Friday, May 04, 2012

CTE (Chronic Traumatic Encephalopathy) and Suicide Link is Premature Speculation

With the recent suicide of Junior Seau from an apparent self-inflicted gunshot wound to the chest, there is once again widespread speculation that the death was caused by possible chronic traumatic encephalopathy (CTE). CTE is a broad term used to refer to repetitive, often subclinical (e.g., asymptomatic), injury to the brain from a variety of contact sports and other causes. Whether or not Seau had this condition (his brain was just donated for scientific study to determine this), it is premature to speculate that he killed himself because of the condition.

Personally, I have never bought into the supposed link between CTE and suicide, as if people are mindlessly controlled to take their lives due to a distant history of concussions that may never have never been documented or known about. Are we to believe that Junior Seau seemed fine and jovial the week prior to his death and that CTE (which is a chronic condition) suddenly took control of his mind and caused him to shoot himself in the chest? That makes absolutely no sense whatsoever. Many of these player's had ample non-neurological explanations (e.g., business failings, federal indictments, depression about lack of post-career football success) for why they would commit suicide. I explain this more in an upcoming chapter on CTE that I wrote with Dr. Shane Bush:

Carone, D., Bush, S. (2012, in press). Dementia pugilistica and chronic traumatic encephalopathy. In R. Dean & C. Noggle (Eds.), Cortical Dementias.  New York:  Springer. 

In Seau’s case, we do not yet know what troubles he may have been experiencing in his life that led him to commit suicide and it is unclear if we will ever know since he did not leave a suicide note. But, the fact is that people kill themselves or try to kill themselves every day, even if they are perceived by others as successful in life. Many people put on a social mask to hide their inner distress from others and are unaware of the emotional distress that someone else may be experiencing. It is known Seau was divorced and was arrested in 2010 for history of domestic violence towards his ex-girlfriend. Hours later, he survived a 100-foot fall down a cliff in his SUV after he claimed he fell asleep. Perhaps, but it is also possible that this was an earlier suicide attempt in reaction to the events from hours earlier. The bottom line is that it is unclear if there was any family matters that could have contributed to his recent actions. 

For those who speculate that CTE caused Seau to commit suicide, it is important to note that suicide is an act that is completed or attempted by many professional and college athletes, including outside the NFL such as college basketball, professional basketball, college baseball, professional baseball, professional golf, and professional tennis players. Do all these athletes have CTE too? Are scientists hunting down their families to have them donate their brains for analysis? Not to my knowledge. Here is just a partial listing of many athletes who have killed themselves even if they didn't actually have a history of concussions or repetitive head trauma.

1. Thomas Emma (Duke basketball player),wp3264

Jim Dinwiddie (Kentucky basketball player)

Mel Turpin (Kentucky basketball player)

4. Troy Raymond (NBA and college basketball player):

5. Nine other basketball players:

6. Erica Blasberg (professional golfer)

7. Mike Flanagan (MLB player)

8. Hideki Irabu (MLB player)

9. Stephan Gant (top MLB prospect)

10. Jennifer Capriati (professional tennis player, attempted suicide)

Also see the entries entitled, Junior Seau did NOT suffer 1500 concussions and Does Second Impact Syndrome Exist?  \


  1. You're missing the point. When the concussions happened and if they were documented is irrelevant. The issue is, did they sustain enough hits to the head to develop CTE. Although concussions are important, the bigger issue may be the thousands of sub concussive hits the players take from Pop Warner to NFL retirement. Persons with brain injury and persons with dementia are at higher risk for suicide. This is well documented. Does the CTE cause suicide? Not likely in one-to-one way, but it very likely increases the risk. Probably significantly. Not to mention, it's not a simple as the CTE "suddenly taking over his mind". Could CTE result in decreased behavioral and emotional regulation making a person more vulnerable erratic, impulsive behavior? Absolutely. Areas of the brain impacted by CTE include the medial temporal and frontal lobes, which (as you know) play an important role in behavioral/ emotional regulation. So is it plausible that CTE contributed to Junior Seau's suicide? Entirely.

