CONCURRENT EXPOSURE TO HEAVY METALS AND COGNITION IN SCHOOL-AGE CHILDREN IN CONGO-KINSHASA: A COMPLEX OVERDUE RESEARCH AGENDA

Publication date: Available online 23 June 2018
Source:Brain Research Bulletin
Author(s): Béatrice Koba Bora, Ana Luiza Ramos-Crawford, Alla Sikorskii, Michael Joseph Boivin, Didier Malamba Lez, Dieudonné Mumba Ngoyi, Abdon Mukalay Wa Mukalay, Daniel Okitundu Luwa, Desiré Tshala-Katumbay
The impact of concurrent exposure to neurotoxic metals is a significant threat to brain function, mostly in contexts of multiple exposures as seen in the developing world. Ninety-five children (46 boys and 49 girls, 6 to 11-year old) from Congo-Kinshasa were assessed for cognition using the Kaufman Assessment Battery for Children (2nd edition) and exposure to Cr, Cu, Zn, Co, Mn, As, Cd, Se, Hg, Fe, and Pb by inductively coupled plasma mass spectrometry (ICPMS) in serum and urine collections. Concentrations of elements were all above normal ranges except for Cd, Se and Hg. General linear mixed effects models were used to predict neurocognitive outcomes with variable selection methods including backward elimination, elastic net, or subsets identified based on subject matter expertise. After adjusting for sex, age, and SES, urinary Co > 5 µg/l was associated with poor simultaneous processing (memory)(p = 0.0237). Higher excretion but normal concentration of Cd in serum was associated with better memory (p = 0.03), planning (p = 0.05), and overall performance scores (p < 0.01); thus appeared to be neuroprotective. However, higher excretion of Zn had negative influence on the overall performance scores (p = 0.02). Predictive neurotoxicology is a challenging task in contexts of multiple and concurrent exposures. Urinary Co > 5 µg/l is a risk factor for poor neurodevelopmental outcomes in such contexts. The impact of heavy metals on cognition is dependent on concentrations of and interactions between toxic and essential elements.



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