Broadcaster Bob Costas on set as the Washington Redskins took on the Dallas Cowboys in 2013. (LM Otero/AP)

While interested viewers await the much-anticipated episode of HBO’s “Real Sports” that will examine the link between brain injury and domestic violence in the NFL (set to air Oct. 21), NBC Sports’ Bob Costas is ready to talk now about that connection. The respected sportscaster, who’s been in the business since the 1980s, went on Lawrence O’Donnell’s “Last Word” Tuesday night, and declared “there is a connection” between violent behavior, and head injuries. The 26-time Emmy winner continued:

“You have to say that many of those who play an inherently violent and brutal game — not a rough and tough game — but a violent and brutal game, will not [be] able to confine that behavior to the field, especially with what we’re learning about head trauma.”

“We already know about the long-range effects. The league itself acknowledges in lawsuits that a considerable percentage of players will have cognitive difficulties well before their peers as a group will, those who did not play football, when they get to middle age.”

“But we also know this, that, short-term, impulse control and aggression are affected, especially by head trauma. And when you mix that with perhaps prescription drugs for pain or performance-enhancing drugs, throw alcohol into the mix and throw the violent culture of the NFL into the mix, some players are going to act in ways that they might not act were they not football players.”

The discussion, which was pinned to the string of incidents set off by the Ray Rice and Adrian Peterson scandals, later turned to the role of helmets, and whether they can help prevent brain trauma and, thus, aggressive behavior off the field. Costas said:

“[H]elmets will protect against a skull fracture, but will not protect — at least as they’re presently designed, maybe technology will advance — will not protect against the brain rattling around within the skull.”

“And damage to the prefrontal cortex, especially when you’re a young man — and the brain does not fully develop until you’re 25 or 26 — can actually have an effect on how you function, decision-making, impulse control.”

Costas’s statements are backed up by numerous studies, many of which were presented as evidence in the NFL’s concussion lawsuit that former players brought. The NFL settled with the group for an uncapped amount of $765 million partly because of a study that found 30 percent of former NFL players will develop “at least moderate neurocognitive problems,” ranging from dementia to CTE, a degenerative brain condition linked to repeated concussions that can cause violent behavioral changes.

Studies on the short-term effects on hits to the head reveal equally disturbing evidence that perpetuates Costas’s theory about football’s link to increased violent behavior. A condition called “Post-concussion syndrome,” a short-term condition that can appear in the weeks or months following a traumatic head injury, can affect the prefrontal cortex, a part of the brain’s frontal lobe, which works to regulate behavior. Studies have linked concussions, a type of traumatic brain injury (TBI), to increased depression, and the scholarly journal Psychiatric Times declares. “Irritability and aggression are probably the most common behavioral consequences of TBI.”

The evidence may sound compelling when parsed out, but it’s important to note the full picture of how head injuries may affect behavior, specifically as said behavior relates to domestic violence, is not yet clear. For instance, the Psychiatric Times adds directly after the above declaration, “However, it can be difficult to know the extent to which brain injury is a factor in aggressive behavior. Many patients who have sustained a TBI were prone to antisocial behavior before the injury.”

What’s important is that the discussion, which is likely long overdue, is finally happening. More importantly, the NFL and the public are both listening.