Neuropsychological correlates of low-level lead exposure in school-age children: a prospective study.

The neuropsychological underpinnings of lead-associated deficits in general cognitive abilities and academic achievement were investigated in a cohort of 148 middle and upper-middle class 10 year-olds. Scores on a battery of neuropsychological tests were examined in relation to blood lead levels measured at birth and ages 6, 12, 18, 24, 57 months, and 10 years. Although numerous indices of the level, nature, and variability to children's performance on the WISC-R were associated with blood lead level measured at 24 months of age (pb24), relatively few significant associations were noted between specific measures of neuropsychological functions and pb24 (or other blood lead measurements). Some evidence was found for an association between recently measured lead levels and qualitative aspects of a child's performance (e.g. perseveration). The presence of more significant lead effects on broad-based measures of functioning than on neuropsychological tests may be attributable to the use of insensitive measures of neuropsychologic function, limitations in coverage provided by the tests, the nature of lead's CNS impact, or individual differences in biologic vulnerability to lead.