Table 1. Descriptive statistics of Stop-signal task performance in healthy control and adult ADHD samples.
| Variable | Controls N = 62 Mean (SD) |
ADHD N = 35 Mean (SD) |
ADHD No Psychostimulants N = 25 Mean (SD) |
ADHD Psychostimulants Used N = 10 Mean (SD) |
Group Comparisons |
|---|---|---|---|---|---|
| Agea | 30.82 (8.97) | 30.86 (10.01) | 31.24(10.37) | 29.90 (9.48) | t(64.42) = −0.02, p 0.05b |
| Gender (%F) | 55% | 46% | 44% | 50% | χ2(l) = 0.42,p > 0.05b |
| Ethnicity (% Hispanic/Latino) |
35% | 17% | 20% | 10% | χ2(1) = 2.83,p > 0.05b |
| Language(% English) |
92% | 100% | 100% | 100% | χ2(1) = 1.55,p > 0.05b |
| Education | 15.10(1.75) | 14.69(1.83) | 14.28 (1.74) | 15.70 (1.70) | t(68.23) = −1.08, p > 0.05b |
| SSRT | 186.38 (52.64) | 198.85 (65.50) | 195.21 (70.80) | 207.95 (52.09) | F(1,90) = 1.09, p > 0.05b |
| Mean Go RT | 494.06 (106.06) | 500.73 (90.29) | 513.46(100.18) | 468.91 (49.57) | F(l,90) = 0.11,p > 0.05b |
| SD Go RT | 111.89 (44.62) | 109.12(39.73) | 112.28 (42.03) | 101.20 (33.98) | F(1,90) = 0.10,p 0.05b |
| Percent correct responses—Go trials |
99.18 (1.76) | 98.18 (5.46) | 97.79 (6.38) | 99.17 (1.61) | F(l,90) = 1.78,p > 0.05b |
| Percent inhibition— Stop trials |
49.45 (5.70) | 49.20 (8.69) | 49.38 (9.46) | 48.75 (6.78) | F(l,90) = 0.03,p > 0.05b |
| ACDS Inattention | NA | 33.94 (2.24) | 33.88 (2.15) | 34.10 (2.56) | t(14.36) = −0.24,p > 0.05c |
| ACDS Hyperactivity | NA | 29.49 (4.49) | 29.60 (4.32) | 29.20 (5.14) | t(14.38) = −0.22,p > 0.05c |
Each sample included participants in the range of 18-50.
Controls (N = 60) vs. all ADHD participants (N = 35).
ADHD participants not currently taking psychostimulant medication (N = 25) vs. ADHD participants currently taking psychostimulant medication (N = 10). ADHD No Psychostimulants = ADHD participants not currently taking psychostimulant medication; ADHD Psychostimulants Used = ADHD participants currently taking psychostimulant medication. %F = percent of each sample comprised of women; % Hispanic/Latino = percent of Hispanic/Latino ethnicity vs. not Hispanic/Latino; % English = percent whose primary language is English vs. Spanish; Education = number of school years competed. SSRT = Stop-signal reaction time; SD = standard deviation. ACDS = ADHD Clinical Diagnostic Scale. Square root transformation of percent correct on Go trials used in ANCOVA, but raw values presented here. Psychostimulant medications taken included preparations containing amphetamine (Adderall XR®, amphetamine and dextroamphetamine mixed salts; or dextroamphetamine sulfate, prescribed either as a generic formulation or as Dexedrine®), lisdexamfetamine dimesylate (Vyvance®), an amphetamine prodrug) or methylphenidate (Con certa® or Metadate™, both extended-release preparations).