Most of those people who get mental health issues with weed they already had those issues. Places where weed is grown naturally you don't get people having mental issues.
It's over here in the UK where they put chemicals in growing the weed to make it stronger because the weather is not there to grow it naturally that's where people get them mental health issues.
To say it sends people loco that's the reason to ban it don't really stand. For every 10 that have mental health issues when they smoke it there are 1000s of people who are fine and I won't even compare it to alcohol and I don't see any real reason to ban weed apart from they won't be able to stop the low level dealers from making a few £s