I'd love to see that research. There is nothing about TBI or PCS that would cause OSA. But, OSA can make PCS much worse. So, someone with mild OSA can be much more symptomatic since the PCS brain is much more sensitive to oxygen levels.

CSA can be caused by neck issues that lead to inflammation that interrupts blood flow to the autonomic nervous system that controls breathing. That was my problem. Once I learned sleep postures to prevent causing neck inflammation, my CSA came under control and was rare. This lead to a stability in my PCS symptoms. No more zombie days.

One of the difficulties with CSA is very few pulmonologists ever see a true case of CSA. Plus, CSA often coexists with OSA. Treating the OSA can reduce CSA to a manageable level so the OSA diagnosis appears to be proper. I had CSA without any OSA but the pulmonologist was determined there was nothing wrong unless it was OSA if he was not able to trigger a CSA episode. My wife counted 16 CSA episodes in one hour. The take home test was worthless because the system did not record properly. Trying to schedule a second test was problematic.

Every time I tried to get a sleep test, the doc wanted to test for OSA only. It can be difficult to get a proper diagnosis if the problem is CSA.