TABLE 3

Selected Effects of Supplementation on Cognitive Performance in Lead-Exposed Children

TaskMain Effect IronMain Effect ZincInteraction
Short-term effectsa,b,c
    PPVT−0.5 (−2.3 to 1.3)1.1 (−0.7 to 2.9)
    MAT−0.3 (−2.7 to 2.0)−1.5 (−3.8 to 0.9)
    Freedom From Distractibility−1.3 (−3.2 to 0.5)−0.4 (−2.2 to 1.5)
    Sternberg−0.8 (−1.5 to −0.1)−0.4 (−1.1 to 0.3)1.0 (0.1 to 2.0)d
    Figure Matching0.1 (−0.4 to 0.7)−0.1 (−0.7 to 0.4)
    Stimulus Discrimination, correct0.6 (0.2 to 1.0)d0.0 (−0.4 to 0.4)
    Stimulus Discrimination, mean decision time−0.1 (−0.2 to 0.1)−0.1 (−0.3 to 0.1)
    Visual Memory Span0.1 (−0.6 to 0.9)0.1 (−0.6 to 0.9)
    Visual Search−0.1 (−1.3 to 1.1)0.2 (−1.0 to 1.4)
    Sequencing0.2 (−0.5 to 1.0)0.1 (−0.7 to 0.8)
    Figure Design0.0 (−0.8 to 0.7)0.7 (−0.04 to 1.4)e
Long-term effectsc
    PPVT−0.6 (−2.4 to 1.1)−0.2 (−1.9 to 1.5)
    MAT−0.7 (−3.4 to 1.9)−2.2 (−4.8 to 0.4)
    Freedom From Distractibility−0.6 (−2.5 to 1.3)−0.4 (−2.5 to 1.5)
    Sternberg−0.3 (−0.8 to 0.1)0.2 (−0.2 to 0.7)
    Figure Matching−0.3 (−0.8 to 0.2)0.0 (−0.4 to 0.6)
    Stimulus Discrimination, correct0.0 (−0.4 to 0.3)−0.1 (−0.4 to 0.3)
    Stimulus Discrimination, mean decision time0.0 (−0.2 to 0.1)−0.1 (−0.2 to 0.1)
    Visual Memory Span0.3 (−0.5 to 1.2)−0.1 (−0.9 to 0.8)
    Visual Search0.4 (−1.0 to 1.8)0.0 (−1.4 to 1.3)
    Sequencing−0.4 (−1.3 to 0.5)0.9 (0.03 to 1.8)d
    Figure Design0.0 (−0.4 to 1.1)0.4 (−0.4 to 1.1)
  • a Reported as β (95% CI); dashes signify lack of interactions.

  • b Adjusted for baseline performance and baseline lead concentration.

  • c Short-term analysis was based on a sample of 519 children, and long-term analysis was based on a sample of 506 children.

  • d P < .05.

  • e P < .1.