Alzheimer's/dementia and muscle memory

I just saw this video on a post on Reddit that shows an elderly man playing piano while someone else plays a trumpet (coronet?).

There is no detail on the man playing the piano. We can only go by the video which looks like he suffers from dementia (to me at least).

My mom, who passed away a few months ago, had profound dementia. She never played an instrument so I never got to see if that part of memory survived.

Does it? Is muscle memory different than regular memory?

And musical muscle memory is a whole different category.

In the documentary about Glen Campbell’s Alzheimer’s, “I’ll Be Me”, he goes from answering questions by saying, “I’ll look that up if I really need to know” to being barely able to feed or dress himself, and almost doesn’t even know who he is, but throughout, he never lost the ability to play the guitar even after he could no longer sing.

He does look like he has dementia. My MIL remembered the strangest things while in full blown Alzheimers. She could get up in the morning and go through her breakfast routine, cooking and getting everything ready for a large family meal. She had done it for so many years, it was just built in her system. We had to warn caregivers who spent the night to get up before 6am or she would be in the kitchen just slamming away.