Table 1.
Sample characteristics
| Heavy cannabis users | Controls | |||
|---|---|---|---|---|
| Baseline | Six‐month follow‐up | Baseline | Six‐month follow‐up | |
| N (% female) | 32 (34) | 30 (34) | 41 (37) | 41 (37) |
| Age, mean (SD) | 21.4 (2.4) | 21.9 (2.4) | 22.0 (2.3) | 22.5 (2.4) |
| Verbal IQ (Dutch Reading Test), mean (SD) | 104.3 (5.4) | – | 104.9 (7.4) | – |
| Alcohol use and related problems (AUDIT), mean (SD) | 6.2 (3.3) | 5.7 (3.3) | 5.0 (3.4) | 4.7 (3.2) |
| Beck Depression Inventory, mean (SD) | 7.1 (5.5) | – | 4.3 (5.0)a | – |
| ADHD self‐rating scale, mean (SD) | 5.7 (4.4) | – | 2.9 (3.0)a | – |
| Cigarette smoking (%) | 69 | 63 | 17a | 22a |
| FTND score, mean (SD) | 2.8 (2.4) | 2.9 (2.5) | 0.5 (1.2)a | 0.6 (1.2)a |
| Duration cigarette smoking (years), mean (SD) | 3.8 (3.6) | 3.8 (3.8) | 0.6 (1.6)a | 0.7 (1.7)a |
| Cigarettes per day, mean (SD) | 6.9 (7.3) | 7.6 (7.0) | 1.4 (3.6)a | 1.3 (3.0)a |
| Cannabis use lifetime (number of joints), mean (SD) | 1,619.5 (1,428.9) | 1,636.7 (1,338.1) | 4.8 (9.3) | 5.3 (10.2) |
| Cannabis use and related problems (CUDIT), mean (SD) | 12.5 (5.8) | 9.6 (6.6)b | 0 (0) | 0.2 (0.5) |
| Duration heavy cannabis use (years), mean (SD) | 2.5 (1.9) | 3.0 (1.9) | – | – |
| Onset heavy cannabis use (age), mean (SD) | 18.9 (2.3) | 18.9 (2.4) | ||
| Current cannabis use days/week, mean (SD) | 5.0 (1.5) | 4.9 (2.1) | – | – |
| Current cannabis use gram/week, mean (SD) | 3.1 (2.3) | 3.0 (3.0) | – | – |
| Self‐reported abstinence (days), mean (SD) | 1.8 (2.3) | |||
a
P < 0.001 for group comparison.
b
P < 0.05 baseline follow‐up comparison.