NINETY-TWO percent of retired National Football League players have decreased cognitive function, according to a new study:
“In the NFL group, baseline neuropsychological assessments showed 92% of players had decreased general cognitive proficiency, 86% had decreased information processing speed, 83% had memory loss, 83% had attentional deficits, and 85% had executive function impairment.”
The Truth?The study reported on a self-selected sample of 161 current and retired NFL players recruited via a blog (“The NFL concealed the danger of brain injuries!!”), the Los Angeles Chapter of the Retired NFL Players Association, The Summit (??), and possibly other sources. Perhaps these players were motivated to participate because they had cognitive complaints, or because they wanted an evaluation in advance of the $1 billion concussion settlement. The League's Baseline Assessment Program is a required part of the settlement.1
The quote above is the full extent of the report on the players' neuropsychological assessments. These were done using computerized test batteries (MicroCog or WebNeuro), which are largely unknown to most clinical neuropsychologists. Was there an adequately matched control population? What norms were used? They don't say.
THE TRUTH IS, we don't know the extent of cognitive impairment in these football players, or the percentage of all players who are affected, or the severity of impairment in those who are. This new paper (by Daniel Amen, Bennet Omalu, and others) doesn't give us enough information, but it succeeds in sounding the alarm about the dangers of football and the inevitability of memory loss and attention deficits.
Are blows to the head bad for your brain? Can repeated concussions cause cognitive impairment and chronic traumatic encephalopathy (CTE)? 2 Yes, almost certainly, but we can't rely on biased samples, appeal to celebrity, and Frontline documentaries (“researchers have identified CTE in 96 percent of NFL players that they’ve examined”) as conclusive scientific evidence. What's needed are better sampling methods (in the short term) and longitudinal studies that follow a diverse cohort over time (in the long term).
The ScansCaption for top figure: SPECT brain scans showing abnormal low blood flow in an NFL player compared to a normal healthy control subject.
The new paper by Amen et al. (2016) was actually focused on SPECT scans, not surprisingly, since these are the backbone of his business at the Amen Clinics. The article claims “90% sensitivity, 86% specificity, and 94% accuracy” in discriminating NFL players from controls. I won't elaborate here, but check out This Neuroimaging Method Has 100% Diagnostic Accuracy (or your money back) and The Dark Side of Diagnosis by Brain Scan for detailed critiques of the methods used here. I will flag one tiny issue, however:
“All NFL players were male, while 56% of the control group were women.”
Why?? The authors have a database of 100,000 SPECT scans...
1 11. What is the Baseline Assessment Program (“BAP”)?
. . .
Retired players who are diagnosed with Level 1 Neurocognitive Impairment (i.e., moderate cognitive impairment) are eligible to receive further medical testing and/or treatment (including counseling and pharmaceuticals) for that condition during the ten-year term of the BAP or within five years from diagnosis, whichever is later.
14. What diagnoses qualify for monetary awards?
Monetary awards are available for the diagnosis of ALS, Parkinson’s Disease, Alzheimer’s Disease, Level 2 Neurocognitive Impairment (i.e., moderate Dementia), Level 1.5 Neurocognitive Impairment (i.e., early Dementia) or Death with CTE (the “Qualifying Diagnoses”). A Qualifying Diagnosis may occur at any time until the end of the 65-year term of the Monetary Award Fund.
2 ADDENDUM (May 1 2016): I should say, “...cause CTE and/or other neurodegenerative disorders and dementias.”
Also see: Here’s What We Don’t Know About Head Injuries And Sport
...and A Clinical Approach to the Diagnosis of Traumatic Encephalopathy Syndrome
Daniel G. Amen, Kristen Willeumier, Bennet Omalu, Andrew Newberg, Cauligi Raghavendra, & Cyrus A. Raji (2016). Perfusion Neuroimaging Abnormalities Alone Distinguish National Football League Players from a Healthy Population Journal of Alzheimer's Disease : 10.3233/JAD-160207
Caption (from press materials): SPECT brain scans showing improvement of abnormal low blood flow in an NFL player compared after 3.5 months on a customized brain rehabilitation program.
ADDENDUM #2 (May 1 2016): The authors' Conflict of Interest statements.
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