Brisbane, Australia: Patients’ cognitive performance is largely unaffected following their consumption of either medical cannabis oil or flower, according to data published in the journal Drug and Alcohol Review.
Australian researchers assessed the acute effects of either vaporized cannabis or the ingestion of cannabis oil on cognitive functions relevant to driving in a cohort of 78 patients. (Australian physicians may prescribe cannabis products to patients unresponsive to conventional prescription treatments.) Participants’ performance was tested at baseline and then again 15 minutes following the vaporization of herbal cannabis and 90 minutes following the ingestion of cannabis oil.
Consistent with prior studies, subjects exhibited tolerance to the acute effects of cannabis dosing. Specifically, participants’ cannabis use “did not measurably affect information processing speed, divided and sustained attention, or inhibitory control performance.”
By contrast, investigators reported that cannabis may negatively influence patients’ “mental flexibility” (the capacity for switching attentional focus) and “visuomotor attention” skills. However, researchers said it is unclear “whether such changes would translate into temporary functional changes to driving capacity.”
The study’s authors concluded: “The absence of measurable change on multiple measures of attentional processing, reaction time, and simple information processing speed suggests that tolerance to THC may mediate the known acute effects of cannabis on neurocognitive function in medicinal cannabis patients. … As the use of medicinal cannabis continues to expand globally, research investigating the acute effects of prescribed THC remains a high priority.”
Full text of the study, “Elucidating the acute effects of medically prescribed oral and vaporized delta-9-tetrahydrocannabinol on cognitive functions important for driving,” appears in Drug and Alcohol Review. Additional information is available in the NORML Fact Sheet, ‘Marijuana and Psychomotor Performance.’