Kristen Stewart has said sometimes it feels like her roles choose her, not the other way around.
In her latest film, Still Alice, the Twilight actress appears opposite Julianne Moore as the daughter of a linguistics professor who is shocked to be diagnosed with early onset Alzheimer's disease.
Kristen revealed at the premiere of the film, at the AFI Fest in Los Angeles: "To commit to the responsibility of bringing a character to life... I know it sounds funny to think about it in those terms, but unless there is just an undeniable urge, an insurmountable...'I would have put my whole life on the fact I can play this part' - it's not a responsible thing to take the part.
"So it feels like they sort of choose you a little bit."
The actress admitted the topic of Alzheimer's is quite frightening to think about.
She said: "I think everybody probably has known someone through a friend or close relative or distant relative who has dealt with that.
"It does feel like a scary thing that you might lose yourself, and nobody wants that. It is a very scary reality for people."
Julianne admitted she felt a lot of pressure taking on the role of a character with the condition.
She said: "You feel a tremendous sense of responsibility because you're dealing with a real disorder, an actual disease that people deal with every day. There's not a lot known about it and not much information out there, but I think the families and the people who are suffering from the disease are anxious for people to know what they're going through."
Julianne added: "I did a lot of research, people were extraordinarily generous with their time and their information - from the heads of the Alzheimer's association, to care givers and families and people who are in the early stages of the disease. Everyone was extraordinary and really went out of their way."