drawn from the Health and Retirement Study (2002-2012), a population-based sample of older adults in the United States. Changes in immediate (IWR) and delayed word recall (DWR) scores were estimated by latent growth modeling in individuals who never had cancer (n=10,939) or had been diagnosed with cancer between 2000 and 2002 and received treatment with some combination of radiation and/or surgery (n=240), chemotherapy only (n=34), or chemotherapy and some combination of radiation and/or surgery (n=64).

RESULTS

In the period immediately following treatment, individuals reporting a recent cancer treated with chemotherapy and surgery/radiation experienced significantly more rapid decline in IWR (b =-0.34, SE =0.17, p=0.047) and DWR (b=-0.38, SE=0.19, p=0.049) than the non-cancer group. Sensitivity analyses addressing mortality selection and memory-related disease at baseline attenuated the strength of these associations. There were no other statistically significant differences in estimated linear or quadratic slope by cancer status or treatment.

CONCLUSION

Our results support a potential association between recent cancer treatment and trajectories of memory decline in older adults and provide guidance on the interpretation of statistical estimates from panel studies of health and aging.

WEALTH INEQUALITY AND ACCUMULATION

Research on wealth inequality and accumulation and the data upon which it relies have expanded substantially in the twenty-first century. While the field has experienced rapid growth, conceptual and methodological challenges remain. We begin by discussing two major unresolved methodological concerns facing wealth research: how to address challenges to causal inference posed by wealth's cumulative nature and how to operationalize net worth, given its highly skewed nature. To underscore the need for continued empirical attention to net worth, we review trends in wealth levels and inequality and evaluate wealth's distinctiveness as an indicator of social stratification. Next, we provide an overview of data sources available for wealth research. We then review recent empirical evidence on the effects of wealth on other social outcomes, as well as research on the determinants of wealth. We close with a list of promising avenues for future research on wealth, its causes, and its consequences.

Racial and ethnic differences in smoking changes after chronic disease diagnosis among middle-aged and older adults in the United States

BACKGROUND

Middle-aged and older Americans from underrepresented racial and ethnic backgrounds are at risk for greater chronic disease morbidity than their white counterparts. Cigarette smoking increases the severity of chronic illness, worsens physical functioning, and impairs the successful management of symptoms. As a result, it is important to understand whether smoking behaviors change after the onset of a chronic condition. We assessed the racial/ethnic differences in smoking behavior change after onset of chronic diseases among middle-aged and older adults in the US.

METHODS

We use longitudinal data from the Health and Retirement Study (HRS 1992-2010) to examine changes in smoking status and quantity of cigarettes smoked after a new heart disease, diabetes, cancer, stroke, or lung disease diagnosis among smokers.

RESULTS

The percentage of middle-aged and older smokers who quit after a new diagnosis varied by racial/ethnic group and disease: for white smokers, the percentage ranged from 14% after diabetes diagnosis to 32% after cancer diagnosis; for black smokers, the percentage ranged from 15% after lung disease diagnosis to 40% after heart disease diagnosis; the percentage of Latino smokers who quit was only statistically significant after stoke, where 38% quit. In logistic models, black (OR = 0.43, 95% CI: 0.19-0.99) and Latino (OR = 0.26, 95% CI: 0.11-0.65) older adults were less likely to continue smoking relative to white older adults after a stroke, and Latinos were more likely to continue smoking relative to black older adults after heart disease onset (OR = 2.69, 95% CI [1.05-6.95]). In models evaluating changes in the number of cigarettes smoked after a new diagnosis, black older adults smoked significantly fewer cigarettes than whites after a new diagnosis of diabetes, heart disease, stroke or cancer, and Latino older adults smoked significantly fewer cigarettes compared to white older adults after newly diagnosed diabetes and heart disease. Relative to black older adults, Latinos smoked significantly fewer cigarettes after newly diagnosed diabetes.

CONCLUSIONS

A large majority of middle-aged and older smokers continued to smoke after diagnosis with a major chronic disease. Black participants demonstrated the largest reductions in smoking behavior. These findings have important implications for tailoring secondary prevention efforts for older adults.

