This was the year after a federal judge approved a class-action lawsuit settlement between the league and thousands of former NFL players, which paid up to $5 million per retired player for serious medical conditions related to repeated head trauma.
The ongoing discussion of chronic traumatic encephalopathy in football players continued Tuesday when a study concluded that 110 of 111 brains of former NFL players had the debilitating disease - including three former Miami Dolphins.
Of the 202, 111 had played in the NFL. Lack of impulse control, aggression, depression, impaired judgment, memory loss, paranoia, confusion and progressive dementia are some of the symptoms that can occur.
She cautioned that the latest case study focused on brains donated by families who considered their loved ones "symptomatic" leading to a "skewed population". The disease was not found in brains from two younger players.
Ken Stabler, the former Raiders legend who passed away a year ago, was one of the brains studied.
While the study doesn't prove a direct cause-and-effect relationship, he said the differences in this sample tend to support the idea there is an association between playing football and the development of neurodegenerative disease.
Most brains from players at advanced levels showed signs of severe CTE, including 86 percent of professional players and 56 percent of semi-professional or college players. A player does not have to suffer a concussion - hits are enough to cause CTE.
Although the disease can not be formally diagnosed until after death, numerous symptoms of CTE that may be experienced during a lifetime, such as depression or anxiety, are treatable, Kutcher said.
After years of direct opposition, the NFL has acknowledged the link between football and CTE.
The NFL issued a statement saying these reports are important for advancing science related to head trauma and said the league "will continue to work with a wide range of experts to improve the health of current and former NFL athletes". Among the participants who had severe CTE, 85 percent had signs of dementia, nearly 90 percent had behavioral symptoms, and 95 percent had cognitive symptoms.
It suggests that CTE "may be related to prior participation in football and that a long duration of play may be related to substantial disease burden". And [researchers] did find increasing CTE pathology in the cases [of players] who were older.
It's undeniable that football is a unsafe sport where the risk of injury is high.
In 2016, the National Football League pledged another $100 million to support research into brain trauma and its prevention.
Of the 202 total players, 87% were found to have traces of CTE.
Mike Brown, owner of the Cincinnati Bengals, said in 2014 that he had yet to be "persuaded there is evidence that we totally understand the long-range impact", but that concussions were a "challenge to the game".
"For the first time, we've established this really rich resource, not only of data, both the clinical symptoms and the pathological features, but also a tissue resource to enable future research in CTE", McKee said.
"We only get to look at these individuals at one point in time, that is at the time of their death", she said.