The latest studies on Repetive Head Injury Syndrome support what Boxing Trainers have long believed, that neurological damage from head blows does'nt require incidents of extreme trauma, a high frequency of lesser blows can cause damage.
Something like 50% of Boxers from punches and 30% of Soccer players from heading and 20% of football players from tackles show MRI irregularities suggesting degrees of impairment from blows.
From what I've seen in the vids shot at Chute Boxe, Silva gets banged hard and frequently , he has a very aggressive training style. The changes I've seen in him, the look in his eyes, the slowdown in verbal responses and the changes in his bodily movement in the last year to a year and a half, not sure when I first noticed it, suggest this possibility to me, but I'm no expert.
If this is happening, it's probably not irreversible,if he takes a break and gets some treatment.