Johnson posted a headline on Hague's condition on Instagram on Saturday and said head trauma was a major reason he left the Octagon. Hague died Sunday at age 34, his family said.
"This is a reality check for me!" Johnson wrote. "I've knocked a lot of [people] out and [I don't know] how this didn't happen when I fought. I've been afraid of this happening to me and after learning about CTE I'm afraid of it happening to anybody."