Cognitive ability in offspring conscripts and cardiovascular disease risk in extended family members: assessing the impact of modifiable risk factors on familial risk

Background and aim Previous studies have demonstrated an inverse association between cognitive ability (CA) and risk of cardiovascular diseases (CVD). This study aims to investigate the associations between CA in offspring and CVD mortality in relatives of the parental generation (i.e., parents, aunts/uncles (A/U), and A/U partners), and assess the role of modifiable risk factors on these associations. Methods This longitudinal study included nearly 3 million adults who were followed up from age 45 until death. Data for participants were obtained through the linkage of various Norwegian surveys and registries. Hazard ratios (HR) for CVD mortality among the parental generation in relation to offspring CA were estimated using Cox proportional hazard regression. Results One standard deviation (SD) unit increase in CA was associated with a reduction in CVD mortality among mothers (HR: 0.77, 95%CI [0.74, 0.81]); fathers (0.83, [0.81, 0.86]); A/U (0.91, [0.87, 0.94]); and A/U partners (0.91, [0.89, 0.94]). Adjusting the models for CVD risk factors in the parental generation attenuated all associations (mothers-HR: 0.91, 95%CI [0.87, 0.96]; fathers: 0.93, [0.91, 0.96]; A/U: 0.99, [0.96, 1.03]; A/U partners: 0.98, [0.95, 1.01]). Conclusions We observed an inverse association between offspring CA and CVD and all-cause mortality in various familial relationships. Our findings suggest the existence of factors shared among relatives that explain familial risk to suffer lower CA and higher CVD mortality. A significant portion of the association between CA and CVD mortality in all familial relationships was explained by modifiable risk factors in relatives of the older generation. Highlights A lower cognitive ability might drive inequalities in cardiovascular disease (CVD). Shared environments explain most of the association between cognitive ability and CVD. The role of genetic factors in this relationship has probably been overestimated.