Based on the same research, two reports with somewhat different emphasis:
The BBC report http://news.bbc.co.uk/2/hi/health/6606931.stm headlines:
Cannabis 'disrupts brain centre'
Thousands are thought to be dependent on cannabis. Scientists have shown how cannabis may trigger psychotic illnesses such as schizophrenia.
The Guardian http://www.guardian.co.uk/science/story/0,,2069736,00.html headlines;
Cannabis chemical curbs psychotic symptoms, study finds.
One of the active chemicals in cannabis inhibits psychotic symptoms in people with schizophrenia, according to a study which compared it with a leading anti-psychotic drug.
More from The Guardian report:
"Most cannabis research focuses on tetrahydrocannabinol (THC), the active ingredient that produces the high. Recent studies have shown THC makes symptoms of schizophrenia worse and triggers the condition in a small proportion of users.
But the new research shows that another chemical, cannabidiol (CBD), has the opposite effect. "One possibility is that there are good guys and bad guys within cannabis," said Markus Leweke, of the University of Cologne. He and his team compared the effects of CBD and a leading anti-psychotic drug, Amisulpride, on 42 patients with schizophrenia. After four weeks the symptoms of both groups had improved, but those treated with CBD suffered fewer side-effects.
"Maybe the cannabidiol ameliorates some of the effects of the THC and maybe it actually might be good for you if you are psychotic," said Robin Murray, of the Institute of Psychiatry at King's College London. They reported their research at the second International Cannabis and Mental Health Conference in London.
There is anecdotal evidence that the number of patients in the UK with psychotic symptoms linked to cannabis use is increasing. Professor Murray speculated that this may be linked to the increased THC content of herbal cannabis sold on the street. Cannabis on sale today has roughly doubled in strength in the last decade."