Exposure of pregnant women to organophosphate insecticides and motor inhibition evaluated by functional MRI at the age of 10 to 12 years (PELAGIE mother-child cohort)
Résumé
Organophosphate insecticides (OP) are widely used for agricultural purposes because of their acute toxicity and non-persistence. Epidemiological studies suggest a neurotoxicity in children, after exposure at low levels but possible pathways remain unclear. The present study aims at investigating effects of prenatal exposure to OP on inhibition control of 10-12 year-old children assessed by a motor inhibition task during functional MRI (fMRI) sequence.
Ninety-five children from the PELAGIE cohort (Brittany-France, from 2002) underwent fMRI examination during which inhibition was assessed with a Go/No-Go task: they were asked to press a button as quickly as possible in response to green smileys but not press when seeing a red smiley (300 items, 10 minutes). Task performance was assessed by average reaction time (RT), commission rate (CR) and composite performance score (PS). Whole brain activations were estimated by modeling hemodynamic response related to successful inhibition and inhibition demand perception.
OP exposure was assessed by measuring six dialkylphosphate (DAP) metabolites in urine of women in early pregnancy (<19 WG). Concentrations were summed to obtain overall levels of diethylphosphate (DE), dimethylphosphate (DM) and total non-specific metabolites (DAP), standardized to homogenize sampling conditions and categorized into levels of exposure: low (reference), moderate or high. Regression models were adjusted on
potential cofounders considered by restriction and statistical criteria. Moderate levels of DAP were associated with decreased CR (p=0.04), without increased PS. There was a suggested lower PS in association with moderate DE levels (p=0.06). Moderate DE and highest DM levels were associated with decreased brain activities in bilateral middle
frontal or left anterior cingular regions during successful inhibition. We didn’t report any differential activitions related to inhibition demand perception. We suggested associations between prenatal OP exposure and motor inhibition, in particular differential brain activity in areas related to inhibition, which required to be confirmed by others studies.