The challenge to the study you referenced is that the subjects also had PTSD. PTSD is a physiological as well as a psychological condition. If the HBOT is resolving the PTSD, that alone would account for the improvements.

All of the prior studies did not show the level of improvements this study showed. In fact, some showed a negative outcome. A blast injury effects more than just the brain. There may be a synergistic effect from the HBOT causing healing to the rest of the body. HBOT's strong suit is improving capillary blood flow and capillary repair.

Niacin also works to help with capillary blood flow and repair.

The HBOT industry has been trying to sell HBOT for brain injuries and such for a decade or so. Your experience was at an expensive HBOT center. Other centers charge much less.