Just say ‘know’: how do cannabinoid concentrations influence users' estimates of cannabis potency and the amount they roll in joints?

Freeman, Tom P.; Morgan, Celia J. A.; Hindocha, Chandni; Schäfer, Gráinne; Das, Ravi; Curran, H. Valerie

doi:10.1111/add.12634

Cited by 117 publications

(113 citation statements)

References 30 publications

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“…This inhaled dose of THC has been found to produce effects on human brain and behaviour, including psychotic-like symptoms and memory impairment 7,40,41 . The 2:1 ratio of CBD:THC reflects the upper limit (mean + 3 SD) found in high CBD/low THC cannabis preparations 42 . Participants were given a test balloon to familiarise themselves with the procedure before any drug administration occurred.…”

Section: Methodsmentioning

confidence: 90%

Individual and combined effects of acute delta-9-tetrahydrocannabinol and cannabidiol on psychotomimetic symptoms and memory function

et al. 2018

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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.

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Section: Methodsmentioning

confidence: 90%

Individual and combined effects of acute delta-9-tetrahydrocannabinol and cannabidiol on psychotomimetic symptoms and memory function

et al. 2018

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“…Only very recently have studies differentiated between different types of cannabis based on THC content 30,[37][38][39] , and most of these studies do not involve measures of THC and CBD content, but proxy measures of potency, such as analysis of police seizures or coffee shop cannabis, and a reliance on self-report measures. Although self-report measures are associated with THC and CBD content, these associations are modest and are weaker among infrequent users 84,85 . Future longitudinal studies may choose to collect cannabis cigarettes (joints) from their participants over the course of the study and collect information as to how often they would smoke such a cigarette.…”

Section: Making Cannabis Safermentioning

confidence: 92%

Can we make cannabis safer?

Englund

Freeman

Murray

et al. 2017

The Lancet Psychiatry

132

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“…Furthermore, although other studies that have used self-report measures have also shown an association with brain structural alterations (Rigucci et al 2016), the lack of objective measures of cannabis use in our study is an important limitation. However, there is published evidence indicating that asking patients with psychosis about their use of cannabis is, at least in some situations, more accurate than, or as reliable as, urine or blood testing which can only provide information on recent use (Freeman et al 2014). The lack of a measure of the potency of cannabinoid compounds might nevertheless also affect the robustness of our findings; indeed, the recent changes in the composition of Bstreet^cannabis have created a new and complex landscape for the understanding the neurobiological impact of cannabis products.…”

Section: Strengths and Limitationsmentioning

confidence: 99%

Cannabis use in early psychosis is associated with reduced glutamate levels in the prefrontal cortex

et al. 2017

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Rationale Recent studies have shown that cannabis may disrupt glutamate (Glu) signaling depressing Glu tone in frequent users. Current evidence have also consistently reported lower Glu-levels in various brain regions, particularly in the medial prefrontal cortex (mPFC) of chronic schizophrenia patients, while findings in early psychosis (EP) are not conclusive. Since cannabis may alter Glu synaptic plasticity and its use is a known risk factor for psychosis, studies focusing on Glu signaling in EP with or without a concomitant cannabis-usage seem crucial.Objective We investigate the effect of cannabis use on prefrontal Glu-levels in EP users vs. both EP non-users and healthy controls (HC). Methods Magnetic resonance spectroscopy was used to measure [Glu mPFC ] of 35 EP subjects (18 of whom were cannabis users) and 33 HC. For correlative analysis, neuropsychological performances were scored by the MATRICS-consensus cognitive battery. Results [Glu mPFC ] was lower in EP users comparing to both HC and EP non-users (p < 0.001 and p = 0.01, respectively), while no differences were observed between EP non-users and HC. A greater [Glu mPFC ]-decline with age was observed in EP users (r = −.46; p = 0.04), but not in EP non-users or HC. Among neuropsychological outcomes, working memory was the only domain that differentiates patients depending on their cannabis use, with users having poorer performances. Conclusions Cannabis use is associated with reduced prefrontal [Glu mPFC ] and with a stronger Glu-levels decline with age. Glutamatergic abnormalities might influence the cognitive impairment observed in users and have some relevance for the progression of the disease.

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Just say ‘know’: how do cannabinoid concentrations influence users' estimates of cannabis potency and the amount they roll in joints?

Abstract: When using their own cannabis in a naturalistic setting, people titrate the amount they roll in joints according to concentrations of delta-9-tetrahydrocannabinol (THC) but not cannabidiol (CBD). Recreational users thus show poor understanding of cannabis potency.

Cited by 117 publications

References 30 publications

Individual and combined effects of acute delta-9-tetrahydrocannabinol and cannabidiol on psychotomimetic symptoms and memory function

Individual and combined effects of acute delta-9-tetrahydrocannabinol and cannabidiol on psychotomimetic symptoms and memory function

Can we make cannabis safer?

Cannabis use in early psychosis is associated with reduced glutamate levels in the prefrontal cortex

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