Barbara – best known as EastEnders’ Peggy Mitchell – was diagnosed with Alzheimer’s disease in 2014 and publicly revealed the news last year.
In a statement calling for people to get behind the new campaign, she said: “I am absolutely delighted to become an ambassador for this wonderful charity, who are helping so many people living with dementia… like me.
“We’re lucky to have amazing support but my heart goes out to the many, many people who are really struggling to get the care they so desperately need.
“Please join us – let’s do everything we can to sort this out.”
Scott said he wanted to “do everything I can” to help those who face a “constant battle to get what they need” after spending the last four months meeting other people living with dementia and their families.
He said: “The last few years have been really hard for both Barbara and I as we’ve had to get used to dementia being in our lives.
“Alzheimer’s Society has shown us there is life after dementia, and we want to do our bit to make sure no-one faces dementia alone.”
He continued: “The Society’s open letter to our new Prime Minister Boris Johnson to tackle the social care crisis is strongly supported by Barbara and me.
“We encourage the fantastic UK public to give their support by signing this letter. It’s time to end the battle people with dementia and their families are facing across the country.”