A Semi-Naturalistic, Open-Label Trial Examining the Effect of Prescribed Medical Cannabis on Neurocognitive Performance

Elucidating the acute effects of medically prescribed oral and vaporised delta-9-tetrahydrocannabinol on cognitive functions important for driving

INTRODUCTION

This program of research investigated the acute effects of orally ingested (Study 1) and vaporised (Study 2) cannabis containing delta-9-tetrahydrocannabinol (THC) on cognitive functions relevant for driving in two samples of medicinal cannabis patients (Study 1 N = 41 oral users; Study 2 N = 37 flower users).

METHOD

Participants completed counterbalanced baseline (no cannabis) and cannabis consumption (post-cannabis) appointments scheduled approximately 1 week apart. During each session, participants were administered a cognitive battery assessing information processing speed, sustained and divided attention, inhibitory control and mental flexibility. In the post-cannabis condition, the battery was completed 90 min after consuming one dose of cannabis oil (Study 1) or 15 min after vaporising one dose of cannabis flower (Study 2).

RESULTS

In both samples, acute cannabis oil and flower administration did not induce a change in information processing speed, divided and sustained attention, or inhibitory control performance (after excluding participants with a positive drug indication at the start of either session), highlighting the moderating role of tolerance. However, significant reductions in TMT B performance were observed. Further, TMT ratio was significantly reduced post consumption of cannabis oil.

DISCUSSION AND CONCLUSIONS

TMT B may be sensitive to acute cannabis consumption in medicinal cannabis patients. However, further research is needed to determine the nature and duration of these effects, and whether such effects vary depending on the population studied (e.g., regular vs. new users).

The acute effects of vaporized cannabis on drivers' hazard perception and risk-taking behaviors in medicinal patients: A within-subjects experiment

INTRODUCTION

As the medically prescribed use of cannabis flower continues to increase, there is a need to understand how vaporized cannabis can acutely affect driving-related skills and risk-taking behaviors in medicinal populations.

METHOD

Given this, the present study examined the acute effects of vaporized cannabis flower on measures of hazard perception, driving-related risk-taking behaviors, and subjective perceptions of driving skills in a sample of adult medicinal cannabis patients. Participants (N = 38, M age = 43) attended both a baseline (no cannabis) and intervention appointment (with cannabis consumption), where they completed video-based tasks and self-report measures of driving ability.

RESULTS

After vaporizing one dose of their prescribed cannabis flower, participants exhibited no significant changes in performance on any of the video-based tasks (hazard perception skill, gap acceptance, following distance or speed) compared to baseline. However, cannabis consumption resulted in significant reductions in perceived hazard perception task performance and on-road traffic conflict prediction ability. Furthermore, there was a lack of association between objective and subjective hazard perception performance at both time points.

PRACTICAL APPLICATIONS

These results suggest that while acute prescribed cannabis consumption may reduce appraisals of selected skills, overall hazard perception ability and driving-related risk-taking behavior may remain unchanged.

Identifying standardised neuropsychological test measures sensitive to cannabis consumption: A systematic review

BACKGROUND

While numerous studies have indicated acute neurocognitive changes following the administration of Δ9-tetrahydrocannabinol (THC; the psychoactive component of cannabis), the standardised neuropsychological tests most sensitive to THC are yet to be identified. As such, this systematic review analysed scientific evidence (since 2000) on the effects of THC on standardised neuropsychological test measures.

METHODS

This review was conducted in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies were eligible for inclusion if they utilised a between or within-subjects design in testing for differences in standardised neuropsychological test performance following the consumption of THC.

RESULTS/DISCUSSION

Sufficient data were identified to examine 8 standardised neuropsychological test measures, with 12 studies being eligible for inclusion in the review. It was identified that the Cambridge Neuropsychological Test Automated Battery (CANTAB) subtest Spatial Working Memory, Hopkins Verbal Learning Test, Prose Recall and Rey Auditory Verbal Learning Test were sensitive to cannabis consumption.

LIMITATIONS

However, due to substantial variability observed across studies, the data could not be quantitatively analysed. It was noted that few studies employed standardised neuropsychological measures in assessing the effects of THC.

