There is a connection.
A person who is a little on the edge mentally and who gets busy with something creative finds him/herself suddenly doing very well.
Creativity is practically therapeutic.
Conversely if someone is very creative, like the artists you mentioned, and for some reason they find themselves not able to maintain their high levels of creativity, they can do quite poorly.
Quite often there is someone close to these highly creative people that are secretly trying to do in the creative person.
John Lennon was taken down by his wife Yoko. That was what she was all about. Of course John didn't have a clue. He didn't go koo koo in the process but he did get taken down.
Others aren't so lucky.
Hemmingway was the effect of someone like this. He ended up in the hands of psychiatrists who electric shocked him and he could no longer write anything or think up a story.
Van Gough definitely had a parasite sucking away at him. I suspect it was his brother. But we'll never know.
The bigger the artist, the more determined these parasites are to stop them.
Hollywood is full of them.
That's why you often see an actor fall out of sight for no reason.
But the problem with the bigger artists is is that when they are taken down they have a lot farther to fall and some just can't handle it and often commit suicide.
Elvis took a long time to hit bottom.
And he came a long way down.
His manager for one was very active in taking him down, though he would not let it be obvious.
There are many many sad stories like these down through history.
The artist can be quite a target.