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Potency of Δ9 -tetrahydrocannabinol and other cannabinoids in cannabis in England in 2016: Implications for public health and pharmacology.

David Potter, Kathy Hammond, Shaun Tuffnell, Christopher Walker, Marta Di Forti

Drug Testing and Analysis April 2018 DOI: 10.1002/dta.2368 (opens in new tab)

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AI-extracted from the abstract
Characteristics Observational study of seized cannabis samples Peer reviewed
Sample size 460
Population Seized cannabis samples from five constabulary areas in England
Topics CBD Cannabis
Keywords Cannabinoid Potency Psychosis Δ9-tetrahydrocannabinol
Key findings Sinsemilla potency remained stable since 2005, with a median THC content of 14.2% and minimal CBD, while resin showed significantly higher mean THC (6.3%) and lower CBD (2.3%) than in 2005. The authors argue that the UK street market is now dominated by high-potency, CBD-poor cannabis, which may have concerning public health implications.

Abstract

In 2005 and 2008, studies reported that cannabis in England had become dominated by the sinsemilla (unseeded female) form. The average potency (Δ9 -tetrahydrocannabinol [THC] content) of this material had doubled over the previous decade. Cannabis resin then circulating contained approximately equal ratios of THC and cannabidiol (CBD), whereas sinsemilla was almost devoid of CBD. Despite raised health concerns regarding sinsemilla use and the development of psychotic disorders, no update on street cannabis potency has been published since 2008. A total of 995 seized cannabis samples were acquired from the same 5 constabulary areas included in the 2005 study. The differing forms were segregated, and a representative 460 samples analyzed to assess their cannabinoid content using gas chromatography. The resultant median sinsemilla potency of 14.2% THC was similar to that observed in 2005 (13.9%). In each case, sinsemilla contained minimal CBD. Compared with 2005, resin had significantly higher mean THC (6.3%) and lower CBD (2.3%) contents (p < 0.0001). Although the average THC concentration in sinsemilla samples across the 5 constabularies has remained stable since 2005, the availability of this potent form of cannabis has further increased. Moreover, the now rarer resin samples show significantly decreased CBD contents and CBD:THC ratios, leaving the United Kingdom's cannabis street market populated by high-potency varieties of cannabis, which may have concerning implications for public health.

Comparable studies

Other observational and cohort studies on cannabis, most cited first.

Study Year Design Participants
High-potency cannabis and the risk of psychosis People with first episode of psychosis and healthy controls from the local population 2009 Case-control study n = 454
Ayahuasca-Assisted Therapy for Addiction: Results from a Preliminary Observational Study in Canada Rural aboriginal population 2013 Observational study
Impaired cognitive performance in drug free users of recreational ecstasy (MDMA) Otherwise healthy young people 2000 Observational
Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study Individuals from the general population in Germany aged 14-24 at baseline 2011 Observational cohort n = 1,923
Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders: follow-up study of 535 incident cases Patients treated for cannabis-induced psychotic symptoms in Denmark between 1994 and... 2005 Observational cohort n = 535

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