updated :

EDIT : To be clear, I am not saying "his musical output is caused by/limited by/due to" his insanity. I mean his mental illness makes his productivity less efficient to the point where there is less output.

So if he's being affected by mental health, it doesn't matter if it's his music or his kid's music, neither is getting completed because he's not going to get anything done, because mental health problems will impede his productivity.