[an9n]

It took me literally a few seconds to find this:

https://www.theguardian.com/society/2015/feb/16/skunk-cannab...

'Smoking powerful skunk cannabis triples the risk of suffering a serious psychotic episode, scientists have found.'

'Those who reported smoking milder forms of the drug, such as hash, did not appear to be at increased risk, for instance. Murray said that, in line with this finding, he recommends hash to patients who are struggling to give up smoking altogether.'