It would have been interesting to see that heat map extend into Canada to see if the trend along the Rockies continued as expected. I found the following paper that at least anecdotally fits this theory:

http://www.pembina.org/reports/10_suicide.pdf

Apparently Calgary is going through a suicide epidemic:

"suicides are the leading cause of death for boys and men 10 to 49 years of age, ahead of murder, traffic accidents, and all other causes of death in this age group"

Note that Calgary is at high altitude as well, roughly 3500 ft.