Shift work in young adults and carotid artery intima–media thickness: The Cardiovascular Risk in Young Finns study

ObjectiveShift work is associated with an elevated risk of cardiovascular disease, but the timing or mechanisms of this association is unclear.Methods and resultsWe examined the relationship between shift work and subclinical atherosclerosis in 1543 (712 men and 831 women, 24–39 years old) young adults as part of the ongoing population-based Cardiovascular Risk in Young Finns study. Carotid atherosclerosis was assessed by measuring the thickness of the common carotid artery intima–media (IMT) complex with ultrasound and carotid plaque. Working schedules were categorized as day work or shift work (2- or 3-shift work, regular evening or night work). In men, shift work was associated with higher mean IMT (B = 0.029, p = 0.021), maximum IMT (B = 0.029, p = 0.028), and a 2.2-fold odds of carotid plaque (95% CI, 1.2–4.0). These relationships persisted after adjustment for age and risk factors, such as low socio-economic position, job strain, smoking, diet, family history of CHD, physical inactivity, alcohol consumption, obesity, homocysteine, C-reactive protein, blood pressure, and lipids. In women, no association was found between shift work and carotid atherosclerosis indicators.ConclusionsOur results suggest that shift work accelerates the atherosclerotic process and that the effects of shift work on subclinical atherosclerosis are observable in men already before age 40.