TABLE 2.
Demographic, neuropsychological and substance use characteristics for participants included in event-related potential (ERPs) analyses.
| Group (n = 64) | Controls (n = 24) | Cannabis users (n = 19) | Polydrug users (n = 21) | Three group | |
| comparisons | |||||
| F2, 61 | P | ||||
| Male/female, % | 50/50 | 52.6/47.4 | 66.7/33.3 | ||
| Age, years, mean (SD) | 28.3 (5.34) | 28.9 (5) | 27.9 (4.34) | 0.246a | 0.783 |
| Highest level of education (Years) | 16.8 (1.86) | 16.8 (2.26) | 16.3 (2.1) | 0.42a | 0.659 |
| IQ test scores | |||||
| WAIS scores Vocabulary | 13.8 (2.1) | 13 (1.73) | 13.4 (1.77) | 0.933a | 0.399 |
| WAIS scores Similarities | 13.1 (2.03) | 13.2 (2.46) | 13 (1.87) | 0.032a | 0.969 |
| WAIS scores Block design | 12.8 (2.95) | 13.3 (2.68) | 13.4 (2.71) | 0.317a | 0.73 |
| WAIS scores Matrix reasoning | 12.5 (2.28) | 13.4 (2.36) | 13 (1.94) | 0.865a | 0.426 |
| WAIS scores Digit span | 12.6 (2.64) | 12.8 (3.08) | 12.6 (3.12) | 0.046a | 0.955 |
| Diagnosed psychiatric disorders (% in group) | 16.7 | 5.7 | 4.8 | ||
| Alcohol, standard drinks per week, % | |||||
| 0 | 4.2 | 0 | 0 | ||
| <1 | 41.7 | 47.4 | 47.6 | ||
| 1–3 | 41.7 | 52.6 | 38.1 | ||
| 4–6 | 12.5 | 0 | 14.3 | ||
| 7–14 | 0 | 0 | 0 | ||
| 14≤ | 0 | 0 | 0 | ||
| Tobacco, % | |||||
| No | 75 | 47.4 | 61.9 | ||
| Occasionally | 25 | 42.1 | 28.6 | ||
| Regularly | 0 | 10.5 | 9.5 | ||
| Cannabis use pattern | |||||
| Onset age, years | – | 19.47 (5.95) | 20.06 (3.56) | ||
| Duration, years | – | 9.47 (7.73) | 8.28 (3.97) | ||
| Frequency of cannabis use (% of subjects) Lifetime | |||||
| 0 | 87.5 | 0 | 0 | ||
| Less than twice a year | 12.5 | 0 | 0 | ||
| 2–3 times per month | 0 | 0 | 9.5 | ||
| 1–3 times per week | 0 | 36.8 | 19 | ||
| 3–6 times per week | 0 | 26.3 | 28.6 | ||
| Daily | 0 | 36.8 | 33.3 | ||
| No answer | 0 | 0 | 9.6 | ||
| Frequency of cannabis use within past 30 days | |||||
| 0 | 100 | 0 | 9.5 | ||
| 2–3 times per month | 0 | 10.5 | 4.8 | ||
| 1–3 times per week | 0 | 36.8 | 23.8 | ||
| 3–6 times per week | 0 | 26.3 | 38.1 | ||
| Daily | 0 | 26.4 | 23.8 | ||
| Dose in grams per week (%) | |||||
| Less than 1 g | 0 | 31.6 | 33.3 | ||
| 1–2 grams | 0 | 36.8 | 23.8 | ||
| 3–5 grams | 0 | 31.6 | 33.3 | ||
| >5 grams | 0 | 0 | 4.8 | ||
| No answer | 0 | 0 | 4.8 | ||
| Dose in puffs per one use | – | 8.2 (2.6) | 6.6 (2.7) | ||
| Time since last cannabis use (%) | |||||
| <12 h | 0 | 10.5 | 4.8 | ||
| 12–24 h | 0 | 42.1 | 52.4 | ||
| 1–3 days | 0 | 15.8 | 23.8 | ||
| 3–7 days | 0 | 21.1 | 10 | ||
| 7–14 days | 0 | 5.3 | 0 | ||
| >14 days ago | 0 | 5.3 | 5 | ||
| Other illicit drug use in last 30 days (% of subjects) | |||||
| 0 | 100 | 100 | 57.1 | ||
| 1 time per month | 0 | 0 | 42.9 | ||
| 2 < per month | 0 | 0 | 0 | ||
| Hair sample pos (number) | |||||
| THC | – | 10 | 15 | ||
| MDMA | – | – | 15 | ||
| LSD | – | – | 1 | ||
| Amphetamine | – | – | 4 | ||
| Methcathinone | – | – | 1 | ||
| Cocaine | – | – | 7 | ||
| Cathine | – | – | 0 | ||
Note: aOne-way ANOVAs; There were no significant differences between CU, PU, and CG in tobacco H(2) = 3.459, p = 0.117 and alcohol use patterns H(2) = 0.837, p = 0.242 as Kruskal–Wallis H tests revealed, gender X(2) = 1.408, p = 0.495, diagnosed psychiatric disorders X(2) = 2.406, p = 0.3 as χ2-tests shown. Comparison between CU and PU on cannabis use pattern shown no significant differences in: onset age t(35) = −0.359, p = 0.722, duration t(35) = 0.587, p = 0.561, dose in puffs per one use t(34) = 1.832, p = 0.076 (series of t-tests has shown), lifetime frequency of use Z = −0.566, p = 0.571, frequency of use in last 30 days Z = −0.028, p = 0.978, dose in grams per week Z = −0.282, p = 0.788 and time since last cannabis use Z = −0.511, p = 0.609 (series of Mann–Whitney U tests). It is important to note that the ordinal data on substance use are presented in table in percentages, however, during analyses (while performing series of Mann–Whitney U or Kruskal–Wallis H tests) they were coded numerically. Hair sample analyses time-window was 3 months preceding study participation.