Table 3-.
Mediation analysis of childhood Pb exposure on adolescent externalizing behaviors, using childhood behavior scores as mediator. Regression coefficients (95% CI) and fit indices (n=212).
| Adolescent | |||
|---|---|---|---|
| Mediator | Externalizing Estimate (95% CI) |
Hyperactivity-impulsivity Estimate (95% CI) |
Conduct disorder Estimate (95% CI) |
| Child externalizing (log2-transformed) | |||
| Child Pb → Child externalizinga | 0.42 (0.15, 0.69) | ||
| Child externalizing → Adolescent externalizingb | 0.77 (0.15, 1.36) | ||
| Direct effect | 0.61 (−0.63, 1.96) | ||
| Indirect effect | 0.32 (0.08, 0.72) | ||
| χ2(df), p-value | 10.24(8), 0.25 | ||
| CFI | 0.92 | ||
| RMSEA (90% CI) | 0.04 (0.00, 0.09) | ||
| Child hyperactivity-impulsivity | |||
| Child Pb → Child hyperactivity-impulsivitya | 0.58 (0.17, 0.99) | ||
| Child hyperactivity-impulsivity → Adolescent hyperactivity-impulsivityc | −0.03 (−0.12, 0.06) | ||
| Direct effect | 0.11 (−0.14, 0.37) | ||
| Indirect effect | −0.02 (−0.09, 0.03) | ||
| χ2(df), p-value | 5.01(8), 0.75 | ||
| CFI | 1.00 | ||
| RMSEA (90% CI) | <0.01 (0.00, 0.06) | ||
| Child oppositional defiant/conduct disorder | |||
| Child Pb → Child OD/CDa | 0.67 (0.11, 1.25) | ||
| Child OD/CD → Adolescent conduct disorderd | 0.02 (−0.03, 0.08) | ||
| Direct effect | 0.02 (−0.20, 0.21) | ||
| Indirect effect | 0.02 (−0.01, 0.07) | ||
| χ2(df), p-value | 7.29(7), 0.40 | ||
| CFI | 0.98 | ||
| RMSEA (90% CI) | 0.01 (0.002, 0.09) | ||
Note : CI, Confidence interval; χ2(df), chi square (degrees of freedom); CFI, comparative fit index; RMSEA, root mean square error of approximation; OD/CD, Oppositional defiant/conduct disorder.
Adjusted for child age and sex, SES, age of the biological mother at delivery, maternal tobacco smoking during pregnancy, and birth weight. Models with child hyperactivity-impulsivity and child OD/CD as mediator were also adjusted for cord Hg (log2-transformed).
Adjusted for adolescent age and sex, provider SES, and child blood Hg (log2-transformed).
Adjusted for adolescent age and sex, provider SES, age of the biological mother at delivery and education level of the primary caregiver at child follow-up .
Adjusted for adolescent age and sex, provider SES, age of the biological mother at delivery, maternal tobacco use during pregnancy, and house crowding at adolescence follow-up.