I recently read a biography of the 19th century English poet John Clare. At one point it talks about a concussion he suffered falling out of a tree when he was young. It goes on to suggest tentatively that this injury may have caused unseen long term damage which may have contributed to his being diagnosed with mental ilness in later life.

So next time your neurologist tells you that you must just have depression because a concussion couldn't be causing your longer term symptoms, or that a concussion doesn't cause long term organic damage, why not ask if you can be referred to a literary biographer? It seems they have a better grasp of the evidence base surrounding head injury!