There is to much conflicting information.
There was just a report like 2 weeks ago that said it made you dumber.
Depends what their agenda is. People who are pro-pot will spin it one way and people who are anti-will try it the other. There's a lot of misinformation from both sides and fear-mongering from the anti-camp. Cannabis isn't a magic medicine for everything, but it has it's uses. I don't think it cures cancer as some claim, but it definitely helps with the pain and sickness of chemo.
I'm pro-Cannabis even though I don't use it. From a past life, I can say without a doubt that it definitely didn't increase my IQ, and learning was more of a struggle. I do believe in it's medicinal properties, and as you've stated it's great for fighting pain and the sickness of chemo.