Table 1. Demographic, substance use, clinical, neuropsychological and brain characteristics.
| Group (n=111) | Controls (n=37) |
Cannabis users (n=74) |
Four-group comparisonsa |
Five-group comparisonsb |
|||||
|---|---|---|---|---|---|---|---|---|---|
| CBDx (n=19) | CBD− (n=30) | CBD+ (n=12) | Former users (n=13) | Fdf | P | Fdf | P | ||
| Sample characteristics | |||||||||
| Male/female, % | 49/51 | 47/53 | 43/57 | 58/42 | 85/15 | 6.713, 74 | 0.082c | 6.974, 111 | 0.138c |
| Age, years | 29.95 (11.29) | 34.26 (10.96) | 32.10 (11.15) | 31.67 (10.34) | 38.69 (9.80) | 1.313, 70 | 0.276 | 1.704, 106 | 0.156d |
| Alcohol, standard drinks per month | 19.9 (26.72) | 25.96 (31.00) | 26.41 (31.03) | 8.69 (10.77) | 41.62 (28.66) | 2.843, 70 | 0.044 | 2.534, 106 | 0.044d |
| Tobacco, cigarettes per week | 5.18 (17.95) | 48.18 (46.44) | 66.97 (54.24) | 63.42 (56.79) | 24.65 (35.38) | 2.403, 70 | 0.075 | 10.964, 106 | <0.005d |
| Anxiety symptoms | 33.73 (7.58) | 42.21 (11.71) | 38.29 (11.40) | 47.33 (12.42) | 34.23 (12.49) | 2.993, 70 | 0.037 | 5.014, 106 | 0.001d |
| Depressive symptoms | 12.17 (2.80) | 15.53 (3.45) | 13.80 (2.99) | 15.50 (3.92) | 12.92 (3.09) | 2.393, 70 | 0.076 | 5.014, 106 | 0.001d |
| Global functioning | 86.76 (4.15) | 69.58 (9.01) | 76.93 (9.31) | 70.67 (10.70) | 78.15 (9.04) | 3.683, 70 | 0.016 | 18.734, 106 | <0.005d |
| Intelligence quotient | 112.32 (12.72) | 103.68 (11.45) | 103.17 (10.38) | 101.26 (14.78) | 109.93 (15.18) | 1.243, 70 | 0.300 | 3.544, 106 | 0.009d |
| Intracranial volume, mm3 | 1468.07 (141.02) | 1459.49 (124.92) | 1401.27 (153.69) | 1447.79 (82.74) | 1480.47 (121.31) | 1.413, 70 | 0.246 | 1.324, 106 | 0.266 |
| Whole-brain volume, mm3 | 1251.02 (120.37) | 1245.24 (107.23) | 1196.91 (131.85) | 1239.19 (69.22) | 1257.65 (103.42) | 1.243, 70 | 0.301 | 1.164, 106 | 0.333 |
| Cannabis use measures | |||||||||
| Frequency, days per month | |||||||||
| Lifetime | — | 23.1 (7.11) | 23.51 (6.78) | 26.14 (4.68) | 26.77 (8.39) | 1.163, 70 | 0.333 | — | |
| Past 12 months | — | 24.31 (9.13) | 25.24 (8.8) | 24.31 (8.80) | — | 0.052, 58 | 0.954 | — | |
| Dosage, joint cumulative | |||||||||
| Lifetime | — | 29,716 (3331) | 20,739 (17,907) | 27,385 (20,337) | 13,151 (12,251) | 8.253, 70 | 0.241 | — | |
| Past 12 months | — | 1728 (1401) | 1617 (1325) | 1623 (917) | — | 0.082, 58 | 0.920 | ||
| Duration, years | — | 16.95 (9.24) | 14.13 (9.53) | 15.92 (10.37) | 15.69 (9.23) | 0.363, 70 | 0.783 | ||
| Onset age, years | — | 17.08 (4.36) | 16.97 (3.04) | 15.58 (2.61) | 18.31 (4.03) | 1.233, 70 | 0.305 | ||
| THC levels in hair, ng mg−1e | — | — | 0.18 (0.31) | 0.27 (0.23) | — | −0.8633 | 0.394 | ||
| CBD levels in hair, ng mg−1e | — | — | — | 0.02 (0.01) | — | ||||
Abbreviations: CBD, cannabidiol; THC, Δ9-tetrahydrocannabinol.
All values presented in mean (s.d.).
Analyses (two tailed) comparing CBDx (those testing positive for urinary cannabinoid metabolites), CBD− (those exposed to THC but not to CBD), CBD+ (those exposed to both THC and CBD) and Former User (former regular users who were abstinent for a prolonged period) groups.
Analyses (two tailed) comparing controls, CBDx, CBD−, CBD+ and Former User groups.
χ2-test.
Variables used as covariates in all statistical analyses of variance.
Hair sample analysis (t-test) was available only for CBD−, CBD+ and Former User groups. Anxiety (trait) assessed by the State and Trait Anxiety Inventory; depressive symptoms assessed by the Community Assessment of Psychic Experiences; global functioning assessed by the Social and Occupational Functioning Assessment Scale; intelligence assessed using the Wechsler Abbreviated Scale of Intelligence (WASI); and cannabis use patterns assessed by structured interview and Timeline Follow-back Procedures to estimate average lifetime frequency of use (since age of regular use initiation) and cumulative dosage (since first initiation of cannabis), duration of regular use and age of regular cannabis use initiation.