CBD in schizophrenia, research on the antipsychotic effects of cannabis

According to the World Health Organization, schizophrenia affects approximately 24 million people worldwide, which translates to 1 in 300 people, and in Poland, the prevalence is estimated at about 0.8 to 1% of the population, or 300,000 to 400,000 patients ([WHO Schizophrenia Fact Sheet](https://www.who.int/news-room/fact-sheets/detail/schizophrenia), 2022). Despite sixty years of pharmacotherapy development, about 30% of patients remain resistant to classic D2 receptor-blocking antipsychotics, and negative symptoms and cognitive dysfunctions are still poorly controlled ([Lancet Psychiatry](https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(19)30416-X/fulltext), 2020). In this context, since 2012, cannabidiol (CBD) has become one of the most interesting molecules tested in psychiatry. This article organizes what is actually known from reliable clinical studies (Leweke 2012, McGuire 2018, GW Research's CBD-002 program), separates rigorous evidence from speculation, and clearly warns against what should not be done.

CBD and mental health, pillar article on mental disorders

What is schizophrenia and how does it progress?

Schizophrenia is a chronic, recurrent mental disorder from the group of schizophrenia spectrum disorders, characterized by positive symptoms (hallucinations, delusions), negative symptoms (anhedonia, withdrawal, abulia), and cognitive symptoms (deficits in attention, working memory). It occurs globally in about 1 in 300 people, with an annual incidence of 15 per 100,000 ([WHO](https://www.who.int/news-room/fact-sheets/detail/schizophrenia), 2022).

Epidemiology in Poland and worldwide

In Poland, approximately 180,000 people are treated for schizophrenia annually under services funded by the National Health Fund, with morbidity estimated at 0.8 to 1% of the adult population ([NFZ o zdrowiu: Schizophrenia](https://ezdrowie.gov.pl/portal/home/badania-i-dane/nfz-o-zdrowiu), 2023). The disease typically appears between the ages of 18 and 35, slightly earlier in men than in women.

The risk of suicide in individuals diagnosed with schizophrenia is about 12 times higher than in the general population, and about 5 to 10% of patients die by suicide ([Schizophrenia Bulletin](https://academic.oup.com/schizophreniabulletin/article/46/4/752/5735821), 2020). This is one of the reasons why self-treatment experiments are particularly dangerous.

DSM-5 and ICD-11 criteria

DSM-5 requires the presence of at least two of five symptoms (hallucinations, delusions, disorganized speech, disorganized behavior, negative symptoms) for at least one month, with persistent functional impairments for a minimum of 6 months ([American Psychiatric Association, DSM-5-TR](https://www.psychiatry.org/psychiatrists/practice/dsm), 2022). ICD-11 introduces similar criteria in category 6A20, abandoning classical subtypes (paranoid, hebephrenic, catatonic) in favor of dimensional assessment.

In consultative practice, we increasingly encounter patients who, after their first psychotic episode, ask about CBD, hoping it will allow them to discontinue antipsychotics. This is a fundamental misunderstanding that this text aims to dismantle.

Citation capsule. Schizophrenia affects about 0.8 to 1% of adults in Poland (approximately 300,000 to 400,000 people), with an annual suicide mortality rate of 0.5 to 1% of patients ([WHO](https://www.who.int/news-room/fact-sheets/detail/schizophrenia), 2022; [Schizophrenia Bulletin](https://academic.oup.com/schizophreniabulletin/article/46/4/752/5735821), 2020).

What neurobiological mechanisms underlie psychosis?

The pathophysiology of schizophrenia involves disturbances in three major neurotransmitter systems: dopaminergic hyperactivity in the mesolimbic pathway, glutamatergic hypofunction (NMDA receptors) in the prefrontal cortex, and neuroinflammation. PET meta-analyses showed a 14% increase in dopamine synthesis in the striatum in patients with their first episode ([Howes & Kapur, Schizophrenia Bulletin](https://academic.oup.com/schizophreniabulletin/article/35/3/549/1915694), 2009).

The dopamine hypothesis, its classics and limitations

The classical dopamine hypothesis states that positive symptoms result from excessive dopamine release in the mesolimbic pathway, while negative symptoms arise from its deficiency in the prefrontal cortex (mesocortical pathway). All current antipsychotics are D2 antagonists or partial agonists ([Nature Reviews Neuroscience](https://www.nature.com/articles/nrn1797), 2006).

The problem: 30% of patients do not respond to D2 blockade, and negative and cognitive symptoms remain poorly controlled. Clozapine, the only effective drug for treatment-resistant schizophrenia, has a complex receptor profile (D4, 5-HT2A, muscarinic), suggesting that dopamine alone does not explain the entire picture ([Lancet Psychiatry](https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(19)30416-X/fulltext), 2020).

