Recently Prescribed Cannabis Did Not Mean Cannabis-Naive in the Cognitive Studies

Some participants had only recently started medicinal cannabis but reported many years of non-prescribed use. Time since prescription was therefore a different exposure-history measure from time since first cannabis use.

The study recorded both histories

The oral and flower groups reported months of medicinal treatment and longer histories of cannabis use. Among participants with three months or less of medicinal use, several had at least five years of prior non-prescribed use. In the flower sample, the paper identified eleven such participants.

A treatment label does not define adaptation

Someone newly receiving a prescription may already have extensive experience with THC. Conversely, prescription status alone cannot establish tolerance to every acute effect. Combining these people into a generic new-user category would conceal the history relevant to interpretation.

The distinction limits comparisons with first exposure

The cognitive results came largely from frequent users with heterogeneous treatment and use histories. They should not be transferred automatically to a person taking THC for the first time. The self-reported histories also do not prove the extent of any individual’s physiological adaptation. For an evidence review, distinguish onset of cannabis use, recent frequency, formulation experience and onset of prescribed treatment. Each can inform a different question, and no single administrative date substitutes for the complete history.

Related analysis: the study’s main findings and limitations.

Research cited

Stefanidis and colleagues. Elucidating the acute effects of medically prescribed oral and vaporised delta-9-tetrahydrocannabinol on cognitive functions important for driving. Drug and Alcohol Review (2025). DOI: 10.1111/dar.14060.