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The purpose of this study is: * To investigate whether the response to antipsychotic treatment can be enhanced by adding cannabidiol (CBD) to the existing treatment, compared to placebo, in participants with a first episode of psychosis, who have had a suboptimal or no response to their first antipsychotic treatment. * To confirm the safety of CBD in people with psychosis. The study is a randomized, double-blind, placebo-controlled, multi-centre, clinical trial. Individuals with a diagnosis of first-episode psychosis, who have had a suboptimal or no response to their first antipsychotic treatment will be recruited. These participants are randomised to treatment with CBD oral solution 500mg twice daily, or a matching placebo for 6 weeks, as an adjunct to their existing antipsychotic treatment. By using a battery of clinical outcome assessments, the trial will also assess several biomarkers to determine if they can be used to predict clinical outcomes and response to treatment with CBD. Biomarkers are being assessed as an exploratory outcome measure. Participants will be invited to provide blood and stool samples, and may be asked to complete neuroimaging assessments at certain eligible sites.
Locally preserved from ClinicalTrials.govOpen ClinicalTrials.govlast source update 2026-09-02
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Interventions
Daily dose 1000mg, taken as 500mg (5ml) b.i.d for 6 weeks. For participants with a weight lower than 50 kg, the dose is to be adjusted to 20 mg/kg/day divided over 2 intakes of 10 mg/kg/day, for a period of 6 weeks
5ml b.i.d for 6 weeks; For participants with a weight lower than 50 kg, the dose is to be adjusted to 20 mg/kg/day divided over 2 intakes of 10 mg/kg/day, for a period of 6 weeks
Eligibility
primary outcomes
Time frame: 6 weeks
Change in Positive and Negative Syndrome Scale (PANSS) total score from baseline to 6 weeks. The minimum value is 1 and the maximum value is 7 for each item of the scale. 1. A patient meets remission criteria if none of the following items score a 4 or higher: P1, P2, P3, N1, N4, N6, G5 and G9. 2. A patient does not meet remission criteria if one or more of these items score a 4 or higher.
secondary outcomes
Time frame: from baseline to 6 weeks and 58weeks
Change in scores on the PANSS positive, negative and general symptom subscales from baseline to 6 weeks and 58 weeks (if participants consent to the optional 12 months long-term follow-up period).
Time frame: 6 weeks and 58weeks
Symptomatic remission after 6 weeks and 58 weeks (if participants consent to the optional 12 months long-term follow-up period as measured using the PANSS, defined using Andreasen (2005) remission criteria. Andreasen, N. C., Carpenter, W. T., Jr, Kane, J. M., Lasser, R. A., Marder, S. R., \& Weinberger, D. R. (2005). Remission in schizophrenia: proposed criteria and rationale for consensus. The American journal of psychiatry, 162(3), 441-449. https://doi.org/10.1176/appi.ajp.162.3.441
Time frame: from baseline to 6 weeks and 58weeks
Change in overall clinical impression, assessed through Clinical Global Impression of Improvement and Severity (CGI-I/S) scales from baseline to 6 weeks and 58 weeks (if participant consent to the optional 12 months long-term follow-up period).
Time frame: from baseline to 6 weeks and 58weeks
Change in functioning, assessed through Social and Occupational Function Scale (SOFAS) from baseline to 6 weeks and 58 weeks (if participants consent to the optional 12 months long-term follow-up period). Score range 1-100, the higher score means the better function
Time frame: from baseline to 6 weeks and 58weeks
Change in functioning, assessed through Functional Remission of General Schizophrenia scale (FROGS) from baseline to 6 weeks and 58 weeks (if participants consent to the optional 12 months long-term follow-up period). Scale range for each item: Do not do=1; Do partially=2; Do a significant part=3; Do almost all the activity=4; Do perfectly =5. The higher score means better functioning.
Time frame: from baseline to 6 weeks and 58weeks
Change in functioning, assessed through Global Functioning Social and Role scales (GF:S, GF:R) from baseline to 6 weeks and 58 weeks (if participants consent to the optional 12 months long-term follow-up period). Scale range 1-100; 1. Different reference period at follow-ups: time since last visit 2. Rate only at baseline At follow-up, the higher score during past observation period can only be above but not below the current score at the last visit (i.e. if lower, the current score of last visit defines score during past observation (usually last 3 months)). The lowest score during past observation period can only be below but not above the current score at the last visit.
