A central role of nutrition in cognitive function among primary school children: a cross-sectional analysis.

Background: Childhood overweight and obesity have implications that extend beyond physical health. Despite evidence linking obesity to poorer cognition, the combined effects of weight status and dietary habits on cognitive function in children remain insufficiently studied. This study took a comprehensive approach investigating effects of weight status on cognition, incorporating socio-economic factors, parental anthropometrics, and detailed nutrition assessments in primary school children.

Methods: Anthropometric measurements, cognitive testing and short interviews were performed in schools from October 2021 until July 2022 in the Rhein-Neckar region, Germany. Cognitive testing included the distractibility and flexibility modules of the PSYTEST KiTap battery, alongside a self-designed short-term memory assessment. Parents were asked to provide information on physical activity, socioeconomic status (SES) and nutrition (3-day food diary and a questionnaire). Pearson's correlations were used for normally distributed continuous data, and Spearman's correlations for nonparametric data Pearson's or Spearman's correlation coefficients were calculated based on data distribution.

Results: A total of 256 children with a mean age of 8.0 years participated in the study. According to German growth reference tables, 16% were underweight, 75% normal weight, 5% overweight and 5% obese. Cognitive testing resulted in an average age- and sex adjusted performance. No significant correlations were found between any of the anthropometric variables collected and the cognitive domains studied. At the same time, cognition was associated with nutrition, physical activity and SES with strongest associations between reaction time in the flexibility task and fat consumption (R -0.35, p < 0.001), total kilocalories (R -0.30, p < 0.001) and protein (R -0.30, p < 0.001).

Conclusions: The cognitive domains studied are not associated with anthropometric variables in primary school children. Nutrition appears to have strongest associations with cognition followed by other factors such as physical activity and SES. This study underlines the importance of nutrition for cognitive function and emphasizes the need to include nutrition in studies on cognitive performance and body weight status in schoolchildren. The study was registered at clinicaltrials.gov on September 21st 2021 under the registration number NCT05077059.