Van Gogh has always been an fascinating case study for psychiatrists and others. Historical psychiatric detective work is always an interesting diversion.
I have always been partial to Kay Redfield Jamison's argument for a manic-depressive illness diagnosis for Van Gogh. This letter to the editor by Kay Redfield Jamison ("Vincent Van Gogh's illness") is well worth reading as an example of sound diagnostic reasoning (which happens to take base rates into account). She rips apart another diagnostician's conclusion that Van Gogh suffered from acute intermittent porphyria and makes a solid case for manic-depression. This special edition of Scientific American has a good article by Jamison on manic-depressive illness and creativity (starting on page 44).
In 2002, the American Journal of Psychiatry published a case study by Dietrich Blumer that argues for a form of epilepsy (combined with a bipolar illness). Here's the abstract:
"I think that we must not count on Dr. Gachet at all. First of all, he is sicker than I am, I think, or shall we say just as much, so that's that. Now when one blind man leads another blind man, don't they both fall into the ditch?"
In a letter dated two days, he wrote, "I have found a true friend in Dr. Gachet, something like another brother, so much do we resemble each other physically and also mentally."
Finally, last summer 60 Minutes aired an interesting segment that suggests that Van Gogh was a victim of a firearm accident, not suicide. You can view it here.