Star NFL Linebacker Junior Seau was suffering from a degenerative brain disease when he took his own life last May.
That was the finding of the National Institution of Health.
Doctors conducted a study of three unidentified brains, one of which was Seau's. They found Seau's brain suffered from Chronic Traumatic Encephalopathy, or CTE.
The disease shows up with people who have had repetitive head injuries... and symptoms include mood swings, insomnia, irrationality and depression. Seau's family says he exhibited those symptoms in private, and it became worse before he shot himself.
The all-pro linebacker played for 20 seasons with San Diego, Miami and New England before retiring in 2009.