Alzheimer's Disease as a form of dementia is said to be inherited based on some research. You can read more about it at this site http://www.relinkdevice.com/alzheimers-disease-is-it-hereditary.html
I have a read an article that is common to the question. You could try looking here - https://www.facebook.com/relinkpage/posts/870493702974788. Hope that it can help.