NMDA hypofunction and the glutamatergic system

NMDA antagonists (ketamine, phencyclidine) induce symptoms very similar to acute schizophrenia in healthy individuals. This has led to the hypothesis of glutamatergic hypofunction in the prefrontal cortex, which some researchers believe is primary to dopaminergic dysregulation ([Molecular Psychiatry](https://www.nature.com/articles/mp2011171), 2012).

Neuroinflammation and microglia

Elevated levels of interleukin-6, TNF-alpha, and CRP have been found in patients with their first episode of psychosis. Microglial activation (imaged by PET with TSPO ligand) correlates with disease progression ([Biological Psychiatry](https://www.biologicalpsychiatryjournal.com/article/S0006-3223(17)32171-4/fulltext), 2018). This is an important point of reference for CBD, which exhibits immunomodulatory properties.

The three aforementioned systems (dopamine, NMDA, inflammation) are not competing hypotheses, but links in the same cascade. Dysfunction of parvalbuminergic (GABA) interneurons weakens control over glutamate, which through projection pathways leads to excessive dopamine release. Inflammation impairs this same parvalbuminergic circuit, closing the loop.

Citation capsule. Schizophrenia is a disorder of three systems: hyperactivity of dopamine (14% increase in synthesis in the striatum), hypofunction of NMDA, and neuroinflammation with microglial activation, as confirmed by PET imaging and inflammatory biomarkers ([Howes & Kapur, Schizophrenia Bulletin](https://academic.oup.com/schizophreniabulletin/article/35/3/549/1915694), 2009).

What role does the endocannabinoid system play in psychosis?

The endocannabinoid system (ECS) consists of CB1 and CB2 receptors, endogenous ligands (anandamide, 2-AG), and enzymes (FAAH, MAGL). In individuals with their first episode of psychosis, significantly elevated levels of anandamide in cerebrospinal fluid are observed , which decrease with clinical improvement ([Leweke et al., Neuroreport](https://journals.lww.com/neuroreport/Abstract/1999/05140/Elevated_endogenous_cannabinoids_in_schizophrenia.17.aspx), 1999).Anandamide as an endogenous protective factor

Data from subsequent years (Giuffrida 2004, Leweke 2007, 2012) showed that increased anandamide may be

a compensatory response of the brain to the disorder. Higher levels of anandamide in prodromal patients were associated with a lower risk of conversion to overt psychosis ([Koethe et al., Psychopharmacology](https://link.springer.com/article/10.1007/s00213-009-1536-1), 2009). CB1 receptors are particularly dense in the hippocampus, prefrontal cortex, and striatum, which are key structures for the pathophysiology of schizophrenia. Therefore, modifying ECS signaling may indirectly influence psychotic symptoms without engaging the D2 receptor.

Why does THC harm, while CBD likely helps?

THC is

a partial agonist of CB1 , which at high doses induces psychotic symptoms (paranoia, anxiety, depersonalization) in healthy individuals. CBD has very low affinity for CB1 and CB2, butinhibits FAAH , leading to an increase in endogenous anandamide, which in turn deepens its presumed protective effect ([Leweke et al., Translational Psychiatry](https://www.nature.com/articles/tp201215), 2012).In the Leweke 2012 study on 42 patients, clinical improvement in the CBD group

significantly correlated with an increase in serum anandamide levels, providing the first mechanistic evidence linking therapeutic effect to ECS activation. In individuals with their first episode of psychosis, elevated anandamides in cerebrospinal fluid are observed, and their increase under the influence of CBD (which inhibits FAAH enzyme) correlates with a reduction in PANSS symptoms, suggesting that the mechanism of CBD is indirect, endocannabinoid ([Leweke, Translational Psychiatry](https://www.nature.com/articles/tp201215), 2012).

Citation capsule. how the endocannabinoid system works, an article explaining ECS

How does CBD pharmacology differ from antipsychotics?

CBD and classic antipsychotics address the same clinical problem through very different pathways. A meta-analysis of 32 antipsychotic drugs in Lancet 2019 showed that

all effective drugs block the D2 receptor (standardized effect 0.38), but at the cost of side effects (EPS, hyperprolactinemia, weight gain) ([Lancet](https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(19)31135-3/fulltext), 2019). CBD has Ki on D2 above 10,000 nM , meaning it does not clinically block this receptor.Receptors that CBD binds to (and those it acts on indirectly)

, partial agonist. It is associated with anxiolytic and antipsychotic effects.

• 5-HT1ATRPV1, TRPV2, TRPA1
• , modulation of vanilloid channels. Impact on neuroinflammation., antagonism, potential effects on the hippocampus.
• GPR55FAAH
• , inhibition, increase in anandamide., activation, anti-inflammatory effect.
• PPAR-gammaCB1/CB2 receptors
• , very low affinity, acts more as an allosteric modulator.Source of receptor profile: review in British Journal of Pharmacology 2019 ([Ibeas Bih et al.](https://bpspubs.onlinelibrary.wiley.com/doi/10.1111/bph.14445), 2019).

