A study of schoolgirls finds that living in polluted areas is more consistently linked to reduced attention than diet quality, and that antioxidant intake offers no clear protection against memory decline.
Study: Interaction between air pollution and diet on cognitive function in schoolchildren. Image Credit: Maja Argakijeva / Shutterstock
In a recent study published in BMC Public Health, researchers investigated the joint and individual effects of air pollution exposure and dietary antioxidants on concentration and memory in young female Iranian students.
Higher levels of dietary antioxidants and lower exposure to air pollution were both significantly associated with better concentration performance, with air pollution showing the most consistent association across fully adjusted statistical models, while no significant interaction or direct association was observed for short-term memory outcomes.
Background: Cognitive Development, Diet, and Environmental Exposure
Short-term memory and concentration are foundational cognitive processes that strongly influence children’s learning and academic performance, as well as outcomes in later life. Short-term memory supports information retention over brief periods, while sustained attention enables task engagement and error control.
Deficits in either domain can impair educational outcomes, even among children with typical levels of intelligence. Previous research has identified multiple contributors to cognitive difficulties, including perinatal factors, exposure to environmental toxins, and dietary quality.
Diets deficient in essential antioxidants and micronutrients have been linked to poorer memory and attention. However, diets that contain high amounts of fish, fruits, and vegetables appear protective. Concurrently, air pollution has emerged as a major environmental risk factor for neurodevelopment, particularly in children living in highly polluted urban areas worldwide.
Oxidative stress is thought to be a shared mechanism underlying both poor diet and pollution-related cognitive impairment. Despite these overlaps, no prior studies have evaluated the combined influence of air pollution exposure and dietary antioxidants on children’s cognition.
Study Design and Population
Researchers used a cross-sectional design, including 300 female students aged 9-12 enrolled in elementary schools in Tehran, a megacity with high recorded pollution levels.
Equal numbers of participants were recruited from high- and low-pollution districts using stratified random sampling.
Assessment of Air Pollution and Dietary Antioxidants
Air pollution exposure was classified based on official monitoring data. Dietary intake was assessed through a semi-quantitative 168-item Food Frequency Questionnaire (FFQ) completed by parents, adapted from the Tehran Lipid and Glucose Study.
The research team calculated dietary total antioxidant capacity (dTAC) using Ferric Reducing Antioxidant Power (FRAP) values for 106 food items, expressed as total daily antioxidant capacity.
Participants were categorized into low- and high-dTAC groups based on the median value.
Cognitive Outcome Measures
Cognitive outcomes were assessed using validated tools. Concentration was measured with the Continuous Performance Test (CPT) to capture omission errors, commission errors, and reaction time.
Short-term memory was assessed using the Wechsler Memory Scale for Children.
Parents completed questionnaires reporting their children’s anthropometric measurements and demographic, socioeconomic, and lifestyle variables.
Statistical Analysis
Statistical analyses included chi-square tests and two-way analysis of variance (ANOVA) to assess main and interaction effects of pollution exposure and dTAC.
Multivariable models adjusted for age, energy intake, socioeconomic factors, dietary micronutrients, and body mass index (BMI).
Key Findings: Dietary Antioxidants and Participant Characteristics
Students were grouped based on dietary antioxidant capacity, low (TAC1) and high (TAC2).
Children with lower dietary antioxidant intake were slightly younger, shorter, and heavier than those in TAC2. They also spent less time outdoors, although differences in anthropometric measures were not statistically significant.
Students with higher dTAC consumed significantly more energy, fruits, carbohydrates, and micronutrients, including vitamins A, C, and B9, as well as iron and zinc.
Air pollution exposure was associated with differences in parental smoking habits, education, and occupation, indicating socioeconomic variation between regions.
Key Findings: Memory Outcomes
Memory scores were modestly higher among students with higher dTAC and among those living in less polluted areas. However, these differences were not statistically significant, even after adjustment for confounders.
Key Findings: Concentration and Attention
Concentration performance differed significantly by pollution exposure, with children in less polluted areas demonstrating better attention scores.
Higher dTAC was also significantly associated with improved concentration in selected adjusted models, although this relationship was less robust and more model-dependent than the association observed for air pollution exposure.
No statistically significant interaction between dTAC and air pollution was observed for either memory or concentration, indicating that dietary antioxidants did not measurably buffer pollution-related effects on cognition.
Conclusions and Public Health Implications
This study provides novel insights into the independent roles of air pollution and dietary antioxidant capacity in children’s cognitive performance.
Consistent with prior literature, higher pollution exposure was associated with poorer concentration, with this association remaining statistically significant after extensive adjustment for socioeconomic, lifestyle, and dietary factors. Higher dTAC was modestly linked to better attention.
No significant associations were observed for short-term memory, nor was there evidence of an interaction between diet and pollution.
Strengths of the study include the use of validated cognitive tests, objective pollution classification, and comprehensive adjustment for socioeconomic and dietary confounders.
Limitations include the cross-sectional design, reliance on an adult FFQ adapted for children, and the inclusion of only female participants, all of which limit generalizability and causal inference.
Overall, while antioxidant-rich diets may support attentional function in polluted environments, exposure to environmental pollution appears to play a more dominant and consistent role in shaping concentration outcomes.
Future studies should employ longitudinal designs and child-specific dietary assessment tools to clarify impacts on cognitive development and memory.