This is a fairly common NVLD trait. It is surprising how many people have problems with navigation. This site has some interesting information, some tests and a forum about navigation issues.
Tyri0n wrote:
It's scary because I have read that this symptom is a sign of Alzheimer's Disease, or that having it can make one especially vulnerable to the development of Alzheimer's.
If your ability to navigate starts dropping sharply then yes, this could indicate Alzheimer's but there are usually many other symptoms as well. Alzheimer's affects a number of brain functions, not just navigation. As far as I know if you are born like this then you are no more or less likely to develop Alzheimer's than anyone else.
_________________
I stopped fighting my inner demons. We're on the same side now.