Traffic-related air pollution and hyperactivity/inattention, dyslexia and dyscalculia in adolescents of the German GINIplus and LISAplus birth cohorts.

Background: Few studies have examined the link between air pollution exposure and behavioural problems and learning disorders during late childhood and adolescence.

Objectives: To determine whether traffic-related air pollution exposure is associated with hyperactivity/inattention, dyslexia and dyscalculia up to age 15years using the German GINIplus and LISAplus birth cohorts (recruitment 1995-1999).

Methods: Hyperactivity/inattention was assessed using the German parent-completed (10years) and self-completed (15years) Strengths and Difficulties Questionnaire. Responses were categorized into normal versus borderline/abnormal. Parent-reported dyslexia and dyscalculia (yes/no) at age 10 and 15years were defined using parent-completed questionnaires. Individual-level annual average estimates of nitrogen dioxide (NO), particulate matter (PM) mass, PM mass and PM absorbance concentrations were assigned to each participant's birth, 10year and 15year home address. Longitudinal associations between the air pollutants and the neurodevelopmental outcomes were assessed using generalized estimation equations, separately for both study areas, and combined in a random-effects meta-analysis. Odds ratios and 95% confidence intervals are given per interquartile range increase in pollutant concentration.

Results: The prevalence of abnormal/borderline hyperactivity/inattention scores and parental-reported dyslexia and dyscalculia at 15years of age was 12.9%, 10.5% and 3.4%, respectively, in the combined population (N=4745). In the meta- analysis, hyperactivity/inattention was associated with PM mass estimated to the 10 and 15year addresses (1.12 [1.01, 1.23] and 1.11 [1.01, 1.22]) and PM absorbance estimated to the 10 and 15year addresses (1.14 [1.05, 1.25] and 1.13 [1.04, 1.23], respectively).

Conclusions: We report associations suggesting a potential link between air pollution exposure and hyperactivity/inattention scores, although these findings require replication.