It's in the genes yes. There is a blood test one can be given apparently.
I know there is a blood test for FAD - familial Alzheimer's disease, which is a very early onset - people usually start being affected in their early 30s and most die before the age of 50. That form of Alzheimer's affects only about 5% - 10% of Alzheimer's sufferers. There is a specific test for this and it is a yes or no answer. If you have this particular mutated gene, you will develop Alzheimer's. And start it early.
The other 90% - 95% suffer from what is referred to as "sporadic Alzheimer's", meaning that there is no explanation at this time. Most of us fall into this group. There is some evidence that having a blood relative with AD can increase one's chances, but it's not a significant increase.
There is also the apoE4 gene. Below is a quote taken from the Alzheimer Society of Canada. My emphasis added.
If a person's pair of apoE genes include one apoE4, they have three times the normal risk of developing Alzheimer's disease, but if they carry two apoE4 genes the risk increases to ten times. It is important to note, however, that people with no apoE4 genes can still develop Alzheimer's disease, and people with two apoE4 genes may not.
If I were tested for the apoE4 gene & found out I had two, it still doesn't mean I will absolutely develop Alzheimer's.
So unless it is the familial form of Alzheimer's in your family, I would not worry too much about it (easier said than done, I know
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
). There is research done regarding lifestyles etc but my post would end up being longer than Gone With The Wind.