Stimulant and medicinal cannabis prescribing in patients referred to an early psychosis service in Queensland: A brief report.
Peter McArdle, Mike Trott, Nicola Warren, Dilprasan De Silva, Lesley A Smith, Sarah Ritchie, Dan Siskind
Australasian Psychiatry June 2026 DOI: 10.1177/10398562251406048 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Retrospective observational study Longitudinal Peer reviewed |
|---|---|
| Sample size | 220 |
| Population | Individuals consecutively referred to an early psychosis service in Queensland, Australia |
| Interventions | Stimulants Medicinal cannabis |
| Topics | Cannabis |
| Keywords | Early psychosis Schizophrenia Stimulants |
| Key findings | Among 220 early psychosis referrals, medicinal cannabis prescribing rose from 3.2% before referral to 6.8% after a psychotic episode, with higher mean THC concentrations post-onset (31.4% vs 16.9%), while stimulant prescribing fell from 4.5% to 3.2%. The authors report that over 70% of those prescribed stimulants and 60% prescribed medicinal cannabis after psychosis had further mental health service contact where these medications were thought to contribute to deterioration, and argue enhanced safeguards are needed. |
Abstract
ObjectiveThis study examined stimulant and medicinal cannabis prescribing in individuals before and after referral to an early psychosis (EP) service in Queensland, Australia.MethodsA retrospective review of 220 consecutive EP referrals (2019-2023) was conducted, extracting data on stimulant and medicinal cannabis prescriptions from clinical records. Longitudinal prescribing patterns were analysed, with descriptive comparisons of Δ9-tetrahydrocannabinol (THC) concentrations in medicinal cannabis prescriptions before and after the onset of psychosis.ResultsPrior to referral, 4.5% of patients were prescribed stimulants and 3.2% medicinal cannabis, with most having a history of substance use. After a psychotic episode, 3.2 % were prescribed stimulants and 6.8% were prescribed medicinal cannabis, with mean THC concentrations higher after the onset of a psychotic illness (31.4% vs 16.9%). Over 70% of those prescribed stimulants and 60% prescribed medicinal cannabis after experiencing a psychotic episode had further contact with mental health services due to concerns about a deterioration in mental state where these medications were thought to be a contributory factor.ConclusionsIt is of concern that THC concentrations were higher in prescriptions made post-EP discharge. Enhanced safeguards are required to mitigate risks and reliably identify patients where such prescription would be contraindicated.
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 |