My work with prisoners in Prison Visiting taught me how badly skunk weed affected the young men. Quite a few became schizophrenic or completely unresponsive and zombie-like. Whole wings of the prison stank, as skunk is very strong stuff. I can quite believe it has a harmful effect on IQ. Smoking 'pot' as was done in the sixties, wasn't the same thing. This latest stuff is much more powerful and IMO should be re-classified as a Class A drug. I suppose the Prison Officers liked to let the lads smoke it as in theory it 'calmed them down'. Very worrying.