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

Abstract

Background: Previous studies have demonstrated an inverse association between cognitive ability (CA) and risk of cardiovascular diseases (CVDs). This study aims to investigate the associations between CA in offspring and CVD mortality in relatives of the parental generation (ie, parents, aunts/uncles (A/U) and the partners of A/U) and assesses 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. HRs for CVD mortality among the parental generation in relation to offspring CA were estimated using Cox proportional hazards regression.

Results: One standard deviation increase in CA was associated with a 23%, 17%, 9% and 9% CVD mortality reduction in 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)), respectively. Accounting for modifiable risk factors in the parental generation attenuated the association in mothers from 23% to 9% (0.91, (0.87, 0.96)), fathers from 17% to 7% (0.93, (0.91, 0.96)), A/U from 9% to 1% (0.99, (0.96, 1.03)) and A/U partners from 9% to 2% (0.98, (0.95, 1.01)).

Conclusions: We observed an inverse CA-CVD association in all familial relationships including non-genetically related duos (offspring-A/U partners). CA and CVD probably have shared causes such as genetic and environmental components common to the family members. These associations were largely accounted for by modifiable risk factors.