Australian researchers have found insomnia patients using medicinal cannabis containing THC experience little or no next-day impairment in findings which could have a significant impact on the debate around drug-driving reform.

The team, including representatives from the Woolcock Institute of Medical Research and the Lambert Initiative for Cannabinoid Therapeutics, studied 20 adults with insomnia to determine next-day impairment following evening administration of a typical medicinal cannabis oil compared to a placebo. 

The ‘infrequent’ cannabis users took a single oral dose of 10mg THC combined with 200mg of CBD. A series of cognitive tests were then conducted within the first two hours of waking, nine to 11 hours after drug administration, with tasks designed to assess attention, working memory, and visuospatial function among other measures.

Driving performance was measured 10 hours post-treatment using a simulator equipped with standard vehicle controls and a custom-built, 30-minute scenario that has previously demonstrated sensitivity to the acute effects of THC in healthy volunteers.

Subjective drug effects were also assessed, with participants asked to rate how ‘stoned’, ‘sedated’, ‘alert’, ‘anxious’ and ‘sleepy’ they felt at baseline, 30 minutes and 10 hours after treatment. 

Measurements stopped after 10 hours because subjective drug effects were not expected to persist beyond this time following a single oral dose of THC.

The team reported “a lack of notable ‘next-day’ impairment… consistent with prior work showing that the impairing effects of oral THC on cognition and driving performance typically resolve within around eight hours”.

Almost all the cognitive tests involving attention, working memory, and speed of information processing showed no ‘next-day’ effects of THC/CBD, they said.  

“Overall, we found little evidence to suggest that a single dose of 10mg oral THC, in conjunction with CBD, impairs ‘next-day’ function in adults with insomnia who infrequently use cannabis,” the researchers concluded.

“Larger studies in patient populations are required to determine the effects of repeated dosing with THC (with or without CBD), and at higher doses of THC, on ‘next-day’ function.”

Prior to launching Cannabiz, Martin was co-founder and CEO of Asia-Pac’s leading B2B media and marketing information brand Mumbrella, overseeing its sale to Diversified Communications in 2017. A journalist...

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