An US study of retired National Football League (NFL) players has cast doubts media reports that such players are at a risk for a neurodegenerative disorder called chronic traumatic encephalopathy (CTE), which causes symptoms such as aggression, depression, suicidality and progressive dementia.
The study led by Christopher Randolph and his colleagues at the Loyola University Medical Center, Chicago, has found no evidence to support this theory.
While there are no clearly defined diagnostic criteria for CTE, the condition has been suggested to be characterized by irritability, impulsivity, aggression, depression, short-term memory loss and heightened suicidal thinking or behavior.
Randolph and colleagues conducted a two-part study. The players who participated in the telephone survey had an average age of 64 and had played in the NFL for an average of 7.5 years. Thirty-five percent of this sample had possible cognitive impairment based on a screening interview known as the AD8.
While the retired NFL players were clearly impaired relative to healthy controls, the patterns of their impairments were virtually identical to those exhibited by the non-athletes with MCI.
"The retired NFL players basically look like regular patients who have mild cognitive impairment and have never played football," Randolph said.
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Randolph believes that if there is indeed an increased risk of late-life cognitive impairment in NFL retirees, it is probably due to diminished cerebral reserve, which is based on the possibility that repetitive head trauma over a long playing career results in a loss of brain cells.
Although this cell loss is not severe enough to produce symptoms when players are young or middle-aged, it could lead to the earlier expression of age-related neurodegenerative diseases such as Alzheimer's, due to insufficient reserve to cope with the disease-related cell loss.
In their paper, Randolph and colleagues wrote that media coverage of this issue 'continues to far outweigh any meaningful results from sound experimental science, and a definitive epidemiological study still has yet to be done'.