Regular cannabis users are more than five times more likely to develop a serious mental disorder.
Cannabis creates a greater mental health risk than any other substance, including class A drugs, scientists have found.
Those who abuse the drug – now more potent than ever in the form of super-strength ‘skunk’ – are 5.2 times as likely to develop schizophrenia as someone who had never smoked it.
But the researchers at Copenhagen University Hospital’s Mental Health Centre also found evidence implying that cannabis made the brain schizophrenic.
In a second study they discovered that pregnant women who abused cannabis gave birth to children six times more likely to become schizophrenics. This suggests the physical effects of the drug could be passed on in the womb.
Study leader Dr Carsten Hjorthøj said: ‘We know a child in its mother’s womb is not doing this by choice.
‘For me, that does set upon the idea that cannabis is a causal mechanism.
‘We know schizophrenia is a disorder of the brain linked to dopamine and cannabis influences levels of dopamine.’