Crackdown on marijuana increases rates of cannabis psychosis

Researchers from the University of York have demonstrated that the change in cannabis declassification in 2009 has coincided with a significant increase in hospital admissions for cannabis psychosis – rather than the decrease it was intended to produce.

The UK Misuse of Drugs Act (1971) divided controlled drugs into three groups – A, B and C – with descending criminal sanctions attached to each class. Cannabis was originally assigned to Group B, but in 2004, it was transferred to the lowest risk group, Group C.