Depression in childhood to early adulthood and respiratory health in early adulthood.

Background: Both depression and respiratory disease are common today in young populations. However, little is known about the relationship between them.

Aims: This study aims to explore the association between depression in childhood to early adulthood and respiratory health outcomes in early adulthood, and the potential underlying mechanisms.

Method: A prospective study was conducted based on the Swedish BAMSE (Barn, Allergi, Miljö, Stockholm, Epidemiologi [Children, Allergy, Milieu, Stockholm, Epidemiology]) birth cohort (n = 4089). We identified clinically diagnosed depression through the dispensation of antidepressants, using national register data confirmed by self-reported diagnosis. At the 24-year follow-up, respiratory health was assessed via questionnaires and clinical evaluation. Metabolic and inflammatory profiles were analysed to explore potential mechanisms.

Results: Among the 2994 participants who provided study data, 403 (13.5%) had depression at any time point from around age 10 to 25 years. Depression was associated with higher risks of any chronic bronchitis symptoms (odds ratio = 1.58, 95% CI 1.21-2.06) and respiratory symptoms (odds ratio = 1.41, 95% CI 1.11-1.80) in early adulthood, independent of body mass index (BMI) and smoking status. Compared to individuals without depression, those with depression had a higher fat mass index (FMI (β = 0.48, 95% CI 0.22-0.74)) and increased blood levels of fibroblast growth factor 21 and Interleukin-6 in early adulthood. These markers together with FMI were found to partly mediate the association between depression and respiratory symptoms (total mediation proportion: 19.8 and 15.4%, respectively, P < 0.01).

Conclusions: Depression in childhood to early adulthood was associated with an increased risk of respiratory ill-health in early adulthood, independently of smoking. Metabolic and inflammatory dysregulations may underlie this link.