Profile of side effects

Classic antipsychotics cause extrapyramidal symptoms, akathisia, tardive dyskinesia, hyperprolactinemia, sedation, weight gain (clozapine, olanzapine, up to 10 kg in 6 months in 30% of patients) and metabolic syndrome ([Lancet Psychiatry](https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(19)30416-X/fulltext), 2020). CBD at doses of 600, 1500 mg/day most commonly causes: diarrhea (10, 20%), fatigue (5, 10%), elevated liver enzymes (8% in registration studies of Epidiolex) and interactions via CYP3A4/CYP2C19 ([Epidiolex EPAR, EMA](https://www.ema.europa.eu/en/medicines/human/EPAR/epidyolex), 2019).

The most clinically significant difference lies not in the absence of EPS, but in the fact that CBD does not cause

hyperprolactinemia and tardive dyskinesia . These two complications are the main reason patients discontinue antipsychotics, especially young women. Adjunctive CBD does not reverse EPS caused by risperidone, but may improve compliance if it enhances other dimensions of the illness not addressed by D2 blockers.CBD has a Ki above 10,000 nM at the D2 receptor and does not clinically act as a dopamine antagonist, instead acting through 5-HT1A, TRPV1, FAAH, PPAR-gamma, and allosteric modulation of CB1/CB2, which is a completely different pathway than all registered antipsychotics ([Ibeas Bih, British Journal of Pharmacology](https://bpspubs.onlinelibrary.wiley.com/doi/10.1111/bph.14445), 2019).

Citation capsule. What did the Leweke 2012 study comparing CBD with amisulpride show?

The Leweke 2012 study is a milestone: the first well-designed RCT comparing cannabidiol with an active comparator, not placebo. It involved

42 individuals in an acute episode of paranoid schizophrenia, randomized to monotherapy with CBD 600, 800 mg/day or amisulpride 600, 800 mg/day for 4 weeks ([Leweke et al., Translational Psychiatry](https://www.nature.com/articles/tp201215), 2012). Clinical outcomes

Both groups showed

significant improvement in the BPRS (Brief Psychiatric Rating Scale) and PANSS (Positive and Negative Syndrome Scale), with no significant difference between CBD and amisulpride. This means that CBD proved to be non-inferior , not worse, compared to the established second-generation drug, in the acute phase of the illness. The reduction in PANSS was 30.5 points for CBD and 28.3 for amisulpride.CBD had

Tolerance

significantly better tolerance. Amisulpride caused a significant increase in prolactin, weight gain (an average of 2.4 kg in 4 weeks), and extrapyramidal symptoms in 4 out of 21 patients. In the CBD group: no EPS, no increase in prolactin, stable body weight. Limitations

Small sample size (n=42), short observation period (4 weeks), lack of a placebo arm, lack of long-term assessment of relapses. Nevertheless, the result is treated as evidence

proof-of-concept , that CBD may have antipsychotic activity in humans, not just in animal models.It is worth noting that the study required doses

up to 800 mg of CBD daily . This is equivalent to about 40 to 80 ml of 1% oil, or several bottles of 10% daily. These doses are economically unfeasible and impractical in the form of dietary supplements, and the pharmacokinetics of oral CBD are variable (bioavailability 6 to 19%).In the 4-week RCT by Leweke 2012 (n=42), CBD at doses of 600, 800 mg/day was

Citation capsule. compared to amisulpride, with a reduction in PANSS of 30.5 vs 28.3 points, with significantly better tolerance (no EPS, no hyperprolactinemia) ([Translational Psychiatry](https://www.nature.com/articles/tp201215), 2012). , not worse, compared to the established second-generation drug, in the acute phase of the illness. The reduction in PANSS was 30.5 points for CBD and 28.3 for amisulpride. What did the adjunctive McGuire 2018 study contribute?

