Blunted hypothalamic-pituitary-adrenal axis and insulin response to psychosocial stress in young adults born preterm at very low birth weight.

Background: Young adults born preterm at very low birth weight (VLBW, ≤1500 g) have higher levels of cardiovascular risk factors, including impaired glucose regulation, than their term-born peers. This could be mediated through altered hypothalamic-pituitary-adrenal axis (HPAA) response to stress.

Objective: To compare HPAA, glucose and insulin responses provoked by psychosocial stress in VLBW subjects versus a comparison group of term-born controls.

Design And Participants: We studied 54 unimpaired young adults, aged 19-27 years, born at VLBW and a comparison group of 40 adults born at term, group-matched for age, sex and birth hospital, from one regional centre in southern Finland. The participants underwent a standardized psychosocial stress test (Trier Social Stress Test, TSST).

Measurements: In conjunction with TSST, we measured salivary cortisol, plasma ACTH, cortisol, glucose and insulin. Data were analysed with mixed-effects model and multiple linear regression analyses.

Results: Baseline concentrations for cortisol, ACTH, insulin and glucose were similar in VLBW and comparison groups. During TSST, analysed with mixed-effects model, overall concentrations of plasma cortisol were 17·2% lower (95% CI; 3·5 to 28·9) in the VLBW group. The VLBW group also had lower salivary (P = 0·04) and plasma cortisol (P = 0·02) responses to TSST. Insulin and glucose concentrations correlated with changes in cortisol concentrations. Accordingly, VLBW subjects had 26·5% lower increment in insulin (95% CI; 9·8-40·1). Analyses were adjusted for age, sex, body mass index, hormonal contraception, menstrual cycle phase, time of day and parental education.

Conclusions: VLBW adults have lower HPAA responses to psychosocial stress than term-born controls. This is accompanied by a lower insulin response.