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Study finds 'skunk' linked to 25% of psychosis cases

A powerful 'skunk-like' form of cannabis is associated with a quarter of new cases of psychosis, according to a new study.

A six-year study by researchers at King's College London found that the potent form of the Class B drug increased the risk for daily users by five - and tripled the risk even for casual users.

The study did not find any such link for the milder form of cannabis, known as hash.

The research followed 800 people aged between 18 and 65 in south London, including 410 who had suffered psychosis and 370 healthy patients.

Lead author on the project, Dr Marta Di Forti, called for a "clear public message" on the use of cannabis, based on the findings.

The results show that psychosis risk in cannabis users depends on both the frequency of use and cannabis potency. The use of hash was not associated with increased risk of psychosis.

As with smoking tobacco and drinking alcohol you need a clear public message.

When a GP or psychiatrist asks if a patient uses cannabis it's not helpful; it's like asking whether someone drinks. As with alcohol, the relevant questions are how often and what type of cannabis. This gives more information about whether the user is at risk of mental health problems. Awareness needs to increase for this to happen.

– Dr Marta Di Forti, lead author

Study: Cannabis linked to 'potentially lethal' damage

Cannabis smoking could lead to lethal heart damage, a study suggests. Credit: PA

Smoking cannabis can cause potentially lethal damage to the heart and arteries of young and middle-aged adults, a study has found.

Researchers in France who looked at almost 2,000 patients with medical problems related to cannabis use identified 35 serious instances of cardiovascular complications.

Twenty heart attacks were recorded, as well as 10 cases involving arteries in the limbs, and three affecting blood vessels in the brain. Nine patients, around a quarter of the total, died.

Most of the patients in the study - published in the Journal of the American Heart Association - were male, with an average age of 34.3 years.

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