Individual and combined effects of acute delta-9-tetrahydrocannabinol and cannabidiol on psychotomimetic symptoms and memory function.
Celia J. A. Morgan, Tom P. Freeman, Chandni Hindocha, Gráinne Schäfer, Chelsea Gardner, Helen Valerie Curran
Translational Psychiatry September 5, 2018 DOI: 10.1038/s41398-018-0191-x (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized, double-blind crossover experimental medicine study Peer reviewed |
|---|---|
| Sample size | 48 |
| Population | Community cannabis users selected by schizotypal personality questionnaire scores (low, high) and frequency of cannabis use (light, heavy) |
| Interventions | THC CBD placebo |
| Dose | THC 8 mg, CBD 16 mg, THC 8 mg + CBD 16 mg |
| Measures | Brief Psychiatric Rating Scale (BPRS), Psychotomimetic States Inventory (PSI), immediate and delayed prose recall, 1- and 2-back |
| Topics | Cannabis CBD |
| Key findings | THC increased overall PSI scores, BPRS negative symptoms, and impaired episodic and working memory, while co-administered CBD at a 2:1 ratio did not attenuate these effects. CBD alone reduced PSI scores only in light cannabis users, suggesting frequent users may show a blunted anti-psychotic response to CBD. |
Abstract
The main active ingredient in cannabis, delta-9-tetrahydrocannabinol (THC), can acutely induce psychotic symptoms and impair episodic and working memory. Another major constituent, cannabidiol (CBD), may attenuate these effects. This study aimed to determine the effects of THC and CBD, both alone and in combination on psychotic symptoms and memory function. A randomised, double-blind crossover design compared the effects of (i) placebo, (ii) THC 8 mg, (iii) CBD 16 mg and (iv) THC 8 mg + CBD 16 mg administered by inhalation through a vaporiser. Using an experimental medicine approach to predict treatment sensitivity, we selected 48 cannabis users from the community on the basis of (1) schizotypal personality questionnaire scores (low, high) and (2) frequency of cannabis use (light, heavy). The Brief Psychiatric Rating Scale (BPRS), Psychotomimetic States Inventory (PSI), immediate and delayed prose recall (episodic memory), 1- and 2-back (working memory) were assessed on each day. Results indicated that THC increased overall scores on the PSI, negative symptoms on BPRS, and robustly impaired episodic and working memory. Co-administration of CBD did not attenuate these effects. CBD alone reduced PSI scores in light users only. At a ratio of 2:1, CBD does not attenuate the acute psychotic and memory impairing effects of vaporised THC. Frequent cannabis users may show a blunted anti- psychotic response to CBD, which is of concern due to the high rates of cannabis use disorders in patients with schizophrenia.
Comparable studies
Other randomized controlled trials on CBD, most cited first.
Citations in the library
Cited by 34
- Association of Ketamine With Psychiatric Symptoms and Implications for Its Therapeutic Use and for Understanding Schizophrenia JAMA Network Open May 1, 2020
- Substance-Induced Psychoses: An Updated Literature Review Frontiers in Psychiatry December 23, 2021
- The acute effects of cannabis with and without cannabidiol in adults and adolescents: A randomised, double‐blind, placebo‐controlled, crossover experiment Addiction February 8, 2023
- Acute effects of cannabis on speech illusions and psychotic-like symptoms: two studies testing the moderating effects of cannabidiol and adolescence Psychological Medicine April 28, 2020
- The altered state of consciousness induced by Δ9-THC. Consciousness and Cognition May 28, 2022
and 29 more in the library
Cites 28
- Cannabidiol inhibits THC-elicited paranoid symptoms and hippocampal-dependent memory impairment Journal of Psychopharmacology October 5, 2012
- Acute and chronic effects of cannabinoids on effort-related decision-making and reward learning: an evaluation of the cannabis ‘amotivational’ hypotheses Psychopharmacology September 2, 2016
- Smoked Cannabis' Psychomotor and Neurocognitive Effects in Occasional and Frequent Smokers Journal of Analytical Toxicology March 4, 2015
- Are adolescents more vulnerable to the harmful effects of cannabis than adults? A placebo-controlled study in human males Translational Psychiatry November 29, 2016
- Cannabis and tolerance: acute drug impairment as a function of cannabis use history Scientific Reports May 26, 2016
and 23 more in the library