After the NFL: Brain Changes in Living Football Players

Welcome to Impact Factor, your weekly dose of commentary on a new medical study. I’m Dr F. Perry Wilson of the Yale School of Medicine.

If you happen to be watching this on a Sunday, Monday, or Thursday and live in the United States, there’s a good chance you’re watching NFL football tonight. Twenty million people on average tune in to these games, myself included. Go, Eagles! It was my wife who captured why, I think: Football players are simply the best athletes out there in terms of all-around ability — strength, speed, power, and so on.

But of course, something else draws us to these games, something a bit more primal. For lack of a better word, it’s the hits: the tackles, the sacks, the bone-crunching collisions. And if we here at Impact Factor had an unlimited licensing budget, you can be sure I’d be showing you some recent highlights right now.

But it’s hard to fully enjoy the games if you’ve done a bit of reading into chronic traumatic encephalopathy (CTE) and the effect that these collisions have on the individuals who play professional football.

A recent autopsy study out of Boston University examined the brains of 376 former NFL players; 345 of those brains had evidence of CTE. That’s 92%.

Of course, selection bias is at play here; NFL players who donate their brains to science after their death are likely to do so for a reason. But it is getting pretty hard to deny that there is a clear link between NFL play and what amounts to brain damage, at least qualitatively.

The problem with the diagnosis of CTE is that, at least for now, it can only be determined after death. Detecting CTE on autopsy is less than ideal for identifying potential treatment strategies, so I was excited to see a new study leveraging the power of PET-MRI to identify brain injury in NFL players who are still alive.

To introduce you to this study, appearing in JAMA Network Open, I first need to introduce you to an 18-kilodalton protein called translocator protein (TSPO). TSPO used to be known as the peripheral benzodiazepine receptor as it was found to bind diazepam. But that does not seem to be central to its purpose.

Rather, it lives on the surface of mitochondria and seems to be a very sensitive marker of inflammation and repair. When tissue is damaged, TSPO is upregulated, and you can see that upregulation in a PET scan using a selective tracer chemical.

With that background, we can understand the JAMA Network Open study. Researchers, led by Jennifer Coughlin at Johns Hopkins, enrolled 27 individuals, all of whom had played in the NFL in at least the past 12 years. The average duration of play had been about 6 years. There were 14 linemen, nine linebackers, two wide receivers, and two kickers.