The McGuire et al. study published in the American Journal of Psychiatry is the largest RCT of CBD in schizophrenia to date. It included

88 patients diagnosed with schizophrenia, treated with antipsychotics for at least 4 weeks with suboptimal response. Randomization to CBD 1000 mg/day or placebo as add-on for 6 weeks ([American Journal of Psychiatry](https://ajp.psychiatryonline.org/doi/10.1176/appi.ajp.2017.17030325), 2018). Results

In the CBD group, a

significant, albeit moderate reduction in positive PANSS symptoms was noted: mean difference of 1.4 points (p=0.019). The CGI-I (Clinical Global Impression, Improvement) assessment was significantly better in the CBD group, and doctors more often rated patients' condition as "improved" or "much improved." Improvement in cognitive functions was positive PANSS symptoms: average difference, 1.4 points (p=0.019). The CGI-I (Clinical Global Impression, Improvement) assessment was significantly better in the CBD group, and doctors more often rated patients' conditions as "improved" or "significantly improved." Improvement in cognitive functions was , but trending in favor of CBD.Interpretation

McGuire 2018 is a turning point, demonstrating that CBD added to antipsychotics provides

additional, measurable benefit in patients who do not fully respond. The effect size (Cohen's d around 0.3) is modest, comparable to adjunctive lamotrigine in depression, positioning CBD as a useful but not groundbreaking adjunct. observed in patients who did not fully respond. The effect size (Cohen's d around 0.3) is modest, comparable to adjunctive lamotrigine in depression, positioning CBD as a useful but not groundbreaking supplement.

Tolerance

No exacerbation of extrapyramidal symptoms and no increase in prolactin despite continued use of the main antipsychotic. In the McGuire 2018 study (n=88, 6 weeks), CBD 1000 mg/day added to antipsychotic significantly reduced positive PANSS symptoms (difference, 1.4 pts, p=0.019) and improved CGI-I assessment, with a minimal adverse event profile ([American Journal of Psychiatry](https://ajp.psychiatryonline.org/doi/10.1176/appi.ajp.2017.17030325), 2018).

Citation capsule. CBD dosing in clinical studies, internal publication

How have subsequent trials developed, Leweke 2021 and the CBD-002 program?

After McGuire 2018, the research program on CBD in psychoses has developed in two main directions:

replication in larger populations expansion to prodromal and clinically high-risk individuals (CHR-P) and . According to the Clinical Trials Register, in 2024 there were about15 registered studies on CBD in psychosis (phases II, III) ([ClinicalTrials.gov](https://clinicaltrials.gov/), 2024). Leweke 2021 and further publications

Leweke et al. in their 2021 paper in Springer Psychopharmacology synthesized data from subsequent cohorts and confirmed that

the correlation between increased anandamide and reduction of symptoms remains a replicable biomarker of response ([Leweke, Psychopharmacology](https://link.springer.com/article/10.1007/s00213-021-05905-9), 2021). This is important as it opens the way for patient stratification. GW Research CBD-002 program

GW Research (the producer of Epidiolex, now Jazz Pharmaceuticals) conducted a large-scale program with one of the main trials involving

about 1000 patients in 35 centers , mainly in Europe and North America. The plan included three populations: first episode of psychosis, patients at clinically high risk, and treatment-resistant schizophrenia ([University of Oxford News](https://www.ox.ac.uk/news/2023-02-16-major-trials-test-effectiveness-cannabidiol-psychosis), 2023).In 2023, 2024, some trials were modified after GW's acquisition by Jazz, and primary data have not yet been fully published. This means that until the results of key phase III trials are announced

there is still no registration of CBD in schizophrenia by the EMA or FDA. Meta-analyses

A systematic review from 2022 (7 RCTs, a total of 326 patients) indicated that adjunctive CBD provides

a small but significant improvement in positive symptoms (SMD = -0.23), with no significant change in negative symptoms or cognitive functions. The heterogeneity of studies was high ([McGuire, Schizophrenia Research](https://pubmed.ncbi.nlm.nih.gov/35902074/), 2022). A meta-analysis of 7 RCTs from 2022 (n=326) showed that adjunctive CBD in patients with schizophrenia provides a small, significant improvement in positive symptoms (SMD = -0.23), while the large GW Research CBD-002 registration study in a 1000-person cohort awaits final results ([Schizophrenia Research](https://pubmed.ncbi.nlm.nih.gov/35902074/), 2022).

Citation capsule. What doses of CBD were used in studies and why are they not consumer doses?

CBD doses studied in psychosis are

definitely not achievable in dietary supplements. Consumer products legally available in the EU typically contain 10 to 100 mg of CBD per daily dose. The difference is 10 to 100 times, which has fundamental medical and pharmacokinetic significance ([EMA Epidiolex EPAR](https://www.ema.europa.eu/en/medicines/human/EPAR/epidyolex), 2019). 600, 1500 mg/day Dose ranges in key trials

Leweke 2012, CBD in monotherapy: 600, 800 mg/day.

• McGuire 2018, adjunct to antipsychotic: 1000 mg/day.
• Boggs 2018, cognitive functions, schizophrenia: 600 mg/day.
• Prodromal/CHR-P studies: 300, 600 mg/day.
• Epidiolex in epilepsy (reference dose): 10, 20 mg/kg, which for an adult is 600, 1400 mg/day.
• Why are consumer doses inadequate in psychosis?

