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Retired NFL players may be at higher risk for depression
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Results from two studies released today indicate that National Football League players who sustained concussions may be at increased risk for depression as they age. The findings will be presented at the 2013 American Academy of Neurology annual meeting in San Diego in March.
“The high incidence of depression in aging athletes highlights the need to thoroughly assess depressive symptoms throughout the lifespan,” study researcher Nyaz Didehbani, PhD, of the Center for BrainHealth at The University of Texas at Dallas, told Psychiatric Annals. “It is also imperative to carefully assess symptoms of depression following a head injury, especially those associated with negative feelings about themselves (ie, pessimism, feelings of guilt, self-dislike) and somatic symptoms (ie, loss of energy, change in sleep and appetite). Depression is a treatable condition if the proper and necessary steps are taken.”
Nyaz Didehbani
Didehbani contributed to both studies.
The first study included 30 retired NFL athletes with a history of concussion and 29 people, matched for age and IQ, who did not have a history of concussion. All participants were screened for depression and completed a full neuropsychological battery of tests. History of concussions was obtained through self-reports and informants using the American Academy of Neurology guidelines.
The researchers found a significant relationship between the number of lifetime concussions and depressive symptoms (P=.004). According to Didehbani and colleagues, NFL players reported more symptoms of depression across three domains — affective, cognitive and somatic — compared with non-concussed participants in the control group. Further analysis revealed that the cognitive domain, which assessed negative feelings about themselves, was significantly correlated with concussions (P<.001).
In the second study, researchers used diffusion tensor MRI brain scans to detect white matter damage as a result of traumatic brain injury in 26 retired NFL athletes. Depression was assessed using the Beck Depression Inventory II. The MRI technology allowed researchers to differentiate NFL athletes with depression from non-depressed athletes with 100% sensitivity and 95% specificity.
Results from the second study indicated that the severity of depressive symptoms was associated with the degree of white matter damage in a range of brain regions (P<.01).
“Most clinicians will be surprised about the possible connection between early concussions and later emergence of depressive symptoms 20 to 30 years after the injury,” Didehbani said. “Scientists and clinicians alike are now recognizing the impact that concussions may have on thought processes, attention and mood, but it is still unclear how these early injuries may manifest in later adulthood.”
Disclosure: Didehbani reports no relevant financial disclosures.
Perspective
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Jeff Victoroff, MD, FAAN
The first abstract reports a study comparing self-reported depression among retired NFL football players vs. among “age- and IQ-matched controls.” The two findings were that (1) football players endorsed more depression symptoms than controls, and (2) depression among the players correlated with number of concussions. These results should be viewed with caution. A 40-year-old victim of multiple previous concussions with a current IQ of 93 is not comparable to a 40-year-old man with no concussion history and the same IQ. The first man’s IQ might well have been 100 or higher before his football career. His behavior should almost certainly be interpreted as that of a man who has suffered dementia (a decline in cognitive function). Hence, the abstract’s conclusions about the relative frequency of depression between these two “matched” samples cannot be relied upon. However, the finding of a direct correlation between number of concussions and degree of depression in the NFL subgroup adds to the existing literature reporting this association.
The second study abstract reports one preliminary effort to determine the pathophysiological basis of depression among retired professional football players. The investigators employed the new tool of diffusion tensor MR imaging (DTI), which allows a rough measure of the integrity of white matter tracts. In healthy white matter tracts, water diffuses reliably along the axis of the tract. In less healthy white matter, water diffuses more randomly. Perfect directional diffusion would earn a tract a fractional anisotropy (FA; a measure of directionality) of 1. Tracts with higher FAs (closer to 1) are more likely to have denser fiber packing and myelination. Despite the small sample size (five depressed players vs. 21 non-depressed players), the authors report statistically significant inverse correlations between FA and depression. This is a potentially important finding, since it confirms research in non-athletes suggesting that DTI may prove useful not only as a biomarker but also as an explanation for depression. Unfortunately, the authors do not report whether their players had suffered concussions or exhibited traumatic encephalopathy. That limits one’s ability to determine whether, in this cohort, any relationship exists between sports-related head trauma and later mood.
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