Table 2.
Corpus callosum microstructural integrity and patterns of cannabis use (potency, frequency and age at first use) across the sample as a whole, and in the two samples of patients with first-episode psychosis and individuals without psychosis
| Potency of cannabis use | Frequency of cannabis use | Age at first use | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Corpus callosum measure | Never used | Low potency | High potency | Statistics a | Never used | Occasional users | Daily users | Statisticsa | <15 years old | >15 years old | Statisticsa |
| Mean FA (s.d.): | |||||||||||
| Whole sample | 0.576 (0.01) | 0.574 (0.01) | 0.573 (0.01) | F2,82 = 1.8, n.s. | 0.576 (0.01) | 0.573 (0.01) | 0.572 (0.01) | F2,87 = 0.6, n.s. | 0.573 (0.01) | 0.574 (0.01) | F1,41 = 0.01, n.s. |
| Patients with psychosis | 0.572 (0.01) | 0.572 (0.01) | 0.572 (0.02) | F2,45 = 0.39, n.s. | 0.575 (0.01) | 0.572 (0.01) | 0.571 (0.01) | F2,48 = 0.9, n.s. | 0.571 (0.01) | 0.572 (0.02) | F1,23 = 0.1, n.s. |
| Individuals without psychosis | 0.582 (0.01) | 0.574 (0.01) | 0.574 (0.01) | F2,35 = 2.4, n.s. | 0.578 (0.01) | 0.576 (0.01) | 0.573 (0.01) | F2,37 = 0.5, n.s. | 0.577 (0.01) | 0.575 (0.01) | F1,18 = 0.4, n.s. |
| Mean MD, × 10−3 mm2/s (s.d.) | |||||||||||
| Whole sample | 0.791 (0.02) | 0.794 (0.02) | 0.807 (0.02) | F2,82 = 5.7, p = 0.005 b | 0.791 (0.01) | 0.792 (0.02) | 0.808 (0.01) | F2,87 = 7.5, p = 0.001 c | 0.805 (0.02) | 0.801 (0.02) | F1,41 = 0.5, n.s. |
| Patients with psychosis | 0.794 (0.02) | 0.798 (0.01) | 0.808 (0.02) | F2,45 = 1.86, n.s. | 0.795 (0.02) | 0.796 (0.01) | 0.809 (0.02) | F2,48 = 2.87, p = 0.06 d | 0.809 (0.02) | 0.802 (0.01) | F1,23 = 0.38, n.s. |
| Individuals without psychosis | 0.788 (0.02) | 0.789 (0.02) | 0.810 (0.01) | F2,35 = 4.32, p = 0.02 e | 0.786 (0.02) | 0.790 (0.02) | 0.807 (0.02) | F2,37 = 4.83, p = 0.01 f | 0.811 (0.01) | 0.791 (0.02) | F1,18 = 3.64, p = 0.07 d |
| Mean RD, × 10−3 mm2/s (s.d.) | |||||||||||
| Whole sample | 0.491 (0.01) | 0.492 (0.02) | 0.502 (0.02) | F2,82 = 3.4, p = 0.04 d | 0.488 (0.02) | 0.492 (0.02) | 0.502 (0.02) | F2,87 = 4.3, p = 0.02 d | 0.499 (0.02) | 0.497 (0.02) | F1,41 = 0.1, n.s. |
| Patients with psychosis | 0.494 (0.02) | 0.496 (0.02) | 0.503 (0.02) | F2,45 = 1.33, n.s. | 0.495 (0.02) | 0.492 (0.01) | 0.504 (0.02) | F2,48 = 2.3 , n.s. | 0.499 (0.02) | 0.504 (0.02) | F1,23 = 0.2, n.s. |
| Individuals without psychosis | 0.489 (0.01) | 0.481 (0.01) | 0.499 (0.01) | F2,35 = 2.88, p = 0.07 | 0.483 (0.01) | 0.490 (0.01) | 0.498 (0.01) | F2,37 = 2.5, n.s. | 0.500 (0.01) | 0.487 (0.01) | F1,18 = 2.4, n.s. |
| Mean AD, × 10−3 mm2/s (s.d.) | |||||||||||
| Whole sample | 1.39 (0.02) | 1.40 (0.03) | 1.41 (0.03) | F2,82 = 6.05, p = 0.004 g | 1.39 (0.03) | 1.40 (0.03) | 1.42 (0.03) | F2,87 = 8.9, p < 0.001 h | 1.41 (0.03) | 1.40 (0.03) | F1,41 = 0.8, n.s. |
| Patients with psychosis | 1.39 (0.03) | 1.40 (0.02) | 1.41 (0.02) | F2,45 = 1.85, n.s. | 1.39 (0.02) | 1.40 (0.02) | 1.41 (0.03) | F2,48 = 2.1, n.s. | 1.42 (0.03) | 1.40 (0.02) | F1,23 = 0.5, n.s. |
| Individuals without psychosis | 1.38 (0.03) | 1.39 (0.04) | 1.42 (0.03) | F2,35 = 4.2, p = 0.02 i | 1.38 (0.03) | 1.39 (0.02) | 1.42 (0.03) | F2,37 = 5.7, p = 0.007 j | 1.43 (0.04) | 1.39 (0.03) | F1,18 = 2.8, p = 0.4 |
FA, Fractional anisotropy; s.d., standard deviation; n.s., non-significant; MD, mean diffusivity; RD, radial diffusivity; AD, axial diffusivity.
Only p's < 0.1 are reported. Post-hoc comparisons are given in notes b to j, all Bonferroni corrected.
High-potency users had higher corpus callosum MD than those who never used (p = 0.004).
Daily users had higher corpus callosum MD than those who never used (p = 0.002), and those who used weekly or less (p = 0.004).
Did not survive Bonferroni correction.
High-potency users had higher corpus callosum MD than those who never used (p = 0.02).
Daily users had higher corpus callosum MD than those who never used (p = 0.02), and those who used weekly or less (p = 0.03).
High-potency users had higher corpus callosum AD than those who never used (p = 0.002).
Daily users had higher corpus callosum AD than those who never used (p = 0.001), and those who used weekly or less (p = 0.006).
High-potency users had higher corpus callosum AD than those who never used (p = 0.02).
Users had higher corpus callosum AD than those who never used (p = 0.008), and those who used weekly or less (p = 0.03).