MANY psychiatric units have become little more than ‘cannabis wards’ because of the huge numbers turned psychotic by the drug, a mental health expert claimed yesterday.

Marjorie Wallace, chief executive of the charity Sane, said the situation had become so serious that the entire mental health system was being ‘distorted’.

Patients with non drug-related mental illnesses were being turned away from some wards because the threat of violence from psychotic cannabis users had made them unsafe, she added.

‘Doctors are saying to non cannabis-users, such as young girls with anorexia and middle-aged women, “I can’t admit you if you are not taking cannabis, because it’s not safe”,’ Miss Wallace said.

‘It means people who may be even more seriously ill and even more of a suicide risk are being neglected.

Cannabis has changed the whole way in which the mental health system operates. The popular view of cannabis is that it is a harmless drug. It is not.’ Miss Wallace’s comments came a day after research in Sweden suggested cannabis can permanently damage the development of teenagers’ brains, with users in the age group up to ten times more likely to suffer long-term mental illness.

One of the most outspoken critics of the Government’s decision to downgrade cannabis from a class B to a class C drug in January last year, Miss Wallace has spent 18 years trying to draw attention to the link between the drug and mental illness.

‘In all the years I have campaigned in the mental health field, I think I have only come across two examples of young people developing psychosis in which cannabis was not a factor,’ she said.

‘In London, 80 per cent of people assessed with a first episode of psychosis are on cannabis. The explosion in cannabis-induced psychosis is already happening.’