Table 1.
Substance use characteristics of the study sample
| a. Substance use characteristics in the Psychosis Groups | |||||
|---|---|---|---|---|---|
| HC-NonACU (n=32) | HC-ACU (n=14) | PSY-NonACU (n=35) | PSY-ACU (n=28) | Statistical Test** | |
| Lifetime Substance Use Disorder Diagnosis | |||||
| Cannabis use - Age of first use | 21.11 (17–35) | 15.57 (14–17) | 17.83 (15–20) | 14.48 (5–17) | F(3,60)=13.79, p<0.001 |
| Cannabis use - Age of last use | 21.00 (10–37) | 24.90 (16–31) | 41.67 (27–55) | 36.60 (15–55) | F(3,29)=0.52, NS |
| Cannabis use - Amount of use | χ2(6)=107.27, p<0.001 | ||||
| Less than 5 times over lifetime | 100% | 0% | 100% | 0% | |
| 5–50 times over lifetime | 0% | 25% | 0% | 4% | |
| More than 50 times over lifetime | 0% | 75% | 0% | 96% | |
| Cannabis Abuse | 0% | 7% | 0% | 4% | χ2(3)=3.91, NS |
| Cannabis Dependence | 0% | 14% | 0% | 32% | χ2(3)=22.8, p=0.001 |
| Other Substance Abuse/Dependence* | 6% | 43% | 26% | 89% | χ2(3)=47.07, p<0.001 |
| b. Substance use characteristics in the Diagnosis Groups | |||||||
|---|---|---|---|---|---|---|---|
| HC-NonACU (n=32) | HC-ACU (n=14) | BP-NonACU (n=12) | BP-ACU (n=7) | SZ-NonACU (n=23) | SZ-ACU (n=21) | Statistical Test* | |
| Lifetime Substance Use Disorder Diagnosis | |||||||
| Cannabis use - Age of first use | 21.11 (17–35) | 15.57 (14–17) | 18.67 (18–20) | 12.64 (5–17) | 17.56 (15–20) | 15.10 (12–17) | F(5,58)=9.26, p<0.001 |
| Cannabis use - Age of last use | 21.00 (10–37) | 24.90 (16–31) | n\a | 32.50 (32–43) | 41.67 (27–55) | 37.23 (15–55) | F(5,27)=0.48, NS |
| Cannabis use - Amount of use | χ2(10)=108.09, p<0.001 | ||||||
| Less than 5 times over lifetime | 100% | 0% | 100% | 0% | 100% | 0% | |
| 5–50 times over lifetime | 0% | 25% | 0% | 14% | 0% | 0% | |
| More than 50 times over lifetime | 0% | 75% | 0% | 86% | 0% | 100% | |
| Cannabis Abuse | 0% | 7% | 0% | 0% | 0% | 5% | χ2(5)=4.57, NS |
| Cannabis Dependence | 0% | 14% | 0% | 29% | 0% | 33% | χ2(5)=22.93, p<0.001 |
| Other Substance Abuse/Dependence* | 6% | 43% | 33% | 86% | 22% | 90% | χ2(5)=47.57, p<0.001 |
Other Substance Abuse/Dependence diagnoses included Alcohol, Cocaine, and Amphetamine use disorders.
Post hoc pairwise comparisons (Tukey HSD or chi square, as appropriate); only statistically significant (p<0.05) differences are reported:
Psychosis Groups:
Cannabis use–Age of first use: HC-NonACU > HC-ACU (p<0.001), PSY-NonACU (p<0.05); PSY-ACU (p<0.001); PSY-NonACU > PSY-ACU (p<0.01).
Cannabis use–Amount of use: There was a higher proportion of heavy users among HC-ACU compared to HC-NonACU (χ2(2)=44.0, p<0.001) and PSY-NonACU (χ2(2)=46.0, p<0.001); and among PSY-ACU compared to HC-NonACU (χ2(2)=56.0, p<0.001) and PSY-NonACU (χ2(2)=58.0, p<0.001).
Cannabis Dependence: There was a higher proportion of Cannabis Dependence among HC-ACU compared to HC-NonACU (χ2(1)=4.78, p=0.029) and PSY-NonACU (χ2(1)=5.21, p=0.022); and among PSY-ACU compared to HC-NonACU (χ2(1)=12.1, p=0.001) and PSY-NonACU (χ2(1)=13.13, p<0.001).
Other Substance Use: There was a higher proportion of Other Substance Use among HC-ACU compared to HC-NonACU (χ2(1)=9.08, p=0.003); and among PSY-ACU compared to HC-ACU (χ2(1)=10.41, p=0.001) and HC-NonACU (χ2(1)=41.6, p<0.001) and PSY-NonACU (χ2(1)=25.31, p<0.001); and among PSY-NonACU compared to HC-NonACU (χ2(1)=4.62, p=0.032).
Diagnosis Groups:
Cannabis use–Age of first use: HC-NonACU > HC-ACU (p<0.001), SZ-ACU (p<0.001); BP-ACU (p<0.001); BP-ACU < SZ-NonACU (p<0.05); BP-NonACU (p<0.05).
Cannabis use–Amount of use: There was a higher proportion of heavy users among HC-ACU compared to HC-NonACU (χ2(2)=44.0, p<0.001) and SZ-NonACU (χ2(2)=34.0, p<0.001) and BP-NonACU (χ2(2)=24.0, p<0.001); and among SZ-ACU compared to HC-NonACU (χ2(2)=49.0, p<0.001) and SZ-NonACU (χ2(2)=39.0, p<0.001) and and BP-NonACU (χ2(2)=29.0, p<0.001); and among BP-ACU compared to HC-NonACU (χ2(2)=39.0, p<0.001) and SZ-NonACU (χ2(2)=29.0, p<0.001) and and BP-NonACU (χ2(2)=19.0, p<0.001).
Cannabis Dependence: There was a higher proportion of Cannabis Dependence among HC-ACU compared to HC-NonACU (χ2(1)=4.78, p=0.029); and among SZ-ACU compared to HC-NonACU (χ2(1)=12.29, p<0.001) and SZ-NonACU (χ2(1)=9.12, p=0.003) and BP-NonACU (χ2(1)=5.08, p=0.024); and among BP-ACU compared to HC-NonACU (χ2(1)=9.64, p=0.002) and SZ-NonACU (χ2(1)=7.04, p=0.008) and BP-NonACU (χ2(1)=3.83, p=0.05).
Other Substance Use: There was a higher proportion of Other Substance Use among HC-ACU compared to HC-NonACU (χ2(1)=9.08, p=0.003); and among SZ-ACU compared to HC-ACU (χ2(1)=9.33, p=0.002) and HC-NonACU (χ2(1)=37.6, p<0.001) and SZ-NonACU (χ2(1)=20.92, p<0.001) and BP-NonACU (χ2(1)=11.81, p=0.001); and among BP-ACU compared to HC-NonACU (χ2(1)=22.24, p<0.001) and SZ-NonACU (χ2(1)=9.46, p=0.002) and BP-NonACU (χ2(1)=4.87, p=0.027); and among BP-NonACU compared to HC-NonACU (χ2(1)=5.44, p=0.02).
HC: healthy controls; PSY: volunteers with psychosis; SZ: volunteers with schizophrenia or schizoaffective disorder; BP: volunteers with psychotic bipolar I disorder, HC: healthy controls; ACU: adolescent onset cannabis use; Non-ACU: cannabis non-users.