Some of us are of an age to remember when weed was weed, not uber skunk strains and all that brings with it. When was the last time you saw a decent bit of Leb or squidgy black? Never, it's all hardcore high THC content skunk.
Out of my original circle of toking friends, back in the late 80's none of them developed any form of use related psychosis. The same can't be said for these smoking these days. It's the type of gear that has lead to increased risk, that and penetration further down the age range.
Prof's Nutt comments are all fair enough, in context, but that's the trouble with context… However the government should know better, wtf is the point of having independent scientific investigative committees if you are going to ignore what they find, because you think you know better…
tsk tsk..