Three NFL players announced Monday they will donate their brains and spinal cord tissue to a Boston University medical school program that studies sports brain injuries.

Even though dozens of former NFL players have agreed to donate their brains after death, center Matt Birk of the Baltimore Ravens, linebacker Lofa Tatupu of the Seattle Seahawks and receiver Sean Morey of the Arizona Cardinals are the first active players to do so.

The goal of the university's Center for the Study of Traumatic Encephalopathy is to better understand the long-term effects of repeated concussions.

"When you are active, your contract — what you get paid — is based on the perception of your health, and no player wants to be perceived as being prone to concussions," said Chris Nowinski, the center's co-director. "That's why I am so impressed with these guys. I hope they are the first of many."

More than 150 former athletes, including 40 retired NFL players, already are in the program's brain donation registry.

"One of the most profound actions I can take personally is to donate my brain to help ensure the safety and welfare of active, retired, and future athletes for decades to come," said Morey, who along with Tatupu has been listed on NFL injury reports in past seasons with injuries described as concussions.

Doctors see sports-related brain trauma as a growing health crisis due to the discovery of the neurodegenerative disease chronic traumatic encephalopathy in a number of athletes who have recently died. The condition is caused by repetitive trauma to the brain.

"This is a bigger threat than we are acknowledging," said Nowinski, who suffered concussions as a college football player and professional wrestler.

Sufferers may experience memory loss, emotional instability, erratic behavior, depression and impulse control problems, progressing eventually to full-blown dementia.

As part of the program, the players will be interviewed annually for the rest of their lives so researchers can examine the relationship between clinical symptoms and pathology.

Birk, Tatupu and Morey have all played in the Pro Bowl, making their pledge all the more significant, Nowinski said.

"These are all great players and with them in the spotlight every weekend it raises the issue with the public," he said, adding that he hoped their participation sparked locker rooms conversations with their teammates about the dangers of head injuries.

The center was created in 2008 as a collaborative venture between BU Medical School and Sports Legacy Institute.