The current fears over Chronic Traumatic Encephalopathy, more commonly known as CTE, appear to be both “misplaced” and miscalculated.
A UPMC research team, in a study published today in the online journal PLOS ONE, found in a review of all published scientific reports over the past eight decades that there exist just 153 unique case studies of this sports-associated repetitive head trauma condition. In fact, the team led by Joseph Maroon, M.D., found 262 individual CTE cases reported in the medical literature, though 113 of those (43 percent) were duplicated, or double-reported. The researchers added four cases reported in the media to reach a total number of 153 unique cases dating to the first pathologically diagnosed case, in 1954. Of that total, they found 69 in boxing and 63 in football, covering both the amateur and professional levels.“Our findings show that thus far the scientific study of CTE has been limited to case reports and small series. Without large, longitudinal studies used to make scientific conclusions, the exaggerated fears surrounding CTE may be misplaced,” said Dr. Maroon, vice chairman, UPMC Department of Neurological Surgery, and a longtime clinician/researcher in concussion and minor traumatic brain injury (mTBI). “Based on this review, any conclusion that concussion will lead to CTE seems extremely premature, going by the current state of the science.
“But eliminating contact sports over the perceived epidemic of CTE appears premature based on our findings. This overreaction to CTE, especially in youth sports, makes little sense because case reports since 2002 have almost exclusively been at the professional level.”
Dr. Maroon and his team, after removing the large cohort of repetitive case studies, reviewed published cases of CTE and dementia pugilistica involving military veterans plus amateurs and pros in boxing, football, ice hockey, wrestling and miscellaneous contact sports. The researchers noted their review showed that the median CTE age range at death (60-69) was lower than in the general American male population (76.2), but concluded that the recent spate of case reports finding CTE in professional football players significantly lowered the average age of death in this group. In the CTE subjects in which a cause of death was reported, the majority died from natural causes (71 percent) followed by accidental death (17.5 percent) and suicide (11.7 percent).
While acknowledging that CTE has delivered pain and tragedy to many, the researchers said that the recent heightened attention has caused a “selection bias.” In other words, families of individuals who died by suicide or accidental death, or who had suffered behaviors or neurodegenerative conditions, were more likely to participate in such brain donation cases. In scientific parlance, there has been no “control group” or other, non-contact-sport subset to balance research. Football has been the most studied group, with all 63 noted cases coming since 2002 and what researchers called “the seminal diagnosis of CTE in a former professional football player by Dr. Bennett Omalu.” However, with millions of athletes having participated in organized football and other contact sports over this period, the researchers said it seems unfounded for some to call CTE an epidemic.
CTE shares numerous neuropathological abnormalities often associated with other neurodegenerative diseases, so it remains unclear what is responsible for CTE specific clinical changes, what is the natural progression, and what are contributing factors from a long, untapped list of possibilities, the researchers said. Some of those factors may include: severity and frequency of head trauma, genetics, diet, and potential substance abuse. Based on their review of existing research, beyond a history of prior head trauma they said they detected no other conclusive evidence linking the occurrence of CTE-related brain changes.
The study was conducted by Dr. Maroon, fellow neurosurgeon and senior author Vince Miele, M.D., along with Christina Mathyssek, Ph.D. and Jeffrey Bost, P.A.-C., plus two Carnegie Mellon University graduates, Robert Winkelman, B.S., of Michigan and Austin Amos, B.S., of Virginia. In addition to his medical and research duties at UPMC, Dr. Maroon has spent the past three decades as the Pittsburgh Steelers’ team neurosurgeon and served in concussion consulting roles with the NFL. PLOS ONE is an open-access, peer-reviewed journal published by the Public Library of Science.
“The bottom line is, there is so much we don’t know about CTE,” Dr. Maroon added. “It is important to point out that it is a real problem, but we need to much more clearly define it and not fall into almost-wild hysteria about this and then extrapolate it to sports in general.”