I'm the first to acknowledge the difference between acute depression and clinical depression. I wouldn't even venture to say that I have experienced depression because I consider self-diagnosis of psychological problems to be incredibly dangerous. Not to mention offensive to my friends who are clinically depressed (and yes, I have had friends and family commit suicide as well).
Me, I have anxiety issues that I have medication for. Sometimes dealing with my startups is overwhelming and I just crash and can't do anything for a week or more. But I am incredibly fortunate that this down state is not my equilibrium and that I have a strong internal correction that lets me realize I have a problem, gets me to actively try to find a problem, and which so far always has eventually gotten me back to a balanced place.
But I do know people who are clinically depressed, and they should frankly not be starting companies. If a friend who was clinically depressed were trying to start a company and came to me saying that their work was making their depression worse, I would do everything in my power to encourage them to seek professional help (which I am not), and to gently encourage them to consider alternative professions. It is not worth your health, mental included.