Alice was a B-plus student through her first three years at college. During the winter holidays in her senior year, while she was driving during a storm, her car ran off the road and hit a tree. Alice banged her head on the steering wheel but never lost consciousness. She was treated for bruises and discharged from the hospital within a day.
But, back at her studies, she began to have difficulties. Suddenly her As and Bs were becoming Cs. She had trouble remembering what she'd read and was irritable, and easily distracted.
Alice was referred to a neuropsychologist for further examination. Although her IQ hadn't changed and standard neurological tests were normal, detailed neuropsychological tests showed she was having memory problems. She could still process new information, but it took longer than before and she became "overloaded" if she tried to do too much at once.
Head injuries are often fatal, or of sufficient severity to require the hospitalization of victims. But there is a large group of people who sustain head injuries which can go undetected through ordinary medical examination. These are the people who seemingly recover from their injuries but still suffer subtle intellectual and behavioural effects that may seriously impair their ability to work and interact normally with other people. They are the victims of what experts call a "silent epidemic". Some never lost consciousness and others never even suffered a direct blow to the head, yet brain damage occurred.