Summary: A large Swedish study finds a link between neighborhood air pollution levels and dispensed medications for psychiatric diagnoses among children and adolescents.
Source: Umeå University
New research from Umeå University in Sweden links dispensed medications for psychiatric conditions among children and adolescents to local air pollution levels. The study uses nationwide register data and was published in the journal BMJ Open.
Growing scientific evidence points to impacts of air pollution on brain development and cognitive function. This study examines whether children and teenagers living in areas with higher air pollution are more likely to receive medications for psychiatric disorders.
This observational study used Swedish national registers that record all dispensed medications together with a national land use regression model estimating local annual concentrations of nitrogen dioxide (NO2), particulate matter PM10 and PM2.5. The research covered the entire population under 18 in four Swedish counties: Stockholm, Västra Götaland, Skåne and Västerbotten. These counties represent a range of urbanisation and pollution levels, from densely populated southern areas to sparsely populated northern regions.
Stockholm, Västra Götaland and Skåne include Sweden’s largest cities and higher population densities (between about 68 and 338 people/km2), whereas Västerbotten is far less dense (around 5 people/km2). The counties differ by geography, migration patterns, socioeconomic characteristics and typical air pollution concentrations; including them provided a broad context to study potential environmental effects on mental health.
The cohort comprised 552,221 individuals under 18 years of age. To reduce family-level confounding, the analysis excluded cohort members whose parents had dispensed medications in the same medication group since the register’s start date. Average follow-up time was 3.5 years, and the analysis used Cox proportional hazards models adjusted for individual- and group-level socioeconomic and demographic factors. Outcomes included dispensed medications for a range of psychiatric diagnoses, including sedatives, sleep medications and antipsychotics.
Over the follow-up period, the researchers observed approximately 21 medication-dispensing events per 1,000 cohort members. The mean annual NO2 concentration in the study areas was 9.8 µg/m³. After adjusting for socioeconomic and demographic variables, each 10 µg/m³ increase in NO2 concentration was associated with a 9% higher risk of a child or adolescent receiving dispensed medication for at least one psychiatric diagnosis (hazard ratio 1.09; 95% CI 1.06–1.12).
The association between NO2 and dispensed psychiatric medication was present in three of the four studied counties, and no statistically significant heterogeneity across counties was detected, suggesting a consistent pattern across diverse settings within the study.
These results suggest a potential link between exposure to air pollution—particularly traffic-related NO2—and indicators of psychiatric disorders among children and adolescents, even at the relatively low pollution levels measured in these Swedish counties. The authors note that reducing air pollution concentrations, especially from traffic sources, could potentially reduce the burden of psychiatric disorders in young people.
As with any observational study, causality cannot be proven from these data alone. The authors call for further research to corroborate these findings in other populations and to explore mechanisms by which air pollution might influence mental health and neurodevelopment.
“The results can mean that a decreased concentration of air pollution, first and foremost traffic-related air pollution, may reduce psychiatric disorders in children and adolescents,” says Anna Oudin from the Unit for Occupational and Environmental Medicine at the Department of Public Health and Clinical Medicine, who led the study.
Funding: The research was funded by Vårdalstiftelsen (Dnr VÅ 2011-25/430).
Publication: The study appears in BMJ Open under the title “Association between neighbourhood air pollution concentrations and dispensed medication for psychiatric disorders in a large longitudinal cohort of Swedish children and adolescents,” authored by Anna Oudin, Lennart Bråbäck, Daniel Oudin Åström, Magnus Strömgren and Bertil Forsberg. Published online June 3, 2016. DOI: 10.1136/bmjopen-2015-010004.
The objective was to investigate associations between air pollution exposure and mental health in children and adolescents using register-based data on dispensed psychiatric medications and a national land use regression model for NO2, PM10 and PM2.5. The cohort included all residents under 18 in four counties, excluding those with parental dispensed medications in the same medication group. Main outcome measures used Cox models adjusted for individual- and group-level covariates. The primary result showed an increased risk of dispensed medication associated with higher NO2 concentrations. The authors conclude there may be a link between neighborhood air pollution and dispensed medications for certain psychiatric disorders in young people, and they recommend further studies to confirm these findings.
The study contributes to an expanding evidence base on environmental influences on child and adolescent mental health and underscores the public health relevance of air quality policies that reduce traffic-related pollution.