My Mom seems to have great memory but experiences imaginary people, places and things. Is this normal for people with dementia?

I am not sure if you mean your mother is completely blind or has macular degeneration. I am not sure it matters, but when my mom had worsening macular degeneration, she would talk about people sitting on her couch and visiting with her and she had a man that lived in her TV. It was very frightening to me, because like your Mom, her memory was good. I was led to believe that the visions were from the worsening eye sight, by her eye Drs. Now, 4 yrs. later, Mom is in full blown dementia and I am convinced that was the beginning of her decline that was fully ignored because of the eyesight issues.
I would say that the three Drs. may be right.

The first sign, that we know of, that my Dad had Lewy Body Dementia was the hallucinations. He saw a number of different people, but they were the same people all the time. They would carry out various activities like having garage sales, moving furniture around, sleeping in his bed, etc. He saw cats and dogs and snakes, also. He saw cracks in the bricks of the house that weren't there, etc. But his long-term memory remained, some of it until he passed. I know that it's normal with LBD for the hallucinations to appear before other symptoms, so it may also be the case with other types of dementia. Of course, we didn't know he had LBD at the time. He was diagnosed with Alzheimer's originally.

I know that we generally think of dementia as primarily a loss of memory. In fact, places that specialize in dealing with dementia are often called "memory care centers." Also, most of what the public knows (or think we know) about dementia is really about Alzheimer's Disease.

But about 40% of those who have dementia have some kind other than Alzheimer's. Not all of the other kinds have memory loss as the primary symptom.

In Lewy Body Dementia, for example, memory loss is less pronounced than it is is ALZ. As virtualhorizon says, hallucinations are often the first noticeable symptom. Delusions are common. Executive function, including decision-making, suffers. You might want to check out the LBD association's web site to see if any other symptoms seem to apply to your mother. NOT that I'm trying to diagnose your mother! But so many of us have limited exposure to the wide range of dementia symptoms possible and a little more knowledge might be useful.

It really does not sound to me like this is the normal aging process you are seeing. It sounds like the beginning of dementia. It may help you to accept that, at least tentatively, and see what develops. This gives you an explanation of Mom's behavior, and a framework in which to respond to her.

The advice to go along with her imaginings is quite common from professionals. It does help in many cases. In my support group was a woman caring for her husband, a minister, with LBD. He frequently saw children in their home, and he wanted to care for them. He'd ask her to set places for them at the table at mealtime. She'd tell him that "The kids just ate while watching a video" or "Their parents will be coming for them in a half an hour and asked that I not feed them." She went along with his delusions but stopped short of feeding the kids! She never tried to convince him that there were no children there. That was his reality and there would have been no way to reason him out of it. In the beginning I tried reasoning my husband out of delusions, but I learned that life was better for him and for me if I could go along with him and redirect him. If you have not joined the rest of the family in accepting your mom's delusions, I recommend trying it.

If at all possible, this would be a very good time to refrain from arguments with your mother. If she does have early stage dementia she is losing her ability to reason, and arguing with her is kind of not fair -- all the brain power is on your side. Obviously you do not need to abide by the decisions she makes, but try to relate to her without a lot of argument and negative emotion. She cannot help her impairments, and you cannot change them.

One of the best moves I made was to join a support group of caregivers whose loved ones had the same disease my husband had. It can be scary -- you'll hear dreadful stories about more advanced symptoms -- but it is also immensely affirming to hear that others are coping with challenges similar to yours.

Do stay in touch here. We are also a support group!