In US States with medical cannabis, the suicide rate seems to fall.
Here is another piece of research on this interesting subject.
You can download the full report from the Timeline on the Dagga Couple website:

Suicide instances fall when medical marijuana is law (Science) – The Leaf Online
theleafonline.com
The enactment of statewide laws allowing for the therapeutic use of cannabis is associated with reduced instances of suicide, according to a discussion paper published in January by the Institute for the Study of Labor in Bonn, Germany. …read more