Abstract
As countries adopt more permissive cannabis policies, it is increasingly important to identify strategies that can reduce the harmful effects of cannabis use. This study aimed to determine if increasing the CBD content of cannabis can reduce its harmful effects. Forty-six healthy, infrequent cannabis users participated in a double-blind, within-subject, randomised trial of cannabis preparations varying in CBD content. There was an initial baseline visit followed by four drug administration visits, in which participants inhaled vaporised cannabis containing 10 mg THC and either 0 mg (0:1 CBD:THC), 10 mg (1:1), 20 mg (2:1), or 30 mg (3:1) CBD, in a randomised, counter-balanced order. The primary outcome was change in delayed verbal recall on the Hopkins Verbal Learning Task. Secondary outcomes included change in severity of psychotic symptoms (e.g., Positive and Negative Syndrome Scale [PANSS] positive subscale), plus further cognitive, subjective, pleasurable, pharmacological and physiological effects. Serial plasma concentrations of THC and CBD were measured. THC (0:1) was associated with impaired delayed verbal recall (t(45) = 3.399, d = 0.50, p = 0.001) and induced positive psychotic symptoms on the PANSS (t(45) = −4.709, d = 0.69, p = 2.41 × 10–5). These effects were not significantly modulated by any dose of CBD. Furthermore, there was no evidence of CBD modulating the effects of THC on other cognitive, psychotic, subjective, pleasurable, and physiological measures. There was a dose-response relationship between CBD dose and plasma CBD concentration, with no effect on plasma THC concentrations. At CBD:THC ratios most common in medicinal and recreational cannabis products, we found no evidence that CBD protects against the acute adverse effects of cannabis. This should be considered in health policy and safety decisions about medicinal and recreational cannabis.
Original language | English |
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Pages (from-to) | 869–876 |
Number of pages | 8 |
Journal | Neuropsychopharmacology |
Volume | 48 |
Issue number | 6 |
Early online date | 16 Nov 2022 |
DOIs | |
Publication status | Published - 31 May 2023 |
Bibliographical note
Funding Information:This study was fully funded by a Research Grant from the Medical Research Council UK (MR/P006841/1). The funder had no involvement in the design, data collection, analysis, interpretation, write up or the decision of where to publish. AE, LC, JH, RMM, and JS are part-funded or supported by the National Institute for Health Research (NIHR) Maudsley Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King’s College London. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.
Funding
This study was fully funded by a Research Grant from the Medical Research Council UK (MR/P006841/1). The funder had no involvement in the design, data collection, analysis, interpretation, write up or the decision of where to publish. AE, LC, JH, RMM, and JS are part-funded or supported by the National Institute for Health Research (NIHR) Maudsley Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King’s College London. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.
ASJC Scopus subject areas
- Pharmacology
- Psychiatry and Mental health