Gene-Obesogenic Environment Interactions on Body Mass Indices for Older Black and White Men and Women from the Health and Retirement Study

BACKGROUND: Gene-obesogenic environment interactions influence body mass index (BMI) across the life-course; however, limited research examines how these interactions may differ by race and sex. METHODS: Utilizing mixed-effects models, we examined the interaction effects of a polygenic risk score (PGS) generated from BMI-associated single nucleotide polymorphisms, and environmental factors, including age, physical activity, alcohol intake and childhood socioeconomic status on measured longitudinal BMI from the Health and Retirement Study (HRS). HRS is a population representative survey of older adults in the United States. This study used a sub-sample of genotyped Black (N=1,796) and White (N=4,925) men and women (50–70 years) with measured BMI. RESULTS: Higher PGS was associated with higher BMI. The association between PGS and BMI weakened as individuals aged among White men (P(interaction)=0.0383) and White women (P(interaction)=0.0514). The mean BMI difference between the 90(th) and 10(th) PGS percentile was 4.25 kg/m(2) among 50-year old White men, and 3.11 kg/m(2) among the 70-year old’s, i.e. a 1.14 kg/m(2) (95%CI: −0.27, 2.82) difference. The difference among 50- and 70-year old White women was 1.34 kg/m(2) (95%CI: 0.09, 2.60). Additionally, the protection effect of physical activity was stronger among White women with higher PGS (P(interaction)=0.0546). Vigorous physical activity (compared to never) was associated with 1.66 kg/m(2) (95%CI: 1.06, 2.29) lower mean BMI among those in the 90(th) PGS percentile, compared to 0.83 kg/m(2) (95%CI: 0.37, 1.29) lower among those in the 10(th) PGS percentile. Interactions were also observed between both PGS and alcohol intake among White men (P(interaction)=0.0034) and women (P(interaction)=0.0664) and Black women (P(interaction)=0.0108), and PGS and childhood socioeconomic status among White women (P(interaction)=0.0007). CONCLUSION: Our findings reinforce the importance of physical activity among those with an elevated genetic risk; additionally, other detected interactions may underscore the influence of broader social environments on obesity-promoting genes.