The family of former USC safety will donate his brain to Boston University CTE research center

This is another donation to further research of the degenerative brain disease that affects athletes in high-impact sports.

The family of Kevin Ellison, a former USC football safety who died last week, plans to donate his brain to the Boston University Chronic Traumatic Encephalopathy Center for research.

Ellison died Thursday, after being struck by a car while walking along the 5 Freeway in the San Fernando Valley. He played for the Trojans from 2005 to 2008 and nine games for the NFL's San Diego Chargers in 2009. Ellison was 31.

In an interview Tuesday with Annenberg Media, Chris Ellison said his brother Kevin struggled with schizophrenia and bipolar disorder that developed in the last few years of his life. That made understanding some of Kevin Ellison's actions difficult. "Is it CTE or schizophrenia? Did the schizophrenia develop from CTE?" Chris Ellison said.

Chronic traumatic encephalopathy is a degenerative brain disease, similar to Alzheimer's disease, that is caused by repetitive head impact.

On Sunday, Chris Ellison said, he received condolences from Chris Nowinski, co-founder of the Boston University CTE Center. "We had talked about [brain donation] as a family before but we didn't know the process," said Ellison. "We want to help other people, especially athletes. We want the information to get out there."

Ellison's family's decision to donate his brain plays into the larger landscape, one that is taking a critical look at how football and other contact sports affect their players later on. Researchers from the CTE Center studied the brains of 111 NFL players from a brain donation program and neuropathologically diagnosed CTE in 110 of them.

"The only known risk factor is brain trauma," said Nowinski.

In CTE, the tau proteins, which usually regulate brain microtubules, clump up and become dead spots in the brain, according to Bobak Abdolmohammadi, a research assistant at the center. For younger people, CTE manifests in impulsivity, suicidality and depression. Older individuals are often misdiagnosed with Alzheimer's, as their symptoms are memory- and motor-related.

"It's going to be hard to reduce that risk significantly, just because contact and hitting is so fundamental to football," said Abdolmohammadi.

However, new research from the University of Pennsylvania shows that it's possible to reduce specific risk factors without challenging the integrity of the game. Working with the Ivy League football conference, co-authors Douglas J. Wiebe and Bernadette D'Alonzo found that changing the kickoff rule reduced the rate of concussions by 81 percent.

"Kickoffs account for 6 percent of plays but 21 percent of concussions," said Wiebe. Under the experiment, kickoffs were moved from the 35-yard line to the 40-yard line. From 2013 to 2015, before the change, 126 concussions occurred. After the change, 2016 to 2017, only 33 occurred.

Though CTE is more often linked to repetitive hits rather than strong hits, like concussions, Wiebe was optimistic about the future of football. "If you break it into little component parts, what are the aspects of an injury problem we can change to make that small part safer?"

Chris Ellison hopes his brother's donation can unravel the complexities of CTE. "Once there are definitive answers of CTE and football," said Ellison, "then all of us in this football world can make better decisions."