WILL FERRELL has backed out of a comedy about Ronald Reagan’s struggle with Alzheimer’s disease amid outrage from the former president’s family. The 48-year-old comic had seen the script for “Reagan” and considered starring in and producing the movie — but had a change of heart, a rep for Ferrell told Page Six exclusively Friday.

    The rep wouldn’t say whether the decision was a direct result of the outcry from Reagan’s daughter Patti Davis, who Thursday called the movie “cruel” and Farrell “heartless.”

    The flick offers an “alternate take” on history and is set at the beginning of Reagan’s second term — when he’s struck by dementia, according to The Hollywood Reporter, which scored a copy of the script. Comedic bits center on the idea that the president had no clue where he was or what he was doing through the term, the show biz news site reported.

    In one scene, a low-level aid is tasked with convincing the commander-in-chief that he is an actor playing the president in a movie.

    In another, there’s a mix-up over a wardrobe assistant named Libby and the country Libya. “I want Libby gone. No more Libby!” Reagan proclaims — leading to the bombing of Libya.

    The script was praised in Hollywood circles and was popular enough to draw actors such as James Brolin, John Cho and Lena Dunham to a reading last March, according to The Hollywood Reporter.

    But it infuriated Reagan’s family, who called it stunningly insensitive.

    “There’s nothing funny about Alzheimer’s. It is terrifying for the families of those who suffer from it. They live with the fear [of] what will change next, they have to live with this terror and grief every day. This movie is cruel, not just to my father, but to the millions of people who have the disease, and the millions more who care for them and watch them suffer every day,” Davis told Page Six Thursday.

    Friday, she cheered Ferrell’s move to ditch the project. “I am so relieved that Will has decided against this film. I can’t imagine that anybody else would sign onto it.”

    Her brother Michael Reagan echoed her praise. “Thank you for taking the right path,” he wrote on Twitter.

    Former Reagan staffer James Rosebush told “Fox & Friends” that Reagan did not suffer from Alzheimer’s in his second term. The movie is “an egregious attempt to rewrite presidential history, which to paraphrase Ronald Reagan, ‘will fall on the ash heap of history,’” he said.

    Ronald Reagan died at age 93 in 2004.(SD-Agencies)