I am ever so sorry you are going through this situation with your mom, and like ano1 and and Rey, would like to somehow offer some comforting words.
In line with ano1’s experiences, I can offer some practical examples. My sister-in-law has lived with this situation for many years, and over the last two years of her life, her mother would not recognize her daughters any more. Her conditions were discovered some 9 years earlier, as a result of the husband’s untimely death from cancer. But, on her deathbed, when her three daughters were gathered around, her awareness came through unexpectedly and she blessed them with a wonderful loving smile before passing.
An aunt of mine declined over a longer period of time, and while she sounded completely confused and lost in everyday life, there were times when she was absolutely lucid. The most lucid time was again on her deathbed, when my parents called me on the phone so that I could speak to her one last time. The conversation was absolutely normal, and she appeared to come from a place of wisdom I never knew she had access to.
As Rey suggested with many examples, I agree that consciousness is non local, and that even the so called normal people only have a little available compared to what NDErs and other people who have special transpersonal experiences are able to access but not to fully explain, as there are no words in our dictionary to describe the things we don’t all know about.
But I would like to offer some personal examples coming from out of the body experiences too.
I have a niece who suffered from asphyxia at time of birth and for almost 50 years now has displayed the understanding of a 4-year old. In one of my OBEs I was shown that she is extremely wise and intelligent, and is going through what appears a trial to us, while being indeed a very powerful and intelligent spirit.
In 2002, when a friend of ours was going through her last days in a coma, as a result of brain cancer, I would see her in my OBEs resting in a beautiful garden, sometimes wearing sunglasses, together with friends who had already passed. A few hours after her passing (we were only told a couple of days later, as the family lived in England) she appeared in an OBE to me at dawn, together with her husband, who had died 40 days earlier: they were standing on the door together, on the door of an non-existing flat on the same floor where my physical flat was, with a wonderful light behind them, waving at me with loving gratitude for the efforts I had made over the last few days to deliver some messages I had got from the husband for the family. Since then, I have heard from them both on a number of occasions.
Again, even though this is just my own personal experience, it suggests that our consciousness, awareness, intelligence, communication need not come through to other physically alive people, but it is nonetheless unharmed and whole, and glimpses of your mom’s awareness may unexpectedly come through to you in everyday life or on other occasions, when you are able to tune in with her, such as during sleep.
I have come to the conclusion that these experiences, as saddening as they may be, have their own purpose and one day we will have the full picture. But just think of family members who do not suffer from any particular condition, but will not speak to each other because of some futile materialist arguments and waste the time that is given us to live together on this planet, lost in their own idea of what is right and what is wrong.
A few days ago, in an extremely vivid dream, I asked a very close family member why she insists on only discussing the positive and often superficial sides of life, and keeps minimising or showing little compassion about sad situations, and she showed me a scar, which apperead to be related to a life-threatening condition she had survived and which I knew had to do with the recent loss of her husband, and told me that, if she were to get involved in the sad side of life as of now, this could shorten her physical life.
As Rey recalled, the notion of filters comes in handy here. If we realize how temporarily unaware and confused "we" may actually be in so many ways, compared to the consciousness/universe we all belong to and in fact share, then I would deem it a privilege to share my physical time with my loved ones, even if their brain were physically impaired, and personally have many regrets about not having this understanding when I was younger and also continue to have at the end of each day, for one reason or another.
How many futile arguments and struggles could be avoided if only I fully realized the blessing of being able to look after each other in this temporary place and time.
Surrounding you and your mom with caring thoughts.