can cbd help schizophrenia

Can cbd help schizophrenia

In terms of effects following continued treatment, results from the same study investigating the effect of 3-week treatment with CBD (600 mg/day) on symptoms and functional brain activation are awaited. 78 In summary, initial evidence supports CBD as a potential novel treatment for people at clinical high risk for psychosis, and its benign side-effect profile as evident from other data (see below) makes it a particularly suitable candidate treatment for this patient group. Whether CBD can actually alter the course of the disorder and prevent the onset of psychosis will require larger-scale clinical trials over longer durations. Such studies have recently been initiated and the results are anticipated to make a significant contribution to the evidence base.

Additional complementary evidence for the use of CBD in psychosis comes from a study of Parkinson’s disease psychosis. In a small, open-label pilot study, six patients with Parkinson’s disease psychosis received oral CBD for 4 weeks, titrated from a mean dose of 150–400 mg/day in addition to their current treatment regimens. 50 CBD was associated with a significant decrease in psychotic symptoms and was well tolerated, with no side effects clinically observed. CBD also improved total scores on the Unified Parkinson’s Disease Rating Scale and did not worsen cognition or motor function. While caution is warranted due to the small sample size and lack of placebo control, these results support the view that CBD is safe, well-tolerated and may have efficacy for the treatment of psychosis in nonschizophrenia spectrum disorders. Phase II clinical trials of CBD for Parkinson’s disease psychosis and behavioural symptoms (including psychotic symptoms) in Alzheimer’s disease are now being planned.

While CBD has been found to be safe and well tolerated in the three (relatively short-term) clinical trials in psychosis to date, 53,55,56 the total volume of data is still small and thus insufficient adverse events may yet have accumulated. When measured in terms of ‘patient-years’ (i.e. the number of patients treated with a new drug multiplied by the duration of treatment), data from at least 1000 patient-years or more are recommended for robust estimates of safety and tolerability. 82 This follows the notion that the greater the clinical use and experience of prescribing drugs in different clinical scenarios, the better (and more nuanced) our knowledge of its true risk-benefit profile. However, 1000 patient-years equates to, for example, 1000 patients taking CBD for 1 year or 500 patients for 2 years. The largest RCT of CBD in psychosis to date randomised 43 patients to receive CBD for 6 weeks. 55 This highlights the significant gulf between the current state of knowledge and the benchmark for sufficient risk-benefit evidence. Larger randomised controlled trials with longer durations of treatment are therefore needed.

Psychosis in nonschizophrenia spectrum disorders

Considering the wider literature (not restricted to studies in psychosis), doses of up to 1500 mg/day have been well tolerated in humans with few or no side effects, although such doses have mainly been administered to very few patients in case series reports. 28,48,49 The first comprehensive review of CBD-related (in vivo and in vitro) side effects suggested that CBD is nontoxic in cell lines and has no adverse effects on physiological parameters such as heart rate, blood pressure and body temperature, gastrointestinal transit, and psychomotor or psychological function. 83 A second review extended these findings and confirmed that overall, CBD has a favourable safety profile. 84 However, CBD is not entirely side-effect free; in vitro work suggests that CBD may affect cell viability, fertilisation potential and drug transporter/P-glycoprotein function, 83,84 and reports of (mostly mild) clinical adverse effects are starting to accumulate as the body of available literature becomes substantiated. The most common adverse effects in clinical studies include diarrhoea, tiredness or sedation, and changes in appetite and weight. 83

A separate study examined the acute effects of a single dose of CBD on cognitive function in 28 patients with schizophrenia. 52 Performance on the Stroop Colour Word Test, which indexes selective attention, was compared at baseline (no drug) to one of three parallel-arm conditions 1 month later: placebo (n = 10), 300 mg CBD (n = 9) and 600 mg CBD (n = 9). While performance improved (numerically) in all three arms from baseline to the second session, indicating a learning effect, only those receiving placebo and the lower CBD dose (300 mg) showed a statistically significant improvement. 52 The authors suggest that sedative effects of CBD may underlie the lack of improvement (related to learning/practice effects) in the higher-dose CBD group. Overall, whether CBD has beneficial effects on cognition in patients with psychosis is currently unclear and remains an important avenue for future research.

Early intervention: prior to psychosis onset

Studies in epilepsy report diarrhoea in approximately 15–20% of CBD-treated individuals. 90 In the largest study in patients with psychosis, 9% of those receiving CBD versus 4% receiving placebo reported this side effect. 55 While the severity was often mild and resolved without treatment, the one withdrawal (out of n = 43) in the CBD group was due to nausea, diarrhoea, abdominal pain and vomiting. 55 Despite the initial review by Bergamaschi and colleagues suggesting no effects on gastric motility, 83 the emerging pattern of findings is that diarrhoea is one of the most common side effects of CBD. This suggests that it does, in fact, increase gastrointestinal transit in humans which could affect its ultimate acceptability. 84

BPRS, Brief Psychiatric Rating Scale; CBD, cannabidiol; CGI, Clinical Global Impression Scale; CHR, clinical high risk; fMRI, functional Magnetic Resonance Imaging; GAF, Global Assessment of Functioning Scale; MATRICS, MATRICS Consensus Cognitive Battery (MCCB); PANSS, Positive and Negative Syndrome Scale.

Can cbd help schizophrenia

Cannabis is a genus of plants with several species containing over 100 types of cannabinoids. Species are bred to promote varying levels of cannabinoids, especially (–)-trans-Δ 9 -tetrahydrocannabinol (THC) and cannabidiol (CBD), which have differing effects. THC is responsible for the intoxicating “high” of cannabis and is likely a component of cannabis that is responsible for the development of CUD in about 10% of users [for review, see (24)]. In contrast, CBD does not appear to cause intoxication, nor is it reinforcing (25, 26).

Inclusion and Exclusion Criteria

Two studies enrolled outpatients on medication who had chronic illness (58, 61, 62), one enrolled patients on medication who were within 5 years of illness onset (63, 64). Two studies involved chronic patients who were acutely psychotic inpatients at the time of participation (35, 59, 60), and these patients initiated the trial off antipsychotic medication. One study appears to have included a mixed sample of outpatients on or off antipsychotic medications (58).

Characteristics of CBD Studies

All three studies assessed the effects of THC on symptoms using the PANSS, as well as changes in feeling “high” and other symptoms such as “panic” using a Visual Analog Scale (VAS). Fisher et al. and Whitfield-Gabrieli et al. also included formal measures of cannabis withdrawal and craving. The studies included measures of cognition, and two reports used fMRI to assess brain activation during a resting state (56, 57, 63). All of the studies collected blood samples to assess plasma THC, while one also collected cortisol and prolactin (55).