[roenxi]

There are roughly 2 ways to define illness - a cause leading to symptoms (HIV virus -> AIDS) or symptoms without a defined cause (eg, nausea).

Depression seems to be the second type, so I'm not sure it makes sense to talk about that sort of discovery. It seems self evident to me that sometimes depression will be caused by inflammation. Other times it'll be caused by other things. Brains are delicate self modifying machines, they can go haywire from pretty much anything and nothing. We can only find that some factors were underweighted or overweighted by the medical community under some circumstances. Depending on what definition of "depression" gets used.