Prenatal stress and childhood asthma risk: taking a broader view

Extending the Environmental influences on Child Health Outcomes (ECHO) Cohort through 2030: Rationale and study protocol

Early life environmental exposures, even those experienced before conception, can shape health and disease trajectories across the lifespan. Optimizing the detection of the constellation of exposure effects on a broad range of child health outcomes across development requires considerable sample size, transdisciplinary expertise, and developmentally sensitive and dimensional measurement. To address this, the National Institutes of Health (NIH) Environmental influences on Child Health Outcomes (ECHO) Cohort Study is an observational longitudinal pediatric cohort study. In the first phase from 2016-2023, the ECHO Program built a robust platform for investigating prenatal and early life environmental exposures on child health outcomes. Now, the ECHO Program is extending longitudinal follow-up of existing ECHO participants <21 years of age and recruiting and following new pregnant participants <20 weeks gestation and their offspring through 2030. Participants will be enrolled at 72 Cohort Study Sites across all 50 US states, the District of Columbia, and Puerto Rico. Exposure assessments span the biological, chemical/physical, lifestyle, and social environment; child health outcomes focus on five broad domains: pre-, peri-, postnatal; airways; obesity; neurodevelopment; and positive health, or one's physical, mental, and social well-being. Data and biospecimens will be collected annually through August 2030, with an expected total sample size of 60,000 children and their caregivers. The ECHO Cohort Study represents the largest national longitudinal study of children's health in the US. Here, we describe the ECHO Cohort "Cycle 2" observational study arm and the ECHO Cohort Protocol version 3.0 (ECP v3.0), which delineates the data elements, measures, and biospecimens that all ECHO Cycle 2 Cohort Study Sites will collect and analyze.

Asthma, classical conditioning, and the autonomic nervous system - a hypothesis for why children wheeze

Paediatric asthma is an increasing global healthcare problem for which current treatments are not always effective. This review explores how abnormal triggering of the autonomic diving reflex might be important in explaining research findings and the real-world experience of asthma. It hypothesises that the way in which stress during pregnancy is associated with childhood asthma could be through effects on the developing nervous system. This results in increased parasympathetic responsiveness and specifically, excessive triggering of the diving reflex in response to wetting and cooling of the face and nose as occurs with upper airway infections and allergic rhinitis. In aquatic mammals the reflex importantly includes the contraction of airway smooth muscle to minimise lung volume and prevent nitrogen narcosis from diving at depth. Misfiring of this reflex in humans could result in the pathological airway narrowing that occurs in asthma. The diving reflex, and possibly also smooth muscle, is a vestigial remnant of our aquatic past. The hypothesis further suggests that classically conditioned reflex responses to neutral cues and contexts that were present at the same time as the stimuli that initially caused symptoms, become of themselves ongoing triggers of recurrent wheeze. Symptoms occurring in this way, irrespective of the presence of allergens and ongoing airway sensitisation, explain why allergen avoidance is poorly effective in alleviating wheeze and why asthma is made worse by stress. Interventions to suppress the diving reflex and to prevent reflex conditioned wheezing could result in more effective asthma management.

Secular Trends of Mortality and Years of Life Lost Due to Chronic Obstructive Pulmonary Disease in Wuhan, China from 2010 to 2019: Age-Period-Cohort Analysis

BACKGROUND

Chronic obstructive pulmonary disease (COPD) has been an important public health issue in China. This study aimed to analyze the temporal trends in mortality and years of life lost (YLL) from COPD, and explore the effects of age, period, and cohort in Wuhan, China from 2010 to 2019.

METHODS

Data were collected from the cause of death surveillance system in Wuhan. Age-standardized mortality rate (ASMR), age-standardized YLL rate (ASYR) and the estimated annual percent changes (EAPC) were calculated to evaluate the temporal trends. The age-period-cohort (APC) model was adopted to estimate the age, period, and cohort effects.

RESULTS

From 2010 to 2019, COPD accounted for 26,051.15 deaths and 394,659.58 person years YLL in Wuhan. Recently, the death burden of COPD in Wuhan has somewhat improved, especially after 2015, with declining trends in ASMR and ASYR. Additionally, the ASMR and ASYR of COPD was higher in males. And these of males showed the overall upward trends, with EAPCs of 1.06 (0.13, 2.00) and 1.21 (0.12, 2.31), respectively, while females showed downward trends since 2010. According to APC model, the age effect of COPD increased with age, and the cohort risk ratios (RRs) followed the overall downward trends. Period RRs for the Wuhan population generally tended to rise and then fall, with females showing a clear downward trend after 2015, while period RRs for males maintained an upward trend throughout the study period.

CONCLUSIONS

Recently, the death burden from COPD in Wuhan has improved, especially after 2015, with improvements in ASMR, ASYR and period RRs. Sex differences still exist. COPD posed a greater threat to the elderly, especially males. Public health managers should continue to execute more targeted programs to lessen the death burden of COPD in Wuhan.

A model of perinatal stress and childhood wheezing: ELSPAC-CZ cohort

BACKGROUND

Prenatal origins of wheezing are not fully understood. This study develops a model of mechanisms linking perinatal stress exposure to wheeze phenotypes in children.

