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Do children with falling blood lead levels have improved cognition?
Xianchen Liu1, Kim N Dietrich, Jerilynn Radcliffe
1Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
Pediatrics
|October 3, 2002
Summary
Cognitive improvements in children with elevated blood lead levels were observed in a study, but these gains were not directly linked to lead reduction via chelation therapy. Other factors appear to influence cognitive development.
Area of Science:
- Environmental Health
- Pediatric Neurology
- Toxicology
Background:
- Lead exposure in urban children is linked to impaired cognitive development.
- Previous studies yielded conflicting results on the efficacy of chelation therapy for improving IQ in children with lead exposure.
Purpose of the Study:
- To re-analyze data from a randomized clinical trial on chelation therapy for lead exposure.
- To investigate the association between changes in blood lead levels and cognitive development in young children.
Main Methods:
- A secondary analysis of a randomized trial involving 741 children (13-33 months old) with blood lead levels of 20-44 microg/dL.
- Blood lead levels and cognitive test scores were measured at baseline, 6 months, and 36 months.
- Change in blood lead level was used as the independent variable to assess its impact on cognitive test scores.
Main Results:
- Blood lead levels decreased similarly in both chelation and placebo groups by 6 months.
- No association was found between blood lead level reduction and cognitive score changes at 6 months.
- In the placebo group, cognitive scores increased by 4.0-5.1 points per 10 microg/dL fall in blood lead level from baseline to 36 months.
Conclusions:
- Cognitive improvements in children with lead exposure may be influenced by factors other than the direct effect of lead level reduction.
- The active drug, succimer, is unlikely to be responsible for cognitive impairment, though it cannot be entirely ruled out.