[Shane Green]

ALS disproportionately affects military personnel and athletes. Also, incidents of ALS seem to be on the rise. Military, athletes, and the generation currently turning 60, 70 years old, is likely to have been exposed to greater than average amounts of sunlight during their teens, twenties, and early thirties. Meaning they likely had very high natural vitamin D levels during their most active years.

Military and athletes in particular probably also have fairly radical drop-offs of sun exposure after their service/careers end. Everyone’s ability to produce/absorb vitamin D also drops off as they enter their 50s, 60s, etc. Perhaps ALS is triggered by the drop off of vitamin D. This would explain the higher incidence in military and athletes, as well as higher incidence among the last generations to actively have sought out tanning without much worry about skin cancer, who are now in their 60’s. Perhaps vitamin D works a bit like a high watermark and the higher it was at the prime of life the more likely a drop-off later in life triggers ALS.

Back in the foraging days, this high-water mark vitamin d level drop-off would have been a solid indicator of elderly family members who stopped contributing to a family’s survival. Perhaps ALS is a familial survival mechanism.

[Shane Green]

I’m very sorry to hear about your twin.  Those are very interesting points/factors you bring up.  The high altitude hiking would certainly have induced high levels of vitamin D like I was suggesting may be a factor later in life (when vitamin D levels drop off), but certainly the other possible factors  you mention could be additional or possibly the primary cause.  Do you mind if I ask roughly the age of onset for your twin, and also, whether are you identical twins?

Someone in my immediate family *may* be dealing with ALS (we’re still hoping for a lesser diagnosis), but I can certainly see the importance of your advice regarding care and power of attorney.