TABLE 1.
Demographic Characteristics
| Characteristic | Controls (n = 33) | ADHD-all (n = 26) | ADHD-C (n = 14) | ADHD-I (n = 12) | p |
|---|---|---|---|---|---|
| Age, y | 10.4 ± 1.7 | 10.2 ± 1.6 | — | — | .579 |
| 10.4 ± 1.7 | — | 9.5 ± 1.4 | 10.9 ± 1.5 | .072 | |
| IQ | 106.3 ± 11.6 | 107 ± 10.8 | — | — | .806 |
| 106.3 ± 11.6 | — | 107.6 ± 8.9 | 106.3 ± 13 | .934 | |
| Inattentiona symptoms | 19 ± 4.6 | 19.6 ± 5.2 | .765 | ||
| Hyperactive-impulsivea symptoms | 16.2 ± 4.9 | 6.1 ± 3.1 | <.001 | ||
| Sex | 17:16 | 16:10 | — | — | .307 |
| (male:female) | 17:16 | — | 11:3 | 5:7 | .125 |
| Raceb | 25:8 | 15:11 | — | — | .116 |
| (white:nonwhite) | 25:8 | — | 7:7 | 8:4 | .224 |
| SESc | 16:17 | 11:15 | — | — | .417 |
| (high school:college) | 16:17 | — | 6:8 | 5:7 | .893 |
| Stimulant naïve (no vs. yes) | NA | — | 11:3 | 6:6 | .133 |
| Current stimulant (yes vs. no) | NA | — | 9:5 | 6:6 | .368 |
Note: For age, IQ, inattention symptoms, and hyperactive-impulsive symptom, data are presented as mean ± SD and were analyzed by one-way analysis of variance or t test. For sex, race, SES, stimulant naïve, and current stimulant, data are presented as ratios and were analyzed by χ2 —exact significance: one-sided for two-group comparisons, two-sided for three-group comparisons. ADHD = attention-deficit/hyperactivity disorder; ADHD-all = all children with ADHD; ADHD-C = ADHD-combined type; ADHD-I = ADHD-predominantly inattentive type; NA = not applicable; SES = socioeconomic status.
Inattention and hyperactive-impulsive symptom scores are presented from the Vanderbilt scales and range from 12 to 27 when consistent with DSM-IV criteria (6 or more symptoms at a level of 2 [often] or 3 [very often]).
U.S. Census Bureau race/ethnicity categories were collapsed into white versus nonwhite because the only nonwhite group represented was African American.
Socioeconomic status as indicated by maternal education.