Along with the findings by other researchers over the past five years linking repetitive head impacts to increased susceptibility to concussion, decreased cognititive function, altered gray matter functional connectivity, and changes in white matter microstructure, and theorizing that, in the long term, retired football players who have sustained high levels of subconcussive impact over their careers are at increased risk of developing neurodegenerative disorders, like amytrophic lateral sclerosis (i.e. Lou Gehrig's disease), Alzheimer's disease, Parkinson's disease, and chronic traumatic encephalopathy (CTE),^[12] the Purdue studies suggest that science is inching closer to an understanding of the neurocognitive, metabolic, cerebrovascular, and brain gray and white matter changes resulting from concussion and from the accumulation of sub-concussive blows.  

Finding the holy grail 

Whether scientists will ever find the head trauma "holy grail": a threshold - whether it is number of hits per week, over the course of the season, of a certain magnitude (both in terms of linear and/or rotational acceleration, or to a certain part of the helmet (e.g. facemask, top of the head) above which a player exposed to RHI is at significantly increased risk of permanent neurocognitive impairment or, worse, degenerative neurological conditions such as chronic traumatic encephalopathy, needed to help guide the development of preventive strategies, is, however, very much an open question.

"We'd like to get to the point where, now that we know we can observe with imaging how the brain changes with exposure [to subconcussive blows], we can intervene to change the hardware, change the helmets, change techniques and training regimens," said Larry Leverenz, clinical professor in the Department of Health and Kinesiology, in an interview with Purdue News.

To that end, the Purdue researchers are working to develop helmet technologies that absorb more energy than conventional helmets to better protect the brain, and have formed the Concussion Neuroimaging Consortium with seven other universities to garner support and funding for research into the neurological effects of contact sports.  

Unfortunately, there appears to be little funding for studies like that those done at Purdue.  As one researcher observed, "Everyone is focusing on only looking at concussions after-the-fact, rather than trying to gain a meaningful understanding of what takes place prior to the injury.  This is unfortunate, as we know from many soft tissue injuries that 'symptoms' (effectively, 'failures') are late-developing situations, with structural and functional changes typically preceding the 'diagnosis' of something being wrong. 

Another concern, some researchers say, is that the timelines for developing and testing cutting edge technology, especially new telemetry devices (i.e. impact sensors) and for predictive modeling of neurological changes that could be used to meter head impacts in, say, practices, is so long (approaching five or six years), that it is not within the window of current entrepreneurship models, given the current venture capital/angel investor climate. In the absence of government funding from the National Institutes of Health or the National Science Foundation, which, according to one researcher, is unlikely, the problem might never be solved.