Sins of the Mind (1997)

A typical American family - photographer father, two talented daughters, Michelle an accomplished commercial artist with a clear upward career path. Then she has an auto accident, and the head trauma leaves behavioral changes. The part of the brain involved in impulse control is damaged (but the lesion is not visible on the usual CAT scan, and psychological tests are not done). Michelle has no control of her sexual impulses, and changes to 'a thief, a liar, and a whore' as her eventual therapist puts it. The family is broken apart, her sister and mother leave, but the father remains convinced that the daughter he loves is in there somewhere. It is a long and harrowing road to understanding of her sex addiction, and the end is not certain, but hopeful.