Ron, People with MS have BBB damage that is strongly correlated to herpes virus infection.

Aftermathman, I agree about the alzheimers. It's got to be similar, just a different pathological catalyst. I suspect it's also something ubiquitous and therefore going unnoticed. But no, I haven't even been able to get traction on this hypothesis yet, however if it's right I'm sure the rest will follow.

I've been itching to post this somewhere, it's been running through my head lately:
"There is a game of puzzles," he resumed, "which is played upon a map. One party playing requires another to find a given word --the name of town, river, state or empire-any word, in short, upon the motley and perplexed surface of the chart. A novice in the game generally seeks to embarrass his opponents by giving them the most minutely lettered names; but the adept selects such words as stretch, in large characters, from one end of the chart to the other." -E.A.Poe, The Purloined Letter