  2. Actually, you are missing the point. Just because a person had a prior history of concussions (or "subconcussive hits" as you say) does not mean that every subsequent behavior by that person was caused by those injuries. Clearly, as noted in my blog, plenty of athletes kill themselves or try to kill themselves in other sports where there is a low incidence of concussion. So, you may very well be dealing with an illusory correlation in these NFL players in terms of possible a CTE-suicide link. Anything is possible as they say, but right now, my point is that statements that such a link is clearly established is going far beyond what the data allows.

    It is absolutely not irrelevant if there is no documentation of concussions in these NFL players. When my chapter comes out, see Table 1 for the list of confounding variables in almost all of these cases that can alternately explain these athletes behaviors, including suicide. The number of confounds are extraordinary. So, before people jump to a conclusion that an undocumented (or documented) history of concussions caused a person to kill themselves, there are far more parsimonious explanations that need to pay attention to and consider. I mentioned some in the prior blog entry.

    In science and medicine,the patient's medical history is very important in understanding pathological findings. So if someone has no documented history of concussion, yet has findings of CTE, then we need to wonder about specificity. Of note, current CTE research is based on case studies and is marred by a selection bias in which cases are only being studied who are believed to confirm the researcher's theories but cases that could disconfirm it are not being studied to my knowledge. This is important to do.

    With regards to subconcussive blows, that term (which I have heard many times) has absolutely no scientific criteria associated with it and it is inherently contradictory if you take it literally. By definition, a concussion is a mild traumatic brain injury, which is defined by either an alteration of mental status after injury or a focal neurological sign. If you did not have a concussion, the conclusion is that you had no brain injury because it is the mildest form of brain injury on the spectrum. Therefore, subconcussive would imply no brain injury occurred but just trauma to the head. Repetitive non-brain injuries still lead to no brain injury. Thus, in this sense, subconcussive blows cannot be used as a neurological explanation of behavior.

    Now, if by subconcussive blows it is meant that hard hits to the head are causing brain damage without an alteration of mental status or focal neurological sign, that's fine to theorize, but please note that there is already significant controversy in the neurosciences that current MTBI criteria are too lax and leads to excessive many false positives. This is consistent with my own research and clinical experience. Thus, any attempt to lower the criteria of brain injury further is going to be fraught with extreme problems and result in even further false positive brain injury diagnoses.

    To be clear, I do not deny that CTE may exist or that the current criteria for MTBI may need to be changed one day as we learn more, but right now, I believe that people are making too many premature conclusions about suicide being caused by CTE. When it is discussed in the media, it is often discussed as if it is a 1:1 relationship. Neuropahologist, Bennett Omalu, for example has literally said as such.

    If brain damage is making someone impulsive, then by definition they are acting without thinking or considering the consequences. That is an externalizing explanation of behavior and it pins the blame squarely on brain damage as causing the person to kill themselves. Same with the concepts of decreased emotional regulation and behaving erratically. These explanations make it sound as if the person was not responsible for their behaviors.

  3. People act impulsively, behave erractically, and have decreased emotional regulation every day without any history of any form of brain damage. What is often missing from these NFL cases is a thorough psychological analysis of these players lives to study reasons that could have led to suicidein favor of an overfocus and excessively neuro-reductionistic explanation of behavior. I am calling for a more nuanced understanding of human behavior. Persons with brain injury and dementia could be at higher risks of suicide because they simply can't adjust to their medical condition. That does not imply brain injury neurologicaly caused them to kill themselves. For example, cancer patients have an increased risk of suicide as well and it has nothing to do with brain damage.

