I would like to share this video with you. I think it's really intriguing.
it shows the effects of music on an alzheimer's/dementia patient.
that's a clip from the documentary "Alive Inside"

he's completely lost at first, but after listening to his favorite songs, he can answer questions, say longer sentences and remember lyrics and melodies.
I was stunned after I've seen the full video, especially the last part where he describes what music does to him