Scientists find link between ’skunk' weed and psychosis -- but that’s not the whole story

Scientists have found a link between regular use of powerful so-called "skunk" marijuana and psychosis in some users. However, extracts of cannabis are being used to ease the symptoms of mental illness in other patients.

New Scientist reported on a study by researchers at King's College London who found that regular users of the powerful "skunk" were three times more likely to suffer from psychosis and that daily users were five times more likely.

However, people who smoked regular hashish -- which contains the same psychoactive ingredient as ultra-powerful marijuana strains, but is not as potent -- showed no variations away from or toward psychosis.

Team co-leader Robin Murray spoke to New Scientist about the study's findings, which explored possible contributing factors in 410 people newly diagnosed with psychosis and compared their lives with a control group of 370 regular people with no history of psychosis.

Psychosis is a blanket term for any mental state involving a disconnection from reality. Psychosis could mean any symptoms from mild to severe depression, temporary or lasting paranoia, slowed or impaired cognition, or other sensory disruptions.

So-called "skunk" weed is the result of years of cultivation by marijuana growers interested in producing a more potent high in users. The new strains of pot are Murray said, "far richer than hash in delta-9-tetrahydrocannabinol, or THC, the ingredient that creates the drug's high but which also triggers psychosis. Even more important, skunk contains hardly any of a substance called cannabidiol, or CBD, which has been shown to counteract the psychotic effects of THC."

Amir Englund, also of King's College, said, "In traditional hash, the proportions of THC and CBD are about equal, at 4 per cent each. In skunk, THC reaches around 14 to 15 per cent, while CBC tumbles to barely a trace."

Englund reported that a U.K. company called GW Pharmaceuticals is reportedly having success using CBD to treat symptoms of psychosis in patients with schizophrenia.

The company is testing 80 individuals in the U.K., Poland and Romania to see if doses of CBD calm their psychotic symptoms.

Murray cited a German study that followed 33 patients with schizophrenia and found that CBD treated their symptoms as well as their prescribed medication, amisulpride, but without the prescription drug's side-effects.