Tuck's family agreed to donate his brain to the Brain Bank and on Saturday morning it was revealed the AFL star battled stage three CTE - which can only be diagnosed after death.
"It's the worst case I've seen so far," neuropathologist professor Michael Buckland told The Age. "It was actually quite shocking, the degree of disease he had."
CTE was also found post-mortem in AFL greats Polly Farmer and Danny Frawley.
"Those cases span three generations of players," Buckland said. "What's disturbing is that the worst case is the most recent, and also the youngest."
A disappointed Shane Tuck after playing his last game for the Tigers.