Sad news. Long troubled, when I saw him in 2002 was touched but disturbed by his state given the joy of the music, the affection of the fans, and his vulnerable state. His mental illness has been long known, but dementia is a new thing – though maybe to be expected given all that problematic brain activity.
I saw written that Yoko Ono has dementia, too.
Musical abilities sometimes hold relative to the decline of intellect in dementia patients. I will resist the obvious gag based on Brian and yoko.
https://theblast.com/578724/beach-boys-brian-wilson-conservatorship-filed-suffering-dementia/