Steve Broglio, PhD is the lead author on a new research study that shows evidence of the cumulative effects of concussions. It may not be a “gross” outwardly as some are envisioning, rather the study does indicate that multiple traumas to the brain – be it subconcussive or concussive – will produce a decline in brain function.
Broglio and his group looked at 162 “control” subjects and 62 subjects that had a history of concussion; as stated above the results were actually subtle in nature, none the less they were only noted in the group with previous head injury. Using balance and walking assessments along with brain electricity studies this research is the foundation for the “hit count” proposals. Is there a threshold for “aging” of the brain? It is number of exposures or the relative level of exposure that will be the catalyst?
Here is the full abstract;
Concussion has been viewed historically as a transient injury with no evidence supporting the existence of persistent effects. However, our recent work demonstrates electroencephalographic and motor control changes in otherwise healthy individuals with a history of concussion. We therefore hypothesize that concussive and subconcussive head impacts set about a cascade of pathological events that accelerates declines in cognitive function typically associated with the aging process.
I will be interested to see comments about this study, I have put in a request to talk to Broglio as well.
The Concussion Blog 
Dustin,
I think the below Abstract content you cited is grossly misleading of available and long-term concussion research that clearly supports the perspective of the cumulative effects of concussions.
“Concussion has been viewed historically as a transient injury with no evidence supporting the existence of persistent effects.”
Excerpts from my 2004 Dissertation pertaining to Active & Retired NFL Players’ Knowledge of Concussions, the 2011 NASP Sport-Related Concussion article written by my wife, Flo, and I along with numerous referenced comments such as Martland’s classic Punch Drunk (1928) article and Gronwall & Wrightson’s 1975 research entitled ‘Cumulaticve Effect of Concussion’ on your blog this past year serve to document the permanent and cumulative effects of suffering a concussion.
Excerpts of my Dissertation follow and was cited for the section entitled:
Cumulative Effect of Concussions
“Symonds (1962), while discussing the effects resulting from any grade of concussion, asserted: “It is questionable whether the effects of concussion, however slight, are reversible” (p. 1). The author also pointed out that since the 1940s clinical evidence has existed for supporting the view that not only does neuron damage occur after a person sustains a concussion, but that repeated minor injury could result in progressive and permanent neuron loss. Maddocks & Saling (1995) further discussed and raised critical concern regarding the acceptance of the transient nature of concussions. …
Postmortem examination of 37 patients who sustained significant brain injury revealed microscopic documentation of axonal and small vessel injury in all subjects (Peerless & Rewcastle, 1967). The authors professed that it was probable that axonal changes were the primary lesion found in all brain injury. They also advocated for a concussion definition that acknowledged that a small number of neurons may have died or become disconnected due to this brain injury. These researchers also concluded the effects of this type of injury may be cumulative, irreversible, and thus clinically significant if a person experienced another brain injury (Peerless & Rewcastle, 1967).
Gronwall (1989) also pointed out that inferential evidence supporting that the brain becomes compromised due to a concussion may be found in concussion research that emerged in the 1970s. This research documented the reduction of information-processing skills along with evidence of damage to brain structure. These findings were subsequently interpreted as supporting the long-term, cumulative and permanent effects of sustaining a concussion (Gronwall & Wrightson, 1974; Gronwall & Wrightson, 1975). In the same vein, Kelly (1995) has emphasized that there is a cumulative neurological effect from an athlete sustaining multiple concussions, while Kaplan reported that there is an exponential factor involved with a person who experiences more than one concussion (D. Kaplan, personal communication, June 24, 1990).
Since the 1970s there has been a growing body of medical and neuropsychological evidence that concussions result in permanent irreversible brain injury. Through the use of animal studies, along with the evaluation of neuropsychological testing and neuroimaging techniques of the magnetic residents imaging (MRI) and computer aided tomography (CAT Scan), researchers have been assisted in providing some substantiation and measurement of brain damage which has been attributed to previously sustained concussions (Barth et al., 1996).
Minnesota high school students participated in a survey study pertaining to concussion incidences and severity. Responses from 3,063 players revealed an injury rate of 78 injuries per 100 players. Analysis of results revealed that players who acknowledged sustaining a previous concussion via losing consciousness were four times more apt to sustain another concussion when compared to players who did not report experiencing a prior concussion (Gerberich, Priest, Boon, Straub, & Maxwell, 1983).
Further support for the cumulative effects of concussion may be found in Saunders and Harbaugh’s (1984) case study of a 19-year-old college football player who was struck in the head during a fist-fight and briefly lost consciousness. Although the player reported a mild headache three days after sustaining the blow to the head, he was allowed to resume football practice. The following day the individual collapsed on the practice field and died several hours later. An autopsy was performed and the findings revealed the player possessed a pre-existing cerebral contusion and concluded that the effects of the impact sustained by the athlete had an additive and lethal effect.
