Sash died from an accidental overdose of painkillers, and his family donated his brain to be studied for chronic traumatic encephalopathy. The Times reports that "representatives from Boston University and the Concussion Legacy Foundation notified the Sash family that CTE had been diagnosed in Tyler's brain and that the disease, which can only be confirmed only posthumously, had advanced to a stage rarely seen in someone his age."
The CTE scale rates severity from 0 to 4. Sash had progressed to Stage 2, about the same stage Junior Seau was at when he committed suicide at age 43, the Times reports.
Chris Nowinski of the Concussion Legacy Foundation confirmed the CTE diagnosis to The Associated Press on Tuesday night.
The Times reports that Sash dealt with "confusion, memory loss and minor fits of temper" that affected his ability to find meaningful employment after he was released by the Giants in 2013.
Sash's mother told the Times that the finding of a high level of CTE helps explain the behavior she says she didn't recognize in her son.
"Now it makes sense," Barnetta Sash told the Times. "The part of the brain that controls impulses, decision-making and reasoning was damaged badly."
Sash suffered multiple concussions during his two-year career with the Giants, in which he played in 23 games over the 2011 and '12 seasons. Months after the Giants' Super Bowl victory, Sash was suspended for four games in 2012 for violating the NFL's performance-enhancing substances policy by testing positive for Adderall, a stimulant used primarily to treat attention deficit hyperactivity disorder and the sleep disorder narcolepsy.
He was released during final roster cuts just before the start of the 2013 season. The Giants reached an injury settlement with him after he suffered a concussion in the preseason finale against New England.
Sash's brother told the Times that Sash also had two concussions in high school and one in college while he played for Iowa.
CTE has been found in the brains of dozens of former football players. Linked to repeated brain trauma, it is associated with symptoms such as memory loss, impaired judgment, depression and, eventually, progressive dementia.
The Associated Press contributed to this report.