Almost all cannabis now ‘super strength’

Ninety-four per cent of drug available on the streets is now high potency variety known as skunk

Nearly all cannabis on Britain’s streets is super-strength skunk that could be contributing to the rise in mental health problems, scientists believe. Researchers at King’s College London tested almost 1,000 police seizures in 2016 and found 94 per cent were dangerously potent. In 2005 just half the cannabis sold on the street was sinsemilla, also known as skunk. A scientist warned the drug puts two million users at risk of schizophrenia, depression, psychosis and delusions.

NEARLY all cannabis on Britain’s streets is super-strength skunk that could be contributing to a rise in mental health problems, scientists believe.

Researchers at King’s College London tested almost 1,000 police seizures from Kent, Derbyshire, Merseyside, Sussex and the capital in 2016 and found that 94 per cent were dangerously potent. In 2005 half the cannabis sold on the street was sinsemilla, also known as skunk.

Dr Marta Di Forti, an MRC clinician scientist at King’s College, warned the powerful drug put Britain’s 2.1 million cannabis users at risk of schizophrenia, bipolar disorder, depression, psychosis, delusions and hallucinations.

“The increase poses a significant hazard to users’ mental health and reduces their ability to choose more benign types,” she said.

“Regular users of high-potency cannabis carry the highest risk for psychotic disorders, compared to those who have never used cannabis.”

Researchers also found that in normal cannabis resin, the average concentration of tetrahydrocannabinol (THC) – the main psychoactive component – had risen by 50 per cent since 2005, to six per cent. In contrast, the ratio of antipsychotic cannabidiol (CBD), which helps mitigate the drug’s psychoactive effects, had fallen dramatically.

Skunk has around 14 per cent THC and is more dangerous because it contains only small amounts of CBD.

In 2015 King’s College showed that in South London, a quarter of new psychosis cases could be attributed to skunk. Researchers fear that the problem could be partly responsible for the growing number of mental health issues in Britain. Latest figures show that there were 7,545 hospital admissions in 2016-2017 for drug-related mental health and behavioural disorders, 12 per cent higher than in 20062007.

There were also 14,053 admissions for poisoning by illegal drugs last year, a 40 per cent increase compared with a decade earlier.

Ian Hamilton, a lecturer in mental health at the University of York, said: “If these seized samples are representative, then it suggests that apart from the dominance of skunk in the UK market, it also seems that resin has increased in strength … so even if people are trying to source lower potency cannabis, they are unable to.”

Prof Valerie Curran, professor of psychopharmacology at UCL, said: “Evidence from our own previous research suggests that high potency varieties are more likely to lead to addiction, so if the market is dominated by these varieties then this inevitably puts more people at risk of addiction.”

The research was published in the journal Drug Testing and Analysis.