The Great Gatsby star has watched her grandmother struggle with the degenerative brain condition since her diagnosis in 2004, and the actress has become a patron for U.K. charity the Alzheimer's Society.

Mulligan has now spoken out to urge fellow Brits not to laugh at elderly relatives who struggle with everyday tasks.

She tells Britain's Radio Times magazine, "One of the last times that we were at home together with her (my grandmother), we had a meal and she sat down and she looked at her knife and fork, and she didn't know what they did... (Alzheimer's is) quite quickly disregarded as being a sort of age-related thing, 'Oh, granny's lost her marbles' - that sort of throwaway comment about somebody who has a brain disease... There's not an awful lot of awareness in society."