Different sedentary behaviors, genetic susceptibility of hypertension, and new-onset hypertension: Mediating effects of body mass index and grip strength.

Abstract

The association between different sedentary behaviors and hypertension risk remains unclear. We aimed to explore the relationship between different domains of sedentary behaviors and new-onset hypertension, investigate whether genetic susceptibility to hypertension modifies the relationship, and examine the extent to which the relationship is mediated by body mass index (BMI) and grip strength. 212 714 participants without baseline hypertension in the UK Biobank were enrolled. The three major sedentary behaviors (TV-watching, nonoccupational computer use, and driving) were measured using touch screen questionnaires. The primary outcome was new-onset hypertension. During a median follow-up of 11.9 years, 13 983 participants developed hypertension. There was a linear positive association between TV-watching time and new-onset hypertension (p for nonlinearity =0.868). A J-shaped association was found for nonoccupational computer use time and driving time with new-onset hypertension, with an inflection point of 0.5 h/day for both (both p for nonlinearity <0.001). Polygenetic risk scores for hypertension (based on 118 related single-nucleotide polymorphisms) did not significantly modify these associations (all p-interactions >0.05). Furthermore, the detrimental effects of long-term sedentary behaviors on hypertension were mediated by BMI by 21%-30%, and the beneficial effects of limited sitting time (within 0.5 h/day) for driving and nonoccupational computer use were mediated by grip strength by 6-25%. There was a positive association for hands-independence sedentary behavior (TV-watching), and a J-shaped association for hands-dependence sedentary behaviors (nonoccupational computer use and driving) with new-onset hypertension, regardless of genetic risks of hypertension. These relationships were partly mediated by BMI and grip strength.