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Study of Cannabidiol and Risperidone for Treatment of Non-Affective Psychosis in Patients with History of Cannabis Use

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial investigates the use of medications for people with non-affective psychosis who have used cannabis in their lifetime. The study examines two medications: cannabidiol (also known as CBD), which is given as an oral solution, and risperidone, which is given as film-coated tablets. Some participants will receive inactive substances (placebo) instead of the actual medications.

The main purpose of this research is to determine if cannabidiol is effective in treating psychosis symptoms. The study focuses on people who have various types of psychotic disorders, including schizophrenia, paranoid psychosis, acute psychotic disorder, schizoaffective psychosis, and cannabis-induced psychotic disorder.

During the study, which lasts seven weeks, participants will take either cannabidiol (up to 600 mg per day), risperidone (up to 4 mg per day), or placebo. The study will monitor various aspects of participants' health, including severity of psychotic symptoms, cannabis use patterns, sleep quality, and overall well-being.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial medication phase

    You will receive either cannabidiol (Epidyolex oral solution) or a matching placebo solution for daily use

    At the same time, you will receive either risperidone tablets or matching placebo tablets for daily use

    The medications will be taken by mouth (oral route)

  2. Step 2

    Symptom monitoring

    Your psychotic symptoms will be regularly evaluated using standardized assessments

    The evaluation includes monitoring of symptoms such as unusual thoughts, confused thinking, or hearing/seeing things others don't

    Your overall mental health status will be assessed throughout the study

  3. Step 3

    Cannabis use assessment

    You will need to report how often you use cannabis and in what amounts

    This information will be collected regularly throughout the study

    The assessment includes recording any periods without cannabis use

  4. Step 4

    Additional evaluations

    Your sleep patterns will be monitored, including how well you sleep and your sleep-wake schedule

    Mental function testing will be conducted to assess memory and thinking abilities

    Your daily functioning and sense of well-being will be evaluated

    Blood samples will be collected for metabolic testing

  5. Step 5

    Study duration

    The study continues until December 31, 2025

    Regular check-ups and assessments will occur throughout this period

    Participation requires maintaining the medication schedule and attending all scheduled evaluations

Who can join the trial?

10 criteria

  • Must be diagnosed with one of the following mental health conditions:
    • Schizophrenia - a serious mental disorder affecting how a person thinks, feels, and behaves
    • Paranoid psychosis - a condition involving false beliefs and suspicions
    • Acute/intermittent psychotic disorder - temporary periods of losing touch with reality
    • Schizoaffective psychosis - a condition combining symptoms of schizophrenia and mood disorders
    • Cannabis-induced psychotic disorder - psychotic symptoms triggered by cannabis use
    • Must have certain levels of psychotic symptoms as measured by the PANSS scale (a tool that measures severity of symptoms):
      • Total score of 60 or higher
      • Score of 4 or higher on at least 2 items from the positive symptoms section, including delusions, disorganized thinking, hallucinations, grandiose beliefs, or suspicious thoughts
      • Must have used cannabis at least once in their lifetime
      • Must be between 18 and 45 years old
      • Women who can become pregnant must use effective birth control during the study

Who cannot join the trial?

15 criteria

  • Current diagnosis of substance use disorder (addiction to drugs or alcohol)
  • History of serious adverse reactions to cannabidiol (CBD) or cannabis-based products
  • Presence of severe liver disease or abnormal liver function tests
  • Current treatment with medications that may interact with CBD
  • Pregnant women or those planning pregnancy during the study period
  • Women who are breastfeeding
  • Significant cardiovascular disease (heart problems)
  • Unstable medical conditions requiring frequent medication changes
  • Participation in another clinical trial within the past 30 days
  • Inability to provide informed consent
  • History of severe psychiatric conditions other than psychosis
  • Known allergies to any components of the study medication
  • Severe kidney dysfunction
  • Current use of illegal drugs
  • Inability to comply with study procedures
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Investigated drugs

Cannabidiol (CBD) is a natural compound found in cannabis plants that doesn't cause a "high." It's being studied as a potential treatment for psychosis symptoms. Unlike THC (the main psychoactive component in cannabis), CBD has calming properties and may help reduce anxiety and unusual thinking patterns. This medication is taken orally and is being investigated for its potential to help people with non-affective psychosis who also use cannabis.

What is already known about the treatment

Cannabidiol (CBD) - A naturally occurring compound extracted from cannabis plants that is administered orally in the form of oil drops or capsules. This non-psychoactive substance has gained significant attention in medical research for its potential therapeutic properties in treating various conditions, particularly psychosis and mental health disorders. CBD works by interacting with the endocannabinoid system in the brain, affecting serotonin receptors and potentially reducing inflammation and anxiety without causing the "high" associated with THC. Classified as a phytocannabinoid, CBD has shown promise in clinical trials for treating psychotic symptoms and potentially helping with cannabis use management, while maintaining a favorable safety profile and minimal side effects.

Investigated diseases

  • Cannabis Use Disorder

    A condition characterized by problematic pattern of cannabis use leading to significant impairment in daily life. Users develop tolerance to cannabis effects and may experience difficulty controlling their usage. The disorder often develops gradually, with individuals using increasing amounts of cannabis over time. Physical and psychological dependence may occur, affecting daily activities and social relationships.

  • Non-affective Psychosis

    A mental health condition characterized by a loss of contact with reality where symptoms are primarily not mood-related. The condition involves disturbances in thinking, perception, and behavior, including hallucinations and delusions. People may experience confused thinking, difficulty organizing thoughts, and changes in behavior. The condition can develop gradually or appear suddenly, affecting how a person interprets and responds to the world around them.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IVTrial ID2024-517630-18-00Estimated enrolment64 patientsSponsorRegion Hovedstaden

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