Table 1.
Demographic and clinical characteristics of dopamine D4 receptor gene (DRD4) groups.
| Characteristic | 2-repeat absent N = 33 | 2-repeat present N = 19 | Test statistic | P value |
|---|---|---|---|---|
| Age (Mean ± SD years) | 9.91 ± 1.94 | 8.84 ± 1.89 | T = 1.925 | 0.060 |
| Gender (female/male) | 3/30 | 3/16 | χ2 = 0.077 | 0.782 |
| IQ (Mean ± SD) | 117.09 ± 16.74 | 115.26 ± 13.79 | T = 0.403 | 0.689 |
| Handedness (right/left) | 33/0 | 19/0 | ||
| ADHD subtype | ||||
| (inattentive/hyperactivity-impulsivity/combined) | 17/4/12 | 6/4/9 | χ2 = 2.070 | 0.355 |
| Conners parent symptom questionnaire | ||||
| Conners index of hyperactivity | 1.48 ± 0.52 | 1.61 ± 0.62 | T = −0.785 | 0.436 |
| Impulsivity-hyperactivity (IH) | 1.53 ± 0.61 | 1.70 ± 0.70 | T = −0.902 | 0.371 |
| Anxiety | 0.49 ± 0.07 | 0.50 ± 0.06 | T = −0.862 | 0.393 |
| Physical and psychological problems | 0.37 ± 0.29 | 0.41 ± 0.37 | T = 1.348 | 0.184 |
| Stroop color and word test (SCWT) | ||||
| Stroop ignored numbers | 43.18 ± 21.76 | 46.79 ± 21.42 | T = −0.579 | 0.565 |
| Stroop reaction time (RT)(s) | 2.73 ± 1.06 | 2.83 ± 1.09 | T = −0.335 | 0.739 |
| Wisconsin card sorting test (WCST) | ||||
| Perseverative errors (WCST-P) | 15.76 ± 9.31 | 15.68 ± 9.68 | T = 0.027 | 0.979 |
| Nonperseverative errors (WCST-NP) | 14.18 ± 6.50 | 12.58 ± 6.25 | T = 0.868 | 0.390 |
SD, standard deviation.