Hi Sailordude, I don't know how to post the link but I recently watched this on YouTube from Stanford University, the professor/dr has spent 30 yrs of his life studying etc depression. Any who thus informative lecture covered all angles biological, environmental etc. maybe you can watch it and get your parents too as well. I would hope it helps them understand depression more. The video was called...

Stanford's Sapolsky On Depression in U.S. (Full Lecture)

I am in Canada too different provinces have different resources google it for your area.. They have help support groups for all sorts dx' s.
All the best to you