The problem is that concussion in many cases locks the brain in anxiety mode as a self defence. It soon becomes learnt behaviour. I think you have to consciously work to get out of it and back to normal by either CBT/mindfulness type techniques or anti depressants.

I found my anxiety reduced a lot by the 6 month mark but progress slowed after that. Getting rid of totally is proving hard. It's not helped by the modern stressful way of life most of us have to lead! But I remember one occasion stepping out of the shower like an old man and thinking why on earth am shuffling about? I then realised I had to take control and claim my pre injury life back. It seems to be paying off, the last two weeks have been the best yet until my tinnitus spiked yesterday, drat!