Table 4.
Associations between physical problems and ADHD symptoms in MZ and DZ twin pairs differing for ADHD symptoms (p value unadjusted).
| Outcome: ADHD symptoms (CBCL/ABCL-attention subscale) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Monozygotic twins | Dizygotic twins | |||||||||||
| All ages, n = 44 pairs | Children, n = 33 pairs | All ages, n = 61 pairs | Children, n = 44 pairs | |||||||||
| β | s.e | p | β | s.e | p | β | s.e | p | β | s.e | p | |
| Exposure variable | ||||||||||||
| Infectious diseases | − 0.27 | 0.24 | 0.257 | − 0.32 | 0.25 | 0.197 | − 1.29 | 0.97 | 0.183 | − 0.37 | 0.94 | 0.690 |
| Covariate 1 | ||||||||||||
| Full-scale IQ | − 0.13 | 0.05 | 0.011 | − 0.16 | 0.08 | 0.033 | − 0.10 | 0.05 | 0.059 | − 0.10 | 0.06 | 0.082 |
| Covariate 2 | ||||||||||||
| ASD | 1.09 | 1.33 | 0.416 | 0.53 | 1.74 | 0.760 | 3.19 | 1.70 | 0.061 | 0.88 | 1.93 | 0.648 |
| Covariate 3 | ||||||||||||
| ADHD medication | 2.94 | 1.46 | 0.044 | 1.42 | 0.65 | 0.029 | 4.75 | 1.50 | 0.001 | 6.57 | 1.20 | < 0.001 |
| Covariate 4 | ||||||||||||
| Gender | – | – | – | – | – | – | − 2.08 | 1.16 | 0.074 | − 1.75 | 1.11 | 0.116 |
| Exposure variable | ||||||||||||
| Neurological Problems | − 0.20 | 0.73 | 0.786 | 0.00 | 0.78 | 0.995 | − 0.96 | 1.23 | 0.436 | 0.25 | 1.27 | 0.842 |
| Covariate 1 | ||||||||||||
| Full-scale IQ | − 0.14 | 0.06 | 0.016 | − 0.16 | 0.08 | 0.039 | − 0.12 | 0.06 | 0.042 | − 0.10 | 0.06 | 0.092 |
| Covariate 2 | ||||||||||||
| ASD | 1.33 | 1.35 | 0.325 | 0.57 | 1.80 | 0.750 | 2.84 | 1.57 | 0.071 | 0.72 | 1.84 | 0.697 |
| Covariate 3 | ||||||||||||
| ADHD medication | 3.11 | 1.71 | 0.070 | 1.41 | 1.31 | 0.280 | 4.69 | 1.61 | 0.004 | 6.81 | 1.25 | < 0.001 |
| Covariate 4 | ||||||||||||
| Gender | – | – | – | – | – | – | − 1.96 | 1.22 | 0.110 | − 1.91 | 1.18 | 0.105 |
| Exposure variable | ||||||||||||
| Gastrointestinal problems | − 1.69 | 1.01 | 0.095 | − 2.72 | 0.83 | 0.001 | 2.97 | 1.76 | 0.092 | 0.50 | 2.39 | 0.834 |
| Covariate 1 | ||||||||||||
| Full-scale IQ | − 0.11 | 0.05 | 0.040 | − 0.16 | 0.07 | 0.035 | − 0.09 | 0.05 | 0.070 | − 0.10 | 0.06 | 0.069 |
| Covariate 2 | ||||||||||||
| ASD | 1.25 | 1.19 | 0.294 | 0.26 | 1.52 | 0.867 | 2.55 | 1.64 | 0.121 | 0.69 | 1.79 | 0.700 |
| Covariate 3 | ||||||||||||
| ADHD medication | 2.83 | 1.88 | 0.131 | 0.27 | 1.27 | 0.833 | 5.87 | 0.99 | < 0.001 | 6.74 | 1.12 | < 0.001 |
| Covariate 4 | ||||||||||||
| Gender | – | – | – | – | – | – | − 1.93 | 0.94 | 0.040 | − 1.80 | 1.10 | 0.100 |
| Exposure variable | ||||||||||||
| Immunological Problems | − 0.76 | 0.78 | 0.326 | − 0.71 | 0.86 | 0.409 | − 0.92 | 0.78 | 0.238 | − 0.84 | 0.82 | 0.308 |
| Covariate 1 | ||||||||||||
| Full-scale IQ | − 0.12 | 0.06 | 0.046 | − 0.15 | 0.08 | 0.063 | − 0.10 | 0.05 | 0.034 | − 0.10 | 0.05 | 0.060 |
| Covariate 2 | ||||||||||||
| ASD | 1.16 | 1.38 | 0.400 | 0.59 | 1.81 | 0.745 | 3.34 | 1.71 | 0.050 | 1.27 | 1.97 | 0.519 |
| Covariate 3 | ||||||||||||
| ADHD medication | 2.89 | 1.61 | 0.072 | 1.15 | 0.65 | 0.077 | 4.41 | 1.61 | 0.006 | 6.31 | 1.20 | < 0.001 |
| Covariate 4 | ||||||||||||
| Gender | – | – | – | – | – | – | − 2.33 | 0.99 | 0.018 | − 1.97 | 0.92 | 0.032 |
Bold value indicate statistical significance
*p < 0.0125.
With Bonferroni correction, the significance level of p values in this table is set at p < 0.0125.
ADHD attention-deficit/hyperactivity disorder, ASD autism spectrum disorder, CBCL the Child Behavior Checklist, ABCL Adult Behaviour Checklist.