Cognitive deficits and depression appear to be more common in aging former National Football League (NFL) players compared with healthy controls, a new study finds.
Moreover, the researchers, led by John Hart Jr, MD, from the University of Texas, Dallas, write that these deficits are correlated with white-matter abnormalities and changes in regional cerebral blood flow seen on imaging.
However, the good news is that many former NFL players who took part in the study, even those with extensive concussion histories, are healthy and cognitively normal, Dr. Hart told Medscape Medical News.
"In 60% of our participants, most of whom had sustained prior concussions, we found no cognitive problems, no mood problems and no structural brain abnormalities," Dr. Hart said.
This should be reassuring news to the former athletes, he added.
Dr. John Hart Jr
"Many former NFL players think that because they played football or had concussions, they are certain to face severe neurological consequences, but that is not always the case," he said. "What's promising is that we were able to locate and document imaging markers that may account for why some patients develop problems and we may be able to determine who might be at risk for cognitive impairment later in life."
Their findings were published online January 7 in JAMA Neurology, formerly the Archives of Neurology.
A Pattern of Impairments?
Dr. Hart said he was prompted to do the current study after he started seeing athletes and former NFL players for neurologic evaluation.
"I noticed a pattern of impairments and wanted to formally study the causes and effects, both cognitively and structurally within the brain," he said.
Dr. Hart and his team compared former NFL players with cognitive impairment and depression, cognitively normal retired players who were not depressed, and a group of healthy controls. The players, with and without a history of concussion, were recruited from the North Texas region.
A total of 34 retired NFL players (mean age, 61.8 years) underwent neurologic and neuropsychological assessment. A subset of 26 players also underwent detailed neuroimaging, including fluid-attenuated inversion recovery (FLAIR), hemosiderin scanning, diffusion tensor imaging, and arterial spin labeling.
The results showed that 14 (41%) NFL players had cognitive deficits, including 4 (12%) with fixed cognitive deficits, 8 (24%) with mild cognitive impairment (MCI), and 2 (6%) with dementia.
"In our sample, the number of individuals with dementia was not different than expected in the general population at this age," Dr. Hart noted. "Previous studies have noted a higher incidence of dementia in retired players as they aged. The lower incidence in the present study could be the result of a small, motivated volunteer sample or the higher mean IQ of the participants."
The number of participants with MCI, on the other hand, was slightly higher than that expected in the general population.
Eight (24%) retired players had clinical depression. "This rate was slightly higher than that expected for this age group, which is approximately 15%. This finding underscores the need for screening for depression and cognitive dysfunction in retired athletes," Dr. Hart said.
Among participants who underwent neuroimaging studies, cognitively impaired individuals showed the greatest deficits on tests of naming, word finding, and visual and verbal episodic memory compared with healthy controls (P < .001).
The researchers also identified a correlation between cognitive impairment and cerebral white-matter abnormalities.
Among the ex-NFL players with cognitive deficits, depression, or both, FLAIR imaging showed significantly more disrupted integrity in the brain's white matter compared with healthy controls (P > .05).
There were also associated brain blood flow changes in those who developed cognitive impairments, providing clues to the active brain changes resulting in deficits, Dr. Hart said.
Fractional anisotropy on diffusion tensor imaging was significantly lower in the ex-NFL players with cognitive impairment, depression, or both, compared with healthy controls (P < .05).
Arterial spin labeling studies showed regions in the left inferior parietal lobe, posterior superior temporal gyrus, bilateral midcingulate gyri, and right middle frontal gyrus that demonstrated significant increases in regional blood flow in impaired players compared with healthy controls (P < .001).
Dr. Hart and colleagues conclude that their comprehensive and multimodal investigation suggests that retired NFL players may be more likely to develop cognitive impairments or depression as they age than the general population.
Nevertheless, Dr. Hart emphasizes: "Just because a concussion is experienced, this does not mean that cognitive, mood and structural brain differences will develop."
"What this study does tell us is that it is important to monitor player safety at all levels," he concludes. "Return-to-play rules need to be outlined and enacted if a head injury is suspected. Physicians should also add a depression screener to their evaluation of any head injury patient."
A Novel Target
In an accompanying editorial, Ramon Diaz-Arrastia, MD, PhD, and Daniel Perl, MD, from Uniformed Services University of the Health Sciences, Bethesda, Maryland, write that the major finding of the study is that cognitive impairment in ex-NFL players was associated with disrupted white matter.
They add that the main value of this study is that it "potentially identifies a novel target for measuring disease progression and developing therapies."
White-matter disruption, the editorialists note, is not widely recognized as a feature of chronic traumatic encephalopathy, a condition increasingly being recognized as the result of repeated blows to the head.
The findings from this study and others suggest that the use of diffusion tensor imaging may be useful for monitoring the cumulative burden of concussions in athletes and other individuals who have sustained multiple mild traumatic brain injuries.
"It also suggests that axonoprotective or axonoregenerative therapies may be useful for preventing or ameliorating the chronic consequences of TBI [traumatic brain injury]," the editorialists conclude.
The study was supported by the Brain Health Institute for Athletes at the Center for Brain-Health, The University of Texas at Dallas, and from the National Institute on Aging. Dr. Hart, Dr. Diaz-Arrastia, and Dr. Perl have disclosed no relevant financial relationships.
JAMA Neurol. Published online January 7, 2013. Abstract Editorial