Firstly, the oral bioavailability of CBD is 6 to 19%. This means that from 50 mg of CBD in a capsule, effectively 3 to 10 mg is absorbed. Secondly, the biological effect on the endocannabinoid system and 5-HT1A is

dose-dependent , and therapeutic thresholds described in psychiatry are several hundred milligrams ([British Journal of Clinical Pharmacology](https://bpspubs.onlinelibrary.wiley.com/doi/10.1111/bcp.13710), 2019).Safety of high doses

Doses of 1000 mg/day pose a burden on the liver. In the registration of Epidiolex, 8% of patients showed an increase in ALT above three times the upper limit of normal, particularly in combination therapy with valproate. CBD is

a CYP3A4 and CYP2C19 inhibitor , which poses a risk of interactions with clozapine, risperidone, carbamazepine, warfarin, SSRIs ([Mayo Clinic Proceedings](https://www.mayoclinicproceedings.org/article/S0025-6196(19)30257-4/fulltext), 2019).In Polish realities, the NFZ reimburses treatment with olanzapine or risperidone for several dozen to several hundred zlotys per month. The cost of 1000 mg of CBD daily from available oils is

several hundred, over a thousand zlotys per month , and regulations do not allow for reimbursement of supplements for this indication. The economics of treating psychosis with high-dose CBD outside of clinical trials is impractical.Effective doses of CBD in psychosis studies are 600 to 1500 mg/day, which is 10 to 100 times more than in dietary supplements. The oral bioavailability of CBD is only 6 to 19%, and high doses require monitoring of liver function ([EMA Epidiolex EPAR](https://www.ema.europa.eu/en/medicines/human/EPAR/epidyolex), 2019).

Citation capsule. Why do THC and marijuana increase the risk of the first psychotic episode?

The association of cannabis use, particularly with high THC content, with an increased risk of psychosis is

one of the best-documented in social psychiatry . A meta-analysis of 10 prospective studies showedan odds ratio (OR) of 3.9 for daily use of high-potency cannabis compared to non-users ([Di Forti et al., Lancet Psychiatry](https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(19)30048-3/fulltext), 2019). This is a strong signal that justifies absolute discouragement of self-treatment. Di Forti studies 2015, 2019

In the EU-GEI study (European Study of Gene-Environment Interactions), Di Forti et al. showed that

daily use of skunk (THC above 10%) was associated with an OR of about 5 for the first psychotic episode. In London, Amsterdam, and Paris, cities with the highest access to high-potency cannabis, as much as 30 to 50% of new cases of schizophrenia could be attributed to the cannabis-related attributable fraction ([Lancet Psychiatry](https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(19)30048-3/fulltext), 2019). Genetics, COMT, AKT1

Individuals with the Val/Val polymorphism of the COMT gene or C/C in AKT1 have

a several-fold higher risk of psychosis after exposure to THC . The context of family history of schizophrenia is particularly important: cannabis use in a person with an affected first-degree relative significantly increases the risk of disease manifestation ([Archives of General Psychiatry](https://jamanetwork.com/journals/jamapsychiatry/fullarticle/482018), 2005).Cannabis-induced psychotic disorder (DSM-5)

DSM-5 defines

substance/medication-induced psychotic disorder (292.9 for cannabinoids) as a syndrome of hallucinations and/or delusions developing during or shortly after substance use, lasting longer than expected by the effect of the substance. In about 34 to 46% of individuals with cannabis-induced psychosis, conversion to schizophrenia occurs within 3 to 8 years ([JAMA Psychiatry](https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2717489), 2018). The "gateway" controversy

The "gateway" controversy

The hypothesis that cannabis is a "gateway" to harder drugs and schizophrenia is an oversimplification. A more established model is "accelerating genetic susceptibility"DO NOT use The key trap: "if CBD helps in psychosis, then marijuana does too." This is fundamentally incorrect. In typical cannabis flower, 1 to 2% CBD is overshadowed by 15 to 25% THC, and the net effect is.

A key trap: "if CBD helps with psychosis, then marijuana does too." This is fundamentally incorrect. In typical cannabis flower, 1-2% CBD is overshadowed by 15-25% THC, and the net effect is , not protective. Extracted CBD with purity above 99% (as in Epidiolex) is a completely different molecule than recreational marijuana.Daily use of high-potency cannabis (skunk, above 10% THC) is associated with about a 5-fold higher risk of the first psychotic episode, and 34 to 46% of individuals with cannabis-induced psychosis convert to schizophrenia within 3 to 8 years ([Di Forti, Lancet Psychiatry](https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(19)30048-3/fulltext), 2019).

Citation capsule. What does standard treatment for schizophrenia look like in Poland?

