Insights from a 25-year study

In a recent study published in JAMA Network Open, researchers examined the impact of prenatal and early life exposure to noise and air pollution on mental health outcomes, specifically depression, anxiety, and psychotic experiences, in individuals aged 13 to 24.

The findings revealed that increased exposure to fine particulate matter (PM2.5) during gestation and childhood is associated with higher rates of depression and psychotic experiences.

Furthermore, higher levels of noise pollution during childhood and adolescence were linked to increased anxiety levels. This study underscores the significant impact of early life pollution exposure on young people’s mental health.

Study: Air and Noise Pollution Exposure in Early Life and Mental Health From Adolescence to Young Adulthood. Image Credit: Mihail Fedorenko/Shutterstock.com

Background

Existing research highlights the critical periods of childhood, adolescence, and early adulthood for the development of psychiatric disorders, with nearly two-thirds of affected individuals becoming unwell by age 25.

Previous studies have suggested a link between air pollution and psychiatric problems, including mood, affective, and psychotic disorders, through mechanisms such as neuroinflammation and oxidative stress.

Despite this, significant research gaps remain, particularly regarding the impact of exposure during early life, including prenatal periods, on mental health.

Additionally, few studies have explored the relationship between air pollution and youth’s mental health or the role of noise pollution.

About the study

The current study aimed to address existing research gaps by using high-resolution pollution data linked to a longitudinal cohort, focusing on depression, anxiety, and psychotic experiences, to advance understanding of how early-life pollution exposure affects mental health from adolescence into early adulthood.

The longitudinal study involved pregnant women in and around Bristol, UK, who had their due dates during the 16 months starting April 1991 and ending December 1992, resulting in 13,988 children alive at one year of age. At age 7, the sample increased to 14,901 infants.

The study used the ELAPSE model and UK Government noise maps to collect high-resolution data on air pollutants, namely nitrogen dioxide (NO2) and PM2.5.

Noise pollution linked to residential addresses from pregnancy to age 12 was also collected. Participants’ mental health was assessed at the ages of 13, 18, and 24 using interviews and diagnostic tools for depression, anxiety, and psychotic experiences.

Covariates included individual- and family-level factors such as ethnicity, family psychiatric history, maternal social class, education, and neighborhood-level factors like population density and greenspace.

Statistical analyses involved logistic regression modeling that adjusted for potential confounders, with multiple imputations used for missing data. Adjusted odds ratios (AOR) were calculated.

Sensitivity analyses considered simultaneous pollutant effects, residence stability, and complete data subsets to ensure the robustness of findings.

Findings

The study sample comprised 9,065 participants, with a mean age of 24.5 years at follow-up, 51.4% were female, and 95.8% were ethnically White.

The mental health data showed that 19.5% of participants reported experiencing psychotic episodes, and 11.4% reported that they had depression. Additionally, 9.7% reported anxiety.

Higher exposure to PM2.5 during pregnancy and childhood was associated with increased odds of psychotic experiences (AOR, 1.11 and 1.09, respectively). Exposure to PM2.5 during pregnancy also correlated with higher depression rates (AOR, 1.10).

Conversely, exposure to noise pollution during childhood and adolescence was linked to higher anxiety (AOR, 1.19 and 1.22, respectively).

No significant associations were found between NO2 exposure and mental health outcomes after adjusting for covariates.

The results highlight the importance of early-life pollution exposure on mental health, suggesting that interventions that target the reduction of noise and air pollution could improve youth mental health outcomes. Sensitivity analyses supported the robustness of these findings.

Conclusions

In this longitudinal birth cohort study spanning approximately 25 years, early-life exposure to PM2.5 during pregnancy and childhood was associated with increased psychotic experiences and depression.

Additionally, childhood and adolescent noise pollution was linked to higher anxiety. These associations remained significant after adjusting for multiple potential confounders, highlighting the importance of early-life environmental exposures in mental health outcomes.

Compared to previous research, this study underscores the particularly detrimental effects of prenatal and early childhood air pollution on mental health, contrasting with findings related to adult exposure.

The study also aligns with existing evidence on the impact of noise pollution on anxiety, emphasizing the role of stress and sleep disruption.

The study’s strengths include its long follow-up period and comprehensive covariate adjustment. However, limitations such as the observational nature of the data, potential residual confounding, and measurement errors in pollution data are acknowledged. The study’s generalizability may be limited due to the relatively affluent and less diverse cohort.

Future research should focus on more precise pollution measurements, including personal exposure estimates, and explore quasi-experimental designs to establish causality better. Additionally, investigating life-course models and sensitive periods versus cumulative effects in larger datasets could further elucidate the pathways linking pollution to mental health.