In this regard I feel a little like the bastards I work with who like to spread rumors and then sit back and be entertained by what happens after.
I started this thread so that I could sit back with interest to see what others think, but now that Nick has raised the issue, I've always appreciated Ashton's
Nick wrote:nine constraining aspects of MS
from a "loss of evolutionary normal" perspective and want to take my "crack" at it.
I don't present this with the presumption on my part that every sensible person should embrace it as "fact" but I do present it as an interesting and alternative for intelligent people to ponder.
Keep in mind that 150 years of disappointing MS research results point towards the need for factors requiring a different way of seeing things.
1. It must be found throughout the world but be specific enough to affect only half or less of the susceptible individuals.
The loss of the parasites commonly considered to have shared evolution with us is unique to the "developed" populations, which experienced the alarming increase in inflammatory immune dysfunctions, while those parasites continue to plague the "undeveloped" populations, which retain their historic low rates of incidence of inflammatory immune dysfunctions.
2. It must affect immigrant children more than it does immigrant adults. On the other hand it must affect susceptible identical twins mainly when they are adults rather than when they are children.
While it doesn't necessarily constitute conclusive evidence, it's especially interesting that both the MS researchers and the "hygiene hypothesis" researchers separately and unknowing used different information to come to very similar conclusions. Most striking is that the age of 14/15 is an important turning point.
Hygiene hypothesis researchers came to the conclusion that experiencing "evolutionary normal" conditions to age 14/15 resulted in an immune system capable of behaving appropriately through adulthood, even in the absence of continued parasitism.
Independently by assimilating the available data, MS researchers came to the conclusion that someone migrating from an area of low MS incidence (which also are areas of high parasitism) to an area of high MS incidence after the age of 14/15 retains the lower risk of incidence, while someone migrating from low incidence to high incidence area before the age of 14/15 (NOT meeting minimal "evolutionary normal" requirement) will experience the higher risk of MS incidence, while people of any age migrating from an area of high MS incidence risk to an area of low MS incidence will retain the original high risk of MS incidence (people from "modern" populations go to great lengths to continue a civilized lifestyle, even when transferred to an "undeveloped" area. In other words, regardless of where we go, we insure that we retain sterile food and water and clean toilet habits).
On the other hand it must affect susceptible identical twins mainly when they are adults rather than when they are children.
It might not seem kosher for me to pick and choose what I do and don't want to answer but that one seems to fallen out of the sky and isn't a valid question. MS affects so few people that it's always been hard recruiting the necessary numbers to do valid studies. MS/Twin studies involve such low numbers that their results are below consideration. The attempt to reverse those results and arrive at reasonable conclusion is counter productive.
3. It must be much more common or effective in northwestern Europe, Canada, United States, Australia and New Zealand than in the rest of the world.
As with anything in life, it's all a matter of perception. I honestly find it painful that possibly/probably the biggest failing in MS research was the early conclusions drawn from the "MS gradient of geographic incidence". That led researchers to the early (and continuing) conviction that because people living farther from the equator were lighter and more affected by MS that lighter skinned people must have a genetic predisposition to MS. In hindsight it's entirely possible and more likely that light skinned people who live farther from the equator were the "go getters" behind the industrial revolution which led to the creation and our being able to bankroll the world's first "developed" populations and lifestyles, part of which involved electricity, well water, flush toilets, sterile food and refrigerators to extend the life of food.
Another way of putting it is that, maybe there isn't a person on earth who doesn't have the "genetic predisposition to MS" when we are separated from the evolutionary normal conditions which was part of our evolutionary history/requirements.
4. It must be more common or effective in higher latitude areas so as to create a pronounced north/south gradient of MS prevalence.
Similarly, although a complicated situation, not only is it harder for parasites to survive in the harsh Northern climes but that is also where the "developed" lifestyle originated and increased.
5. It must have enough variation so as to create significant MS prevalence and incidence differences within ethnically homogeneous populations over relatively short distances.
Hygiene hypothesis is complicated but also very interesting. As mentioned earlier, higher latitudes make it increasingly hard for parasites to survive but it's also become obvious that the MS "exceptions to the rules" invariably involve "undeveloped" populations living in proximity to "developed" populations. Almost invariably involving aboriginal populations who live in closer quarters than "developed" populations, which is a necessity for continued parasite life cycle in hostile climes. Additionally aboriginal populations traditionally eat more wildlife and seafood (highly parasitized-zoonotic) and don't have what we would consider sanitary means of storing their food. In other words, the obvious difference between these genetically similar and latitudinally similar populations is their NOT sharing the "developed" lifestyle.
6. In Hawaii it must adversely affect those of Japanese origin whereas at the same time have a positive effect on Caucasians.
I wish we had better info on what studies Ashton used to arrive at this conclusion but what has long been obvious in my studies is that MS incidence is a continually evolving situation. Despite that, people aren't hesitant to compare study results from the 40's with results from the 80's etc....which leads to absolutely impertinent conclusions and I think that is what is going on here.
I think Ashton derived this from two studies, one regarding people from California having higher MS incidence than those in Hawaii and another showing that people from Japan experienced higher MS incidence in Hawaii. Both studies are too old for me to easily acquire. Truth be told, in the not too distant past (as late as the 1960's) it would have been correct to consider large parts of Hawaii as living under "undeveloped" conditions, but considering that MS information is totally derived from averages it really depends on the point in time in which the Hawaii averages were compared to the Japan averages in regards to which was more "developed" and had the higher MS rate at that particular point in time.
Another way of putting it is that both Japan and Hawaii lagged far behind the mainland US in meeting "developed" conditions and it's not hard to believe that at varying times Japan and Hawaii were neck and neck in their degree (percentage of population) of "development".
7. It must be transportable so as to explain the sudden increase in MS prevalence in the Faroes following British troop occupation during World War II.
Among the biggest reasons that the Hygiene Hypothesis/Loss of Evolutionary Normal Conditions is slow to be accepted is that it's not only complicated but it's the reverse of what everyone is looking for. Ashton didn't word it in a way that is easy to respond to but rather than the British bringing something with them to the Faroes it's possible, and I say likely/certain that the British presence changed the Faroese lifestyle/diet which eliminated their previously evolutionary normal lifestyle/living conditions.
8. It cannot be transmitted by either person to person contact or by a blood transfusion.
With the Hygiene Hypothesis/Loss of Evolutionary Normal Conditions in mind it's obvious that you can't transmit the
absence of something via contact or a transfusion.
9. It must be increasingly more widespread and effective over the last 100 years.
"Developed" conditions and what it entails is more widespread and complete over the last 100 years. Regardless of a person's beliefs as to what "caused" the increasing MS incidence, that is a very good point because as we notice an increasingly global economy, the "MS gradient of geographic incidence" becomes more and more faint to the point that now some people attempt to make the argument that our strongest clue to the cause(s) never really existed at all.
Bob