Cannabis use disorders and age at onset of psychosis in 606 patients with first episode psychosis
B. Schimmelmann, S. Kupferschmid, Philippe Conus, S. Cotton, Patrick D. Mcgorry, M. Lambert
European Psychiatry March 1, 2011 DOI: 10.1016/s0924-9338(11)73204-7 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Sample size | 606 |
| Population | First-episode psychosis patients aged 14 to 29 years admitted to the Melbourne Early Psychosis Prevention and Intervention Centre |
| Topics | Cannabis |
| Key findings | Lifetime cannabis use disorder was not associated with age at onset of psychosis overall. Cannabis use disorder beginning before age 14 was associated with an earlier age at onset, with a small effect size, but only in adult-onset first-episode psychosis; in early-onset psychosis, cannabis use disorder was associated with a later age at onset. |
Abstract
Background: Age at onset of psychosis (AAO) may be younger in patients with cannabis use disorders (CUD) compared to those without CUD (NCUD). Most previous studies did not control for potential confounders, did not report effect sizes and included mostly adult patients from non-representative samples.
Methods: Controlling for relevant confounders, differences in AAO between patients with and without lifetime CUD were analysed in a large epidemiologically based cohort of 606 first-episode psychosis (FEP) patients (age 14 to 29 years) admitted within three years to the Melbourne Early Psychosis Prevention and Intervention Centre. Data were collected from medical files using a standardized scale.
Results: Overall, AAO was not significantly different in CUD (n = 449; 74.1%) compared to NCUD, neither univariate nor when controlling for gender and premorbid functioning. However, AAO was younger in those with early CUD (starting before age 14) compared to NCUD (F(1) = 11.3; p = 0.001; partial η2 = 0.042). When considering the subgroups of early versus late onset psychosis, AAO was even later in early onset psychosis patients with CUD compared to those with NCUD (F(1) = 8.4; p = 0.004; partial η2 = 0.072). These findings were consistent for patients with non-affective psychoses, in those with CUD without other substance use disorders and in those with CUD explicitly starting in the pre-psychotic phase. Notably, 89.1% started cannabis before the onset of psychotic symptoms.
Conclusions: CUD starting before age 14 was associated with an earlier AAO at a small effect size, but only in adult onset FEP patients.
Comparable studies
Other observational and cohort studies on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| High-potency cannabis and the risk of psychosis People with first episode of psychosis and healthy controls from the local population | 2009 | Case-control study | n = 454 |
| Ayahuasca-Assisted Therapy for Addiction: Results from a Preliminary Observational Study in Canada Rural aboriginal population | 2013 | Observational study | |
| Impaired cognitive performance in drug free users of recreational ecstasy (MDMA) Otherwise healthy young people | 2000 | Observational | |
| Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study Individuals from the general population in Germany aged 14-24 at baseline | 2011 | Observational cohort | n = 1,923 |
| Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders: follow-up study of 535 incident cases Patients treated for cannabis-induced psychotic symptoms in Denmark between 1994 and... | 2005 | Observational cohort | n = 535 |