Does this sound like Alzheimer's?

My grandpa has not been diagnosed with Alzheimer's, but he definately has dementia. There is good reason to think that it may just be dementia, because the symptoms started almost immediately after my grandma died. However, the symptoms seem very severe. They are:

-not recognizing my father and my uncle
-not recognizing my sister, my mom, and myself
-thinking he has two dogs (one died years ago) but he just can't find one of them
-crawling under the porch because he thinks his brother wants to chop his head off
-being paranoid about a mail scam and going to the neighbor's house with a gun
-"seeing" my dead grandmother in the bathroom, and insisting that my dad takes him to the funeral home to ask them questions

A lot of people are confused about the relationship between Alzheimer's and dementia. Alzheimer's is a TYPE of dementia. It's a disease which causes dementia. There are other ways, like damage from a stroke or head injury, from cancer, etc., to get dementia. So your grandfather may have dementia caused by something other than Alzheimer's disease. A person can also have more than one type of dementia. My dad has Alzheimer's and he also has brain damage from a bad fall.
The diagnosis of Alzheimer's is only given after all other causes of dementia are ruled out. If the doctors did not say your grandfather has it, they have reason to believe it's dementia of another type. The only true way to diagnosis Alzheimer's, of course, is after death, during the autopsy, when the plaques and tangles of Alzheimer's can be seen under a microscope when viewing brain tissue.

There are many neurogenerative diseases relating to dementia. Alzheimer's could be it, though I would definitely recommend you take him to a actual physician.

Take him to his doctor, or to save some money, wait until he gets his flu shot. Then ask as they give it to him.