WTH does his being cognisant of what he was doing have to do with the fact that he was suffering from the throes of severe clincical depression? Do you have even a rudimentary understanding of depression, it's manifestations, and effects? That it is a classified psychological disorder? Depressives are aware that they're depressed---the salient psychological problem is that their minds can not allow them to see a proverbial "light a the end of the tunnel" and that's what they struggle to try to get to either alone, with therapy, with pharmaceuticals, etc. Some have success, some have a measure of success, some get relief through "remissions" between their bouts of depression and some like Dave Duerson never manage---with or without help/aids---to drag themselves out of depression's hold. What's so difficult to understand here?