Table 1.
Demographic and impulsivity measures for healthy volunteers and cocaine-dependent individuals
| Group characteristics | Healthy volunteers | Cocaine dependent | t-value or χ2 | P-value |
|---|---|---|---|---|
| Demographics | n = 60 | n = 60 | ||
| Age (years) | 32.3 ± 8.3 | 32.5 ± 8.5 | −0.12 | 0.905 |
| Gender (M : F) | 46 : 14 | 53 : 7 | 2.83 | 0.148 |
| IQ (NART) | 110.0 ± 7.0 | 109.5 ± 6.9 | 0.36 | 0.716 |
| Depressive mood (BDI-II total score) | 2.1 ± 3.2 | 13.2 ± 11.6 | −7.20 | <0.001 |
| Education (years of formal education) | 12.3 ± 1.6 | 11.5 ± 1.7 | 2.78 | 0.006 |
| Trait-impulsivity (BIS-11 scale, total score) | 60.8 ± 7.5 | 76.4 ± 9.6 | −9.89 | <0.001 |
| BIS-11 attention | 14.3 ± 2.8 | 18.6 ± 3.9 | −6.91 | <0.001 |
| BIS-11 motor | 22.8 ± 3.3 | 27.5 ± 5.4 | −5.77 | <0.001 |
| BIS-11 non-planning | 23.8 ± 4.0 | 31.3 ± 4.3 | −8.63 | <0.001 |
| Anxiety-avoidance (BIS/BAS scale) | ||||
| BIS score | 18.6 ± 3.4 | 19.4 ± 3.7 | −1.14 | 0.258 |
| Reward-approach (BIS/BAS scale) | ||||
| BAS drive | 11.0 ± 1.9 | 12.1 ± 2.6 | −2.50 | 0.014 |
| BAS fun-seeking | 12.0 ± 1.8 | 13.6 ± 1.8 | −4.91 | <0.001 |
| BAS reward responsiveness | 16.4 ± 1.9 | 16.9 ± 2.2 | −1.16 | 0.248 |
| Sustained attention (CANTAB-RVIP) | ||||
| Signal detection (A’) | 0.92 ± 0.05 | 0.89 ± 0.04 | 3.22 | 0.002 |
| Response bias (B′′) | 0.9 ± 0.3 | 1.0 ± 0.0 | −1.71 | 0.093 |
| Commission errors (number) | 1.5 ± 2.1 | 1.0 ± 1.2 | 1.42 | 0.158 |
| Omission errors (number) | 8.5 ± 4.8 | 11.5 ± 4.7 | −3.43 | 0.001 |
| Correct responses/hits (number) | 18.5 ± 4.8 | 15.5 ± 4.7 | 3.42 | 0.001 |
| Mean reaction time (ms) | 407.8 ± 96.3 | 439.4 ± 85.2 | −1.89 | 0.061 |
| Response inhibition (stop-signal task) | ||||
| Percentage of successful stops | 54.4 ± 3.1 | 53.4 ± 4.8 | 1.32 | 0.189 |
| Mean reaction time on successful Go-trials (ms) | 481.3 ± 61.6 | 532.9 ± 87.7 | −3.68 | <0.001 |
| Mean reaction time on unsuccessful Stop-trials (ms) | 447.1 ± 51.2 | 476.7 ± 56.0 | −2.97 | 0.003 |
| Stop-signal reaction time (ms) | 234.9 ± 46.2 | 263.2 ± 55.2 | −3.01 | 0.003 |
| Post-stop slowing (ms) | 485.7 ± 99.2 | 560.1 ± 253.1 | −2.10 | 0.038 |
| Principal components | F(1,111) | P-value | ||
| Inattention | − 0.51 ± 0.81 | 0.54 ± 0.90 | 19.43 | <0.001 |
| Impulsive reward-seeking | − 0.40 ± 0.89 | 0.42 ± 0.94 | 17.16 | <0.001 |
| Response slowing | 0.00 ± 0.92 | 0.00 ± 1.09 | 0.32 | 0.572 |
| Impulsive responding | 0.27 ± 1.00 | −0.28 ± 0.92 | 3.30 | 0.072 |
| Anxious responding | −0.03 ± 1.09 | 0.03 ± 0.91 | 0.60 | 0.439 |
BDI-II = Beck Depression Inventory, Version 2; BIS-11 = Barratt Impulsiveness Scale; BIS/BAS = Behavioural Inhibition/Activation System scale; CANTAB = Cambridge Neuropsychological Test Automated Battery; NART = National Adult Reading Test.