Is a type of dementia that can be early on set or late on set and is distinct from age related declines. Some neurons that are significantly affected in AD are the ones involved in critical thinking, memory and emotions, and location neurons. No known cures, only a few genes have been identified such as APP, presenilin, and ApoE. Critical questions in AD are, how early is the point of return, whether there is a point of no return for the disease, and any diagnostic markers. The current diagnosis is for patients who have severely compromised cognitive function. Psychological tests, and PT scans are not reliable. Early detection does not exist.