Table 1.
Demographic and clinical features of study participants. IQ were only available for around half the cases, and only one of the non-affected children (ADHD sibling with an IQ of 116). Three cases (one each of ADHD, ASD, and comorbid ADHD+ASD) furthermore had the diagnosis mental retardation (F70F71), while one ADHD case were diagnosed with borderline intellectual functioning (R41.8). Feces consistency described the fecal sample that was investigated and was rated by the parents according to the Bristol stool chart. All participants using Polyethylene Glycol 3350 (MovicolTM) were diagnosed with chronic constipation. No other medications targeting gastrointestinal symptoms were utilized by the study participants. Study participants were in some cases, evaluated with more than one diagnostic instrument. For a few study participants, the diagnostic instrument used for diagnosis, or the specific type of ADHD medication were not specified. ADOS2: the Autism Diagnostic Observation Schedule 2nd edition. ADHD-RS: ADHD rating scale. T.O.V.A: Test of Variables of Attention. KSADS-COMP: Kiddie Schedule for Affective Disorders and Schizophrenia, Computer version. Only the specified ADHD medications were utilized amongst children included in this manuscript, which corresponds to the most commonly used ADHD medications prescribed to children and adolescents in Denmark. Statistical significance is presented as □ = p < 0.05 compared to ADHD cases, ○ = p < 0.05 compared to ASD cases, ▲= p < 0.05 compared to comorbid ADHD/ASD.
| ADHD |
ASD |
Comorbid ADHD/ASD |
Non-related controls | ||||
|---|---|---|---|---|---|---|---|
| Features | Cases n = 32 |
Siblings n = 14 |
Cases n = 12 |
Siblings n = 5 |
Cases n = 11 |
Siblings n = 4 |
N = 17 |
| Samples available (n) | |||||||
| Feces | 32 | 14 | 12 | 5 | 11 | 4 | 17 |
| Blood plasma | 30 | 13 | 9 | 3 | 9 | 4 | 17 |
| Age, years (Median, Q1-Q3) |
9 (8–11) |
8 (6–9) |
12 (10–14) |
15 (10–15) |
11 (10–13) |
11 (10–12) |
10 (8–12) |
| Gender (male) % | 65.6 | 57.1 | 75.0 | 60.0 | 81.8 | 50.0 | 52.9 |
| IQ (Median, Q1-Q3) |
90.5 (82–100) |
- | 92 (83–109) |
- | 104 (93–108) |
- | - |
| Constipation, % | 15.6 | 7.1 | 8.3 | 0.0 | 18.2 | 0.0 | 5.9 |
| Abdominal pain, % | 3.1 | 0.0 | 16.7 | 0.0 | 18.2 | 0.0 | 0.0 |
| GI reflux, % | 3.1 | 0.0 | 0.0 | 0.0 | 9.1 | 0.0 | 0.0 |
| Feces consistency, % | |||||||
| 1–2 | 9.4 | 21.4 | 16.7 | 20.0 | 18.2 | 0.0 | 0.0 |
| 3–5 | 84.4 | 64.3 | 83.3 | 80.0 | 81.8 | 100 | 94.1 |
| 6–7 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| NA | 6.3 | 14.3 | 0.0 | 0.0 | 0.0 | 0.0 | 5.9 |
| Diet, % | |||||||
| Atypical diet | 9.4 | 0.0 | 50.0 | 0.0 | 9.1 | 0.0 | 5.9○ |
| Vitamins | 15.6 | 14.3 | 33.3 | 40.0 | 27.3 | 50.0 | 35.3 |
| Fish oil | 15.6 | 14.3 | 8.3 | 0.0 | 18.2 | 0 | 0.0 |
| Diagnostic instrument, % | |||||||
| ADOS2 | 3.1 | 7.1 | 66.7 | 0.0 | 54.5 | 0.0 | 0.0 |
| ADHD-RS | 87.5 | 7.1 | 25.0 | 0.0 | 45.5 | 0.0 | 0.0 |
| T.O.V.A | 62.6 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0% |
| KSADS-COMP | 6.2 | 0.0 | 8.3 | 0.0 | 0.0 | 0.0 | 0.0 |
| Not specified | 12.5 | 0.0 | 33.3 | 0.0 | 27.3 | 0.0 | 0.0 |
| Not tested | 0.0 | 92.9 | 0.0 | 100.0 | 0.0 | 100.0 | 100.0 |
| Medication, % | |||||||
| ADHD medication | 46.9 | 0.0□ | 0.0 | 0.0 | 36.4 | 0.0▲ | 0.0□▲ |
| Methylphenidate | 73.3 | 0.0□ | 0.0 | 0.0 | 75.0 | 0.0▲ | 0.0□▲ |
| Lisdexamfetamine | 13.3 | 0.0□ | 0.0 | 0.0 | 0.0 | 0.0 | 0.0□ |
| Dexamfetamine | 0.0 | 0.0 | 0.0 | 0.0 | 25.5 | 0.0▲ | 0.0▲ |
| Atomoxetine | 6.6 | 0.0□ | 0.0 | 0.0 | 0.0 | 0.0 | 0.0□ |
| Not specified | 6.6 | 0.0□ | 0.0 | 0.0 | 0.0 | 0.0 | 0.0□ |
| Polyethylene Glycol 3350 | 12.5 | 7.1 | 0.0 | 0.0 | 18.2 | 0.0 | 5.9 |