Table 2.
Relationship between urinary levels of heavy metals, ADHD clinical symptoms, and neuropsychological functions among all participants (n = 122).
| Variables | Mn | Pb | Cd | Hg | Sb | Bi |
|---|---|---|---|---|---|---|
| WISC-IV | ||||||
| Full Scale Intelligence Quotient | −0.116 | −0.294 ** | −0.185 * | −0.057 | −0.086 | −0.052 |
| Verbal Comprehension Index | −0.135 | −0.273 ** | −0.162 | 0.025 | −0.145 | −0.115 |
| Perceptual Reasoning Index | −0.006 | −0.094 | −0.155 | −0.002 | 0.024 | 0.005 |
| Working Memory Index | −0.050 | −0.393 *** | −0.158 | −0.100 | −0.122 | −0.088 |
| Processing Speed Index | −0.133 | −0.262 ** | −0.097 | 0.033 | −0.091 | −0.024 |
| Clinical measures | ||||||
| SNAP-IV parent form (I) | −0.079 | 0.231 * | −0.027 | 0.058 | 0.116 | 0.139 |
| SNAP-IV parent form (H) | −0.093 | 0.220 * | −0.095 | 0.199 * | 0.060 | 0.147 |
| SNAP-IV parent form (O) | −0.049 | 0.186 * | −0.067 | 0.160 | 0.004 | 0.161 |
| SNAP-IV teacher form (I) | 0.017 | 0.242 ** | −0.086 | 0.130 | 0.273 ** | −0.024 |
| SNAP-IV teacher form (H) | 0.027 | 0.214 * | −0.148 | 0.055 | 0.317 *** | 0.005 |
| SNAP-IV teacher form (O) | 0.000 | 0.214 * | −0.142 | 0.095 | 0.196 * | 0.026 |
Note: Data are expressed as Spearman’s correlation coefficient; * p < 0.05, ** p < 0.01, *** p < 0.001. WISC-IV, the Wechsler Intelligence Scale for Children–Fourth Edition; SNAP-IV, the Swanson, Nolan, and Pelham Version IV Scale; I, inattention scores; H, hyperactivity/impulsivity scores; O, oppositional scores.