Lead exposure levels and duration of exposure absence predict neurobehavioral performance

We investigated cognitive functions in currently lead exposed and formerly lead exposed men. The aim of the study was to verify the hypothesis that lead induced cognitive deficits are reversible.

Forty-seven lead exposed subjects with a mean blood level (PbB) of 30.8 microg/100 ml and 48 formerly exposed aged-matched subjects (PbB: 5.5 microg/100 ml) with the same socio-economic background were investigated. Both groups were matched on verbal intelligence. Cognitive functions were assessed by using the Modified Wisconsin Card Sorting Test, Block Design Test, Visual Recognition Test, Simple Reaction Time, Choice Reaction and Digit Symbol Substitution. Lead exposure was assessed by using current and cumulative measures. The sample was divided according to their exposure duration versus exposure absence into four groups for subsequent ANOVA models analyses.

Currently exposed men performed significantly worse in the Wisconsin Test and Block Design Test. No differences were found in the Visual Recognition Test, Simple Reaction Time, Choice Reaction and Digit Symbol Substitution. Splitting the sample according to their exposure duration versus exposure absence resulted in better cognitive performance of subjects with shorter exposure duration and longer exposure absence in the Block Design Test and the Wisconsin Test.

Our results provide further evidence that cognitive deficits induced by occupationally lead are most likely reversible.