After her father announced his diagnosis of Alzheimer's disease in 1994, Maureen Reagan became a member of the Alzheimer's Association board of directors and served as the group's spokeswoman. While hospitalized for melanoma cancer towards the end of her life, Maureen was only floors away from her father who had suffered a severe fall.
In 1960, Maureen's by-then divorced parents became concerned about her. Ronald Reagan used his connections at the FBI − established during his work as an anti-communist informant − to request the agency to investigate her romantic life. The agency did so on condition that the FBI not be cited as a source, and reported that she was living with an older, married man who was a police officer.
Maureen Reagan was married three times:
John Filippone, a policeman; they were married in 1961 and divorced the following year.
David G. Sills, a lawyer and Marine Corps officer; they married on February 28, 1964; the couple divorced in 1967.
Dennis C. Revell, CEO of Revell Communications (a national public relations/public affairs firm), whom she married on April 25, 1981. She and Revell had one daughter, Margaret "Rita" Mirembe Revell, who was born in Uganda. The Revells became Rita's guardians in 1994. They adopted her in 2001. Rita was the beneficiary of a private bill to facilitate her adoption as Maureen and Dennis Revell were unable to complete the necessary paperwork and other requirements by the Ugandan government, including a personal visitation to that country, due, in large part, to Maureen Reagan Revell's terminal cancer.
Reagan died in Granite Bay, California, on August 8, 2001, aged 60, from melanoma. She is interred at Calvary Catholic Cemetery and Mausoleum in Sacramento, California.
Reagan volunteered with actor David Hyde Pierce, of TV's Frasier, at the Alzheimer's Association. At her funeral on August 19, 2001, Pierce spoke to the gathering at Cathedral of Blessed Sacrament in Sacramento, and recalled his friend's tireless devotion to fighting the mind-robbing illness. "When she was given lemons, she did not make lemonade. She took the lemons, threw them back and said, 'Oh, no you don't.'"