Like many in my field, I have been closely following both the debate and the science around chronic traumatic encephalopathy (CTE). I am a Veteran of the U.S. Armed Forces and a neuropsychologist whose 21st century training occurred in the neuroscience cauldron of the San Francisco Bay area, where we were surrounded by brain research at neighboring UC-Berkeley, UC-San Francisco Medical Center, and VA-funded research centers, which later served me well in military medicine as an active duty neuropsychologist.
While at the so-called “tip of the spear” of traumatic brain injury assessment in Afghanistan in 2013, concussion assessment struck me as “the war within the war.” This meant that some people were at war within themselves about whether they could return to war, based simply on fears of what could happen to their brain should they experience a concussion, or should inadequate rest be achieved. Should they report their symptoms, for fear of a well-meaning doctor returning them home to prevent complicated recovery or reinjury? I would later encounter individuals stateside who stated they downplayed their symptoms while in the combat zone, for fear of being sent home or being medically discharged from the military.
There is a generation of OEF/OIF veterans who succeed and thrive despite the fears of some concerning what could or should happen to their brains and minds (should this new condition called CTE arise from concussion?, for example). On the heels of the Concussion movie, do those who sustained concussions in Afghanistan need to fear that they will develop CTE? Do their employers and the American public as a whole need to fear that people who report experiencing a concussion will develop CTE? Is America’s obsession with concussion, epitomized by the “signature injury of the war” language, and now CTE, one more societal caricature of the service member as vulnerable?
The America I saw in Afghanistan differed. Instead, I recall 18 year olds running to lunch chow, “fired up” to go on another mission “outside the wire,” including those with unspoken or unreported psychological injuries and concussion. In stark contrast to the Concussion movie, the state of the science seemed to suggest that with proper rest, the brain could heal from concussion, or that repeated mild head injuries do not necessarily result in dementia. We honor the service of both those who were medically evacuated and those who were not, and yet the American public would soon be challenged to not equate concussion with CTE or dementia in the wake of the Concussion movie.
With the release of the Concussion movie, a debate about concussion in America had been born, initially fueled by the release of case studies on a relatively small set of autopsies conducted on professional athletes (Dr. Ann McKee’s group in Boston), which posit that an accumulation of tau seen in the brain at autopsy is related to self-reported concussions occurring earlier in that person’s lifetime. The Concussion movie expanded on the history behind this side of the debate but it remains silent about the larger body of scientific evidence I see when I browse National Institutes of Health archives, leaving me uneasy.
I turn to the science in trying to understand CTE. But I cannot find any solid evidence that CTE can be diagnosed at any time, before or after death.
Instead I would see that the Concussion movie and media attention led some in the general public to assume a clear and convincing relationship between concussion and a dementia like state, without consideration of other factors such as genetics, drug and alcohol, stresses, mental health problems, and unknown factors.
I examined self-report studies conducted by researcher Guskiewicz which suggested that athletes with multiple concussions report a higher rate of early dementia and depression. However, scientists argue that this research is retrospective, meaning the person self-reported on concussions occurring years earlier, and it is not evident that the people self-reporting received comprehensive neuropsychological evaluations and other medical studies that could have investigated other factors explaining the tau accumulations in their brains.
For years, concussion researchers had documented other (non-concussion related) factors as responsible for changes after concussion (for example, as early as 1994, Putnam and Millis published a research paper entitled “Psychosocial factors in the development and maintenance of chronic somatic and functional symptoms following mild traumatic brain injury.” 1994 Advances in Medical Psychotherapy, v. 7, 1-22). There have been many studies and now several meta-analyses (studies synthesizing results across studies) showing no significant long-term neuropsychological consequences of concussion.
A critical review of the Concussion movie in Slate authored by Daniel Engber points to a study of several thousand NFL retirees, conducted by researchers at the National Institute for Occupational Safety and Health in 2012, which found that the former football players lived significantly longer than race- and age-matched controls. They were much less likely to die from cancer, heart disease, diabetes, accidental falls, or homicides than anybody else. In the fall of 2008, researchers at the University of Michigan asked 1000 former players from the NFL questions about their physical and mental health. About 3 or 4 percent described themselves as being in the middle of a major depression—the same as in the normal population. When asked if they had ever been diagnosed with depression, about 16 percent of the players said they had—again about the same as other people.
It appeared that former NFL athletes weren’t really more depressed than anyone else. What about violent mood swings? The researchers in Michigan asked the ex-players if they’d ever experienced “attacks of anger when all of a sudden
[they] lost control” and became violent. About 30 percent said they had. The baseline rate for U.S. men is much higher—more than 50 percent.
Some doctors have expressed that the fear about CTE generated by recent observational CTE studies has led to individuals’ self-diagnosing, to the point where some people severely restrict their activities who are able to be more active and independent.
This self-imposed activity limitation may do more harm than good, some say, and in some cases may cause symptoms that “mimic” neurologic symptoms but are not truly neurologic. In other words, fear of CTE becomes an anxiety related condition in cases where it is not justified. Existing evidence suggests that it is important to be careful in mistaking a low base rate hypothesized condition (CTE) for a high base rate condition.
We know from other studies that some degree of tau-protein buildup is a normal part of aging and that the presence of neurofibrillary tangles is not predictive of or share a 1:1 relationship with cognitive impairment.
This is not to say that CTE does not exist. Rather, it appears that the science of this proposed illness is still in a formative stage. The study of concussion in sports and, by extension, the military, is rapidly developing. The instruments and methods used to inform “return to war” decisions were derived from sports concussion research, in part because of the motivation to return to play or duty that both groups were presumed to share.
A number of important research questions remain unanswered, however, and admittedly many of us in the field find ourselves in places where return to play, or, sentiently, return to war decisions are sometimes being made within the context of incomplete evidence about long term implications of concussion. As a scientist I examine the evidence for a particular phenomenon such as chronic traumatic encephalopathy (CTE), rely on scientific data, make inferences from base rates and large descriptive studies, and consider alternative explanations for phenomenon when the research in the area appears unclear. As a Veteran I examine the evidence so as to provide compassionate care to other Veterans and so as to avoid misleading myself and others. And in this war within the war about the impact of concussion, the debate continues.