Retired U.S. Supreme Court Justice Sandra Day O’Connor says she has been diagnosed with dementia, probably Alzheimer’s disease, and is stepping away from public activities.

The 88-year-old O’Connor, the first woman to serve on the Supreme Court, said in an open letter released by the court Tuesday that doctors diagnosed her “some time ago” with the beginning stages of dementia.

“As this condition has progressed, I am no longer able to participate in public life,” she wrote. “Since many people have asked about my current status and activities, I want to be open about these changes, and while I am still able, share some personal thoughts.”

O’Connor, appointed in 1981 by President Ronald Reagan, became the decisive vote on hot-button social issues, including religion and race, during a history-making tenure. She disappointed conservatives when she voted to reaffirm abortion rights in the 1992 Planned Parenthood v. Casey decision.

She retired in 2006, in part to care for her husband, John, who had Alzheimer’s disease and died in 2009.

O’Connor was among the best-known of the justices and frequently appeared on lists of the most admired Americans. During her first term on the court, she received as many as 500 letters a week, many from young girls who saw her as a role model. She grew up on an Arizona ranch, where she learned to ride horses and handle farm equipment.

‘Towering Figure’

Chief Justice John Roberts called O’Connor “a towering figure in the history of the United States and indeed the world.”

“Although she has announced that she is withdrawing from public life, no illness or condition can take away the inspiration she provides for those who will follow the many paths she has blazed,” Roberts said in a statement.

O’Connor is a breast cancer survivor who underwent a mastectomy in 1988. When she learned about her condition, she informed her colleagues in a typically matter-of-fact way, sending each a note saying, “please do not be unduly concerned about it.”

Years later, she advised another cancer patient, Justice Ruth Bader Ginsburg, on how to handle chemotherapy without missing any of the court’s public sessions.

“She said when you’re up to chemotherapy, you do it on Friday, Friday afternoon,” Ginsburg said in 2009. “You’ll get over it over the weekend and you’ll be able to come to the court on Monday.” Neither justice missed any time on the bench.

Civic Education

In the years since her retirement, O’Connor has worked to promote civic learning. Her iCivics program, which uses online materials and games to teach middle and high school students, reaches half the country’s youth, she said.

“I can no longer help lead this cause, due to my physical condition,” O’Connor said in her letter. “It is time for new leaders to make civic learning and civic engagement a reality for all.”

On the court, O’Connor typically preferred narrow rulings that focused on the particular facts of the case. She wrote the court’s 5-4 decision in 2003 upholding race-conscious college admissions, so long as each applicant received individual consideration and wasn’t automatically given a preference on the basis of race.

She said government bodies could acknowledge religion as long as they stopped short of “endorsing” it. That approach meant making fine distinctions, as when she voted to allow a nativity scene that was part of a larger city-sponsored holiday display while rejecting a similar creche that stood by itself.

She wrote the lead opinion for the court when it ruled in 2004 that the federal government must give a hearing to American citizens detained at Guantanamo Bay as enemy combatants.

“A state of war is not a blank check for the president when it comes to the rights of the nation’s citizens,” she wrote.

O’Connor joined the 5-4 majority that stopped a ballot recount in Florida, ending the hotly contested 2000 presidential election in favor of Republican George W. Bush over Democrat Al Gore.

In 2013, O’Connor said the court might have been better off not weighing in on the recount. The case “gave the court a less-than-perfect reputation,” she told the Chicago Tribune’s editorial board.

“Maybe the court should have said, ‘We’re not going to take it, goodbye,’” she said.