Only very early cannabis use (≤14 years) is associated with an earlier onset of psychosis; CUD overall shows no significant effect on age of onset of illness.
Summary
Retrospective analysis of n=625 first-episode psychosis patients (age 14–29 years); 75% had a cannabis use disorder (CUD). Cannabis use began before psychosis onset in 87,6%. Early CUD onset (≤14 years) was associated with a younger age of onset of illness (F(1)=5,2; p=0,024; partial η²=0,026); earlier age of onset of use predicted earlier age of onset of psychosis (β=−0,49; R²-change=0,25; p<0,001). CUD overall (without further SUD) vs. non-CUD: no significant difference in age of onset of illness.
P
PopulationFirst-episode psychosis patients (FEP), age 14–29 years, n=625, of which CUD without other SUD n=201, NCUD n=157
I
InterventionCannabis use disorder (CUD), onset ≤14 years vs. CUD onset after the 14th year of life
C
ControlPatients without cannabis use disorder and without other substance use disorders (NCUD, n=157)
O
OutcomeEarlier age of onset of illness for CUD onset ≤14 years vs. NCUD (F(1)=5,2; p=0,024; partial η²=0,026); no significant difference for CUD overall vs. NCUD; earlier age of cannabis onset predicts earlier age of psychosis onset (β=-0,49, p<0,001)
Confidence in the evidence
Very lowLowModerateHigh
Low
The second of four GRADE levels, the effect estimate is of limited reliability.
Quality profile
Sample size★★★★★
Blinding—
Effect sizeMixed
Citations / year★★★★★
Authors
Schimmelmann BG, Conus P, Cotton SM, Kupferschmid S, Karow A, Schultze-Lutter F, McGorry PD, Lambert M.
<h4>Introduction</h4>Age at onset of psychosis (AAO) may be younger in patients with cannabis use disorders (CUD) compared to those without CUD (NCUD). Previous studies included CUD co-morbid with other substance use disorders (SUD), and many did not control for confounders.<h4>Methods</h4>Controlling for relevant confounders, differences in AAO between patients with and without CUD excluding those with any other SUD were analyzed in a large representative file audit of 625 first-episode psychosis (FEP) patients (age 14 to 29years) admitted to the Early Psychosis Prevention and Intervention Centre in Melbourne, Australia.<h4>Results</h4>Three quarters of the 625 FEP patients had a CUD. Cannabis use started before psychosis onset in 87.6% of patients. AAO was not significantly different between CUD (without other SUD, n=201) and NCUD (n=157). However, AAO was younger in those with early CUD (starting age 14 or younger) compared to NCUD (F(1)=5.2; p=0.024; partial η(2)=0.026). Earlier age at onset of cannabis use predicted earlier age at onset of psychosis (β=-0.49, R(2)-change=0.25, p<0.001).<h4>Conclusion</h4>Only CUD starting age 14 or younger was associated with an earlier AAO at a small effect size. These findings suggest that CUD may exert an indirect effect on brain maturation resulting in earlier AAO potentially only in cannabis sensitive subjects.