Cold, Cold Heart by Tami Hoag

Young and beautiful Dana Nolan was on the way to a big career as a TV reporter when she was kidnapped by serial killer Doc Holiday. Unlike his other victims, she managed to escape, but her life will never be the same. Suffering from both a brain injury and a disfigured face, along with an understandable amount of paranoia, she returns to her small hometown near Louisville to recuperate at the home of her loving mom and distant stepfather--a politician in the middle of a close campaign.
Returning home brings back memories of her best friend Casey, who had vanished seven years earlier and never been found. When Dana tries to work out what happened to Casey, it puts her own life in jeopardy as she stumbles dangerously close to the truth.

Even though I figured out who Casey's killer was--and what happened to someone else who had gone missing--way before the end of the book, it was a good story. You feel Dana's frustration when she can't remember words or how to do simple tasks and you feel her fear when she's not sure whom she can trust.