Taking a class at Noble Horizons in Salisbury CT on Alzheimer's (still room if interested Wed.s in Oct 2013) made it clear there is not an quick easy way to tell if someone has dementia or what kind. A lot of symptoms have to do with people losing aspects of their memory, which is located in various parts of the brain.
Some may not recognize people, others forget names and still others (or with some overlap) may get lost or have problems doing things they used to with their hands or following directions, staying organized or keeping up with ADL (activities of daily living). Good screenings