Synthetic cannabinoid-receptor agonists may precipitate psychosis in vulnerable individuals, as shown by recent experience within a New Zealand forensic psychiatric in-patient service.

Since 2006, a number of novel products such as K2, Spice, Aroma and Dream have appeared, masquerading as ‘herbal incense’ but marketed as cannabis substitutes. These products are surprisingly psychoactive. Mass spectrometry reveals the reason for their potency: the benign ‘herbal’ ingredients specified on the packaging have been deliberately adulterated with unlisted synthetic cannabinoid-receptor agonists such as CP47,497 [1], JWH-018 [1] and HU-210 [2]. These cannabimimetics have been declared illegal in some countries, but JWH compounds remain unregulated in many countries, including New Zealand and the United States (although banned recently in seven American states).

While there is a significant growing body of evidence that cannabis is associated with the development and exacerbation of psychosis in some individuals (e.g. [3]), almost nothing is known about the metabolism, toxicology and psychiatric effects of these new cannabimimetic agents. A recent literature search found two case reports relating to Spice (which at that time contained JWH-018 and CP47,497): one report involved tolerance and withdrawal phenomena [4] and the other described drug-induced psychosis [5].

During the last year some patients within our service have been surreptitiously smoking a cannabimimetic called Aroma which, like K2, has been shown to contain JWH-018 (personal communication, Mark Heffernan, Analyst—National Drug Policy, New Zealand Ministry of Health). JWH-018 has similar receptor activity to 9-delta-tetrahydrocannabinol (THC), but its greater affinity to CB1 and CB2 cannabinoid receptors may make it more potent [6]. JWH compounds cannot be detected currently by conventional urinalysis, limiting the ability to identify and regulate these substances.

The mental states of at least five forensic patients have deteriorated significantly after using products containing CP47,497 and/or JWH-018. This has manifested as the sudden re-emergence of florid psychosis; predominantly agitation, disorganization and delusional beliefs (paranoid and grandiose types) in previously stable patients with histories of mental illness.

We are conducting further research into the use and effects of synthetic cannabimimetics in our forensic population. However, until additional information becomes available, our experience suggests that JWH-018 and CP47,497 compounds may precipitate psychosis in a similar fashion to cannabis. People with risk factors for psychosis should be educated as to the potential risks and advised to avoid these substances. Clinicians should also consider the possible use of synthetic cannabimimetics in patients with unexplained psychotic relapses and negative drug screening.

Declarations of interest