title: The effect of five day dosing with THCV on THC-induced cognitive, psychological and physiological effects in healthy male human volunteers: A placebo-controlled, double-blind, crossover pilot trial.
abstract: BACKGROUND
  Cannabis is mostly grown under illegal and unregulated circumstances, which seems to favour a product increasingly high in its main cannabinoid ∆-9-tetrahydrocannabinol (THC). ∆-9-tetrahydrocannabivarin (THCV) is a relatively untested cannabinoid which is said to be a cannabinoid receptor neutral antagonist, and may inhibit the effects of THC.
  
  
  OBJECTIVE
  To explore the safety and tolerability of repeated THCV administration and its effects on symptoms normally induced by THC in a sample of healthy volunteers.
  
  
  METHODS
  Ten male cannabis users (<25 use occasions) were recruited for this within-subjects, placebo-controlled, double-blind, cross-over pilot study. 10mg oral pure THCV or placebo were administered daily for five days, followed by 1mg intravenous THC on the fifth day.
  
  
  RESULTS
  THCV was well tolerated and subjectively indistinguishable from placebo. THC did not significantly increase psychotic symptoms, paranoia or impair short-term memory, while still producing significant intoxicating effects. Delayed verbal recall was impaired by THC and only occurred under placebo condition (Z=-2.201, p=0.028), suggesting a protective effect of THCV. THCV also inhibited THC-induced increased heart rate (Z=-2.193, p=0.028). Nine out of ten participants reported THC under THCV condition (compared to placebo) to be subjectively weaker or less intense (χ(2)=6.4, p=0.011). THCV in combination with THC significantly increased memory intrusions (Z=-2.155, p=0.031).
  
  
  CONCLUSIONS
  In this first study of THC and THCV, THCV inhibited some of the well-known effects of THC, while potentiating others. These findings need to be interpreted with caution due to a small sample size and lack of THC-induced psychotomimetic and memory-impairing effect, probably owing to the choice of dose.
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK amir.englund@kcl.ac.uk.
authors.forename: Amir
authors.initials: A
authors.lastname: Englund
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: Zerrin
authors.initials: Z
authors.lastname: Atakan
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Kralj
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: Nigel
authors.initials: N
authors.lastname: Tunstall
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: Robin
authors.initials: R
authors.lastname: Murray
authors.affiliation: Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Morrison
mesh_terms: D000328:Adult; D003071:Cognition / Q000187:drug effects*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D013759:Dronabinol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D006213:Hallucinogens / Q000008:administration & dosage / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects*; D011939:Mental Recall / Q000187:drug effects; D010865:Pilot Projects; D055815:Young Adult
chemical_list: D006213:Hallucinogens; C003403:tetrahydrocannabivarin 9; D013759:Dronabinol
keywords: THC; THCV; cannabinoid; cannabis; human; memory; psychosis; Δ9-tetrahydrocannabinol; Δ9-tetrahydrocannabivarin