The effect of chelation therapy with succimer on neuropsychological development in children exposed to lead.

Background: Thousands of children, especially poor children living in deter iorated urban housing, are exposed to enough lead to produce cognitive impa irment. It is not known whether treatment to reduce blood lead levels preve nts or reduces such impairment. Methods: We enrolled 780 children with blood lead levels of 20 to 44 mug pe r deciliter (1.0 to 2.1 mu mol per liter) in a randomized, placebo-controll ed, double-blind trial of up to three 26-day courses of treatment with succ imer, a lead chelator that is administered orally. The children lived in de teriorating inner-city housing and were 12 to 33 months of age at enrollmen t; 77 percent were black, and 5 percent were Hispanic. Follow-up included t ests of cognitive, motor, behavioral, and neuropsychological function over a period of 36 months. Results: During the first six months of the trial, the mean blood lead leve l in the children given succimer was 4.5 mug per deciliter (0.2 mu mol per liter) lower than the mean level in the children given placebo (95 percent confidence interval, 3.7 to 5.3 mug per deciliter [0.2 to 0.3 mu mol per li ter]). At 36 months of follow-up, the mean IQ score of children given succi mer was 1 point lower than that of children given placebo, and the behavior of children given succimer was slightly worse as rated by a parent. Howeve r, the children given succimer scored slightly better on the Developmental Neuropsychological Assessment, a battery of tests designed to measure neuro psychological deficits thought to interfere with learning. All these differ ences were small, and none were statistically significant. Conclusions: Treatment with succimer lowered blood lead levels but did not improve scores on tests of cognition, behavior, or neuropsychological funct ion in children with blood lead levels below 45 mug per deciliter. Since su ccimer is as effective as any lead chelator currently available, chelation therapy is not indicated for children with these blood lead levels. (N Engl J Med 2001;344:1421-6.) Copyright (C) 2001 Massachusetts Medical Society.