Polish psychiatry operates on standards consistent with NICE CG178, APA Practice Guidelines, and recommendations from the Polish Psychiatric Association. First-line treatment in the first episode of psychosis is

monotherapy with a second-generation antipsychotic , most often olanzapine, risperidone, aripiprazole, or amisulpride, at the lowest effective dose ([NICE CG178](https://www.nice.org.uk/guidance/cg178), update 2024).Pharmacological treatment lines

First line:

1. risperidone 2 to 6 mg, olanzapine 10 to 20 mg, aripiprazole 10 to 30 mg, amisulpride 400 to 800 mg, quetiapine 400 to 800 mg. Selection based on the profile of side effects. Second line:
2. switching to another second-generation antipsychotic after 4 to 6 weeks of lack of response at the optimal dose. Third line:
3. clozapine after two failed attempts, the standard in treatment-resistant schizophrenia. Requires monitoring of blood morphology (neutropenia). Psychosocial interventions

NICE CG178 recommends

cognitive-behavioral therapy for psychosis (CBT-p) , family therapy (Family Intervention) for families with an ill member, social skills training, andsupported employment (Individual Placement and Support) . Despite the evidence, availability in the Polish NFZ remains limited.Early intervention (EIP, Early Intervention in Psychosis)

EIP programs in the UK and Australia reduce mortality, hospitalizations, and costs in the first 3 years after onset by 20 to 40%. In Poland, the NFZ program "Community Mental Health Centers" (CZP) implements a similar approach, with an increasing number of facilities since 2018 ([Ministerstwo Zdrowia](https://www.gov.pl/web/zdrowie/), 2023).

EIP programs in the UK and Australia reduce mortality, hospitalizations, and costs in the first 3 years after illness by 20-40%. In Poland, the NFZ program "Community Mental Health Centers" (CZP) implements a similar approach, with an increasing number of facilities since 2018 ([Ministry of Health](https://www.gov.pl/web/zdrowie/), 2023).

Relapses of psychosis after discontinuation of antipsychotics occur in

77% of patients within a year compared to 18% of those continuing treatment. Each subsequent relapse is associated with a worse response to the next treatment and a more severe functional deficit ([Lancet](https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)60239-6/fulltext), 2012). The most common scenario that ends tragically: a patient after 6 to 12 months of "well-being" believes they have "recovered," discontinues risperidone, and starts trying CBD from the drugstore. After 2 to 4 weeks, acute psychosis returns, this time more severe, requiring involuntary hospitalization. This scenario can only be interrupted by talking to a psychiatrist and gradual, supervised tapering, never on one's own.

The most common scenario that ends tragically: a patient after 6-12 months of "well-being" believes they are "cured," stops taking risperidone, and starts trying CBD from the drugstore. After 2-4 weeks, acute psychosis returns, this time more severe, requiring involuntary hospitalization. This scenario can only be interrupted slowly through discussions with a psychiatrist and gradual, supervised tapering, never on one's own.

Citation capsule. mental health centers in Poland, map of available facilities

Can CBD be used in individuals at high risk of psychosis?

clinically high risk for psychosis (CHR-P, Clinical High Risk for Psychosis)

People from , formerly called "prodrome," is a particularly difficult group to treat. Conversion to full psychosis occurs in, previously called "prodrome," is a particularly difficult group to treat. Conversion to full psychosis occurs in , and classic antipsychotics are not recommended as prevention due to the benefit-risk ratio ([JAMA Psychiatry](https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2535745), 2016).The potential role of CBD in CHR-P

Bhattacharyya et al. in a 2018 study showed that

a single dose of 600 mg of CBD in CHR-P individuals normalized activity in the hippocampus, striatum, and medial prefrontal cortex in a memory task in fMRI, bringing it closer to the pattern of healthy controls ([JAMA Psychiatry](https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2685446), 2018). This is a biological signal, not clinical evidence. Why is this still an experiment and not a recommendation?

There is no evidence that CBD reduces

• actual conversion to psychosis in large RCTs. High doses (600, 1000 mg/day) in young individuals with an immature endocannabinoid system, unknown long-term effects.
• Risk of false sense of security and postponing effective psychosocial intervention (CBT-p).
• Current EPA (European Psychiatric Association) guidelines for CHR-P recommend

CBT-p as first-line treatment , and pharmacotherapy only in the presence of co-occurring depressive/anxiety symptoms. CBD is not recommended in these guidelines outside of clinical trials ([European Psychiatry](https://www.cambridge.org/core/journals/european-psychiatry), 2020).In individuals at clinically high risk for psychosis (CHR-P), a single dose of 600 mg of CBD normalized hippocampal, striatal, and prefrontal cortex activity in fMRI, but EPA guidelines still recommend CBT-p, not CBD, as first-line treatment ([JAMA Psychiatry](https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2685446), 2018).

Citation capsule. What CBD to choose if the doctor allows adjunctive support?

