Pilot Study for Geospatial Analysis of Neighborhood Environmental Stress in Relation to Biological Markers of Cardiovascular Health and Health Behaviors in Women

National Heart, Lung, And Blood Institute

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Abstract

We used epidemiologic data from the 1999-2002 National Health and Nutrition Examination Surveys to assess the relationship between neighborhood deprivation index (NDI) and log-transformed leukocyte telomere length (LTL) to begin to assess the biological mechanisms by which deprived neighborhood conditions may lead to poor cardiovascular (CV) health. We used multilevel modeling to control for census tract level clustering. We constructed models using tertiles of NDI (ref = low NDI). NDI was calculated using census tract level socioeconomic indicators from the 2000 U.S. Census. The sample (n = 5,106 adults) was 49.8% female and consisted of 82.9% non-Hispanic whites, 9.4% non-Hispanic blacks, and 7.6% Mexican Americans. Mean age was 45.8 years. Residents of neighborhoods with high NDI were younger, non-white, and had lower socioeconomic levels (all p < 0.0001). Neighborhood deprivation was inversely associated with LTL among individuals living in neighborhoods with medium NDI and high NDI as compared to low NDI. Among men, both medium and high NDI were associated with shorter LTL as compared to low NDI. Among women, only medium NDI was associated with shorter LTL as compared to low NDI. After controlling for individual characteristics, including individual-level socioeconomic status, increasing neighborhood socioeconomic deprivation is associated with shorter LTL among a nationally representative sample of adults in the United States. Our findings suggest that telomere shortening may be a biologic mechanism through which neighborhood deprivation results in poor CV health outcomes. To characterize immune cells that may be impacted by the chronic stressors of neighborhood environment, we combined a variety of flow cytometry antibodies in one staining protocol to characterize granulocyte, lymphocyte, and monocyte sub-populations and their platelet aggregates with low blood volumes (500 microliters of whole blood). This flow cytometry panel enabled a more extensive comparison than what is possible with a complete blood count and differential. While establishing the low-volume flow panel with blood samples from blood bank donors, we found that the immune cell populations differed when comparing African-American and Caucasian blood donors. We found previously reported differences in granulocyte and lymphocyte counts between the racial/ethnic groups, supporting the validity of our panel. We also detected differences that had not been previously reported, like differences in the monocyte subset distribution, natural killer (NK) cell subsets, NKT cells, and platelet-monocyte subset aggregates. Identifying racial/ethnic differences in monocyte and NK subtypes are important preliminary data as 1) monocytes are crucial to atherogenesis; 2) NK cells, in particular, can be altered by social stress, and 3) monocyte-platelet aggregates have been highlighted to be of significance for myocardial infarction risk among women. These findings have led us to focus on monocyte and NK cell populations as immune cells of interest and their potential involvement in linking chronic stress from adverse environmental conditions to CV risk. Given the clear health disparities laid bare by the COVID-19 pandemic, we highlighted the critical need for interdisciplinary studies that combine both epidemiologic methods with translational science, including phenotyping of immune system function. While numerous challenges exist in this type of work, these studies could identify key biologic pathways that are most impacted by adverse psychosocial and environmental conditions and serve as targets for intervention. Studies that examine the biologic impact of adversity hold promise for creating tailored interventions for at-risk, underserved populations. Finally, we sought to evaluate relationships between neighborhood social environment and cardiovascular health markers. First, we examined the relationship between neighborhood socioeconomic disadvantage and depression using data from the National Health and Nutrition Examination Survey. We found that those living in neighborhoods with higher socioeconomic disadvantage was associated with greater depression severity and a greater likelihood of clinically relevant depression. However, this association was attenuated by individual-level socioeconomic status. We also examined the associations between perceived neighborhood environment and sleep duration and quality with physical activity and psychosocial stressors as potential mediators in the Jackson Heart Study cohort. We found that perceived neighborhood violence, problems, and social cohesion were associated with sleep duration, and these associations were mediated by physical activity, lifetime discrimination, perceived stress and depressive symptoms. These findings support further work to uncover biologic mechanisms by which adverse neighborhood conditions promote cardiovascular risk.