Cannabis use severely affects the outcome of people with psychotic disorders, yet there is a lack of treatments. To address this, in 2019 the National Health Service (NHS) Cannabis Clinic for Psychosis (CCP) was developed to support adults suffering from psychosis to reduce and/or stop their cannabis use.

Examine outcome data from the first 46 individuals to complete the CCP's intervention.

The sample (N = 46) consisted of adults (aged ≥ 18) with psychosis under the care of the South London and Maudsley NHS Foundation Trust, referred to the CCP between January 2020 and February 2023, who completed their intervention by September 2023. Clinical and functional measures were collected before (T0) and after (T1) the CCP intervention (one-to-one sessions and peer group attendance). Primary outcomes were changes in the Cannabis Use Disorders Identification Test-Revised (CUDIT-R) score and pattern of cannabis use. Secondary outcomes included T0–T1 changes in measures of delusions, paranoia, depression, anxiety and functioning.

A reduction in the mean CUDIT-R score was observed between T0 (mean difference = 17.10, 95% CI = 15.54–18.67) and T1, with 73.91% of participants achieving abstinence and 26.09% reducing the frequency and potency of their use. Significant improvements in all clinical and functional outcomes were observed, with 90.70% being in work or education at T1 compared with 8.70% at T0. The variance in CUDIT-R scores explained between 34 and 64% of the variance in our secondary measures.

The CCP intervention is a feasible strategy to support cannabis use cessation/reduction and improve clinical and functional outcomes of people with psychotic disorders.

Hippocampal hyperperfusion has been observed in people at Clinical High Risk for Psychosis (CHR), is associated with adverse longitudinal outcomes and represents a potential treatment target for novel pharmacotherapies. Whether cannabidiol (CBD) has ameliorative effects on hippocampal blood flow (rCBF) in CHR patients remains unknown.

Using a double-blind, parallel-group design, 33 CHR patients were randomized to a single oral 600 mg dose of CBD or placebo; 19 healthy controls did not receive any drug. Hippocampal rCBF was measured using Arterial Spin Labeling. We examined differences relating to CHR status (controls v. placebo), effects of CBD in CHR (placebo v. CBD) and linear between-group relationships, such that placebo > CBD > controls or controls > CBD > placebo, using a combination of hypothesis-driven and exploratory wholebrain analyses.

Placebo-treated patients had significantly higher hippocampal rCBF bilaterally (all pFWE<0.01) compared to healthy controls. There were no suprathreshold effects in the CBD v. placebo contrast. However, we found a significant linear relationship in the right hippocampus (pFWE = 0.035) such that rCBF was highest in the placebo group, lowest in controls and intermediate in the CBD group. Exploratory wholebrain results replicated previous findings of hyperperfusion in the hippocampus, striatum and midbrain in CHR patients, and provided novel evidence of increased rCBF in inferior-temporal and lateral-occipital regions in patients under CBD compared to placebo.

These findings suggest that hippocampal blood flow is elevated in the CHR state and may be partially normalized by a single dose of CBD. CBD therefore merits further investigation as a potential novel treatment for this population.

Psychiatric morbidity in prisons and police custody is well established, but little is known about individuals attending criminal court. There is international concern that vulnerable defendants are not identified, undermining their right to a fair trial.

To explore the prevalence of a wide range of mental disorders in criminal defendants and estimate the proportion likely to be unfit to plead.

We employed two-stage screening methodology to estimate the prevalence of mental illness, neurodevelopmental disorders and unfitness to plead, in 3322 criminal defendants in South London. Sampling was stratified according to whether defendants attended court from the community or custody. Face-to-face interviews, using diagnostic instruments and assessments of fitness to plead, were administered (n = 503). Post-stratification probability weighting provided estimates of the overall prevalence of mental disorders and unfitness to plead.

Mental disorder was more common in those attending court from custody, with 48.5% having at least one psychiatric diagnosis compared with 20.3% from the community. Suicidality was frequently reported (weighted prevalence 71.2%; 95% CI 64.2–77.3). Only 16.7% of participants from custody and 4.6% from the community were referred to the liaison and diversion team; 2.1% (1.1–4.0) of defendants were estimated to be unfit to plead, with a further 3.2% (1.9–5.3) deemed ‘borderline unfit’.

The prevalence of mental illness and neurodevelopmental disorders in defendants is high. Many are at risk of being unfit to plead and require additional support at court, yet are not identified by existing services. Our evidence challenges policy makers and healthcare providers to ensure that vulnerable defendants are adequately supported at court.