Skip to main content
. Author manuscript; available in PMC: 2015 Dec 22.
Published in final edited form as: JAMA Pediatr. 2015 Sep;169(9):822–829. doi: 10.1001/jamapediatrics.2015.1475

Table 4.

Socioeconomic Status, Brain Development, and WASI Scores in the National Institutes of Health Magnetic Resonance Imaging Study of Normal Brain Developmenta

Variable Frontal Lobe, β Temporal Lobe, β Hippocampus, β Amygdala, β
WASI full-scale IQ (n = 802)
 Direct effect −6.92 −6.61 −6.88 −7.62
 Indirect effect −1.08 −1.4 −1.12 −0.41
  Percentile 95% CI −1.96 to −0.34 −2.37 to −0.52 −1.97 to −0.39 −1.00 to 0.03
  Bias-corrected 95% CI −1.98 to −0.36 −2.43 to −0.57 −1.98 to −0.41 −1.09 to −0.001
 Indirect/total effect 0.14 0.17 0.14 0.05
WASI performance IQ (n = 802)
 Direct effect −5.65 −5.32 −5.66 −6.37
 Indirect effect −1.09 −1.43 −1.08 −0.4
  Percentile 95% CI −2.00 to −0.34 −2.47 to −0.57 −1.86 to −0.39 −0.97 to 0.017
  Bias-corrected 95% CI −2.08 to −0.40 −2.56 to −0.63 −1.92 to −0.44 −1.05 to −0.02
 Indirect/total effect 0.16 0.21 0.16 0.06
WASI verbal IQ (n = 802)
 Direct effect −6.67 −6.46 −6.57 −7.2
 Indirect effect −0.83 −1.05 −0.93 −0.33
  Percentile 95% CI −1.53 to −0.26 −1.90 to −0.39 −1.67 to −0.31 −0.86 to 0.015
  Bias-corrected 95% CI −1.58 to −0.29 −1.97 to −0.45 −1.72 to −0.35 −0.95 to −0.02
 Indirect/total effect 0.11 0.14 0.12 0.04

Abbreviation: WASI, Wechsler Abbreviated Scale of Intelligence.

a

Mediation analyses correspond to specifications in eTable 9 in the Supplement. Estimates of the direct and indirect (mediated through influence on structural brain development) effects of low income on a standardized test of achievement are shown. Mean (SD) tests scores are standardized (100 [15]). Standard errors have been bootstrapped. The 95% CIs were constructed using bootstrap resampling with 5000 iterations.