Table 1.
Descriptive statistics of study participants, with respect to familial risk and stimulant drug use, if not stated otherwise, shown in means and SD in parentheses
| No familial risk | Familial risk | Familial risk vs. no fam. risk | Drug use vs. no drug use | |||||
| No stimulant use | Stimulant use | No stimulant use | Stimulant use | |||||
| Demographics | Mean (±SD) | Mean (±SD) | Mean (±SD) | Mean (±SD) | F, t, or χ2 P | F, t, or χ2 P | ||
| Number | 48 | 25 | 47 | 42 | 162 | 162 | ||
| Gender, % male | 63% | 48% | 51% | 95% | 3.7 | 0.056 | 7.5 | 0.006 |
| Handedness, % right | 85% | 84% | 89% | 81% | 0.01 | 0.934 | 0.9 | 0.352 |
| Ethnicity, white: black: Asian: mixed | 48: 0: 0: 0 | 25: 0: 0 | 36: 4: 2: 5 | 32: 3: 2: 5 | 20.7 | 0.001 | 0.8 | 0.560 |
| Age, y | 32.4 (±8.8) | 28.4 (±6.7) | 32.2 (±8.2) | 34.7 (±7.7) | 2.7 | 0.103 | 0.1 | 0.797 |
| Body mass index | 25.2 (±3.3) | 24.8 (±4.2) | 26.3 (±5.6) | 24.7 (±3.9) | 0.6 | 0.451 | 2.3 | 0.127 |
| Duration of formal education, y | 12.7 (±1.9) | 13.4 (±1.8) | 12.2 (±2.0) | 11.6 (±1.6) | 12.2 | 0.001 | 0.3 | 0.586 |
| Verbal intelligence, NART score | 112.6 (±7.9) | 116.2 (±5.2) | 108.6 (±8.9) | 110.4 (±7.1) | 14.2 | <0.001 | 1.5 | 0.216 |
| Childhood adversity, CTQ abuse | 17.5 (±5.4) | 18.5 (±3.9) | 24.3 (±10.8) | 27.0 (±11.9) | 28.5 | <0.001 | 32 | 0.077 |
| Community Integration, CIQ-II score | 17.9 (±3.2) | 18.3 (±2.9) | 17.6 (±3.4) | 14.4 (±3.9) | 9.8 | 0.002 | 7.1 | 0.009 |
| Disposable income, £ per month | 663.8 (±938.3) | 710.4 (±1149.7) | 403.8 (±4.13.5) | 415.2 (±667.1) | 5.0 | 0.026 | 0.02 | 0.883 |
| Alcohol consumption, AUDIT score | 3.2 (±2.3) | 5.7 (±1.6) | 4.0 (±4.6) | 11.3 (±10.9) | 7.0 | 0.009 | 23.7 | <0.001 |
| Tobacco, % never/current/past | 43/15/42 | 12/72/16 | 4/58/38 | 2/93/5 | 36.8 | <0.001 | 36.9 | <0.001 |
| Cannabis, % never/current/past | 79/0/21 | 0/44/56 | 26/17/57 | 0/69/31 | 30.3 | <0.001 | 70.1 | <0.001 |
| Age of onset tobacco use, y | 16.2 (±2.8) | 16.1 (±4.0) | 14.5 (±2.1) | 13.1 (±3.0) | 19.6 | <0.001 | 2.8 | 0.094 |
| Age of onset cannabis use, y | 17.9 (±4.2) | 16.6 (±2.4) | 17.8 (±4.3) | 15.0 (±2.8) | 0.8 | 0.367 | 10.7 | <0.001 |
| Age of onset stimulant drug use, y | – | 19.0 (±2.7) | – | 16.4 (±2.5) | 4.1 | <0.001 | ||
The term “stimulant use” does not reflect severity and includes both recreational and addictive use. Verbal intelligence estimated by the National Adult Reading Test (NART), childhood adversity assessed by the abuse score of the Childhood Trauma Questionnaire (CTQ), community integration was evaluated from the Community Integration Questionnaire Version 2 (CIQ-II), and alcohol consumption assessed by the Alcohol Use Disorders Identification Test (AUDIT).