Time frame: from baseline to 6 weeks
Change in cognitive functioning as assessed through the PsyCog battery from baseline to 6 weeks. PsyCog comprises four tests that were chosen from the larger CANTAB battery to assess the key cognitive deficits associated with psychosis, including:: * Paired Associates Learning (PAL): key measures including PAL total errors adjusted (score range 0-70; lower is better) and PAL first attempt memory score (score range 0-20; higher is better) * Rapid Visual Information Processing (RVP): key measures including RVP A' (score range 0-1; higher is better) and RVP median response latency(ms) (score range 100-1900; lower is better) * Emotion Recognition Task (ERT): key measures including ERT overall median reaction time (ms) (score range 100-00; lower is better) and ERT total hits (score range 0-48; higher is better) * Spatial Span (SSP): key measures including SSP forward span length (score range 3-9; higher is better) and SSP reserve span length (score range 3-9; higher is better)
Time frame: from baseline to 6 weeks and 58weeks
Change in quality of life, assessed using the EQ-5D three-level version (EQ-5D-3L) from baseline to 6 weeks and 58 weeks (if participants consent to the optional 12 months long-term follow-up period). It includes five dimensions-MOBILITY, SELF-CARE, USUAL ACTIVITIES, PAIN /DISCOMFORT and ANXIETY / DEPRESSION. Each dimension has three levels: no problems, some problems, extreme problems (labelled1-3). The respondent is asked to indicate his / her health state by checking the box against the most appropriate statement in each of the five dimensions. The EQ VAS records the respondent's self-rated health on a vertical VAS where the endpoints are labelled 'The best health you can imagine' and 'The worst health you can imagine'. This information can be used as a quantitative measure of health outcome as judged by the individual respondents.
Time frame: from baseline to 6 weeks and 58weeks
Change in quality of life, assessed using the World Health Organization Quality-of-Life Scale (WHOQOL-BREF) from baseline to 6 weeks and 58 weeks (if participants consent to the optional 12 months long-term follow-up period). The WHOQOL-BREF is a 26-item instrument consisting of four domains: physical health (7 items), psychological health (6 items), social relationships (3 items), and environmental health (8 items); it also contains QOL and general health items. Each individual item of the WHOQOL-BREF is scored from 1 to 5 on a response scale, which is stipulated as a five-point ordinal scale.
Time frame: 6 weeks
Acceptability of CBD treatment, measured through all-cause discontinuation over 6 weeks
Time frame: 6 weeks and 30 days post treatment
Incidence of adverse events, measured through Glasgow Antipsychotic Side-effect Scale (GASS) over 6 weeks. Spontaneous adverse event reporting is until 30 days after the study intervention has been discontinued.
Time frame: from baseline to 6 weeks
Measure the severity of anxiety symptoms via Hamilton Anxiety Scale (HAM-A) from baseline to 6weeks. Each item is scored on a scale of 0 (not present) to 4 (severe), with a total score range of 0-56, where \<17 indicates mild severity, 18-24 mild to moderate severity and 25-30 moderate to severe.
Time frame: from baseline to 6 weeks
Measure the severity of anxiety symptoms via the Overall Anxiety Severity and Impairment Scale (OASIS) from baseline to 6weeks. It consists of five items that measure the frequency and severity of anxiety, as well as level of avoidance, work/school/home interference, and social interference associated with anxiety. Respondents select among five different response options for each item, which are coded 0-4 and summed to obtain a total score. Score range is 0-20. The lower score is better in symptoms.
Time frame: from baseline to 6 weeks
Measure the depression in schizophrenia without overlap with negative symptoms and extrapyramidal symptoms by using the Calgary Depression Scale for schizophrenia (CDSS) from baseline to 6weeks. it includes 9 items in the scale. All ratings of the items are defined according to operational criteria from 0-3. The CDSS depression score is obtained by adding each of the item scores. Score range is 0-27, which is the lower score is better.
Time frame: baseline and 6 weeks
Measure the neuroimaging (Magnetic resonance imaging (MRI)) from baseline to 6 weeks if participant consents to it. The Magnetic resonance imaging (MRI) scan includes: T1 - brain structure T2 FLAIR - brain structure / clinical reporting Neuromelanin sensitive MRI - neuromelanin content of substantial nigra (proxy of dopamine activity) Magnetic Resonance Spectroscopy of the anterior cingulate cortex - metabolites e.g. glutamate Resting state fMRI - bold activation during "rest" or free mind wandering
Time frame: baseline and 6 weeks
Measure the microbiome samples from baseline to 6 weeks if participant consents to it. The gut-microbiome (the microorganisms e.g. bacteria, normally found in participant's gut) is likely to be at play in determining whether participant respond or experience side effects from CBD. Two tubes of stool samples to be collected at two time points(baseline and week 6) if participant consent to it.
Time frame: from baseline to 6 weeks
Measure the blood samples for central lab assessment including (Epi)genetics, proteomics, inflammation, metabolomics, Redox markers from baseline to 6 weeks if participant consents to it.
other outcomes
Time frame: from baseline to 6 weeks and 58weeks
Change in overall patient impression, assessed through Patient Global Impression of Improvement and Severity (PGI-I/S) scales from baseline to 6 weeks and 58 weeks (if participant consents to the optional 12 months long-term follow-up period) The Patient Global Impression of Improvement (PGI-I) is a single question asking the patient to rate how their psychotic symptoms is now compared to the previous study visit on a scale of 1. very much better to 7. very much worse. The lower score is better in symptoms' improvement. The Patient Global Impression of Severity (PGI-S) is a single question asking the patient to rate how their psychotic symptoms is now on a scale of 1. not present to 7. very severe. The lower score is better in symptoms.
Publications
No exact PMID-linked public article is currently readable locally.