The Association of Neighborhood Gene-Environment Susceptibility with Cortisol and Blood Pressure in African-American Adults.

BACKGROUND: African-American adults are disproportionately affected by stress-related chronic conditions like high blood pressure (BP), and both environmental stress and genetic risk may play a role in its development. PURPOSE: This study tested whether the dual risk of low neighborhood socioeconomic status (SES) and glucocorticoid genetic sensitivity interacted to predict waking cortisol and BP. METHODS: Cross-sectional waking cortisol and BP were collected from 208 African-American adults who were participating in a follow-up visit as part of the Positive Action for Today's Health trial. Three single-nucleotide polymorphisms were genotyped, salivary cortisol samples were collected, and neighborhood SES was calculated using 2010 Census data. RESULTS: The sample was mostly female (65 %), with weight classified as overweight or obese (M BMI = 32.74, SD = 8.88) and a mean age of 55.64 (SD = 15.21). The gene-by-neighborhood SES interaction predicted cortisol (B = 0.235, p = .001, r (2) = .036), but not BP. For adults with high genetic sensitivity, waking cortisol was lower with lower SES but higher with higher SES (B = 0.87). Lower neighborhood SES was also related to higher systolic BP (B = -0.794, p = .028). CONCLUSIONS: Findings demonstrated an interaction whereby African-American adults with high genetic sensitivity had high levels of waking cortisol with higher neighborhood SES, and low levels with lower neighborhood SES. This moderation effect is consistent with a differential susceptibility gene-environment pattern, rather than a dual-risk pattern. These findings contribute to a growing body of evidence that demonstrates the importance of investigating complex gene-environment relations in order to better understand stress-related health disparities.