Childhood Trauma Leads to Brains Wired for Fear: If you're an adult and life's been good to you, and then something bad happens, that sort of injures a little piece of the whole structure. But toxic stress in childhood from abandonment or chronic violence has pervasive effects on the capacity to pay attention, to learn, to see where other people are coming from, and it really creates havoc with the whole social environment.

http://soundmedicine.org/post/childhood-trauma-leads-brains-wired-fear