M. Kristen Peek

The association between emotional well-being and the incidence of stroke in older adults

Objective Individuals with high levels of depressive symptoms have an increased risk of many illnesses, including stroke. Measures of depressive symptoms include questions about the presence of negative affect, such as sadness, as well as the absence of positive affect, such as happiness and optimism. We assessed whether positive or negative affect, or both, predicted risk of stroke. Methods Data were from a 6-year prospective cohort study of a population-based sample of 2478 older whites and blacks from five counties in North Carolina who reported no history of stroke at the baseline interview. Baseline, in-person interviews were conducted to gather information on sociodemographic, psychosocial, and health-related characteristics of subjects. Thereafter interviews were conducted annually for 6 years. Results Increasing scores on the modified version of the Center for Epidemiological Studies Depression Scale (CES-D) were significantly associated with stroke incidence for the overall sample (relative risk [RR] = 1.04 for each one-point increase, 95% confidence interval [CI] = 1.01–1.09) over the 6-year follow-up period after adjusting for sociodemographic characteristics, blood pressure, body mass index, smoking status, and selected chronic diseases. Positive affect score demonstrated a strong inverse association with stroke incidence (RR = 0.74, 95% CI = 0.62–0.88). Conclusions Increasing scores on the modified CES-D are related to an increased risk of stroke, whereas high levels of positive affect seem to protect against stroke in older adults.

Neighborhood context and self-rated health in older Mexican Americans

PURPOSE To determine whether neighborhood characteristics are associated with self-rated health in older Mexican Americans. METHODS Epidemiologic data on 3050 older Mexican Americans residing in the southwestern United States during 1993 and 1994 were merged with 1990 US Census data. All subjects were matched to one of 210 census tracts (neighborhoods). Multilevel ordinal logit models were used to examine relationships between self-rated health and individual- and neighborhood-level variables. RESULTS After adjusting for individual characteristics, older Mexican Americans were more likely to rate their health poorer if they lived in neighborhoods that were economically disadvantaged, less populated by other Hispanics, or located within 50 miles of the US-Mexico border. In addition, residence in a border community moderated the relationship between self-rated health and neighborhood economic disadvantage. The effect of neighborhood economic disadvantage on poorer self-rated health was two to three times stronger for subjects living near the border region than subjects living further away from the border. CONCLUSIONS This study demonstrates the importance of considering several dimensions of neighborhood context, especially for Mexican Americans. Residence in a border community and neighborhood economic disadvantage were important predictors of poorer self-rated health status. In addition, older Mexican Americans experience a health benefit from living in neighborhoods populated with other Hispanics.

Frailty in Older Mexican Americans

Objectives: To identify sociodemographic characteristics and health performance variables associated with frailty in older Mexican Americans.

Cognitive status, muscle strength, and subsequent disability in older Mexican Americans

Objectives: To examine the association between Mini‐Mental State Examination (MMSE) score and subsequent muscle strength (measured using handgrip strength) and to test the hypothesis that muscle strength will mediate any association between impaired cognition and incident activity of daily living (ADL) disability over a 7‐year period in elderly Mexican Americans who were initially not disabled.

Allostatic Load Among Non-Hispanic Whites, Non-Hispanic Blacks, and People of Mexican Origin: Effects of Ethnicity, Nativity, and Acculturation

OBJECTIVES We investigated ethnic differences in allostatic load in a population-based sample of adults living in Texas City, TX, and assessed the effects of nativity and acculturation status on allostatic load among people of Mexican origin. METHODS We used logistic regression models to examine ethnic variations in allostatic load scores among non-Hispanic Whites, non-Hispanic Blacks, and people of Mexican origin. We also examined associations between measures of acculturation and allostatic load scores among people of Mexican origin only. RESULTS Foreign-born Mexicans were the least likely group to score in the higher allostatic load categories. Among individuals of Mexican origin, US-born Mexican Americans had higher allostatic load scores than foreign-born Mexicans, and acculturation measures did not account for the difference. CONCLUSIONS Our findings expand on recent research from the National Health and Nutrition Examination Survey with respect to ethnicity and allostatic load. Our results are consistent with the healthy immigrant hypothesis (i.e., newer immigrants are healthier) and the acculturation hypothesis, according to which the longer Mexican immigrants reside in the United States, the greater their likelihood of potentially losing culture-related health-protective effects.

Plasma Cytokine Levels in a Population-Based Study: Relation to Age and Ethnicity

BACKGROUND Aging is one factor believed to contribute to processes that underlie chronic low-grade inflammation in older adults. Moreover, more recent studies have suggested that cytokine levels are influenced by ethnicity. METHODS In this study, we determined plasma cytokine profiles in a population-based sample (n = 1,411; aged 25-91 years) to determine the relationship between circulating cytokine levels, aging, and ethnicity. We measured interleukin-1 receptor antagonist (IL-1ra), interleukin (IL)-6, -10, C-reactive protein (CRP), and tumor necrosis factor-receptor 1 (TNF-r1). RESULTS IL-6 and TNF-r1 significantly increased with age, whereas IL-1ra, IL-10, and CRP did not significantly increase with age. After adjusting for age, non-Hispanic whites had significantly higher levels of IL-1ra than Mexican Americans, whereas non-Hispanic blacks had significantly higher levels of IL-6 and CRP than Mexican Americans as well as non-Hispanic whites. CRP levels in non-Hispanic blacks were no longer significantly higher after adjusting for body mass index (BMI), indicating that BMI is an important predictor of this inflammatory marker. CONCLUSIONS These results demonstrate that cytokine levels are influenced by both age and ethnicity. Furthermore, these results show that inflammatory profiles for Mexican Americans are lower than non-Hispanic whites and non-Hispanic blacks.