Forecasting Trends in Disability in a Super-Aging Society: Adapting the Future Elderly Model to Japan

Japan has experienced pronounced population aging, and now has the highest proportion of elderly adults in the world. Yet few projections of Japan's future demography go beyond estimating population by age and sex to forecast the complex evolution of the health and functioning of the future elderly. This study estimates a new state-transition microsimulation model - the Japanese Future Elderly Model (FEM) - for Japan. We use the model to forecast disability and health for Japan's future elderly. Our simulation suggests that by 2040, over 27 percent of Japan's elderly will exhibit 3 or more limitations in IADLs and social functioning; almost one in 4 will experience difficulties with 3 or more ADLs; and approximately one in 5 will suffer limitations in cognitive or intellectual functioning. Since the majority of the increase in disability arises from the aging of the Japanese population, prevention efforts that reduce age-specific morbidity can help reduce the burden of disability but may have only a limited impact on reducing the overall prevalence of disability among Japanese elderly. While both age and morbidity contribute to a predicted increase in disability burden among elderly Japanese in the future, our simulation results suggest that the impact of population aging exceeds the effect of age-specific morbidity on increasing disability in Japan's future.

Estimating the Co-Development of Cognitive Decline and Physical Mobility Limitations in Older U.S. Adults

This study examines the co-development of cognitive and physical function in older Americans using an age-heterogeneous sample drawn from the Health and Retirement Study (1998–2008). We used multiple-group parallel process latent growth models to estimate the association between trajectories of cognitive function as measured by immediate word recall scores, and limitations in physical function as measured as an index of functional mobility limitations. Nested model fit testing was used to assess model fit for the separate trajectories followed by estimation of an unconditional parallel process model. Controls for demographic characteristics, socioeconomic status, and chronic health conditions were added to the best-fitting parallel process model. Pattern mixture models were used to assess the sensitivity of the parameter estimates to the effect of selective attrition. Results indicated that favorable cognitive health and mobility at initial measurement were associated with faster decline in the alternate functional domain. The cross-process associations remained significant when we adjusted estimates for the influence of covariates and selective attrition. Demographic and socioeconomic characteristics were consistently associated with initial cognitive and physical health but had few relations with change in these measures.

Why do older people change their ratings of childhood health?

A growing number of studies in life course epidemiology and biodemography make use of a retrospective question tapping self-rated childhood health to assess overall physical health status. Analyzing repeated measures of self-rated childhood health from the Health and Retirement Study (HRS), this study examines several possible explanations for why respondents might change their ratings of childhood health. Results reveal that nearly one-half of the sample revised their rating of childhood health during the 10-year observation period. Whites and relatively advantaged older adults-those with more socioeconomic resources and better memory-were less likely to revise their rating of childhood health, while those who experienced multiple childhood health problems were more likely to revise their childhood health rating, either positively or negatively. Changes in current self-rated health and several incident physical health problems were also related to the revision of one's rating of childhood health, while the development of psychological disorders was associated with more negative revised ratings. We then illustrate the impact that these changes may have on an adult outcomes: namely, depressive symptoms. Whereas adult ratings of childhood health are likely to change over time, we recommend their use only if adjusting for factors associated with these changes, such as memory, psychological disorder, adult self-rated health, and socioeconomic resources.

History of alcohol use disorders and risk of severe cognitive impairment: a 19-year prospective cohort study

OBJECTIVE

To assess the effects of a history of alcohol use disorders (AUDs) on risk of severe cognitive and memory impairment in later life.

METHODS

We studied the association between history of AUDs and the onset of severe cognitive and memory impairment in 6,542 middle-aged adults born 1931 through 1941 who participated in the Health and Retirement Study, a prospective nationally representative U.S. cohort. Participants were assessed at 1992 baseline and follow-up cognitive assessments were conducted biannually from 1996 through 2010. History of AUDs was identified using the three-item modified CAGE questionnaire. Cognitive outcomes were assessed using the 35-item modified Telephone Interview for Cognitive Status at last follow-up with incident severe cognitive impairment defined as a score ≤ 8, and incident severe memory impairment defined as a score ≤ 1 on a 20-item memory subscale.

RESULTS

During up to 19 years of follow-up (mean: 16.7 years, standard deviation: 3.0, range: 3.5-19.1 years), 90 participants experienced severe cognitive impairment and 74 participants experienced severe memory impairment. History of AUDs more than doubled the odds of severe memory impairment (odds ratio [OR] = 2.21, 95% confidence interval [CI] = 1.27-3.85, t = 2.88, df = 52, p = 0.01). The association with severe cognitive impairment was statistically non-significant but in the same direction (OR = 1.80, 95% CI = 0.97-3.33, t = 1.92, df = 52, p = 0.06).

