Lol at 'mental skills'... they should do a study next comparing the relative drop in mental skills from smoking pot as compared to an equally effective painkilling dose of traditionl opiate painkillers. I'll bet it's way worse. Also I'd like to know what exactly the 'mental skills' were that were tested. Did it have to do strictly with memory or with creative problem-solving? Different tasks would definitely produce different results. While stoned, I think a smoker would have an easier time writing an essay than, say, playing 'memory' lol.
We already knew that it was effective against degenerative nerve diseases triggered by illness (MS) or injury (Phantom pains).