Use of the Rey-Osterrieth Complex Figure Test for neurotoxicity evaluation of mixtures in children

The aim of this study was to assess the value of the children's version of the Rey-Osterrieth Complex Figure Test as a screening test in a population exposed to different mixtures of neurotoxicants. Copy and Immediate Recall scores were evaluated through the test. Children were recruited from three sites; an area with natural contamination by fluoride and arsenic (F-As), a mining-metallurgical area with lead and arsenic contamination (Pb-As) and a malaria zone with the evidence of fish contaminated with dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs). Children aged 6-11 years old, living in one of the three polluted sites since birth were recruited (n=166). The exposure was evaluated as follows: fluoride and arsenic in urine, lead in blood and DDT, dichlorodiphenyldichloroethylene (DDE) and PCBs in serum. To evaluate the test performance, z-scores for Copy and Immediate Recall were calculated. The proportion of children by residence area with performance lower than expected by age (below -1 SD) for Copy and Immediate Recall was in the F-As area (88.7% and 59%) and in the DDT-PCBs area (73% and 43.8%), respectively. In the Pb-As area, the proportion was 62% for both tests. After adjustment, Copy correlated inversely with fluoride in urine (r=-0.29; p<0.001) and Immediate Recall correlated inversely with fluoride in urine (r=-0.27; p<0.05), lead in blood (r=-0.72; p<0.01), arsenic in urine (r=-0.63; p<0.05) and DDE (r=-0.25; p<0.05). This study provided evidence that children included in this research are living in high risk areas and were exposed to neurotoxicants. Poor performance in the test could be explained in some way by F, Pb, As or DDE exposure, however social factors or the low quality of school education prevalent in the areas could be playing an important role.