[caseyohara]

Studies seem to confirm that concussion increases the risk of subsequent concussion, and I guess it might be true that the brain loses the ability to balance the body leading to more concussions. But the brain itself seems more susceptible to concussion after having one; I don't think it's exclusively a matter of balance or body movements. Especially when you consider athletes (esp. American football) where their concussions are not usually the result of a slip-and-fall type incident like an elderly person.

> Also, it is now known that, after a concussion, there is greater susceptibility to sustaining another concussion and that subsequent concussions occur with less force and take longer to resolve.

Source: Concussions and their consequences: current diagnosis, management and prevention https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3735746/

That paper cites this paper (https://jamanetwork.com/journals/jama/article-abstract/19766...) which seems to suggest it has more to do with post-injury neuronal vulnerability.

> Our study suggests that players with a history of previous concussions are more likely to have future concussive injuries than those with no history; 1 in 15 players with a concussion may have additional concussions in the same playing season; and previous concussions may be associated with slower recovery of neurological function.

> Additionally, our study suggests that a history of concussion is associated with prolonged recovery following subsequent concussions. The increased risk of future injury, as well as slower recovery, may be indicative of increased neuronal vulnerability following recurrent concussive injuries.