Vitamin D is a very potent vitamin which the body only can produce in direct exposure of sunlight and is stored in the fat of the body.
It also exist in a small range of foods.
The problem is when you don't get any exposure of sunlight and you don't eat any food which contain vitamin D.
Vitamin D deficiency has been seen to result in a wide range of consequences such as Osteomalacia, Rickets, multiple sclerosis, rheumatoid arthritis, juvenile diabetes, Parkinson's, Alzheimer's disease, depression and low immune defence.
As you all know old people mostly cover up their body to not get cold, which in result leads to very little sun exposure.
I am not saying it is an universal cure, but I wonder if it can have a connection??