Table 2.
Patient characteristics
| Age (Years) | Age at 1st occurrence of symptoms (Years) | Age at 1st ADHD-diagnosis (Years) | |||||
| N (%) | Mean | SD | Mean | SD | Mean | SD | |
| All patients | 421 (100) | 11.1 | 2.74 | 4.0 | 2.03 | 8.1 | 2.59 |
| Boys | 338 (80.3) | 11.0 | 2.70 | 4.0 | 1.94 | 7.9 | 2.54 |
| Girls | 83 (19.7) | 11.6 | 2.87 | 4.3 | 2.35 | 8.8 | 2.70 |
| Combined subtype* | 278 (66.0) | 10.6 | 2.58 | 3.7 | 1.92 | 7.6 | 2.42 |
| Predominantly inattentive subtype* | 124 (29.5) | 12.4 | 2.59 | 4.7 | 1.93 | 9.2 | 2.58 |
| Predominantly hyperactive-impulsive subtype* | 6 (1.4) | 8.6 | 2.33 | 4.2 | 2.01 | 6.6 | 2.22 |
| ADHD, not otherwise specified * | 13 (3.1) | 11.7 | 3.08 | 4.8 | 3.42 | 9.6 | 2.30 |
* According to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition
ADHD = Attention-Deficit/Hyperactivity Disorder; SD = standard deviation.