Table 2.
Phenotypic and twin correlations.
| Cannabis use |
||
|---|---|---|
| Correlation (CI) | N | |
| Phenotypic correlations | ||
| Psychotic experiences | ||
| Paranoia | 0.22 (0.17, 0.27) | 2441 |
| Hallucinations | 0.17 (0.11, 0.22) | 2445 |
| Cognitive disorganization | 0.18 (0.11, 0.24) | 2441 |
| Grandiosity | 0.07 (0.01, 0.12) | 2444 |
| Anhedonia | −0.06 (−0.12, −0.01) | 2443 |
| Parent-rated negative symptoms | 0.14 (0.08, 0.20) | 2430 |
| Twin correlations | ||
| MZ | DZ | |
| Correlation (CI) | Correlation (CI) | |
| Univariate twin correlations | ||
| Psychotic experiences | ||
| Paranoia | 0.54 (0.50, 0.58) | 0.30 (0.25, 0.35) |
| Hallucinations | 0.48 (0.43, 0.52) | 0.33 (0.28, 0.38) |
| Cognitive disorganization | 0.50 (0.46, 0.54) | 0.30 (0.25, 0.35) |
| Parent-rated negative symptoms | 0.88 (0.87, 0.90) | 0.63 (0.60, 0.67) |
| Cannabis | 0.92 (0.88, 0.95) | 0.74 (0.65, 0.82) |
| Cross-trait cross-twin correlations | ||
| Psychotic experiences and cannabis | ||
| Paranoia | 0.17 (0.10, 0.23) | 0.15 (0.08, 0.22) |
| Hallucinations | 0.15 (0.08, 0.21) | 0.10 (0.03, 0.17) |
| Cognitive disorganization | 0.13 (0.06, 0.19) | 0.12 (0.04, 0.28) |
| Parent-rated negative symptoms | 0.14 (0.07, 0.20) | 0.18 (0.11, 0.24) |
Note: phenotypic correlations were performed using one random member of each twin pair. CI=confidence intervals.
All genetic analyses (including phenotypic and twin correlations) were performed using ordinal scales of PEs.