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

Brooke Manning, Amie C. Hayley, Sarah Catchlove, Con Stough, Luke A. Downey

Research output: Contribution to journalArticleResearchpeer-review


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)

Original languageEnglish
Pages (from-to)35-43
Number of pages9
JournalEuropean Neuropsychopharmacology
Publication statusPublished - May 2024
Externally publishedYes


  • Attention
  • Cannabidiol
  • Visuospatial memory
  • Δ9-tetrahydrocannabinol

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