[Millennium]

Depression is largely an episodic thing (dysthymia, though it's sometimes called "chronic depression", is actually a distinct issue). Many people do indeed go through one or more episodes in their lives, and this is not necessarily a problem. But like all mental faculties, it can get out of control, and then the problem becomes serious.

I'd say that going through a depressive episode actually is a barrier to doing a startup. The reason is simple: getting a startup off the ground requires almost all-consuming motivation, but one of the most common symptoms of depression is impaired motivation. In other words, depression hits right at the heart of what makes startups workable, and while this is not necessarily insurmountable, calling it suboptimal is an understatement. The wise thing to do would be to get it back under control, and then start the business when you're in a better state to see it through.