Julie Christie is suffering from a rare and irreversible condition that has left her unable to remember events from her past.
Christie won the Best Actress Golden Globe last week for her role as a woman with Alzheimer's disease in 'Away From Her' - a portrayal influenced by her own experience as a victim of autobiographical amnesia.
She says: "It makes learning my lines very difficult. Because of that I've been happy to stay away from films and stage work. I have turned down a lot of offers from Hollywood producers and West End directors.
The 66-year-old, who was diagnosed with the condition more than a decade ago, was determined to hide her handicap from the cast and crew while filming the 2006 drama.
A member of the production team says: "I am absolutely astonished to learn this. She impressed throughout filming as nothing less than a consummate professional.
"My heart goes out to her. No one would guess she had any trouble remembering her lines."