Cognitive and neurobehavioural disorders in school-age children in Haut-Katanga province, an environment exposed to trace metals

Abstract

Introduction: Cognitive and neurobehavioural disorders in children are poorly documented in Haut-Katanga Province, an environment exposed to trace metals. Objective: To characterize children's behaviour in relation to cognitive performance and exposure to trace metals in urban and rural environments. Methods: A cross-sectional study was carried out on fifty-two children aged 6 to 11 years, including thirty children from urban areas, exposed to trace metals, in the city of Lubumbashi and twenty-two children from rural areas presumed to be less exposed to trace metals, but more exposed to malnutrition. The NEPSY-II tests, the Strengths and Difficulties Questionnaire (SDQ-tutor) and blood and urine trace metals spectrometry assays were used. Results: Total behavioural difficulties predominated in rural area, compared to urban environment, while no difference in the stress or impairment related to difficulties was observed between the groups. Children in urban area performed better cognitively than children of rural environment, particularly on the facial affect recognition and on inhibition. Overall, growth nutritional status determined the level of total behavioural difficulties. Cobalt and lead were detected in the blood of children at levels exceeding the upper reference limits of non-occupationally exposed individuals, especially in urban area for cobalt. The presence of metals in urine and blood was correlated in a complex way with behavioral difficulties and cognitive performance. Conclusion: The extent of the behavioural problems, in relation to cognitive performance, and their association with nutritional problems and exposure to trace metals indicate a multifactorial neurodevelopmental origin requiring further study.