Thanks.
Yes, I always thought Audrey was a bad choice for this type of storyline. I suppose it showed that GH itself did not see her as a matriarchal figure, which would soon be reinforced as she was slowly phased out of the canvas through the rest of the decade. I think it would have made more sense possibly for a character like Ruby, who was beloved but also in a more limited space (and Norma passed away only a few years later), but I think it may have just been too much for viewers anyway.
Dementia is not a story soaps have done a good job with. I have never seen GH's story with Mike, but most I have seen just felt exploitive and cheap, or they focused on the wrong things (in several cases, they become, "Oh it's so sad that our heroine can't find happiness with a man because he's still stuck with that wife who has dementia."). The one I have seen that I think was well-constructed was Ashley's on Emmerdale.
Casualty, the UK medical soap, gave one of their longtime nurses, Duffy, a dementia story a few years ago.