Maria Puente

USA TODAY

Patty Duke, the teen who won an Oscar for The Miracle Worker and later played "identical cousins" in her own TV sitcom, has died. She was 69.

The news was confirmed Tuesday by one of her representatives, Mitchell Stubbs.

"Anna 'Patty Duke' Pearce passed away this morning March 29, 2016 at 1:20 am," his statement read. "Her cause of death was sepsis from a ruptured intestine. She was a wife, a mother, a grandmother, a friend, a mental health advocate and a cultural icon. She will be missed."

Duke died at a hospital in Coeur D'Alene, Idaho, where she had lived for the last 25 years with fourth husband Michael Pearce.

Duke's last tweets, earlier this month, alluded to being "absent" recently.

She also tweeted on her wedding anniversary.

Acclaimed for her acting (her career dates back to the late 1950s), Duke became best known in later life as an advocate for mental health issues, after she was diagnosed with bipolar disorder in 1982 and wrote about it in her 1987 autobiography.

Experts on brain disorders hailed her courage in being one of the first celebrities to speak out about her disorder, depression and substance abuse.

"By bravely sharing her personal story — so at odds with her professional image — with the public, she became an inspiration and role model for people and their loved ones who are dealing with mental illness, and worked toward eliminating the stigma that prevents so many people from seeking help. She will be missed," said Jeffrey Borenstein, president and CEO of the Brain & Behavior Research Foundation, who interviewed Duke for his PBS show Healthy Minds.

Appreciation: Patty Duke, resilient 'miracle worker'

Duke won an Academy Award for Best Supporting Actress for her role in The Miracle Worker, becoming the then-youngest person to win an Oscar and thus one of the most famous American teenagers ever. She earned it playing the blind-and-deaf American icon Helen Keller, first on stage and later in the 1962 film, both of which told the story of how Keller learned to communicate as a child through her tutor Anne Sullivan (Anne Bancroft).

But Duke really charmed her way into American pop culture in 1963, when she was given her own series, The Patty Duke Show, created especially for her. At the time, no one knew, not even Duke, that she had bipolar disorder.

Stars remember Patty Duke on Twitter

But producer Sidney Sheldon had noticed that she had two distinct sides to her personality and the two came up with the idea of a show about "identical cousins" with contrasting personalities, and even different accents.

The show, which ran from 1963 to 1966, was hard work: She played both characters, Patricia "Patty" Lane, a "typical" rock 'n roll American teenager who occasionally got into minor trouble at school and home, and Catherine "Cathy" Lane, her more well-behaved cousin from Scotland who adores "a minuet, The Ballet Russes and crepe suzette."

Besides appearing on stage and screen, Duke even had success as a singer, with two Top 40 hits in 1965, Don't Just Stand There and Say Something Funny. She also wrote two books, Call Me Anna, and Brilliant Madness: Living with Manic Depressive Illness.

And she served as president of the actors union, the Screen Actors Guild, from 1983 to 1988.

She was married four times and had multiple affairs, which led to some confusion over the father of one of her three children, Lord of the Rings actor Sean Astin (his biological dad turned out to be one of her lovers-turned-short-lived husbands).

Duke's life and career were tumultuous, and not just because of her bipolar disorder or the fact she worked so much (her Internet Movie Database page shows she has a movie, Power of the Air, coming out in 2017), but because of her personal life.

"I think maybe the most important part of her legacy is her acting work," said her son Sean Astin, in an interview with the Associated Press. "Above and beyond anything, the reason any of the other stuff is possible in terms of the scope of the impact that she was able to have with people was her talent and her work and her work ethic, her discipline. She worked extremely hard."

Astin said she had dealt with a multitude of ailments over the years, including emphysema after years of smoking. He said he was grateful to the rush of tributes for his mother.

"It's just such an affirmation of the best part of her and such a relief to be able to enjoy that as opposed to the pain that everyone was feeling," Astin said. "We're so grateful to her for living a life that generates that amount of compassion and feeling in others. So, this last hour's a joy moment for me."

Duke married her fourth husband, drill sergeant Michael Pearce, in 1986, after meeting on the set of a TV movie, A Time to Triumph, for which Pearce served as a consultant. They moved to Hayden, Idaho, adopted a son, Kevin, born in 1988. After her marriage, Duke used the name Anna Duke-Pearce in her writings and other professional work.

As is now routine, condolences started piling up on Twitter, addressed to Duke and to her son, Sean Astin, from famous friends and from fans.

Contributing: The Associated Press