Cannabis causing London psychosis epidemic, new study reveals

Almost a third of psychotic disorders in London are caused by cannabis use, a new study has revealed.

Published by The Lancet Psychiatry, the report suggests that if people stopped using the drug, an estimated 1,000 Britons a year could be spared from the condition.

Taking any version of cannabis daily was found to triple the chances of developing a mental disorder. But using forms with high levels of the active ingredient THC made users five times more likely to be affected.


It is estimated that 94 per cent of cannabis in London is the high potency ‘skunk’ – the stronger form of the drug.

The international study found the link with psychosis to be greater in London and Amsterdam where high-potency cannabis is more readily available.

Ad Gridley suffered with schizophrenia, before attempting to take his own life, after years of cannabis use.

He said: “I couldn’t function, and I was in and out of hospital ten times, I wasn’t doing anything meaningful with my life.”

‘Devastate, ruin, damage’

A Home Office spokesperson said: “No illegal drug can be assumed to be safe as there is no safe way to take them. Drugs can devastate lives, ruin families and damage communities.”

Recently the UK Government has faced pressure to legalise recreational cannabis use.

Former Metropolitan Police Chief Bernard Hogan-Howe previously said the UK should reconsider its position on the drug following the legalisation of cannabis in Canada and some US states.

The Home Office confirmed that the recent law change of medicinal cannabis “does not pave the way towards legalising cannabis for recreational use.”

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