Has Joe Biden ever been "all there"?

From nine years ago:

Biden kept cracking lame jokes that no one got. He seemed like a nice guy, but reminded me of someone's drunken uncle at Christmas dinner.

Mark Owen 

No Easy Day: The Firsthand Account of the Mission That Killed Osama Bin Laden

And this is Joe from 1974:

PORTRAIT OF THE MEDIOCRITY AS A YOUNG MAN

Related:

Joe Biden: Senile or psychopath? One of a continuing series