Objectives African Americans (AA) experience higher levels of stress related to living in racially segregated and poor neighborhoods. However, little is known about the associations between perceived neighborhood environments and cellular aging among adult AA. This study examined whether perceived neighborhood environments were associated with telomere length (TL) in AA after adjustment for individual-level risk factors. Methods The analysis included 158 women and 75 men AA aged 30 to 55 years from the Morehouse School of Medicine Study. Relative TL (T/S ratio) was measured from peripheral blood leukocytes using quantitative real-time polymerase chain reaction. Multivariable linear regression models were used to examine the associations of perceived neighborhood social cohesion, problems, and overall unfavorable perceptions with log-TL. Results Women had significantly longer TL than men (0.59 vs. 0.54, p=0.012). After controlling for sociodemographic, and biomedical and psychosocial factors, a 1-SD increase in perceived neighborhood problems was associated with 7.3% shorter TL in women (Mean Difference [MD] = −0.073 (Standard Error =0.03), p = 0.012). Overall unfavorable perception of neighborhood was also associated with 5.9% shorter TL among women (MD =  – 0.059(0.03), p= 0.023). Better perceived social cohesion were associated with 2.4 % longer TL, but did not reach statistical significance (MD = 0.024(0.02), p=0.218). No association was observed between perceived neighborhood environments and TL in men. Conclusions Our findings suggest that perceived neighborhood environments may be predictive of cellular aging in AA women even after accounting for individual-level risk factors. Additional research with a larger sample is needed to determine whether perceived neighborhood environments are causally related to TL.

ObjectiveBoth environmental and genetic factors play important roles in the development of metabolic syndrome (MetS). Studies about its associated factors and genetic contribution in African Americans (AA) are sparse. Our aim was to report the prevalence, associated factors and heritability estimates of MetS and its components in AA men and women.Participants and settingData of this cross-sectional study come from a large community-based Jackson Heart Study (JHS). We analysed a total of 5227 participants, of whom 1636 from 281 families were part of a family study subset of JHS.MethodsParticipants were classified as having MetS according to the Adult Treatment Panel III criteria. Multiple logistic regression analysis was performed to isolate independently associated factors of MetS (n=5227). Heritability was estimated from the family study subset using variance component methods (n=1636).ResultsAbout 27% of men and 40% of women had MetS. For men, associated factors with having MetS were older age, lower physical activity, higher body mass index, and higher homocysteine and adiponectin levels (p<0.05 for all). For women, in addition to all these, lower education, current smoking and higher stress were also significant (p<0.05 for all). After adjusting for covariates, the heritability of MetS was 32% (p<0.001). Heritability ranged from 14 to 45% among its individual components. Relatively higher heritability was estimated for waist circumference (45%), high density lipoprotein-cholesterol (43%) and triglycerides (42%). Heritability of systolic blood pressure (BP), diastolic BP and fasting blood glucose was 16%, 15% and 14%, respectively.ConclusionsStress and low education were associated with having MetS in AA women, but not in men. Higher heritability estimates for lipids and waist circumference support the hypothesis of lipid metabolism playing a central role in the development of MetS and encourage additional efforts to identify the underlying susceptibility genes for this syndrome in AA.

BackgroundCircadian rhythms regulate key biological processes and the dysregulation of the intrinsic clock mechanism affects sleep patterns and obesity onset. The CLOCK (circadian locomotor output cycles protein kaput) gene encodes a core transcription factor of the molecular circadian clock influencing diverse metabolic pathways, including glucose and lipid homeostasis. The primary objective of this study was to evaluate the associations between CLOCK single nucleotide polymorphisms (SNPs) and body mass index (BMI). We also evaluated the association of SNPs with BMI related factors such as sleep duration and quality, adiponectin and leptin, in 2962 participants (1116 men and 1810 women) from the Jackson Heart Study. Genotype data for the selected 23 CLOCK gene SNPS was obtained by imputation with IMPUTE2 software and reference phase data from the 1000 genome project. Genetic analyses were conducted with PLINKResultsWe found a significant association between the CLOCK SNP rs2070062 and sleep duration, participants carriers of the T allele showed significantly shorter sleep duration compared to non-carriers after the adjustment for individual proportions of European ancestry (PEA), socio economic status (SES), body mass index (BMI), alcohol consumption and smoking status that reach the significance threshold after multiple testing correction. In addition, we found nominal associations of the CLOCK SNP rs6853192 with longer sleep duration and the rs6820823, rs3792603 and rs11726609 with BMI. However, these associations did not reach the significance threshold after correction for multiple testing.ConclusionsIn this work, CLOCK gene variants were associated with sleep duration and BMI suggesting that the effects of these polymorphisms on circadian rhythmicity may affect sleep duration and body weight regulation in Africans Americans.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-017-0522-6) contains supplementary material, which is available to authorized users.