It probably makes for a better story to say it's a "toxic fish banned in Italy and Japan", but Escolar is sold widely in quality food markets in the US. Our local quality supermarket (Market of Choice in Oregon--an awesome chain) used to carry it in volume and maybe still does. I recall my wife informed them of the symptoms. She found out the fish was the cause from the Escolar Wikipedia page, by the way.

In any case, "toxic" is a misleading, even if technically it's true (I don't know the scientific def of the term). It's a fish that's sold in many countries, it does not cause permanent damage despite the disturbing symptoms, and if I recall correctly few people experience these symptoms and not when consumed in moderation.

The exact same project done at most universities would at best get a reference of "scientists do XYZ". Harvard does it (or MIT, even more) and not only it's more likely to get promoted, it also gets the headline "Harvard researchers do XYZ". Slashdot is for intelligent people (ok, mostly). We shouldn't be feeding the hype cycle.

Keep in mind that lower weights are correlated with Alzheimer's. (In a separate comment--sorry--I complained that the current study introduces bias by excluding people who already showed signs of dementia.)

        http://www.understanding-alzheimers.com/articles/Linking-Alzheimers-to-Weight-Loss.html

"The September 2005 study, which stemmed from longitudinal research done on the aging process in 820 members of the Catholic clergy since 1993, found that a decrease in BMI significantly increased the chances of developing Alzheimer's disease. Even maintaining the same BMI was linked to a significantly increased chance of developing the disease compared to those seniors who experienced an increase in BMI."

So, if you are older, think twice before dieting for the purpose of "helping" your brain.

The "correlation is not causation" maxim is doubly applicable here, because their sample is purposely biased. They only studied 70+ year olds who did *not* show any sign of dementia. But there is a well-established correlation between lower body weight and Alzheimer's:

  http://www.understanding-alzheimers.com/articles/Linking-Alzheimers-to-Weight-Loss.html

"The September 2005 study, which stemmed from longitudinal research done on the aging process in 820 members of the Catholic clergy since 1993, found that a decrease in BMI significantly increased the chances of developing Alzheimer's disease. Even maintaining the same BMI was linked to a significantly increased chance of developing the disease compared to those seniors who experienced an increase in BMI."

In other words, it is possible they included overweight people who might otherwise, were they not overweight, have suffered from Alzheimer's. In contrast, they may have excluded slimmer people with reduced brain tissue because these have already started showing signs of dementia.

These are *very* tricky correlations and it is irresponsible to suggest anything like causation.