That has already been accounted for in the calculation
“That (life expectancy differences) has already been accounted for in the calculation (for different rates of Alzheimer’s in high-curry consuming India vs. Pennsylvania)”
In that case, it is likely a very dramatic comparison, indicating a role for curcumin in preventing Alzheimer’s.
I don’t want to rain on the powerful support for curcumin found in that comparison (which I believe). Population studies are just so vulnerable to confounding factors. Vegetarianism is the norm in rural Hindu India. Genetic factors could be very distinct between those populations. Other components in curry (or chai tea) might be factors.
In my cursory analysis, I would think that Life expectancy would likely be the major confounding factor (as Alzheimer’s is so correlated to age), and other factors would be relatively much less influential.
The controlled study just published in Nature is much more definitive evidence.