Although anecdotal reports suggest that CBD is viewed relatively positively by patients with psychotic disorders as a potential treatment, there is surprisingly little evidence for this. This study sought to address this issue by conducting a survey among patients with psychotic disorders in secondary care. Our findings indicate that for most patients with psychosis CBD is an acceptable treatment.

At present, although there is preliminary evidence that CBD may be effective in psychosis,^14,15 it is not yet approved as a treatment. Although none of the patients who completed our survey had ever taken pharmaceutical-grade CBD, most had heard of CBD and 29% had used an over-the-counter product containing it. In addition, 67% of the sample had previously used cannabis which may have contained CBD. CBD is thus an unusual novel candidate treatment, in that the patient population already has a high degree of familiarity with it. This is likely to increase the willingness of patients to participate in clinical trials of CBD and, if it is subsequently licenced as a medication, to accept it as a treatment for psychosis. In contrast, many patients with psychosis are reluctant to take antipsychotic medications, which have a low level of acceptability as a treatment. As a result, adherence to treatment with these drugs is often poor⁷ and this increases the risk of adverse clinical outcomes, such as acute relapse, hospital admission, functional decline and mortality.^{8bibr9-20451253221128445–10}

As well as being willing to accept CBD as a treatment, most respondents thought that it would improve their symptoms and would be associated with fewer side effects than their current medication. Indeed, almost half of the sample thought that CBD would have no side effects at all. These results show that patients’ positive expectations about CBD extend to both its therapeutic and its adverse effects. In contrast, many patients have a negative view of antipsychotic medications. In one survey of 212 patients with schizophrenia, 46% said they had a ‘negative’ or ‘very negative’ opinion of antipsychotics compared with 42% who said they had a ‘positive’ or ‘very positive’ opinion of them.²⁶ In another survey, 31 of 61 patients (51%) said they had a positive view of antipsychotic medications; the majority of this group (20/31), however, expressed ‘distinct reservations’.²⁷ Expectations about treatment have been shown to modify the clinical response to treatments for depression, anxiety and pain^{28bibr29-20451253221128445–30} and may contribute to the placebo effect, which can be significant in patients with psychosis.³¹ It is thus possible that the relatively positive expectations about treatment with CBD will enhance its effectiveness in real-world practice, by augmenting its therapeutic effects and diminishing adverse events.

Non-psychotic symptoms, such as irritability, insomnia, anxiety and low mood, are often the first signs of a psychotic relapse³² and are also features of the clinical high risk state that precedes the onset of psychosis.³³ As these symptoms are also among the most common lay indications for the use of over-the-counter CBD products,²⁵ patients with psychosis may also be inclined to accept CBD as a treatment because they think it will help with these other symptoms.

Most of the participants in our sample were past or current cannabis users. This is in keeping with the generally high prevalence of cannabis use among patients with psychosis.^34,35 In this study, a history of cannabis use was the strongest predictor of willingness to consider treatment with CBD: 100% of cannabis users were open to CBD, compared with 57% of never users. Among patients with psychosis, those with co-morbid cannabis use have more severe symptoms and an increased risk of relapse,³⁶ which is partly attributable to relatively poor adherence to antipsychotic medications.³⁷ The very high acceptability of CBD in these patients suggests that it could be particularly useful as a treatment in this subgroup. Moreover, independent research indicates that CBD can counteract the pro-psychotic effects of cannabis, which are mediated through delta-9-tetrahydrocannabinol.^17,18 CBD might thus have a dual benefit in these patients, acting as an antipsychotic and reducing the adverse effects of concurrent cannabis use.³⁸

The participants who were least willing to consider treatment with CBD were those who had never used cannabis. The most common concerns were that CBD would exacerbate their psychotic symptoms or cause sedation. These patients may have been confusing the effects of CBD with those of cannabis and this finding highlights the importance of educational work on the distinctions between the two. In particular, in contrast to cannabis, CBD is legal; is not intoxicating, sedative or addictive; and may reduce psychotic symptoms rather than exacerbate them. It is also important that patients are aware of the difference between pharmaceutical-grade and over-the-counter CBD products. Pharmaceutical-grade medicines are highly purified and usually contain CBD at considerably higher doses than is present in over-the-counter products. Moreover, some over-the-counter products have been found to contain significant levels of delta-9-tetrahydrocannabinol and other compounds that could have unwanted effects.²⁴

One limitation of this study is the sampling strategy. As a non-random convenience sampling strategy was used, there is a risk that the sample may not be representative of the overall population of people with psychotic disorders. Of note, the majority of the participants had used cannabis previously. Although the prevalence of cannabis use in our patient sample is similar to that described in other samples from large urban areas with a diverse population, the prevalence is often lower in other regions.^35,39 In this study, because a high proportion of the patients had used cannabis, and this was strongly associated with a willingness to try CBD, the acceptability may be higher than it would be in samples recruited from areas where cannabis use among patients is less common. Our sample only included patients who had agreed to participate in the survey and therefore may not be representative of all patients, as it may have been less likely to include those who had not engaged well with mental health services. We did not record the number of patients who did not agree to participate in the survey, so the potential extent of this issue is unclear. A further limitation was that when participants were asked about their willingness to be treated with CBD, the survey did not specify whether this was as a monotherapy or as an adjunct to antipsychotic medication.

Importantly, to our knowledge, this is the first ever study to assess the acceptability of CBD as a treatment in psychosis. When added to the emerging evidence that CBD has therapeutic effects and a low risk of side effects, this apparently high level of acceptability highlights the potential value of CBD as a novel treatment.