Date Published: April 22, 2019
Publisher: Public Library of Science
Author(s): Melissa Lamar, Ramon A. Durazo-Arvizu, Shruti Sachdeva, Amber Pirzada, Krista M. Perreira, Tatjana Rundek, Linda C. Gallo, Ellen Grober, Charles DeCarli, Richard B. Lipton, Wassim Tarraf, Hector M. González, Martha L. Daviglus, Dana C. Crawford.
Hispanics/Latinos have some of the highest prevalence rates for cardiovascular disease risk factors, but stark differences exist by self-reported background. Cardiovascular disease risk factors negatively impact cognition in Hispanics/Latinos; less is known about these relationships by Hispanic/Latino backgrounds. We investigated cognitive associations with cardiovascular disease risk factor burden in a diverse cohort, the Hispanic Community Health Study/Study of Latinos.
Baseline data from this observational study of cardiovascular disease and its antecedents was collected from 2008–2011. We included 7,121 participants 45–74 years old from Central American, Cuban, Dominican, Mexican, Puerto Rican, or South American backgrounds. Dichotomous indicators for hypertension, diabetes, hypercholesterolemia, obesity, and smoking were evaluated and totaled, with participants grouped by lowest (0–2), middle (3) or highest (4–5) burden. Cognitive testing included the Brief Spanish English Verbal Learning Test, letter fluency, and digit symbol substitution.
In separate fully-adjusted linear regression models, lower fluency and digit symbol substitution performance were restricted to the highest compared to the lowest burden group; whereas the middle burden group displayed impaired memory performance compared to the lowest burden group (p-values≤0.05). Background interacted with burden for learning and memory performance. That is, the association of burden level (i.e., lowest, middle, or highest) with cognitive performance was modified by background (e.g., Mexicans vs Cuban).
Hispanics/Latinos with higher levels of cardiovascular disease risk factor burden displayed lower levels of cognitive performance, with learning and memory performance modified by background.
Approximately 12% of older Hispanics/Latinos are diagnosed with Alzheimer’s disease (AD). While this is the highest proportion among US ethnic groups , differences in incidence rates of dementia including AD have also been reported by Hispanic/Latino background . For example, Hispanics/Latinos from a Mexican background have a reported 0.8% annual incidence of dementia while Hispanics/Latinos from a Caribbean background have a 2.3%-5.3% annual incidence of dementia . These distinctions may be due, in part, to distinctions in cumulative cardiovascular disease risk factor (CVD-RF) burden including the presence of the major and readily measurable risk factors of hypertension, diabetes, hypercholesterolemia, obesity, and smoking [4–6]. In fact, studies comparing racially or ethnically diverse populations consistently report that higher cumulative CVD-RF burden is associated with lower cognitive performance [7–10]. Furthermore, it is well-known that baseline CVD-RF burden increases the risk of later cognitive impairment and dementia in non-Hispanic Whites and Blacks [11–13] with increasing support in Hispanics/Latinos [7, 14]. Less work has enumerated the cognitive correlates of cumulative CVD-RF burden in Hispanics/Latinos by self-reported background despite stark differences in rates of CVD-RF burden.
The HCHS/SOL is a population-based, probability sample prospective cohort study of 16,415 Hispanics/Latinos aged 18–74 years from Chicago, IL, Miami, FL, Bronx, NY, and San Diego, CA . In 2008–2011 the HCHS/SOL sampled households in these four US cities using a stratified 2-stage area probability sample design. This design oversampled certain areas to increase the likelihood that a selected address would yield a Hispanic/Latino household, and oversampled those ages 45–74 years to facilitate examination of target outcomes . The baseline examination (2008–2011)  was conducted by trained professionals in a single visit at each city’s designated study site and consisted of biological, behavioral and socio-demographic assessments as well as a review and scanning of all prescription medications . Cognitive testing was also conducted during this baseline examination, but only for individuals 45 years and older. The cohort includes participants who self-identified as having a Central American, Cuban, Dominican, Mexican, Puerto Rican, or South American background and oversampled persons ages 45–74. This study was approved by the Institutional Review Boards at each site, with the University of Illinois at Chicago Office for the Protection of Research Subjects IRB #3 providing the approval for our specific study. All participants gave written informed consent.
The lowest-burden group had 2,759 participants, the middle-burden group had 2,499 participants, and the highest-burden group had 1,827 participants. Table 1 shows the prevalence rates of individual CVD-RFs by burden group. Descriptive characteristics were compared across the three CVD-RF burden groups (Table 2). Groups differed on age (i.e., the lowest-burden group was youngest), education (e.g., the highest-burden group had disproportionately fewer individuals with more than a high school education), health insurance (i.e., the highest-burden group had a higher percentage of insured individuals than the lowest-burden group), income (i.e., the highest-burden group had fewer individuals making more than $50,000 than the lowest-burden group), and SIS (i.e., the highest-burden group scored the lowest). Hispanic/Latino background also differed, however, no other characteristics were significantly different across CVD-RF burden groups (Table 2). Thus, we included age, education, health insurance status, income, Hispanic/Latino background, and physical activity as covariates in fully-adjusted models. We also added terms for sex and language preference during testing given that these variables are known to be associated not only with our predictor variable but also our outcome variables.
We identified associations between higher CVD-RF burden and lower cognition in Hispanics/Latinos generally and by self-reported background specifically. Hispanics/Latinos at the highest levels of CVD-RF burden performed worse than Hispanics/Latinos at the lowest levels of CVD-RF burden on a task of mental processing speed and a measure of fluency in a fully-adjusted models. Hispanic/Latino background modified the effect of burden on learning and post-interference recall with participants from a Cuban, Puerto Rican, or Dominican background with the lowest, middle, and/or highest CVD-RF burden showing reduced cognitive functioning when compared to their Mexican counterparts in the identical CVD-RF burden groups. Thus, it is important to consider not only CVD-RF burden when evaluating cognitive functioning in Hispanics/Latinos but also self-reported background, particularly when using normative data that may or may not represent that individual’s background, let alone ethnicity.