He's still around, though a bit sad to watch.
I think he suffered from severe depression and had electro shock therapy and that may have affected him. Seems I remember hearing about a particular disorder he suffers from now, but I can't recall the name of it.
He was wrongly given many prescription drugs in the '70s & '80s in an attempt to cure his drug addiction. His "doctor" tried to take over his life, even writing himself into BW's will. BW's family sued the doctor, got his medical license revoked, and BW has been slowly recovering under the care of "real" doctors ever since. In the last seven years or so he's been touring regularly, overcoming his stage fright, and finished the long-discarded SMiLE album. He's not back 100%, but he's certainly doing better now personally and professionally than he has in forty years.
Mike Love is playing county fairs with a bunch of sidemen and calling them "The Beach Boys."