I would be remiss if I neglected to mention a religious solution to your/friend's problem. I personally think(and with examples from the Seerah) that depression is curable via walking the "path" and with some guidance, with the will of Allah.
The dua is from Rasool Ullah(S.A.W) himself(taught by him), and is referenced in Shahih Bukhari.
If you have 20 mins, I
highly recommend you go through the video but in case you couldn't manage, I have marked the video to where the speaker teaches it.
https://www.youtube.com/watch?v=_1B60L4m60M&t=13m31s
I suppose if you weren't inclined, please ignore this post. Somebody else might be able to benefit from it. I do though, contrary to how it would seem; have faith in SSRIs and antidepressants for extreme cases.
May Allah have mercy.
Good luck.