If you check when he started having depression and what he was reading at the time
Are you referring specifically to the JSTOR/MIT case, or to something else further back? If it's the latter, can you give a reference?
If it's the former, you are aware, aren't you, that Swartz was on record years before the JSTOR/MIT case describing his depression?
http://www.aaronsw.com/weblog/verysick
His description here sounds like the classic symptoms of chemical depression. Which is not to say, once again, that there weren't also other factors involved in the JSTOR/MIT case.