Table 4. Bivariate probit regression analysis of intensity of cannabis or cigarette use at 16 and depression and PEs at age 18 in the imputed dataset.
| N = 4345 | Depression | Psychotic Experiences | |||||
|---|---|---|---|---|---|---|---|
| OR | 95% CI | p | OR | 95% CI | p | Wald test (p value) | |
| Cannabis | |||||||
| 1 | 1.34 | 1.18, 1.51 | <0.001 | 1.38 | 1.23, 1.55 | 0.001 | -0.023 (0.637) |
| 3 | 1.29 | 1.13, 1.47 | <0.001 | 1.41 | 1.24, 1.59 | <0.001 | -0.056 (0.292) |
| 5 | 1.11 | 0.89, 1.38 | 0.343 | 1.12 | 0.91, 1.39 | 0.260 | -0.010 (0.913) |
| Cigarettes | |||||||
| 1 | 1.37 | 1.23, 1.53 | <0.001 | 1.42 | 1.28, 1.57 | <0.001 | -0.018 (0.654) |
| 3 | 1.24 | 1.10, 1.39 | <0.001 | 1.33 | 1.19, 1.49 | <0.001 | -0.046 (0.307) |
| 5 | 1.08 | 0.91, 1.28 | 0.367 | 1.15 | 0.98, 1.36 | 0.069 | -0.043 (0.523) |
Model 1—Case depression at 18 and suspected/definite PEs at 18 by unit increase of 4-level categorical cumulative cannabis use or frequency of cigarette use at 16.
Model 3—as model 2 with additional adjustment for childhood confounders (borderline personality, IQ at age 8, PEs at age 12, conduct disorder trajectory group membership, peer problems, bullied).
Model 5—as model 3 with additional adjustment for cigarette (or cannabis), alcohol and other illicit drug use.