Carlsson, Svardsudd and Welin (1987), in a study of 1112 males, found a direct relationship between the number of concussions with impaired consciousness a person sustained, and (a) the subsequent postconcussional-like symptoms reported, and (b) an inferior performance on neurological tests (i.e., finger tapping, single choice reaction time, multiple choice reaction time). The authors concluded that repeated brain injuries resulted in an adverse cumulative effect on the brain.”
Again the above is an excerpt…more info is discussed under this section of the Dissertation.
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Futhermore, an excerpt from the 2011 Sport-realed Concussion article follows:
“A concussion should not be viewed as a brief occurrence, but as both a short-term and potentially long-term process where primary and secondary brain injury occurs. The adverse and destructive consequences of a concussion may follow a continuum from subtle to grossly overt. Altered cell functioning and cell death along with subtle to more visible physical, cognitive, and emotional impairments reflect a potentially diverse range of lifelong negative consequences of concussion. Substantial credible experimental and clinical evidence pertaining to the adverse effects of concussion indicate that the brain is injured as a result of a concussion (Holbourn, 1943; Hovda et al., 1995; Gronwall & Wrightson, 1975; Gronwall, 1991; Ommaya & Gennarelli, 1974: Strich, 1961). Expressions such as “just a ding” and “had his bell rung” serve to minimize, discount, and invalidate the adverse implications of sustaining a concussion. Further evidence of the potential seriousness of a concussion was reiterated by Kieslich et al. (2002) when they reported that minor brain injuries were related to strokes occurring in children.
Subtle does not imply statistically significant. Walking and balance tests lack sensitivity and depending on the variance of the electricity element it could be inferred that the measures are little more than noise.
This does not suggest that there is not a decline but the experiment failed to show evidence of a statistically meaningful one.
It will be interesting to review the paper but on face it would seem it may be the publication of a result that may not be statistically or clinically meaningful.
A friend of mine recently viewed the slides taken of her husband’s (a former professional athlete) brain after his death. I think she would tell you the cumulative affects were more than subtle and the outcome was tragic and heart wrenching. It seems to me the endless debate has paralyzed us from taking action to improve the lives and the futures of our athletes and their families. Dr. Brady as done a great job citing study after and study and the Concerned Mom share with us that eye-opening Sports Illustrated Article from 18 years ago. How many more studies do we need to make a change?
Re being paralyzed:
Unfortunately, numerous Dr. No’s presently exist within the SRC field at both the individual and organizational level.
As noted in my above Blog response, a comprehensive review of concussion literature/history easily and readily reveals ample evidence re adverse effects of concussions.
If we are to make advancements in the area of SRC, then WE MUST KNOW THE HISTORY
of both SRC and concussions.
Knowledge of history was essential to General Patton. The illustrious General was quoted as saying:
To be a successful soldier you must know history. Read it objectively.
Juxaposing a few words…
To be a successful as an AT, MD, psychologist, neurologist, educator, parent and so on… you must know concussion and SRC history. Read it objectively.
I think those ‘on the front line’ wishing to enhance their concussion assessment & management skills need to absorb and accurately comprehend concussion history and its corresponding controversies.
This history includes the existence of the mine-laden field of self-servicing COIs that result in the gladiator-like athletes being used as ‘cannon fodder’ for the selfish benefit of others.
Over the past year I have been interviewed by various media and a legal firm representing former NFL players re sport-related concussions.
During each interview I shared the following significant personal concerns re the status of the SRC field:
“Sadly, there is a significant amount of conflicts of interest, corruption and corresponding deliberate dissemination of misinformation that exists in this emerging SRC field.”
Now traveling back 8 years…
Eight years ago this month I successfully defended my NFL Concussion Dissertation research. During the PhD journey my eyes and mind were guided and opened to apparent conflicts of interest (COI) that existed within the SRC research arena.
A ‘laser highlight’ re COIs occurred when I presented preliminary findings of my concussion research at a national concussion convention held in Pittsburgh. The highlight was not the presentation of the research results…but the following occurrence during an formal discussion of current status of SRC research.
A ‘prominent professional within the emerging field of SRC finished sharing various ‘knowledge’ about SRCs. He then asked if there were any questions?
I subsequently raised my hand and queried:
“Given all the information that has been shared at this convention, what is being done to educate the general public re the adverse effects of concussions?”
The ‘professional’ promptly exclaimed… “Next question !” That absurd and arrogant response further spurred me on to expand the Conflict of Interest section within my Dissertation…
and to continue accurately (as much as possible) writing and speaking about sport-related concussions…aquired from readings, observations, dialogues with others, and my own personal journey with a “mild” concussion.