In light of research showing that an ingredient in cannabis, cannabidiol, seems to actually reduce the risk of psychosis, I speculated previously on Mind Hacks whether smokers might be attracted to high-cannabidiol dope.

A study of UK street cannabis published in the Journal of Forensic Sciences suggests that cannabis resin (hashish) has the average highest rates of cannabidiol, while ‘skunk’ and imported herbal cannabis (weed) have the lowest.

For people who take cannabis, it’s not the cannabidiol that makes you ‘high’, it’s mainly a substance called tetrahydrocannabinol or THC.

There’s accumulating evidence that THC increases the risk of psychosis, while cannabidiol reduces it – so the ratio of the two substances in the street drug might give a ‘risk profile’ in terms of mental health.

‘Might’ is the operative word here, as the research is still preliminary and the studies are still largely correlational with regard to cannabidiol-to-THC ratio and psychosis-like symptoms.

However, if this does turn out to be case, the new survey of UK street cannabis suggests that, on average, cannabis resin has higher levels of cannabidiol, with the implication that this might be less risky in terms of developing schizophrenia or other psychotic disorders.

This finding is an average over all the samples, however, and the study also found that resin had quite a bit of variability with regards to cannabidiol-to-THC ratio.

However, imported herbal cannabis and skunk was generally very low in cannabidiol. Additionally, skunk also had about 6 times the THC content of normal weed, making it especially potent.

The study concludes:

This study suggests that cannabis in England in 2005 remains a very variable drug with unpredictable pharmacological and psychological activity. The potency (THC content) of the cannabis varies widely, as does the content of other cannabinoids, especially in herbal cannabis and cannabis resin. The average potency within the country appears to be increasing, but large variations remain within and between different areas of the country. CBD affects the pharmacological qualities of THC and reduces it psychoactive potential. The relative proportions of THC and CBD in resin are wide ranging, supporting the view that the potential effects of resin cannot be judged by measuring the THC content alone. The resin samples were all similar in appearance and gave the user no indication of their cannabinoid content. Of the three principle forms of cannabis, sinsemilla [skunk] commonly had the highest THC content and almost totally lacked CBD. Had CBD been present it would have reduced the psychoactive potential of this material. In addition to having increased in potency, sinsemilla also appears to have become the most widely used form of cannabis. The current trends in cannabis use suggest that those susceptible to the harmful psychological effects associated with THC are at ever greater risk. This is due to the combined rise in potency and popularity of sinsemilla and the absence of CBD in this product.

The lead scientist in the study is called Professor Potter. Do with that fact as you will.

Link to abstract of Journal of Forensic Sciences study.