League of Denial: The NFL, Concussions and the Battle for Truth by Mark Fainaru-Wada and Steve Fainaru:
The study’s conclusion was blunt: “Our findings suggest that the onset of dementia-related syndromes may be initiated by repetitive cerebral concussions in professional football players.”
Guskiewicz kept going. He now focused on the earlier finding suggesting that concussions triggered depression. He isolated players reporting at least three concussions and found that they were three times more likely to be diagnosed with clinical depression.
Guskiewicz observed these results with pity and sadness. What had happened on the field to players such as Al Toon, Merril Hoge, and Troy Aikman was certainly powerful. But Guskiewicz—in his lab at UNC, away from the fans and the pressures of the NFL—was discovering something even more profound: a persuasive argument that concussions were not only an inevitable part of professional football but often led to misery and torment later in life—not only for the players but for everyone around them. The results were “daunting,” he wrote, “given that depression is typically characterized by sadness, loss of interest in activities, decreased energy, and loss of confidence and self-esteem. Those findings call into question how effectively retired professional football players with a history of three or more concussions are able to meet the mental and physical demands of life after playing professional football.”
Guskiewicz, Bailes, and their colleagues made it clear that they believed that the game itself was causing something destructive and insidious to occur deep inside the brains of huge numbers of retired players. Football-induced concussions, they wrote, “can result in diffuse lesions in the brain. . . . These lesions result in biochemical changes, including an increase in excitatory neurotransmitters, which has been implicated in neuronal loss and cell death. A potential mechanism for lifelong depression could be this initial loss of neurons, which could be compounded by additional concussions, eventually leading to the structural changes seen with major depression.”