Recently the BMJ Open online journal published the first large-scale prospective, population-based study, involving 24 057 participants, followed for a 7-year period, documenting an association between childhood adversities and register-verified asthma diagnosis in adulthood.
Previous research has shown that anxiety disorders and major depression are linked to asthma development, and two previous longitudinal studies reported bidirectional associations between panic disorder/attacks and asthma.
The BMJ Open study by Jyrki Korkeila and colleagues from the University of Turku and University of Helsinki, Finland included 8556 men and 11 946 women. Altogether, 12 126 (59%) participants in the study reported that they encountered a childhood adversity. Of these participants, 8449 (41% of all participants) reported 1–2 adversities and 3677 (18% of all participants) 3–6 adversities.
The investigators report that during the 7 years’ follow-up about 3% of the individuals developed asthma, and the participants reporting 3 or more childhood adversities had almost doubled risk of developing asthma when compared to those without childhood adversities.
As per this study, self-reported childhood adversities are associated with register-verified asthma diagnoses. The authors assume that about half of this association is mediated by several factors. Thus, psychiatric morbidity attenuated the relative risk most, almost a quarter, and demographic factors by about a fifth, whereas asthma risk factors accounted for a smaller portion of the attenuation.
Furthermore, psychiatric disorder, having no relationship, being female, belonging to an older age group, low level of education, having allergy or atopia, health behaviours contribute to the excess risk of adult onset asthma associated with childhood adversity.
According to the authors psycho-neuro-immunological pathways may drive the link between adversity and asthma including elevated levels of inflammatory biomarkers and stress-immune or stress-inflammation interactions and adversary effects. The authors also suggest that socioeconomic status may be a precursor to this, often resulting in poor health related behavior, and running a higher risk of mental health disorders. Parenting difficulties have, likewise, been linked to childhood asthma and the risk seemed to be highest among those, who also had elevated IgE levels.
This work highlights the importance of early risk factors in the identification and treatment of risk groups for poor health outcomes, and may warrant further studies along these lines.
A 2015 systematic review included 12 studies concerning the relationship between adverse childhood experience and asthma onset among a total of 31 524 evaluated individuals. 10 of the 12 studies reported statistically significant effects of early life stress on asthma onset with odds ratios ranging from borderline significance to exceeding double the baseline measure. Two studies produced significant effects only under certain conditions.
Of note, the study suggested that chronic stress exposure and maternal distress in pregnancy operate synergistically with known triggers such as traffic-related air pollution to increase asthma risk.
In conclusion, this systematic review indicates that exposure to perinatal or early-life stress significantly increases the risk of asthma onset alongside elevating levels of asthma-relevant biomarkers.
A 2021 population-based studyby Raija Lietzén examined whether adulthood risk factors for asthma mediate the association between the exposure to multiple adverse childhood experiences (ACEs) assessed retrospectively and the risk of new-onset asthma in adulthood.
The investigators report that exposure to multiple childhood adversities increased the risk of asthma in adulthood and that adulthood risk factors mediated a significant proportion of the effect of ACEs on asthma.
The increased risk of asthma onset among individuals with multiple ACEs compared with those with ≤1 ACE was partially attributed to an increased likelihood of having risk factors of asthma in adulthood, such as smoking, prevalent allergic rhinitis, low education level, obesity, and stressful life events. The most important mediators were severe financial difficulties; exposure to emotional, physical, or sexual violence; and marital problems.
A 2022 systematic review by Yasemin Saygideger retrieving a total of 5245 articles, included 36 in the study. As per this study several genes and pathways that may contribute to pathogenesis of asthma development, increased inflammation, or response to asthma treatment were found epigenetically affected by childhood traumas.
The study demonstrated that childhood adversity, including sexual and physical abuse and neglect, influences the epigenetic regulation of asthma related genes. Up to date scientific investigations of asthma pathogenesis indicate a multi-complex pathophysiologic process that might be responsible of the diverse phenotypes among asthma patients and recent studies indicate a contribution of lifelong epigenetic influences to this pathophysiology.
The complexity increases while the type of the adversity and its relationship with asthma may differ from population to population, related to cultures and traditions, and therefore, contributing to limitation of this systematic review.
In conclusion, childhood adversity, causing epigenetic changes in DNA, may lead to asthma development or influence the course of the disease and therefore should be taken into account for the prolonged health consequences.