This mostly works for me. My mother has dementia, and I can relate to most of the lyric. Every journey is different, of course.
I wonder the most about one line: "Sometimes I hear those blackbirds singing after dark". When I see "Memories of singing in the park", I interpret that as meaning a person or people doing the singing, and the memory is a nostalgic connection to that event. Then it goes to the blackbirds and I don't understand. And the next line confirms (for me, anyway), my original connection to the first line as a memory by or about people.
Should there be some specific idea or feel I should be getting from the blackbirds line and I'm just totally missing it? If not, perhaps that line could be changed somehow to fit with the other two, maybe expanding a little on the memories of the park. Something like, "Arm in arm we ramble and talk till after dark". Or whatever fits your story.
That's my only real nit, and it might be just my lack of perception. In other news, I don't think hair ever really stops growing while one is still alive, but I can understand feeling like it does, because it may slow down, and often it does start falling out faster, so one has less, one way or the other. Regardless, I think the line suits the song.
I like this one, the message and the way you tell it. I'm interested in hearing how it works when set to music.
Vicki