Welcome to NT!

It saddens me when a young, active person has to deal with concussion.

As for your first question, helmets can reduce the severity of concussion, but they can't always prevent it. That's because the concussion is caused by what's going on inside your head: the impact of your brain against your skull as the force of a sudden stop makes it move back and forth and/or side to side. There are a number of excellent videos on YouTube that explain the mechanics on concussion.

As for depression, it's common after a head injury. Part of it is caused by the sudden alteration in one's lifestyle and health (headache, can't play sports, go to work/school, etc...) and anxiety about the future. However, it is also an effect of physical changes wrought by the brain injury itself. That's why even the most positive, optomistic, naturally cheerful people (like me) can have dark moments after a TBI.

As for testing, CT scans and standard MRIs are pretty useless in diagnosing PCS. You really need neuro-psychological testing.

I am really concerned because this is your third known concussion. The effects of multiple impacts can be devastating. You need to make "brain care" your number one priority. You might want to visit the Brain Injury Association of America webpage to learn more about your condition www.biausa.org As I said, YouTube also has a number of excellent videos on concussion.

Please take care of yourself.