Multilevel Mediators on the Associations of Neighborhood Social Environmental Factors and Severity of Metabolic Syndrome: The Jackson Heart Study

Abstract

Background: Neighborhood characteristics serve as risk factors for metabolic syndrome (MetS). However, the intermediary factors linking this relationship remain understudied. Thus, we investigated the sex-specific mediating role of C-reactive protein, physical activity (PA), and perceived stress in the associations of perceived neighborhood social environment (PNSE) with MetS severity among Black adults.

Methods and results: This cross-sectional study included 3185 adults (64% women) from exam 1 (2000-2004) of the Jackson Heart Study. MetS severity Z scores were calculated based on the Adult Treatment Panel III criteria formula. PNSE included neighborhood violence, problems, and social cohesion. Men and women were analyzed separately. A bootstrap resampling technique with 95% bias-corrected CI (95% BC CI) was used to evaluate whether C-reactive protein, PA, and perceived stress mediated the association between each PNSE and MetS severity, adjusting for covariates. All PNSE factors were directly related to MetS severity in women but not in men. In women, neighborhood problems were indirectly associated with MetS severity mediated through PA (β=0.02 [95% BC CI, 0.00-0.05]). In men, neighborhood violence, problems, and social cohesion were indirectly associated with MetS severity mediated through PA (β=0.05 [95% BC CI, 0.01-0.10]; β=0.03 [95% BC CI, 0.00-0.06]; and β=-0.04 [95% BC CI, -0.09 to -0.01], respectively). Neither C-reactive protein nor perceived stress mediated such associations in either women or men.

Conclusions: All PNSEs (violence, problems, and social cohesion) were directly related to MetS severity in women only. PA mediated the relationship between each PNSE and MetS in a sex-specific manner. Efforts focusing on local conditions are needed to better understand why such disparities exist for at-risk minoritized groups.

Keywords: C‐reactive protein; mediation analysis; metabolic syndrome; neighborhood; physical activity.

Figure 1. Mediation model and hypothesis.

The indirect effect (paths a × b) describes the relationships between each neighborhood social environment factor and MetS severity, mediated separately through inflammatory biomarkers, physical activity, and perceived stress among Jackson Heart Study participants, controlling for covariates. The direct effect (path c′) describes the relationships between each neighborhood social environment factor and MetS severity while controlling for mediators in the model along with other covariates. Neighborhood social environment factors include neighborhood violence, problems, and social cohesion. MetS indicates metabolic syndrome.

Figure 2. Indirect and direct relationships between neighborhood problems and MetS severity among Black women.

The indirect relationship is mediated through total physical activity. *95% CI. +95% bias‐corrected CI. MetS indicates metabolic syndrome.