Reduced cognitive abilities in lead-exposed men.

Objectives: Since it is still controversial whether-low-to moderate long-term lead exposure below current threshold values causes neurobehavioural deficits in adults, we investigated executive functions of the prefrontal cortex, attention, and visuospatial and visuomotor functioning in lead-exposed subjects.

Methods: Forty-seven lead-exposed subjects with a mean blood lead (PbB) level of 30.8 microg/100 ml and 53 non-lead-exposed aged-matched subjects (PbB: 4.32 microg/100 ml) with the same socio-economic background were investigated. Both groups were also matched on verbal intelligence. Neuropsychological tests were done by 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 current and cumulative measures.

Results: While there were significant differences in the results of the Wisconsin, block design and visual recognition tests, no differences were found in simple reaction time, choice reaction and digit symbol substitution. Significant correlations existed between current exposure and cognitive deficits. No correlation was found between cumulative exposure measures and cognitive parameters.

Conclusions: Our results show that PbB below 70 microg/100 ml reduce neurobehavioural abilities, particularly visuospatial abilities and executive functions referring to the prefrontal cortex. As neurobiological substrate of the prefrontal dysfunction, glutamatergic system disturbances are discussed.