Genetic susceptibility, screen-based sedentary activities and incidence of coronary heart disease.
BMC medicine 2022 ; 20: 188.
PubMed ID : 35606845
Whether the associations of time spent in screen-based sedentary activities with CHD vary by genetic susceptibility is currently unknown. The objective of this study was to examine the interplay of genetic susceptibility to CHD and two prevalent types of screen-based sedentary activities (television [TV] viewing and computer use) for CHD incidence.
This prospective cohort study included 373,026 individuals of European ancestry without prevalent CHD/stroke from UK Biobank data. Genetic susceptibility to CHD was assessed using weighted polygenic risk scores, calculated by summing the number of risk-increasing alleles among 300 single-nucleotide polymorphisms, multiplied by their corresponding effect estimates. TV viewing and computer use were assessed through touch-screen questionnaires. CHD incidence (n=9185) was adjudicated over a median 12.6-year follow-up.
Compared with ≥4h/day of TV viewing, the hazard ratio of CHD was 0.84 (95% confidence interval [CI] 0.79-0.90) and 0.94 (0.90-0.99) for ≤1h/day and 2-3h/day of TV viewing, respectively, after adjusting for confounders including the genetic risk. CHD hazards were higher for medium and high genetic risk than for low genetic risk. Across all levels of genetic risk including high-genetic risk, ≤1h/day of TV viewing had lower CHD hazards, compared with ≥4h/day: no evidence of interaction between genetic risk and TV viewing (p value: 0.362). Estimates of the population attributable fraction (PAF) suggested that 10.9% (95% CI 6.1-15.3%) of CHD could be prevented if TV viewing time were reduced to ≤1h/day, assuming causality. The PAF values were relatively larger for medium-to-high genetic risk than for low genetic risk, although the CIs were wide and overlapping. No associations were observed for computer use.
Less TV viewing time was associated with lower CHD risk independently of genetic risk. Clinical trials targeted at individuals with high genetic susceptibility should consider reducing TV viewing as as a behavioural target for prevention of an early onset of cardiovascular events.
Excess screen time has been recognised as a strong risk marker of coronary heart disease. However, it is not known if the reduction in coronary heart disease risk associated with less time spent in screen-based sedentary behaviours (such as TV viewing and leisure-time computer use) differs according to varying levels of genetic susceptibility to coronary heart disease. We filled this critical knowledge gap by utilising both genotype and phenotype data collected from the UK Biobank study, an ongoing prospective UK cohort of over 500,000 adults. In the present study, we estimated each individual’s unique genetic susceptibility to coronary heart disease by calculating polygenic risk scores on the basis of 300 genetic variants known for risk of coronary heart disease.
Major findings of the present study are summarised below:
· Risk of developing coronary heart disease was higher in individuals with higher polygenic risk scores (indicative of greater genetic susceptibility to coronary heart disease).
· Compared with ≥4hours/day of TV viewing, however, watching TV for ≤1hour/day was associated with a 16% lower risk of developing coronary heart disease risk, independently of individuals’ unique genetic susceptibility, as well as other known risk markers (including socio-demographic indicators, BMI, diet, smoking, alcohol drinking and physical activity).
· Spending less time watching TV was independently associated with lower coronary heart disease risk in individuals with high genetic susceptibility.
· Approximately 11% of coronary heart disease cases could be averted if TV viewing time were reduced to ≤1hour/day, even after accounting for genetic risk and traditional risk markers.
· There was no evidence of associations for leisure-time computer use with coronary heart disease risk.
These results suggest that reducing time spent watching TV can serve as an important behavioural target for prevention of coronary heart disease, irrespective of genetic susceptibility and traditional risk markers. Importantly, individuals with high genetic susceptibility to coronary heart disease may have a lower risk of developing coronary heart disease merely by limiting time spent on TV viewing. Our study, therefore, informs lifestyle-modification clinical trials targeted at genetically susceptible individuals for prevention of cardiovascular events.