This paragraph is for informational purposes only and concerns

high-quality dietary supplements , which may support well-being in limited clinical situations (with full psychiatric care). The supplement DOES NOT treat schizophrenia. The CBD market in Poland grew to about500 to 700 million PLN annually , with a huge variance in quality ([PMR Research](https://mypmr.pro/), 2024).What to look for

Declared CBD content confirmed

• by a current analytical certificate (COA) from an independent laboratory. broad-spectrum
• Profile (without THC) for individuals with a confirmed diagnosis of psychosis, THC must be at an undetectable level. No pesticides, heavy metals, mycotoxins in testing.
• Label compliant with EU law as a dietary supplement, manufacturer with an address in the EU.
• Examples of products (for educational purposes only)

SOOL CBD Oil 5%, broad spectrum, 10 ml.

Mild concentration for those starting their CBD journey, 500 mg of CBD per bottle, price 76 PLN. A good choice for exploring tolerance. Link to product card: SOOL CBD 5% (ubucha.pl) SOOL CBD Oil 10%, broad spectrum, 10 ml..

1000 mg of CBD per bottle, 99 PLN. A popular choice when lower concentrations prove insufficient. Link: SOOL CBD 10% (ubucha.pl) . Remember, this is still asupplemental dose , not clinical.Cannova CBG Oil 15%, 10 ml.

1500 mg of CBG (cannabigerol), price 240 PLN. CBG is another cannabinoid, modulating 5-HT1A and alpha-2 receptors, worth considering alongside CBD in mood support. No evidence in psychosis. Link: Cannova CBG 15% (ubucha.pl) Mars Hemp Flower CBD 9%..

A variant for those preferring a form other than oil, exclusively for vaporization. Price 59 PLN. In individuals with a history of psychosis or CHR-P, vaporizing any hemp flower (even low-tetrahydrocannabinol) is discouraged due to difficulty in dose control and isolated reports of contamination. Link: ATTENTION: Mars Flower 9% (ubucha.pl) What to absolutely avoid.

Products without COA or with COA older than 12 months.

• "full spectrum" oils with unclear THC content.
• "full spectrum" oils with unclear THC content.
• Online advice recommending discontinuation of antipsychotics.
• CBD supplements available in the EU typically provide 10 to 100 mg of CBD per dose and are 10 to 100 times below the clinical doses studied in schizophrenia (600 to 1500 mg/day), therefore they do not replace antipsychotics and require consultation with a psychiatrist ([EMA Epidiolex EPAR](https://www.ema.europa.eu/en/medicines/human/EPAR/epidyolex), 2019).

Citation capsule. What are the interactions of CBD with antipsychotic medications?

a substrate and inhibitor of many cytochrome P450 enzymes

CBD is , including CYP3A4, CYP2C19, CYP2C9. This is crucial for psychiatric patients, as clozapine, risperidone, aripiprazole, carbamazepine, and SSRIs are metabolized by the same pathways, which can lead to increases in their blood concentrations by 20 to 80% ([Mayo Clinic Proceedings](https://www.mayoclinicproceedings.org/article/S0025-6196(19)30257-4/fulltext), 2019).Key interactions

Clozapine

• , increased concentration, risk of sedation, neutropenia, seizures. Requires monitoring of clozapine levels in the blood.Risperidone
• , increased concentration of the active metabolite (paliperidone), risk of EPS and hyperprolactinemia., doubled risk of hepatotoxicity with CBD.
• Valproate(sertraline, escitalopram), increased concentrations, intensified serotonergic effects.
• SSRI , increased INR.
• Warfarin, increased sedation.
• BenzodiazepinesAdditionally, CBD induces drowsiness, dry mouth, decreased blood pressure, diarrhea, which may overlap with the effects of antipsychotics. Monitoring of transaminases (ALT, AST) every 1 to 3 months at doses above 300 mg/day is recommended ([Epidiolex Label, FDA](https://www.accessdata.fov.fda.gov/drugsatfda_docs/label/2018/210365lbl.pdf), 2018).

CBD inhibits CYP3A4 and CYP2C19, which may increase clozapine, risperidone, valproate, SSRIs, and warfarin concentrations by 20 to 80%, thus adjunctive use requires monitoring of drug levels and liver enzymes ([Mayo Clinic Proceedings](https://www.mayoclinicproceedings.org/article/S0025-6196(19)30257-4/fulltext), 2019).

Citation capsule. FAQ, frequently asked questions about CBD and schizophrenia

Can CBD replace antipsychotic medications?

No, under any circumstances.

A single study by Leweke 2012 on 42 individuals showed non-inferiority to amisulpride in the acute phase, but there are no long-term data on preventing relapses. All guidelines (APA, NICE CG178, PTP) recommend antipsychotics as the standard. Discontinuing medication risks relapse in 77% of patients within a year ([NICE CG178](https://www.nice.org.uk/guidance/cg178), 2024). Can medical marijuana help in schizophrenia?

