Neuroticism, extraversion, stressful life events and asthma: a cohort study of middle-aged adults.

Background: Stressful life events can trigger asthma exacerbations, but could also contribute to the development of incident asthma. However, only few studies have investigated the association between stressful life events and adult asthma prospectively. Likewise, stress-related personality traits (e.g. neuroticism and extraversion) may increase asthma risk, but this has been examined in only one prospective study. We therefore aimed to investigate the association between neuroticism, extraversion, stressful life events and incident asthma.
Methods: A population-based sample of 5114 middle-aged adults completed questionnaires between 1992 and 1995. Among those alive in 2002/2003, 4010 (83%) were followed-up by questionnaires. Exposures of interest included neuroticism, extraversion and three stressful life events (unemployment, having broken off a life partnership and death of a close person). Associations with incident asthma were estimated by multivariable risk ratios (RR) and 95% confidence intervals (95% CI) using Poisson regression.
Results: High vs low neuroticism predisposed to developing asthma (RR = 3.07, 95% CI = 1.71-5.48), but high extraversion did not (RR = 1.30, 95% CI = 0.79-2.15). Having broken off a life partnership significantly increased asthma risk (RR = 2.24, 95% CI = 1.20-4.21) in contrast to death of a close person (RR = 1.06, 95% CI = 0.64-1.75) or unemployment (RR = 1.65, 95% CI = 0.72-3.78).
Conclusions: High levels of neuroticism may increase the risk of asthma in middle-aged adults. Having broken off a life partnership was the only stressful event, which was associated with incident asthma. Synthesized with evidence from earlier studies, this could reflect that interpersonal conflicts may increase asthma risk, possibly along an immunological pathway.