Hi, a vegan diet can be very beneficial for the brain. Be sure to include foods that are high in omega-3s, tryptophan, folate, calcium, vitamin D, and of course take a good B-12 supplement.
If you go to the website
http://www.drnedley.com and get almost any of his books, they will tell you how to optimize your diet for brain health. The depression books are very specific, and although they focus on depression they come at it from a brain health perspective. The depression clinic I participated in relieved almost all of my symptoms after more than a year of PCS, and I started my vegan diet while there (I had previously been a lacto-ovo vegetarian).
There's a thread specifically on brain-friendly nutrition here:
http://neurotalk.psychcentral.com/sh...d.php?t=165807