METHODS

Data were obtained from 1880 mother-child dyads participating in ELSPAC-CZ birth cohort. Wheeze phenotypes assessed between birth and age 7 years included "never wheeze," "early-onset transient (EOT) wheeze," "early-onset persistent (EOP) wheeze," and "late-onset (LO) wheeze." Prenatal and postnatal stress exposures were assessed in mid-pregnancy and 6 months after delivery, respectively, using an inventory of 42 life events.

RESULTS

In adjusted models, children in the highest tercile (high) versus lowest tercile (low) for prenatal life events had a 38% higher risk of EOT wheeze (relative risk ratio [RRR] = 1.38; 95% confidence interval [CI] = 1.01-1.88; p = .041) and 50% higher risk of LO wheeze (RRR = 1.50; 95% CI = 1.00-2.25; p = .047). High versus low exposure to postnatal life events predicted a 60% increase in relative risk of EOT wheeze (RRR = 1.60; 95% CI = 1.17-2.19; p = .003) and medium versus low exposure was related to an 85% increase in relative risk of EOP wheeze (RRR = 1.85; 95% CI = 1.16-2.95; p = .010). Lower respiratory tract infections and postpartum depression partially mediated between postnatal life events and any wheeze (indirect effects 1.06, 95% CI = 1.02-1.09, p = .003 and odds ratio [OR] = 1.08, 95% CI = 1.02-1.15, p = .012, respectively), while postnatal events mediate for prenatal events (indirect effect OR = 1.11; 95% CI = 1.03-1.18; p = .005).

CONCLUSIONS

Exposures to prenatal and postnatal life events are risk factors for the development of wheezing. Prenatal stress contributes to wheeze directly and also through postnatal life events, respiratory infections, and maternal depression.

Parental stress and air pollution increase childhood asthma in China

BACKGROUND

Although air pollution and social stress may independently increase childhood asthma, little is known on their synergistic effect on asthma, particularly in China with high levels of stress and air pollution.

OBJECTIVES

To examine associations between exposure to a combination of parental stress and air pollution and asthma prevalence in children.

METHODS

We conducted a cohort study of 2406 preschool children in Changsha (2011-2012). A questionnaire was used to collect children's lifetime prevalence of asthma and their parental stress. Parental socioeconomic and psychosocial stresses were respectively defined in terms of housing size and difficulty concentrating. Children's exposure to ambient air pollutants was estimated using concentrations measured at monitoring stations. Associations between exposure to parental stress and air pollution and childhood asthma were estimated by multiple logistic regression models using odds ratio (OR) and 95% confidence interval (CI).

RESULTS

Life time prevalence of asthma in preschool children (6.7%) was significantly associated with parental socioeconomic and psychosocial stresses with OR (95% CI) respectively 1.48 (1.02-2.16) and 1.64 (1.00-2.71). Asthma was also associated with exposure to air pollutants, with adjusted OR (95% CI) during prenatal and postnatal periods respectively 1.43 (1.10-1.86) and 1.35 (1.02-1.79) for SO₂ and 1.61 (1.19-2.18) and 1.76 (1.19-2.61) for NO₂. The association with air pollution was significant only in children exposed to high parental stress, the association with parental stress was significant only in children exposed to high air pollution, and the association was the strongest in children exposed to a combination of parental stress and air pollution. Sensitivity analysis showed that the synergistic effects of parental stress and air pollution on childhood asthma were stronger in boys.

CONCLUSIONS

Parental stress and air pollution were synergistically associated with increased childhood asthma, indicating a common biological effect of parental stress and air pollution during both prenatal and postnatal periods.

Lung Development and Aging

The onset of chronic obstructive pulmonary disease (COPD) can arise either from failure to attain the normal spirometric plateau or from an accelerated decline in lung function. Despite reports from numerous big cohorts, no single adult life factor, including smoking, accounts for this accelerated decline. By contrast, five childhood risk factors (maternal and paternal asthma, maternal smoking, childhood asthma and respiratory infections) are strongly associated with an accelerated rate of lung function decline and COPD. Among adverse effects on lung development are transgenerational (grandmaternal smoking), antenatal (exposure to tobacco and pollution), and early childhood (exposure to tobacco and pollution including pesticides) factors. Antenatal adverse events can operate by causing structural changes in the developing lung, causing low birth weight and prematurity and altered immunological responses. Also important are mode of delivery, early microbiological exposures, and multiple early atopic sensitizations. Early bronchial hyperresponsiveness, before any evidence of airway inflammation, is associated with adverse respiratory outcomes. Overlapping cohort studies established that spirometry tracks from the preschool years to late middle age, and those with COPD in the sixth decade already had the worst spirometry at age 10 years. Alveolar development is now believed to continue throughout somatic growth and is adversely impacted by early tobacco smoke exposure. Genetic factors are also important, with genes important in lung development and early wheezing also being implicated in COPD. The inescapable conclusion is that the roots of COPD are in early life, and COPD is a disease of childhood adverse factors interacting with genetic factors.