Her husband Scott Mitchell has revealed the news in a new interview in order to help other families whose loved ones may be going through similar and so members of the public are not confused when meeting Barbara, which they regularly do, such is her popularity. She loves going out and it's good for her - she comes alive.
At first I was frustrated when my granny would ask for the fifth time that morning whether she had RSVPed to my wedding. I'm lucky that my granny still knows who I am, for now.
Her husband, Scott, 55, has now detailed her condition which he has revealed was diagnosed in 2014.
Dame Barbara was said by Ms Moore yesterday to be "thrilled" by the public reaction to the announcement.
He continued on to say that he first noticed the symptoms in 2009 before she first left the show as she couldn't remember her lines for each episode.
She explained: "You can be relieved to know that's what it is and then you can begin to plan - but it is a terminal illness and it is sad".
After undergoing a series of mental agility tests, a brain scan and a lumbar puncture, the diagnosis was confirmed.
By 2016, her forgetfulness and confusion were getting worse, and it was agreed she would leave EastEnders for the final time, Mr Mitchell said.
Speaking about Scott's decision to announce the news, Pam said: "It came as a shock but as a welcomed one. I'd cross an ocean for Scott".
Dame Barbara had suffered health issues before, including multiple abortions and a nervous breakdown following the collapse of her first marriage to the underworld figure Ronnie Knight, who was eventually jailed for seven years.
As well as retiring from acting, Barbara has now stepped down from her charity work as her confusion has "started to set in much more over the past few weeks". But if she forgets that she gave me her blessing, well, I'll just have to deal with that'. Do you have a message for Barbara? Ruth and I wish the #NationalTreasure that is Dame Barbara Windsor the very best after her Alzheimer's diagnosis'.
"We are here to support people like Barbara and want to reach everyone with a dementia concern or diagnosis".
Television presenter Lorraine Kelly extended her sympathy, tweeting: 'Such sad news about Barbara Windsor - a amusing, kind, generous, big hearted woman'.
"Our hearts go out to Dame Barbara and her family, and we hope she is able to maintain and enjoy her quality of life for as long as possible".