title: Impact of contrast sensitivity performance on visually presented neurobehavioral tests in mercury-exposed children.
abstract: Presentation of neuropsychological tests on a computer screen may involve a visual challenge to the examinee. The possible need for adjustment for visual contrast sensitivity on test performance was therefore determined from data on 917 mercury-exposed children who were examined at age 7 years. Contrast sensitivity was found to be associated with performance on the computer-assisted Continuous Performance Test. However, it showed similar associations with performance on traditional pencil-and-paper tests, especially Bender Visual Motor Gestalt Test and Wechsler Intelligence Scale for Children-Revised (WISC-R) Block Designs. Contrast sensitivity was not associated with prenatal mercury exposure, and adjustment for visual function had only a negligible effect on the regression coefficients for mercury as predictor of neuropsychological deficits. The mercury-associated neurobehavioral deficits are therefore unlikely to be due to mercury-induced visual system dysfunction causing secondary deficits in cognitive domain testing. Visuospatial processing appears to be a determinant in contrast sensitivity performance, and careful consideration of whether to control for contrast sensitivity in future studies of neurotoxicant effects is therefore recommended.
authors.affiliation: Institute of Public Health, University of Southern Denmark, DK-5000 Odense, Denmark. pgrand@health.sdu.dk
authors.forename: P
authors.initials: P
authors.lastname: Grandjean
authors.forename: R F
authors.initials: RF
authors.lastname: White
authors.forename: K
authors.initials: K
authors.lastname: Sullivan
authors.forename: F
authors.initials: F
authors.lastname: Debes
authors.forename: K
authors.initials: K
authors.lastname: Murata
authors.forename: D A
authors.initials: DA
authors.lastname: Otto
authors.forename: P
authors.initials: P
authors.lastname: Weihe
mesh_terms: D001538:Bender-Gestalt Test; D002648:Child; D015331:Cohort Studies; D015350:Contrast Sensitivity / Q000187:drug effects*; D005074:Evoked Potentials, Visual / Q000187:drug effects; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008628:Mercury / Q000633:toxicity*; D008767:Methylmercury Compounds / Q000633:toxicity; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000187:drug effects; D014792:Visual Acuity / Q000187:drug effects
chemical_list: D008767:Methylmercury Compounds; D008628:Mercury