As for the concussion issue specifically and the topic of repeated concussions. It has been studied and it took me less than a second to find some.
A concussion is an injury to the brain that results in temporary loss of normal brain function. Medically, it is defined as a clinical syndrome
www.aans.org
I will post part of this that directly applies:
University of Pittsburgh’s Brain Trauma Research Center reports more than 300,000 sports-related concussions occur annually in the U.S. Additionally, the likelihood of suffering a concussion while playing a contact sport is estimated to be as high as 19% per year of play; in other words, almost all athletes of contact sports suffer from a concussion within five years of participation. It has been reported that more than 62,000 concussions are sustained each year in high school contact sports. Among college football players, 34% have had one concussion and 20% have endured multiple concussions. Estimates show that 4-20% of college and high school football players sustain a brain injury over the course of one season. The risk of concussion in football is three to six times higher in players who have had a previous concussion.
A study conducted by McGill University in Montreal found that 60% of college soccer players reported symptoms of a concussion at least once during the season. The study also reveals that concussion rates in soccer players were comparable to those in football. According to this study, athletes who suffered a concussion were four to six times more likely to suffer a second concussion. Research such as this has led to greater interest in developing protective headgear for soccer participants, but it is not clear that such headgear actually reduces the risk of concussion.
So yeah... Tons of talented doctors and researchers have done studies and they came up with the same results. up to 6 times more likely to suffer additional concussions.
Remember, The University of Pittsburgh's brain trauma research center did this study.... So they are specialists and experts in the field of brain trauma and injury. This is not some guy getting his friends together in his mom's basement discussing this over beers.
Up to 6 times more likely.
Please take as much time as you need to process this.