CONCLUSION

Overall, the findings highlight the need for further research examining the effects of cannabis on standardised and validated measures of neurocognitive function. Such an approach can be considered an important first step towards developing behavioural measures of impairment.

Attitudes toward driving after cannabis use: a systematic review

BACKGROUND

Driving after cannabis use (DACU) is associated with increased risk of motor vehicle collisions. As cannabis legalization expands, DACU is emerging as a major public safety concern. Attitudes have a significant impact on behavioural decision making. As such, understanding the degree to which people have favorable or unfavorable evaluations of DACU is an important first step for informing prevention efforts. This systematic review summarizes existing evidence on attitudes toward DACU, their association with actual or intended DACU, and changes in attitudes following legalization of recreational cannabis.

METHODS

Four electronic databases (MEDLINE, EMBASE, PsycINFO, and TRID) were searched for studies that reported attitudes or changes in attitudes toward DACU published between their inception dates and February 26 2024. A total of 1,099 records were retrieved. Studies were analyzed using an inductive thematic synthesis approach.

RESULTS

Seventy studies from seven countries originating predominantly from the United States and Canada met inclusion criteria. Thematic analysis identified six themes. (I) Attitudes toward the safety and acceptability of DACU are mixed; participants in 35 studies predominantly expressed negative attitudes toward DACU (e.g., DACU is dangerous, affects driving ability, and increases crash risk). However, 20 studies reported opposing views. (II) Attitudes toward DACU vary by age, sex/gender, and cannabis use frequency; youth, men, and frequent cannabis users tended to view DACU more favorably than older participants, women, and occasional or non-users. (III) Attitudes toward DACU are associated with past DACU and intention to DACU. (IV) DACU is viewed more favorably than driving after drinking alcohol. (V) The relationship between legal status of recreational cannabis and attitudes toward DACU is unclear. (VI) Perceived risk of apprehension for DACU is low to moderate.

CONCLUSIONS

This review found that perceptions of DACU are primarily negative but mixed. Findings suggest that attitudes toward DACU are important targets for interventions to reduce this behaviour.

A randomised, placebo-controlled, double blind, crossover trial on the effect of a 20:1 cannabidiol: Δ9-tetrahydrocannabinol medical cannabis product on neurocognition, attention, and mood

As cannabinoid-based medications gain popularity in the treatment of refractory medical conditions, it is crucial to examine the neurocognitive effects of commonly prescribed products to ensure associated safety profiles. The present study aims to investigate the acute effects of a standard 1 mL sublingual dose of CannEpil®, a medicinal cannabis oil containing 100 mg cannabidiol (CBD) and 5 mg Δ9-tetrahydrocannabinol (THC) on neurocognition, attention, and mood. A randomised, double-blind, placebo-controlled, within-subjects design assessed 31 healthy participants (16 female, 15 male), aged between 21 and 58 years, over a two-week experimental protocol. Neurocognitive performance outcomes were assessed using the Cambridge Neuropsychological Test Automated Battery, with the Profile of Mood States questionnaire, and the Bond-Lader Visual Analogue Scale used to assess subjective state and mood. CannEpil increased Total Errors in Spatial Span and Correct Latency (median) in Pattern Recognition Memory, while also increasing Efficiency Score (lower score indicates greater efficiency) relative to placebo (all p < .05). Subjective Contentedness (p < .01) and Amicability (p < .05) were also increased at around 2.5 h post dosing, relative to placebo. Drowsiness or sedative effect was reported by 23 % of participants between three to six hours post CannEpil administration. Plasma concentrations of CBD, THC, and their metabolites were not significantly correlated with any observed alterations in neurocognition, subjective state, or adverse event occurrence. An acute dose of CannEpil impairs select aspects of visuospatial working memory and delayed pattern recognition, while largely preserving mood states among healthy individuals. Intermittent reports of drowsiness and sedation underscore the inter-individual variability of medicinal cannabis effects on subjective state. (ANZCTR; ACTRN12619000932167; https://www.anzctr.org.au).