Safe versus unsafe: a difficult line to draw
"Virtually all subjects with exposures exceeding the threshold levels had [significant white matter abnormalities], suggesting that heading above some defined level may be generally unsafe. The important obverse of this finding is that exposure below the threshold level may be generally safe," writes Lipton, although researchers did detect a subset of players who, despite reporting heading numbers below a threshold, nevertheless had white matter abnormalities and impaired memory.
"This pattern suggests that, although exposure below a threshold may be generally safe, some individuals may be particularly sensitive to the effect of subconcussive heading and at higher risk for brain injury and adverse cognitive outcomes after even modest exposure," says the study.
'Robust' findings
Commenting on the study for MomsTEAM, Frank M. Webbe, Ph.D., Professor of Psychology at Florida Institute of Technology, and an expert on the subject of soccer heading, [2-6, 25] said, "It is not a perfect study by any means, but I believe that their findings are robust with respect to the basic question, 'Does heading a soccer ball relate to impaired white matter integrity in the brain?'" He noted that the findings were consistent with a 2011 study in the Journal of Neurotrauma [7] which found that concussed athletes showed increased FA in DTI compared to control athletes without a history of concussion.
"The current findings that Lipton and his colleagues report extends these findings to an association with subconcussive events. The finding of statistically significant differences in FA among the three heading groups in such a small sample suggests a fairly robust effect. The fact that differences due to heading were observed only with the memory scores among quite a few neurocognitive measures will be seen as problematic by some, since this clearly is not strong support for cognitive deterioration," said Webbe.
"However, I appreciate and agree with the discussion where the authors note that the DTI outcomes indicate an ongoing pathological process which has not yet reached a level where clinical signs are prominent. This is much the same as our current understanding of Alzheimer's disease. There, we now understand that the brain pathology may be present rather early in adulthood, but the insidious changes are not detectable clinically until much later in life," Webbe said.
Indeed, just such a possible link between mild TBI (concussion) and early Alzheimer's is suggested in a June 2013 study by researchers at the University of Pittsburgh Medical Center [23] published in the journal Radiology, which found FA abnormalities in the white matter of the brains of concussed patients related to auditory processing and sleep disturbances, changes resembling in their distribution abnormalities in people with Alzheimer's disease. The study has, however, prompted criticism from concussion and Alzheimer's experts as going too far in trying to draw a link between concussion damage and chronic damage found in Alzheimer's.
Chris Koutures, MD, FAAP, a pediatric and sports medicine physician in Anaheim Hills, California, team doctor at Cal State Fullerton and for the USA National Volleyball Teams, and lead author of the American Academy of Pediatrics' 2010 clinical report on injuries in youth soccer, [21] found the DTI findings "worrisome," but said further studies were "essential to understand the full potential impact of these abnormalities."
"When I read of these results, I immediately thought of the recent study out of UCLA [32] where for the first time, researchers were able to use identify lesions consistent with Chronic Traumatic Encephalopathy in 5 living ex-NFL players (previously, all findings were autopsy-based). Of interest, the players symptoms ranged from significant decline (needed professional and family caretaker assistance) to fairly asymptomatic. It seems once again, the multifactorial, broad spectrum of concussion pathology (e.g. cognitive reserve) is evident."
"Clinically, we use several formats of evaluation in cases of concussion (symptoms, neurocognitive testing, balance testing, physical exam, visual testing, radiologic imaging), and it seems that the Lipton study did use neurocognitive testing as another evaluation platform along with DTI. It would be fascinating to see several other types of testing used to better evaluate for issues," Coutures said.
