Wired's Jonah Lehrer Expands on the Parkinson's and Traumatic Brain Injury Connection

Covering topics like brain trauma on a combat sports website can seem counter intuitive on the surface. Casual fans just want to know who's fighting next, and even hardcore fans can feel like the coverage over such issues simply further educates the critics, and by consequence, fuels the potency of their criticism.

For me, this information is not about my own struggle to keep watching combat sports. It's about properly defining the safety of these athletes who we respect, and are inspired by. In addition, I get to satiate my own curiosity with material that is well over my head.

In any job, there are laws that protect you from hazards. Sports, however, don't come with easily established legislation concerning safety. In the broad arena of neuroscience, this is especially difficult since we are only just now learning what it means to say that "we are our brains". The implications of modern neuroscience are finally being felt, and for proof, just consider a recent $4.85 million dollar grant to help broaden the scope of criminal justice with a neuroscientific underscore.

It only makes sense that in the area of sports health, we recognize similar principles. Just as the goal of neuroscience in a law setting might be to make better sense of rehabilitation, rather than institute absolution, the goal of neuroscience in a sports setting would be a better sense of how to protect, say, fighters, rather than how to outlaw them.

The American Academy of Pediatrics recently came out with an emphatic statement discouraging youth boxing for the very valid reason that children have a harder time than adults in recovering from brain injury but as Scott Christ over at Bed Left Hook points out, "for many of them, it's not about "conditioning and athleticism." It's about a way out of something worse, something more hopeless than even the dream of making it in a very hard sport". Boxing has always been topical for the socioeconomic themes it speaks to, where for some, the choice is between jail, or the ring. Rather than strive for banishment, the middle ground here is identifying those that are physiologically ill equipped to deal with combat sports (for which there are actual genetic markers).     

So on that rambling note, last week I wrote about the recent discovery concerning the link between Parkinson's (a mental disorder that attacks dopamine neurons), and Traumatic Brain Injury (TBI), which is just a general intracranial injury. The link is that the risk of Parkinson's is increased by decreasing (through TBI) the amount of dopaminergic neurons in the brain. 

What I wrote last week was heavily cribbed from a writer whose work has more or less inspired me ever since I got a hold of How We Decide, by a fellow named Jonah Lehrer, a Contributing Editor at Wired.

What interested me about the Parkinson's news is why such a link would exist in the first place. More specifically, can dopamine be inhibited by factors beyond the presence of TBI and Parkinson's? Might there be a connection between dopamine and TBI on its own? Mr. Lehrer was kind enough to answer my layman questions via email:  

The reason dopamine neurons are so vulnerable to any sort of brain injury in dopaminergic areas (such as the basal ganglia) is that dopamine neurons are actually pretty rare. It's hard to get a precise estimate, but they seem to only account for between 1-3 percent of all cortical neurons. Nevertheless, they play an outsized role (as demonstrated in Parkinson's) in the assessment of alternatives and the generation of emotion. So even a little damage to particular dopamine-rich areas can have pretty severe consequences...

As for the genetics of it all...Most dopamine gene association studies look at particular receptors subtypes, such as DRD1a. There's also the COMT Val/Met polymorphism.

Most of these studies actually find meaningful correlations at the high-end of dopamine, so that people with more of the chemical sloshing around the brain seem more impulsive and more into risky behavior, such as competing in MMA and jumping out of planes...