No, quite the opposite.

THC present in marijuana is pro-psychotic, and daily use of high-potency skunk is associated with about a 5-fold higher risk of the first psychotic episode. Isolated CBD with purity above 99% (Epidiolex) used in studies is something entirely different ([Di Forti, Lancet Psychiatry](https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(19)30048-3/fulltext), 2019). Medical marijuana in schizophrenia is NOT recommended. What doses of CBD were used in studies on patients with schizophrenia?

600 to 1500 mg/day, most commonly 1000 mg in the McGuire 2018 study. This is

10 to 100 times more than in typical dietary supplements (10 to 100 mg). Oral bioavailability is 6 to 19%, and high doses require monitoring of liver function. Self-experimenting with such doses without psychiatric and internist supervision is dangerous ([EMA Epidiolex EPAR](https://www.ema.europa.eu/en/medicines/human/EPAR/epidyolex), 2019). Does CBD interact with olanzapine or clozapine?

Yes. CBD inhibits CYP3A4 and CYP2C19, which may raise the concentration of clozapine, olanzapine (to a lesser extent), risperidone, valproate, and SSRIs by 20 to 80%. Monitoring of drug levels in the blood, transaminases, and morphology (with clozapine) is required. Any addition of CBD to chronic pharmacotherapy for psychosis must be consulted with the treating psychiatrist ([Mayo Clinic Proceedings](https://www.mayoclinicproceedings.org/article/S0025-6196(19)30257-4/fulltext), 2019).

Where to seek help in a mental health crisis in Poland?

In an acute crisis, suicidal thoughts, or acute psychosis, call

(free Helpline for Adults, 24/7). For youth 112 (emergency services) or 116 123 116 111 116 111 Summary and practical conclusions

Schizophrenia is a disease in which

systematic antipsychotic treatment saves lives . Evidence for the efficacy of CBD is encouraging but still limited: rigorous RCTs Leweke 2012 (n=42), McGuire 2018 (n=88), several smaller trials, and the ongoing CBD-002 program. The 2022 meta-analysis indicatesa small, significant improvement in positive symptoms with adjunctive CBD (SMD = -0.23), without a groundbreaking effect on negative and cognitive symptoms. completely differently

CBD works than classic antipsychotics, it does not block the D2 receptor, but acts through FAAH, 5-HT1A, TRPV1, PPAR-gamma, and indirect modulation of the endocannabinoid system. This is the only mechanistic hypothesis in psychiatry in the last 30 years that has the potential to add something original to the standard of care. Four key takeaways to remember:

CBD may be an adjunct, never monotherapy.

1. Added to antipsychotics, not replacing them. Clinical doses (600, 1500 mg/day) are unavailable in supplements.
2. Do not attempt to recreate them from consumer oils. THC and marijuana are absolutely discouraged
3. , as they increase the risk of psychosis, especially in predisposed individuals.Any change in treatment should be under the supervision of a psychiatrist.
4. Self-discontinuation results in relapse in three out of four patients. If a loved one is struggling with psychosis, the most important steps are:

contacting a psychiatrist or CZP, consistently taking prescribed medications, cognitive-behavioral therapy, family support, social and vocational rehabilitation. CBD may be , but only after discussing it with the treatment team. an adjunctmental health and CBD, related articles

WHO Fact Sheet, Schizophrenia

Sources

1. , 2022., 2022.
2. , 2012, CBD vs amisulpride.McGuire et al., American Journal of Psychiatry
3. , 2018, adjunctive CBD.Di Forti et al., Lancet Psychiatry
4. , 2019, high-potency cannabis and psychosis.Bhattacharyya et al., JAMA Psychiatry
5. , 2018, CBD and brain function in CHR-P.Leweke et al., Psychopharmacology
6. , 2021, update.Howes & Kapur, Schizophrenia Bulletin
7. Howes & Kapur, Schizophrenia BulletinIbeas Bih et al., British Journal of Pharmacology
8. , 2019, CBD receptor pharmacology.NICE CG178, Psychosis and Schizophrenia in Adults
9. , update 2024.EMA Epidiolex EPAR
10. , 2019., 2019.
11. , 2022, meta-analysis.Mayo Clinic Proceedings
12. , 2019, CBD drug interactions.Author: Michał Waluk. This article is for educational purposes and does not constitute medical advice. Discuss any treatment decisions regarding schizophrenia with the treating psychiatrist.

A reliable review of CBD studies in schizophrenia: Leweke 2012, McGuire 2018, receptor mechanisms, dosing 600-1500 mg, warning about THC and psychosis.