| Patients (n = 259) | Controls (n = 96) | T or χ2 | F | p (Effect size) |
---|---|---|---|---|---|
Age, mean (SD) years | 8.8 (2.4) | 10.5 (3.0) | 4.957 | 11.306 | < .001a (0.63*) |
Male, n (%) | 202 (78.0) | 52 (54.2) | 19.531 | Â | < .001a (0.51**) |
IQ, mean (SD) | 105.9 (14.5) | 113.3 (16.4) | 4.100 | 1.668 | < .001a (0.48*) |
ADHD subtypes, n (%) | |||||
Combined | 73 (28.4) | Â | Â | Â | Â |
Inattentive | 98 (38.1) | Â | Â | Â | Â |
Hyperactive-impulsive | 57 (22.2) | Â | Â | Â | Â |
Not otherwise specified | 29 (11.3) | Â | Â | Â | Â |
ADHD Rating Scale, mean (SD) | |||||
Inattention | 15.0 (5.6) | 3.6 (4.0) | −20.343 | 15.542 | < .001a (2.76*) |
Hyperactivity-impulsivity | 10.2 (6.5) | 1.7 (2.0) | −17.769 | 88.912 | < .001a (2.02*) |
Total | 25.2 (10.7) | 5.5 (5.7) | −21.239 | 34.852 | < .001a (2.30*) |
Continuous Performance Test, mean (SD) | |||||
Omission errors | 65.5 (20.4) | 53.5 (15.1) | −5.879 | 33.913 | < .001a (0.70*) |
Commission errors | 65.5 (19.2) | 55.5 (15.2) | −5.028 | 16.181 | < .001a (0.58*) |
Response time | 55.4 (12.1) | 54.4 (13.2) | −0.669 | 0.402 | .504 (0.08*) |
Response time variability | 63.3 (17.9) | 50.8 (15.4) | −6.402 | 10.405 | < .001a (0.75*) |
Stroop Color-Word Test, mean (SD) | |||||
Word reading score | 44.0 (11.6) | 49.0 (9.5) | 0.692 | 3.755 | < .001a (0.47*) |
Color naming score | 45.4 (10.9) | 50.9 (9.7) | 0.846 | 4.244 | < .001a (0.53*) |
Color-Word score | 45.3 (12.5) | 50.3 (11.9) | 0.546 | 3.344 | .001a (0.41*) |
Interference score | 52.5 (11.3) | 49.1 (13.8) | 3.067 | −2.311 | .021a (0.27*) |
Environmental measure, mean (SD) | |||||
Lead (μg/dL) | |||||
Total | 1.4 (.5) | 1.3 (.5) | −2.818 | 0.526 | .005a (0.20*) |
Male | 1.5 (0.5) | 1.4 (0.6) | 0.775 | 0.808 | .439 (0.18*) |
Female | 1.3 (0.5) | 1.1 (0.3) | 2.432 | 7.295 | .017a (0.49*) |
Genotype | |||||
DAT1, n (%)* | Â | Â | 1.288 | Â | .525 (0.15**) |
10/10 | 217 (83.8) | 85 (88.5) | Â | Â | Â |
With a 10 | 39 (15.1) | 10 (10.4) | Â | Â | Â |
Without 10 | 3 (1.2) | 1 (1.0) | Â | Â | Â |
DRD4, n (%)* | Â | Â | 0.742 | Â | .690 (0.08**) |
With 4/4 | 146 (56.4) | 58 (60.4) | Â | Â | Â |
With a 4 | 99 (38.2) | 32 (33.3) | Â | Â | Â |
Without 4 | 14 (5.4) | 6 (6.3) | Â | Â | Â |
ADRA2A MspI, n (%)* | Â | Â | 0.470 | Â | .791 (0.03**) |
C/C | 30 (11.6) | 12 (12.5) | Â | Â | Â |
G/C | 113 (43.6) | 38 (39.6) | Â | Â | Â |
G/G | 116 (44.8) | 46 (47.9) | Â | Â | Â |
ADRA2A DraI, n (%)* | Â | Â | 1.833 | Â | .400 (0.16**) |
C/C | 80 (30.9) | 23 (24.0) | Â | Â | Â |
C/T | 125 (48.3) | 53 (55.2) | Â | Â | Â |
T/T | 54 (20.8) | 20 (20.8) | Â | Â | Â |