Adolescent Intelligence and Imaging-Based Atherosclerosis in middle age: A Population Study of Swedish Men

Importance

Childhood or adolescent intelligence has been linked to major somatic diseases and premature mortality, but the underlying pathways remain unclear.

Objective

To determine whether adolescent intelligence is associated with atheroscle-rosis 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.

Design

Population-based prospective cohort study.

Setting

Six university hospitals in Sweden.

Participants

Men in the Swedish CArdioPulmonary bioImage Study who underwent mandatory military conscription in adolescence.

Exposure

A standardized intelligence test 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).

Main Outcomes and Measures

Atherosclerosis in middle age (mean age 56.6 years; SD, 3.9), assessed using coronary computed tomography angiography (coronary stenosis: 0%, 1–49% and ≥50%) and coronary artery calcium (CAC) scores (0, 1–99, ≥100 Agatston units), and presence of unilateral or bilateral carotid plaque/s via ultrasound. 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 inversely associated with atherosclerosis in middle age. In analyses with extended 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 carotid plaque. Mediation via LE8 accounted for 41% to 68% of the association across outcomes; the only direct effect not mediated via LE8 was observed for unilateral carotid plaque.

Conclusions

Higher adolescent intelligence was associated with a lower burden of atherosclerosis in middle age, with a substantial proportion of the association mediated by modifiable cardiovascular health factors.

Key Points

Question: Is there a relationship between adolescent intelligence and atherosclerosis in middle age, and could this association be mediated through cardiovascular health factors?

Findings: In this population-based cohort of Swedish men, higher adolescent intelligence was associated with a lower burden of atherosclerosis in middle age, measured using coronary computed tomography angiography and carotid ultrasound. About half of this association was mediated by modifiable cardiovascular health factors.

Meaning: These findings suggest that adolescent intelligence may shape cardiovascular health decades later, and this may be due to changes in cardiovascular health factors.