On 1/13/09, Salon.com published a news article by Dr. Robert Burton entitled, Should Johnny play linebacker? Concussions sustained in high school sports may put young athletes at increased risk for Alzheimer's disease. MTBIFacts.com examines some of the statements made in the article below.

The article begins by defining what a concussion is by stating: ”A concussion -- often referred to as a mild traumatic brain injury -- is generally defined as a blow to the head followed by transient alterations in mental state ranging from confusion, disorientation and short-term memory defects to an actual loss of consciousness of less than 30 minutes in duration.” This statement is correct.

The next sentence, however, is where problems begin to occur, when it is stated that: “It's generally accepted that a mild concussion results in less than 30 minutes of amnesia, a moderate concussion causes 30 minutes to 24 hours of amnesia, while with a severe concussion, the amnesia persists for greater than 24 hours.” In actuality, it is generally accepted that a period of less than 24 hours of post-traumatic amnesia (PTA) reflects a mild traumatic brain injury (CDC, 2003, Kay, 1993; Stein, 1996). PTA refers to the period of time after trauma in which one cannot clearly and consistently remember day-to-day information. The World Health Organization’s definition of MTBI also includes the less than 24 hours of PTA criteria (Holm et al., 2005). In fact, some classification schemes do not even consider more than 60 minutes of post-traumatic amnesia to be a mild traumatic brain injury (Lezak et al., 2004), instead classifying it as a moderate to severe traumatic brain injury. It should also be noted that none of the commonly used systems classify concussions as mild, moderate, or severe.

It appears that the classification system Dr. Burton is referring to is the one mentioned in the article he cites showing an association between head injury and Alzheimer’s disease (Plassman, 2000). Notice in the reference section below that the Plassman article uses the word “head injury” and not concussion. Despite this, the article on Salon.com states that “Perhaps the best place to begin is with a systematic review of the medical records of a group of 548 veterans who sustained a moderate or severe concussion during World War II. Over the subsequent 40 years, the incidence of Alzheimer's disease in the moderate concussion group was twice the rate in those soldiers without a prior head injury. Those with a severe concussion had a risk four times that of the control group. The effect of minor concussion was not adequately assessed in this study.”

There are several problems with this quote. The first is that the word “concussion” does not appear a single time in the Plassman article. This is because the study included patients with more severe injuries than a concussion. Specifically, the study also included patients with moderate and severe traumatic brain injuries (in which PTA exceeded 24 hours). Moderate and severe traumatic brain injuries are not referred to as concussions. Unfortunately, the Salon.com article refers to these patients as having has “severe concussions.” As described in the MTBIFacts.com article showing that all brain injuries are not the same, mild TBIs are a completely separate entity from moderate to severe TBIs. As such, one cannot take data from studies that combine patients with moderate to severe brain injuries and apply them to patients with mild brain injuries. It would make sense that patients who had moderate to severe brain injuries may have an increased risk of Alzheimer’s disease, but the jury is still out with regards to the risk incurred by concussive injuries.

Another problem with the article is that it states the following: “In 2003, an editorial in the Journal of Neurology, Neurosurgery, and Psychiatry opined that, at least in males, the risk of Alzheimer's in patients with mild traumatic brain injury was sufficient to advise head-injured patients of the risk of further injuries.”

The editorial Dr. Burton is referring to was written by Wilson (2003) but does not actually state what is written above. What Wilson stated in his editorial was: “The balance of evidence, at least in males, is now firmly for the existence of an association.” (between head injury and Alzheimer’s disease, p. 841). But remember, head injury is a broad term that also includes moderate to severe brain injuries. Nowhere in the article does it say that head injured patients need to be advised that they run the risk of Alzheimer’s disease with further injuries. In fact, the editorial states, “Should advice about the increased risk of developing Alzheimer’s disease be given routinely to head injured people? Advice might encourage the person to avoid the risk of further injury and aid them in seeking help early if symptoms of the disease became apparent.” (p. 841, emphasis added). The question, followed by a sentence with the word “might” in it is not a prescriptive statement for what health care providers should tell athletes. However, one would infer that from the Salon.com article.

It is also worth noting that the Salon.com did not mention another key aspect of Wilson’s editorial, which is: “The epidemiological studies reviewed by Fleminger et al suffer from inherent weaknesses. Crucially, all the studies described rely on the report of an informant to ascertain whether a head injury causing loss of consciousness had occurred in the lifetime of the individual. Recall bias and inaccuracy are thus major limitations. In these studies it is impossible to establish reliably the nature and severity of the original injury. Such uncertainty may account for some of the inconsistencies in published reports. The difference between men and women, for example, may arise because men have typically had more severe injuries. More generally the case–control approach is too imprecise to answer questions remaining concerning the link.” (p. 841).

The study by Guskiewicz et al. (2005) with retired NFL players (cited in the Salon.com article) was also retrospective, making it impossible to make a definitive link between concussions and Alzheimer’s disease. Although a prospective longitudinal research design may eventually find a definitive link between concussions and Alzheimer’s disease, tempered language is suggested until then. It is also worth noting that there is no guarantee that three or more concussions will lead to permanent neurological impairment. For example, one study showed no difference in cognitive performance in patients who suffered three or more concussions and patients who suffered fewer concussions (Pellman, 2004). Another study showed no difference between patients who suffered two previous concussions versus patients with no history of concussions on neuropsychological testing (Iverson et al., 2006).

MTBIFacts.com supports concussion safety awareness and suggests that patients consult with a qualified physician before making decisions regarding return to play. However, high school students who suffer concussions should not live their life in fear that they are going to develop Alzheimer’s disease.

On 1/14/09, a link to this article was posted to the Salon.com blog. A response will be awaited. Click here to return to media watch.

REFERENCES

Centers for Disease Control and Injury Prevention (2003). Report to Congress on Mild Traumatic Brain Injury in the United States: Steps to Prevent a Serious Public Health Problem.

Guskiewicz, K. et al. (2005). Association between recurrent concussion and late-life cognitive impairment in retired professional football players. Neurosurgery, 57, 719-726.

Holm, L. (2005). Summary of the WHO Collaborating Centre for Neurotrauma Task Force on Mild Traumatic Brain Injury. J Rehabil Med, 37, 137-41.

Iverson, G. et al. (2006). No cumulative effects for one or two previous concussions. British Journal of Sports Medicine, 40, 72-5.

Kay T. (1993). Mild traumatic brain injury committee of the head injury interdisciplinary special interest group of the American Congress of Rehabilitation Medicine. Definition of mild traumatic brain injury. Journal of Head Trauma Rehabilitation 1993, 86–87.

Lezak, M. et al. (2004). Neuropsychological Assessment (4th ed). New York: oxford University Press.

Pellman, E. et al. (2005). Concussion in Professional Football : Neuropsychological Testing – part 6. Neurosurgery, 55, 1290-1305.

Plassman et al. (2000). Documented head injury in early adulthood and risk of Alzheimer’s disease and other dementias. Neurology, 55, 1155-1166.

Stein., M. (1996). Classification of head injury. In: Narayan, RK et al. (eds). Neurotrauma. New York: McGraw-Hill, 31-42.

Wilson, J. (2003) Head injury and Alzheimer’s disease. J. Neurol. Neurosurg. Psychiatry. 74;841.