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Background: Childhood or adolescent intelligence has been linked to major somatic diseases and premature mortality, but the underlying pathways remain unclear. The aim of this study was therefore to determine whether adolescent intelligence is associated with atherosclerosis in middle age and whether this association is mediated by the American Heart Association’s Life’s Essential 8 (LE8) metric of cardiovascular health markers.

Methods: This population-based prospective cohort study linked data from men who underwent mandatory military conscription in adolescence with data from the Swedish CArdioPulmonary bioImage Study (SCAPIS). A standardized intelligence test was administered at conscription (mean age, 18.3 years; standard deviation [SD], 0.5), assessing logical reasoning, spatial ability, technical skills, and verbal comprehension. Scores were standardized to a mean of 100 (SD, 15). Atherosclerosis in middle age (mean age, 56.6 years; SD, 3.9) was assessed using coronary computed tomography angiography (CCTA) for coronary stenosis (0%, 1–49%, and ≥ 50%), coronary artery calcium (CAC) scores (0, 1–99, and ≥ 100 Agatston units), and carotid ultrasound for unilateral or bilateral carotid plaque/s. LE8 components assessed in SCAPIS were analyzed as potential mediators. Associations were modeled using multinomial logistic regression, and mediation was estimated using counterfactual mediation analysis.

Results: A total of 8,117 men were included in the analysis of coronary stenosis, 7,958 for CAC, and 9,092 for carotid plaque. Higher adolescent intelligence was generally inversely associated with atherosclerosis in middle age. In analyses with adjustments (Model 2) for coronary stenosis, each 15-point (1 SD) increase in adolescent intelligence was associated with 17% lower odds of having ≥ 50% coronary stenosis (OR: 0.83; 95% CI: 0.75–0.90; P-value: <0.001). An intelligence difference between 70 and 130 corresponded to a prevalence difference of 4.1 percentage points (10.3% vs. 6.2%) of coronary stenosis ≥ 50%. Similar associations were observed for CAC scores and bilateral carotid plaques. Mediation via LE8 accounted for 41% to 68% of the association across outcomes.

Conclusions: Higher adolescent intelligence was associated with a lower burden of atherosclerosis in middle age, an association that may be partly mediated by modifiable cardiovascular health factors.