Neighborhood Context and Cognitive Decline in Older Mexican Americans: Results From the Hispanic Established Populations for Epidemiologic Studies of the Elderly

In previous research on cognitive decline among older adults, investigators have not considered the potential impact of contextual variables, such as neighborhood-level conditions. In the present investigation, the authors examined the association between 2 neighborhood-context variables-socioeconomic status and percentage of Mexican-American residents-and individual-level cognitive function over a 5-year follow-up period (1993-1998). Data were obtained from the Hispanic Established Populations for Epidemiologic Studies of the Elderly, a longitudinal study of community-dwelling older Mexican Americans (n = 3,050) residing in the southwestern United States. Individual records were linked with 1990 US Census tract data, which provided information on neighborhood characteristics. Hierarchical linear growth-curve models and hierarchical logistic models were used to examine relations between individual- and neighborhood-level variables and the rate and incidence of cognitive decline. Results showed that baseline cognitive function and rates of cognitive decline varied significantly across US Census tracts. Respondents living in economically disadvantaged neighborhoods experienced significantly faster rates of cognitive decline than those in more advantaged neighborhoods. Odds of incident cognitive decline decreased as a function of neighborhood percentage of Mexican-American residents and increased with neighborhood economic disadvantage. The authors conclude that neighborhood context is associated with late-life cognitive function and that the effects are independent of individual-level risk factors.

Census Disability Rates Among Older People by Race/Ethnicity and Type of Hispanic Origin

Over the last 20 years or so there has been mounting evidence that Hispanics as a group as well as Hispanic populations from individual countries are characterized by relatively favorable mortality profiles despite generally disadvantaged socioeconomic profiles (Markides and Coreil, 1986; Markides, Rudkin, Angel, and Espino, 1977; Markides and Eschbach, 2005; Franzini, Ribble, and Keddie, 2001; Palloni and Morenoff, 2001; Sorlie, Rogot, and Johnson, 1993). The advantage shown in vital statistics is greatest, though such data likely underestimate mortality rates because of misclassification of Hispanic ethnicity on death certificates (Sorlie, Rogot, and Johnson, 1992). A somewhat lower advantage is shown with data from large population surveys linked to the National Death Index where misclassification of ethnicity on death certificates is not an issue, though completeness of record linkage may be (Hummer, Benjamins, and Rogers, 2004). The advantage is further reduced—but remains substantial—among older people when data are taken from the Social Security Administration’s Master Beneficiary record and the NUMIDENT file (Elo et al., 2004). While there is a lively debate about the source of a Hispanic mortality advantage that persists into old age (Abraido-Lanza, Dohrenwend, Ng-Mak, and Turner, 1999; Franzini et al., 2001; Markides and Eschbach, 2005; Palloni and Arias, 2004), it is generally accepted that the advantage is real and is also present at older ages. The data appear to show that the advantage is greatest among immigrants from Mexico, as well as among immigrant members of the residual category that the U.S. statistical system labels “other Hispanics” (Palloni and Arias, 2004). “Other Hispanics” are a diverse group that includes Dominicans, Spaniards; Central and South Americans, some Mexicans, Puerto Ricans, and Cubans who do not disclose a specific national origin; and persons of mixed ancestry. If indeed Hispanic populations experience low mortality rates—including at older ages—one would expect that they would also enjoy other health advantages; for example, in self-ratings of health. However, what may be most paradoxical about the Hispanic paradox is that this expectation is not what the data show. While

Examining the disablement process among older Mexican American adults

The Disablement Process model (Verbrugge and Jette, Social Science & Medicine 38 (1994) 1) describes a pathway leading from pathology to impairment to functional limitations, and, ultimately to disability. Components of this model have been examined among older White adults; however, very little research has examined the disablement process among older adults of other ethnic groups. Our goal in this research is to evaluate the Disablement Process model using Activities of Daily Living (ADL) disability as the outcome among a representative group of older Mexican American adults in the Southwestern United States. Respondents are from two waves of the Hispanic Established Populations Epidemiologic Study of the Elderly (EPESE) (n=2439). Structural equation models (LISREL 8.30) are utilized to examine the Disablement Process model. We also investigate aspects of the original model that have potentially important effects on the process of becoming disabled, such as cognitive impairment and perceived emotional support. Findings from structural equation models suggest that the main pathway from pathology to ADL disability is through functional limitations among older Mexican Americans. Risk factors, especially age and gender, have significant indirect effects on ADL disability. The main pathway in the Disablement Process model receives preliminary support among older Mexican Americans. We discuss implications of this model for future research.

Networks in Later Life: An Examination of Race Differences in Social Support Networks

Although there has been considerable interest in the effects of social support networks on various health outcomes for older adults, there has been little research directed toward the predictors of networks. In this study, we examine race differences in the determinants of social support network characteristics (size, frequency of interaction with network members, proportion of kin, and amount of support received and given to network members) using data from an older community sample drawn from the North Carolina site of the Established Populations for Epidemiologic Studies of the Elderly (EPESE) focusing on adults sixty-five and older (n = 4124). This research focuses on the extent to which race differences in network dimensions are present and whether these variations can be attributed to varying social structural positions held by African Americans and Whites. The results indicate that several race differences persist even when controlling for social structural variables. The structural argument and future implications are discussed.