Launching a start-up takes an enormous amount of dedication and positive energy, but there is a dark side.

Entrepreneurs are generally credited with having a bright, optimistic outlook on their business pursuits. But lately the gloomy topic of depression has been swirling.

Could it be that everyone has it backwards, and entrepreneurs are, in fact, especially susceptible to depression? Some seem to think so.

Brad Feld, managing director at the Foundry Group, fielded the question in a recent blog post. His exploration comes weeks after Reddit founder and Internet activist Aaron Swartz’s suicide on Jan. 11, a tragedy that revived a discussion about suicide in the tech start-up world.

The question seems to hinge on two interrelated factors: personality types and the pressures that can exacerbate any pre-existing fragility.

A commentor to Feld’s post, Rob Emrich, wrote: “I think there is correlation between the type of people who become entrepreneurs and those prone to depression. I also think most entrepreneurs know that the daily ups and downs, and constant uncertainty can easily cause and reinforce a tendency toward depression.”

Pressure, also, seems to play a role.

“One has to be or look strong and confident, so there may not be as much opportunity or willingness to openly talk about feelings,” said Irina Firstein, a therapist in New York who specializes in depression and anxiety. “There is an image to uphold, and it can be lonely place.”

Entrepreneurs typically hold themselves to a high standard, and believe that others do as well. An extreme example: Just before taking his own life in 2002, Gene Kan, a 26-year-old programmer and founder of InfraSearch.com, updated his e-resume on the UC-Berkeley server to read: “Summary: Sad example of a human being, specializing in failure.”

Another commentor on Feld’s post, jerrycolonna, wrote: “My unscientific analysis is that so much of the challenge stems from our inability to separate ourselves from the work. The work becomes the sole determinant of how we perceive ourselves and the world and we are lost when it fails. The same is true for anyone for whom the external world is a source of validation and affirmation.”

Rising above depression means, more than anything, conquering that fear of failure. Set realistic goals, but be willing and able to recognize a lost cause. Or as Selena Cuffe, Inc. columnist and CEO of Heritage Link Brands recently wrote: “Understand and respect your imperfections and the imperfections of others. Perfection is boring, and unacknowledged imperfections are dangerous. Entrepreneurs must seek innovative ways to work around such growth areas. Only then will we find the amazing ‘perfect imperfections’ that make many of our businesses click.”