Vaporized CBD Produced Subjective Effects Without Measurable Deficits on the Tested Tasks
Participants could feel effects after vaporized CBD even when the study did not detect cognitive or psychomotor impairment on its test battery. Subjective drug effects and measured performance are related questions, but they are not interchangeable.
Four controlled conditions
Eighteen healthy infrequent cannabis users completed a blinded, double-dummy crossover study. Conditions were 100 mg oral CBD, 100 mg vaporized CBD, vaporized CBD-dominant cannabis containing 100 mg CBD and 3.7 mg THC, and placebo.
Outcomes included subjective ratings, vital signs, laboratory performance and whole-blood cannabinoids. Companion pharmacokinetic papers from this research are not independent replications involving new participants.
Route changed the reported experience
Vaporized CBD and CBD-dominant cannabis increased some subjective drug-effect ratings relative to placebo. Oral CBD did not significantly differ from placebo on the reported subjective effects. The cannabis preparation generally produced stronger subjective effects than vaporized CBD alone.
Pure CBD did not reproduce every THC-associated rating. For example, CBD did not increase paranoia ratings. Some sex-related observations were exploratory; the small sample could not settle broad sex-difference claims.
The performance null result has boundaries
The researchers did not observe cognitive or psychomotor impairment in any active condition on the administered tasks. This meaningful null finding is limited to the measures, doses and observation period tested.
Feeling an effect does not necessarily demonstrate a task deficit. Conversely, a small laboratory trial cannot prove that every CBD dose, route or combination leaves all safety-sensitive functions unaffected.
Composition remains important
The cannabis preparation contained THC, whereas the pure-CBD conditions isolated CBD. The THC-containing preparation also increased heart rate relative to placebo. Calling all conditions CBD hides those differences.
The experiment did not establish an on-road safety certification. Its contribution is a controlled demonstration that route, composition, subjective experience and performance can diverge.
For the separate forensic question, see our discussion of cannabinoid concentrations and evidence of impairment.
Primary research
Pharmacodynamic effects of vaporized and oral cannabidiol (CBD) and vaporized CBD-dominant cannabis in infrequent cannabis users. Drug and alcohol dependence (2020). DOI: 10.1016/j.drugalcdep.2020.107937.
