Firstly yes, they are already suggesting it a correlation -- people who get transplants get given certain drugs which (might) stop you getting dementia. Second

Firstly yes, they are already suggesting it a correlation -- people who get transplants get given certain drugs which (might) stop you getting dementia. Secondly, even if the corrolation is caused by another effect, whatever it is it's a REALLY strong corrolation, so we should find out what it is!