Table 2.
Comparisons of physical problems between ADHD and non-ADHD.
| (a) Comparison in the total sample (p value unadjusted) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Physical systems | All ages | Children | Adults | |||||||||
| ADHD | Non-ADHD | t | p /H1:H0 | ADHD | Non-ADHD | t | p /H1:H0 | ADHD | Non-ADHD | t | p /H1:H0 | |
| n = 103 | n = 279 | n = 92 | n = 162 | n = 11 | n = 117 | |||||||
| Infectious diseases | ||||||||||||
| Sum of diseases for each individual, mean | 1.55 | 1.50 | 0.50 | 0.620/0.14 | 1.55 | 1.47 | 0.72 | 0.474/0.18 | 1.55 | 1.55 | − 0.01 | 0.996/0.31 |
| Measles, n (%) | 0 | 5 (1.8) | 0 | 5 (3.1) | 0 | 0 | ||||||
| Mumps, n (%) | 0 | 5 (1.8) | 0 | 0 | 0 | 5 (4.3) | ||||||
| Encephalitis, n (%) | 1 (1.0) | 2 (0.7) | 1 (1.1) | 1 (0.6) | 0 | 1 (0.9) | ||||||
| Chickenpox, n (%) | 94 (91.3) | 244 (87.5) | 84 (91.3) | 139 (85.8) | 10 (90.9) | 105 (89.7) | ||||||
| Pertussis, n (%) | 4 (3.9) | 29 (10.4) | 2 (2.2) | 7 (4.3) | 2 (18.2) | 22 (18.8) | ||||||
| Lyme disease, n (%) | 3 (2.9) | 12 (4.3) | 3 (3.3) | 8 (4.9) | 0 | 4 (3.4) | ||||||
| Scarlet fever, n (%) | 9 (8.7) | 14 (5.0) | 9 (9.8) | 10 (6.2) | 0 | 4 (3.4) | ||||||
| Frequent cold, n (%) | 22 (21.4) | 33 (11.8) | 20 (21.7) | 25 (15.4) | 2 (18.2) | 8 (6.8) | ||||||
| Frequent ear infection, n (%) | 23 (22.3) | 62 (22.2) | 20 (21.7) | 35 (21.6) | 3 (27.3) | 27 (23.1) | ||||||
| RS virus infection, n (%) | 2 (1.9) | 6 (2.2) | 2 (2.2) | 3 (1.9) | 0 | 3 (2.6) | ||||||
| Pneumonia, n (%) | 2 (1.9) | 7 (2.5) | 2 (2.2) | 5 (3.1) | 0 | 2 (1.7) | ||||||
| Neurological problems | ||||||||||||
| Sum of diseases for each individual, mean | 0.62 | 0.38 | 2.55 | 0.012*/9.21 | 0.63 | 0.38 | 2.28 | 0.024/2.99 | 0.55 | 0.37 | 0.90 | 0.372/0.42 |
| Epilepsy, n (%) | 5 (4.9) | 4 (1.4) | 4 (4.3) | 2 (1.2) | 1 (9.1) | 2 (1.7) | ||||||
| Vertigo, n (%) | 8 (7.8) | 7 (2.5) | 8 (8.7) | 4 (2.5) | 0 | 3 (2.6) | ||||||
| Headache, n (%) | 31 (30.1) | 50 (17.9) | 29 (31.5) | 31 (19.1) | 2 (18.2) | 19 (16.2) | ||||||
| Brain injury, n (%) | 13 (12.6) | 26 (9.3) | 12 (13.0) | 15 (9.3) | 1 (9.1) | 11 (9.4) | ||||||
| Hearing impairment, n (%) | 7 (6.8) | 17 (6.1) | 5 (5.4) | 9 (5.6) | ||||||||
| Gastrointestinal problems | ||||||||||||
| Sum of diseases for each individual, mean | 0.18 | 0.19 | − 0.11 | 0.916/0.13 | 0.20 | 0.17 | 0.53 | 0.600/0.16 | 0.09 | 0.22 | − 0.81 | 0.418/0.40 |
| Lactose intolerance, n (%) | 10 (9.7) | 30 (10.8) | 10 (10.9) | 16 (9.9) | 0 | 14 (12.0) | ||||||
| Gluten intolerance, n (%) | 1 (1.0) | 3 (1.1) | 1 (1.1) | 2 (1.2) | 0 | 1 (0.9) | ||||||
| Irritable bowel, n (%) | 1 (1.0) | 5 (1.8) | 0 | 1 (0.6) | 1 (9.1) | 4 (3.4) | ||||||
| Diarrhea, n (%) | 2 (1.9) | 0 | 2 (2.2) | 0 | 0 | 0 | ||||||
| Constipation, n (%) | 1 (1.0) | 4 (1.4) | 1 (1.1) | 4 (2.5) | 0 | 0 | ||||||
| Stomach problems, n (%) | 0 | 6 (2.2) | 0 | 2 (1.2) | 0 | 4 (3.4) | ||||||
| Other GI problems, n (%) | 4 (3.9) | 5 (1.8) | 4 (4.3) | 2 (1.2) | 0 | 3 (2.6) | ||||||
| Immunological problems | ||||||||||||
| Sum of diseases for each individual, mean | 0.78 | 0.68 | 0.94 | 0.348/0.19 | 0.77 | 0.74 | 0.26 | 0.793/0.15 | 0.82 | 0.60 | 0.83 | 0.410/0.40 |
| Asthma, n (%) | 21 (20.4) | 54 (19.4) | 19 (20.7) | 38 (23.5) | 2 (18.2) | 16 (13.7) | ||||||
| Eczema, n (%) | 27 (26.2) | 70 (25.1) | 24 (26.1) | 43 (26.5) | 3 (27.3) | 27 (23.1) | ||||||
