Saturday, April 30, 2016

The Truth About Cognitive Impairment in Retired NFL Players

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 Scans

Caption 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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At May 01, 2016 1:02 PM, Blogger Unknown said...

Cognitive impairment is a difficult topic to grasp, especially when it deals with consciousness, unconsciousness, and brain activity. The cognitive impairment of NFL players has become a very popular topic within society due to the fact that it is something that is very widely noted these days. Back in the 70's or 80's the same thing was happening but maybe not to as great of an extent since the players back in those days were notably smaller than they are in present times. Either way, football players know the risks that they are putting towards their bodies and minds. They should understand that they can have severe damage to their bodies and minds and not expect some sort of settlement fund to be paid to them if something of the sort happens. It is inevitable that there will be memory loss or attention deficits if they place their body and mind into a risky career such as professional football.

At May 01, 2016 3:13 PM, Blogger Dr. William Lu said...

Ideally, pre-neuropsych testing should be administered before entering the NFL and then post- and follow-up testing. Effort measures should also be given throughout to screen for secondary gain. With these and other data (minutes played, # of concussions, etc) we can then better determine the impact of concussions on cognitive functioning across and beyond the player's NFL career.

At May 01, 2016 5:07 PM, Blogger The Neurocritic said...

Thanks for your comments. William, you're absolutely right. Given the financial incentives to perform poorly, effort testing is essential, and this of course applies to Amen et al.'s "92% are impaired". We'd hope that careful longitudinal studies (as you described) are underway (or soon to be underway). But it seems that neuropsych testing is a neglected part of many large research efforts, like the UNITE study (which is not specific to NFL players). UNITE is only informant questionnaires. Why not do prospective neuropsychiatric evaluation and cognitive testing?

At May 01, 2016 7:45 PM, Blogger Unknown said...

As football players constantly get whacked in the head during their games as well as during practices there is an increased risked of the possibility for head injuries which in turn leads to brain injuries and cognitive impairment. Because of the number of head injuries that football player’s face and that they keep playing with over time these injuries take longer to heal which could cause them not to end up healing at all. Kalat (2014), goes even as far as to suggest that football players need to have gear that extends down their shoulders.
This conclusion about football players having gear go down past their shoulders was made after studying woodpeckers whose main goal is to bash their heads into something until it eventually comes open. When they looked at the structure of the woodpeckers head researchers saw that they keep a ridged neck. Because of them keeping their neck in a rigid position allows them to escape the harms of whiplash. These tiny annoying birds are also made for this type of constant pounding, whereas humans are not quite as fortune to be equipped with the brain structure that these birds have. Because of the impacted that football players experience this can cause denervation supersensitivity which could mean that even mild input could cause enhanced response to outside stimuli.

Kalat, J. W. (2014). Biological psychology. Boston, MA: Cengage.

At May 03, 2016 12:41 AM, Blogger Neuroskeptic said...

Good post, the paper is extremely thin on details so the results are impossible to critique. There are no descriptive statistics, very brief methods, etc. I get the impression that this was a "rush job"... Hopefully a more detailed publication of these results will appear eventually.

At May 03, 2016 8:33 AM, Blogger The Neurocritic said...

Thanks. An earlier 2011 paper by Amen et al. actually had more details, although it's not clear if that group (n=100) was less impaired on MicroCog than the current population. The demographic matching was less than ideal (there were some confounds). But for SPECT at least, the control group was all male (n=20).

At January 10, 2017 4:39 PM, Blogger #LottMen said...

I agree that the science of the brain, specifically cognitive impairment is difficult to grasp. But not an impossible task, as has been recently demonstrated by NFL Properties with the concussion protocol program and mandatory removal from games. Now I would disagree with your assessment of the nature of the game, and the level of knowledgeable facts being communicated to players and coaches. I will be tested, I do have issues and I did play in the NFL. People that know me would agree that if I was to receive funds for my injuries, I earned them. I didn't formally retire from the NFL, but when I entered the league via the 1975 NFL Draft, I may have known the dangers of a pulled muscle, wrecked knee or at worse a broken bone. But to be faced with daily memory loss, fits of rage, dizzyness, unemployability, blurred vision, slurred speech, depression, anxiety, anger, violence and loss of knowledge daily. And I never played a full season! Brain trauma happens one time, first time and any time after on the football field. But I have never been told that. As a fan, you will yell louder if the impact between players is harder. I am sorry for being so long so there are many football players that "tried out for the pros". They didn't make the squad, but they took the hits, and they didn't receive proper medical advice of treatment. How much, where, when and who knew what. We will never know because the NFL admitted no wrong doing as a condition of the settlement. You understand why? They earn $1 billion a week


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