  4. Although I appreciate your prompt and lengthy response, I still disagree with your take on suicide and CTE.  Of course suicide is multifactorial. People commit suicide in a variety of situations but saying that other athletes in non-contact sports commit suicide isn't mutually exclusive with CTE being a contributor to suicide in athletes.  Even in severe TBI people commit suicide for different reasons, but the TBI increases risk, directly or indirectly.  Lung cancer is multifactorial but smoking increases the risk.  But I do agree the jury of peer reviewed research is still out.   But if Seau is identified with CTE, attention and reach dollars brought to the issue will increase exponentially. Sad that it takes this but it's true.

    As for causes of CTE,  it is likely that concussion isn't going to be the biggest contributor to its development.  So having a documented history of concussion may be irrelevant.  Medical history is critical, but in this case the most important medical history may be whether someone has participated in an activity over the  course of years where their brain was consistently exposed blows.  That is the relevant medical history.  Whether the acute behavior change the we call concussion occurred  may not be important at all.  The accumulation of hits over time may result in long term brain changes that cause CTE.  That's the issue that needs to be further investigated.  

    Changes  in the brain can occur without apparent behavioral change.  Happens all the time.  In regards to football, there is already research in the extant literature showing changes in brain functioning even in those with no documented concussion.  For instance, the 2010 Purdue University study done with high school football players showed cognitive changes after the season even in those with no documented concussion history.  I believe the research will show that CTE is an accumulation disorder, rather than a severity disorder.  Only time and more research will tell. 

    Until more research comes in, I'm pushing my kids toward cross-country.  

  5. Thanks for the reply but based on the wording of your last reply I don't think we are too far off here. Please note that I never said CTE cannot possibly contribute to suicide. What I said was that making definitive statements about CTE directly neurologically causing these athletes to kill themselves is mere speculation at this time. I do not believe that a "smoking causes lung cancer" analogy is appropriate. In that case, we have direct scientific evidence that smoking destroys lung tissue and leads to cancer. We do not have direct scientific evidence in these cases that the concussive history is directly causing the suicidal behavior. That requires an inferential leap that often does not consider the effect of mediating third variables.

    For instance, take the study done by Barnes et al (2012) entitled, "Does a history of mild traumatic brain injury increase suicide risk in veterans with PTSD?" The research compared suicide risk factors among a matched sample of Operation Enduring Freedom and Operation Iraqi Freedom (OEF/OIF) military personnel and veterans with PTSD (posttraumatic stress disorder) alone or PTSD and a history of an mTBI.Differences in the assessed risk factors were small and suggest that if PTSD and mTBI are associated with elevations in suicide risk relative to PTSD alone, the added risk is likely mediated or confounded by PTSD symptom severity. This finding highlighted the importance of screening and treating military personnel and veterans for PTSD.

    So, the bottom line to me is that when you look at the problems in many of these athletes' lives that could easily have led to suicidal behavior, jumping straight to the conclusion that TBI neurologically caused the person to kill himself is going way beyond the available data right now.

    As to your other point on repetitive blows to the head, we agree that the topic needs to be studied more but for those blows to be affecting brain functioning they have to be causing some type of altered neurophysiology/structural damage. My point is that we currently have no clinical criteria whatsoever to determine if that is happening. We have criteria for defining concussion but not for how to tell if repeated blows that do not currently meet even liberal criteria for concussion are also causing brain damage/dysfunction. And if these blows are causing dysfunction/damage, then I suggest that we get rid of the term "subconcussive" for the reasons I mentioned earlier. It can be taken to mean "no brain injury."

    Lastly, as for the Purdue study, the results are interesting but it is a correlational study with few subjects and uses fMRI technology, which the American College of Radiology ACR Appropriateness Criteria rates as being usually not appropriate in the clinical care of TBI. It is essentially a research tool only so you need to be very careful about the inferences made from results from such studies.

  6. This EXCELLENT piece at published today supports exactly what I have been saying:

    The Concussion Panic

  7. Yes, it was reported today that Seau had CTE, which contradicts initial reports. However, the alleged connection between CTE and suicide is what I believe to be the most controversial.

  8. thanks for well saying..

  9. Thanks for writing this good post.


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