Table 1.
Sample characteristics.
| Risk genotype (S/S) | Other genotypes (S/L, L/L) | Test statistics | p-value | Contrasts | |||
|---|---|---|---|---|---|---|---|
| (n=60) | (n=230) | ||||||
| Gender (% male) | 58.3% | 61.7% | χ2(1)=.232 | .367 | – | ||
| ADHD (% diagnosed) | 66.7% | 63.9% | χ2(1)=.158 | .406 | – | ||
| Number of ADHD symptoms (M, SD) | |||||||
| Total | 9.75 (6.76) | 8.26 (6.32) | H(3)=3.956, w2=.01 | .047 | Risk > other | ||
| Inattention | 5.13 (3.55) | 4.66 (3.62) | H(3)=.884, w2=.00 | .347 | |||
| Hyperactivity-impulsivity | 4.62 (3.53) | 3.60 (3.20) | H(3)=4.414, w2=.02 | .036 | Risk > other | ||
|
| |||||||
| Risk males | Risk females | Other males | Other females | Test statistics | p-value | Contrastsa | |
| (n=35) | (n=25) | (n=142) | (n=88) | ||||
|
| |||||||
| Age, years (M, SD) | 17.80 (3.29) | 16.76 (3.72) | 17.22 (2.84) | 16.57 (3.51) | F(3,289)=1.52 | .208 | – |
| IQ (M, SD) | 102.08 (14.97) | 100.15 (14.98) | 98.83 (14.80) | 101.99 (13.95) | F(3,288)=1.05 | .373 | – |
| Scan site (% Amsterdam) | 48.6% | 36.0% | 53.3% | 34.1% | χ2(3)=9.35 | .025 | 2 < 3, 3 < 4 |
| Number of ADHD symptoms (M, SD) | |||||||
| Total | 10.74 (6.45) | 8.36 (7.06) | 9.04 (6.04) | 7.00 (6.60) | H(3)=10.020, w2=.03 | <.018 | 1 > 4, 3 > 4 |
| Inattention | 5.54 (3.36) | 4.56 (3.79) | 5.24 (3.48) | 3.73 (3.67) | H(3)=10.358, w2=.04 | <.016 | 1 > 4, 3 > 4 |
| Hyperactivity-impulsivity | 5.20 (3.52) | 3.80 (3.45) | 3.8 (3.08) | 3.27 (3.38) | H(3)=9.093, w2=.03 | <.028 | 1 > 3, 1 > 4 |
| Autism spectrum scorec | 10.29 (9.11) | 8.80 (8.73) | 8.47 (8.27) | 7.26 (8.35) | F(3,285)=1.13 | .337 | – |
| ODD/CD comorbidityd | 20.0% | 16.0% | 20.4% | 15.9% | χ2(3)=0.89 | .828 | – |
| History of medication use (%) | 71.0% | 63.2% | 64.2% | 50.0% | χ2(3)=5.70 | .127 | – |
a
1=males with risk genotype; 2=females with risk genotype; 3=males with other genotype; 4=females with other genotype
b
Combined symptom count from K-SADS-PL and Conners’ ADHD questionnaires
c
Using the Children’s Social Behaviour Questionnaire
d
Comorbid diagnosis of oppositional defiant disorder (ODD) or conduct disorder (CD), as determined by the K-SADS interview