I was reading this link, which is one I'd had in my files and one Granny Storm Crow has on her list of pro-cannabis links, too. This has some good all-purpose information that says the same "depends on the person" thing we've all heard and read before.
AAMC: Cannabis and Depression

In general, it says, Indica strains are the more sedating ones, which is probably meant to imply that they can also be more depressing ones, whereas Sativas are more of the uppers. The only hitch is that different types of depression can vary with how they respond to the effects of those strains, too. People who have a lot of anxiety and panic with their depression can get aggravation of those symptoms with sativas, I know. Yet people who are the sad, lethargic, couch-locked depressives wouldn't be good candidates for pure Indicas, certainly.

This is why we need this to be medicinally legal in all states and according to federal law, so the information about what works and what doesn't and who can benefit can be studied, in depth. Then people who get benefit from their depression symptoms can use it freely and those who don't can try the other things that work, like exercise and, for many, prescribed medicines.