| Milk allergy, n (%) | 5 (4.9) | 12 (4.3) | 5 (5.4) | 7 (4.3) | 0 | 5 (4.3) | ||||||
| Allergy to specific allergen, n (%) | 25 (24.3) | 51 (18.3) | 21 (22.8) | 32 (19.8) | 4 (36.4) | 19 (16.2) | ||||||
| Other immunological problems, n (%) | 2 (1.9) | 3 (1.1) | 2 (2.2) | 0 | 0 | 3 (2.6) | ||||||
| (b) Comparison in twins discordant for ADHD diagnosis (p value unadjusted) | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Physical systems (sum of diseases for each individual, mean) | Monozygotic twins | Dizygotic twins | ||||||||||||||
| All ages, n = 14 pairs | Children, n = 12 pairs | All ages, n = 35 pairs | Children, n = 30 pairs | |||||||||||||
| ADHD | Non-ADHD | Z | p/H1:H0 | ADHD | Non-ADHD | Z | p/H1:H0 | ADHD | Non-ADHD | Z | p/H1:H0 | ADHD | Non-ADHD | Z | p/H1:H0 | |
| Infectious diseases | 1.43 | 1.35 | − 1.00 | 0.317/0.41 | 1.42 | 1.33 | − 1.00 | 0.317/0.44 | 1.40 | 1.57 | − 0.88 | 0.378/0.26 | 1.37 | 1.53 | − 0.89 | 0.372/0.26 |
| Neurological problems | 0.64 | 0.28 | − 0.88 | 0.830/0.43 | 0.67 | 0.33 | − 0.65 | 0.516/0.39 | 0.43 | 0.37 | − 0.42 | 0.672/0.20 | 0.43 | 0.43 | − 0.04 | 0.971/0.19 |
| Gastrointestinal problems | 0.14 | 0.21 | − 0.58 | 0.564/0.31 | 0.08 | 0.25 | − 1.41 | 0.157/0.69 | 0.20 | 0.29 | − 0.54 | 0.593/0.23 | 0.23 | 0.13 | − 1.13 | 0.257/0.35 |
| Immunological problems | 1.00 | 1.07 | − 0.38 | 0.705/0.29 | 0.92 | 1.08 | − 0.82 | 0.414/0.38 | 0.51 | 0.86 | − 1.40 | 0.161/0.52 | 0.53 | 0.87 | − 1.32 | 0.186/0.46 |
| (c) Comparison in twins differing for ADHD symptoms (p value unadjusted) | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Physical systems (sum of diseases for each individual, mean) | Monozygotic twins | Dizygotic twins | ||||||||||||||
| All ages, n = 44 pairs | Children, n = 33 pairs | All ages, n = 61 pairs | Children, n = 44 pairs | |||||||||||||
| Higher attention score | Lower attention score | Z | p/H1:H0 | Higher attention score | Lower attention score | Z | p/H1:H0 | Higher attention score | Lower attention score | Z | p/H1:H0 | Higher attention score | Lower attention score | Z | p/H1:H0 | |
| Infectious diseases | 1.68 | 1.80 | − 0.28 | 0.776/0.22 | 1.67 | 1.88 | − 0.81 | 0.417/0.33 | 1.36 | 1.66 | − 2.15 | 0.032/1.13 | 1.32 | 1.55 | − 1.41 | 0.159/0.37 |
| Neurological problems | 0.59 | 0.34 | − 1.46 | 0.145/0.53 | 0.73 | 0.45 | − 1.19 | 0.236/0.42 | 0.43 | 0.51 | − 0.53 | 0.596/0.17 | 0.50 | 0.50 | − 0.16 | 0.870/0.16 |
| Gastrointestinal problems | 0.16 | 0.30 | − 2.12 | 0.034/1.47 | 0.18 | 0.36 | − 2.45 | 0.014/3.76 | 0.21 | 0.13 | − 1.00 | 0.317/0.25 | 0.16 | 0.14 | − 0.33 | 0.739/0.17 |
| Immunological problems | 1.00 | 1.16 | − 1.24 | 0.216/0.36 | 0.97 | 1.12 | − 0.91 | 0.361/0.29 | 0.57 | 0.72 | − 0.93 | 0.352/0.22 | 0.57 | 0.82 | − 1.26 | 0.209/0.36 |
*p < 0.0125.
With Bonferroni correction, the significance level of p values in this table is set at p < 0.0125. Brain injuries included hydrocephalus, cerebral palsy, intracerebral hemorrhage, congenital cerebral malformation, and concussion; other GI problems included gastroenteritis, intestinal polyps, abdominal pain, esophagitis, and biliary atresia; other immunological problems included type 1 diabetes, ankylosing spondylitis, and immunodeficiency.
H0 null hypothesis, H1 alternative hypothesis.