The research is not conflicting in this. There is research being done to find ways to spur the brain into a healing mode because there is not a natural healing system that can overcome all the damage done, even the very minor damage.

Why do you think there ought to be conflicting research ?

I did not say "that impairments only can arise during stress." I said that is when they are likely to arise. There are many other factors at play. Age related brain changes can also cause concussion/mTBI symptoms to arise. They can be expected in the late 30's to mid 40's for many people.

Plus, stress has many different forms.