I know this is completely irrelevant to the linked article, but using white text on a dark background is such a significant violation of readability and visual comfort (unless you're reading several such articles in a row) that I can't help but be completely distracted from the article at hand.
Also the metaphor of ink on paper is still with us in a big way. Dark text on a light background is the norm, light on dark is the exception.
Personally I find a dark background better on the eyes.
Has anyone gone through this sort of testing ? Care to share the thoughts ?
Try to have some compassion: the man just discovered that he has a substantially higher than average risk of developing Parkinson's. He's dealing with that knowledge by blogging about it, just as millions of others have blogged about their personal lives as a sort of public diary.