Impact of contrast sensitivity performance on visually presented neurobehavioral tests in mercury-exposed children

• Published in: Neurotoxicology and teratology Vol. 23; no. 2; pp. 141 - 146
• Main Authors: Grandjean, Philippe, White, Roberta F, Sullivan, Kimberly, Debes, Frodi, Murata, Katsuyuki, Otto, David A, Weihe, Pal
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01-03-2001; Elsevier Science
• Subjects: Bender-Gestalt Test; Biological and medical sciences; Chemical and industrial products toxicology. Toxic occupational diseases; Child; Cohort Studies; Contrast Sensitivity - drug effects; Contrast sensitivity/physiology; Embryology: invertebrates and vertebrates. Teratology; Evoked Potentials, Visual - drug effects; Female; Functional Laterality - physiology; Fundamental and applied biological sciences. Psychology; Humans; Male; Medical sciences; Mercury - toxicity; Metals and various inorganic compounds; Methylmercury compounds; Methylmercury Compounds - toxicity; Neuropsychological Tests; Prenatal exposure delayed effects; Preschool child; Psychomotor Performance - drug effects; Teratology. Teratogens; Toxicology; Visual Acuity - drug effects; Visual acuity/physiology; Preschool child; Visual acuity/physiology; Contrast sensitivity/physiology; Methylmercury compounds; Neuropsychological tests; Prenatal exposure delayed effects; Human; Cognitive disorder; Toxicity; Vision disorder; Neuropsychological test; Visual evoked potential; Developmental disorder; Cognition; In utero; Heavy metal; Pregnancy; Visual system; Sensitivity; Visual stimulus; Investigation method; Teratogen; Child; Mercury
• ISSN: 0892-0362; 1872-9738
• DOI: 10.1016/S0892-0362(01)00134-9

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.