CONCLUSION

Middle-aged adults with a history of AUDs have increased odds of developing severe memory impairment later in life. These results reinforce the need to consider the relationship between alcohol consumption and cognition from a multifactorial lifespan perspective.

New strategies for biosample collection in population-based social research

This paper aims to increase understanding of the methodological issues involved in adding biomeasures to social research by investigating the potential of an event-triggered, self-collection technique for monitoring biological response to social events. We use data from the Relationship Dynamics and Social Life (RDSL) study, which collected saliva samples triggered by a life event important to the aims of the study - the end of a romantic relationship. Our investigation found little evidence that those who complied in the biosample collection were different from those who did not comply in terms of key study measures and sociodemographic characteristics. We also found no evidence that the biosample collection had adverse consequences for subsequent panel participation. We did find that prior cooperation in the study was an important predictor of biosample cooperation, which is important information in developing biosample collection strategies. As demand for biological samples directly linked to social data continues to grow, effective low-cost collection methods will become increasingly valuable. The evidence here indicates that self-collected biosamples may offer tremendous potential to meet this demand.

Consideration of Age-Related Changes in Behavior Trends in Older Adults in Assessing Risks of Environmental Exposures

Objectives: To explore age-related behavior differences between older and younger adults, and to review how older adult activity patterns are considered in evaluating the potential risk of exposure to environmental pollutants. Methods: Activity pattern data and their use in risk assessments were analyzed using the U.S. EPA Exposure Factors Handbook (EFH), U.S. EPA Consolidated Human Activity Pattern Database (CHAD), and peer-reviewed literature describing human health risk assessments. Results: The characterization by age of some factors likely to impact older adults’ exposures remains limited. We demonstrate that age-related behavior trends vary between younger and older adults, and these differences are rarely explicitly considered in environmental health risk assessment for older adults. Discussion: Incorporating older adult exposure factors into risk assessments may be challenging because of data gaps and difficulty in defining and appropriately binning older adults. Additional data related to older adult exposure factors are warranted for evaluating risk among this susceptible population.

Survey results show that adults are willing to pay higher insurance premiums for generous coverage of specialty drugs

Generous coverage of specialty drugs for cancer and other diseases may be valuable not only for sick patients currently using these drugs, but also for healthy people who recognize the potential need for them in the future. This study estimated how healthy people value insurance coverage of specialty drugs, defined as high-cost drugs that treat cancer and other serious health conditions like multiple sclerosis, by quantifying willingness to pay via a survey. US adults were estimated to be willing to pay an extra $12.94 on average in insurance premiums per month for generous specialty-drug coverage--in effect, $2.58 for every dollar in out-of-pocket costs that they would expect to pay with a less generous insurance plan. Given the value that people assign to generous coverage of specialty drugs, having high cost sharing on these drugs seemingly runs contrary to what people value in their health insurance.

Racial and ethnic differences in hypertension risk: new diagnoses after age 50

OBJECTIVES

Our study examines the differences in estimated risk of developing hypertension in Whites, Blacks, and Mexican-Americans aged > or = 50 for a period of 11 years.

DESIGN, SETTING, AND PARTICIPANTS

Data came from 9,259 respondents who reported being hypertension-free at the baseline in the Health and Retirement Study (HRS) with up to five time intervals (1998-2006). Discrete-time survival models were used to analyze ethnic variations in the probability of developing hypertension.

MAIN OUTCOME MEASURE

Estimated odds of developing hypertension.

RESULTS

The risk of newly diagnosed hypertension increased between 1995 and 2006 for HRS participants aged > or = 50. After adjusting for demographic and health status, the probability of incident hypertension among Black Americans was .10 during the period of 1995/96-1998, which increased steadily to .17 in 2004-2006, with cumulative incidence over the 11-year period at 51%. In contrast, among White Americans the risk was .07 during 1995/96-1998 and .13 in 2004-2006, with cumulative incidence at 43%. For Mexican-Americans, the probability also increased from .08 during 1995/ 96-1998 to .14 during 2004-2006, with cumulative incidence at 42%.

CONCLUSIONS

Relative to White and Mexican-Americans, Black Americans had an elevated risk of incident hypertension throughout the 11-year period of observation. These variations persisted even when differences in health behaviors, socioeconomic status, demographic, and time-varying health characteristics were accounted for.