I'm looking for the pile of studies I had come across, here's a few to help link to more.

Cerebral Creatine levels seem to be a different thing.

Creatine and TBI:

https://health.mil/Reference-Center/Publications/2025/09/25/...

https://www.ncbi.nlm.nih.gov/books/NBK209321/

Creatine supplementation for naturally declining creatine levels:

https://jpbs.hapres.com/htmls/JPBS_1766_Detail.html

https://pmc.ncbi.nlm.nih.gov/articles/PMC10526554/