Not all cannabis strains affect memory equally

October, 2010

Current strains of cannabis may put users at greater risk of cognitive impairment.

A study involving 134 cannabis users aged 16-23 has found that when they were smoking cannabis containing a low percentage of cannabidiol they performed much worse on the memory tests. In contrast, those smoking cannabis high in cannabidiol performed just as well on the tests when they were intoxicated as when they were sober. There were no differences in the THC content of the cannabis smoked by any of the participants (THC is the main psychoactive ingredient, which gives the characteristic ‘stoned’ feeling, and feelings of paranoia).

For the study, the participants were tested on two separate occasions — once while they were smoking their own preferred type of cannabis and were intoxicated, and once when they had not smoked for the last 24 hours and were sober.

Levels of cannabidiol in cannabis can range from virtually none to 40%. This study suggests that cannabidiol can counteract the memory-impairing effects of THC. Unfortunately, low-cannabidiol strains (like skunk) now dominate the market of street cannabis, suggesting current users will be more at risk of cognitive impairment.



I'm sorry but there is no way

I'm sorry but there is no way almost half the mass of the plant material is CBD, that's preposterous. THC content is at most 30%, and that's pushing it. And THC degrades into CBD with light, so it's really hard to believe CBD content would exceed that of THC.

Re: I'm sorry but there is no way

I don't have any expertise in chemistry so can't speak to the absurdity of it, but the paper advises that CBD and THC are the main constituents of cannabis, and that in the UK, "on average, cannabis resin contains approximately equal levels of THC and cannabidiol, whereas herbal cannabis contains only moderate levels of THC and almost no cannabidiol. By contrast, sinsemilla, or skunk, contains high levels of THC and almost no cannabidiol." The 40% figure I quoted was taken from the press release.


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