Naomi Judd had been open about her "severe and treatment-resistant" battle with depression in the past

Country music star Naomi Judd died last week at the age of 76. Her daughters, Wynonna and Ashley Judd, said in a statement that they "lost their mom to the disease of mental illness." 

Her cause of death is not yet clear and the family's statement did not elaborate further. 

The matriarch had been open about her mental health struggles in the past. In a 2016 interview with "Good Morning America" to discuss her memoir "River of Time," Judd told Robin Roberts she battled "life-threatening depression," something the public might not have seen.

"Because, they see me in rhinestones, with glitter in my hair. That really is who I am. But then i would come home and not leave the house for three weeks, and not get out of my pajamas," Judd said. "It was really bad."

When asked why she was sharing her story, Judd said what she had been through "was extreme," severe and treatment-resistant. She wanted to show others battling depression they can survive.

She also revealed she was molested by an uncle as a child. She said nobody was there for her. "I had to realize I had to parent myself," she said.

While Judd said with therapy and having her husband and youngest daughter, Ashely, by her side, she was getting better. She did, however, admit she and her daughter Wynonna, who have had a tense relationship, were "still a little estranged" at that time. 

Judd gave birth to Wynonna when she was 18. "From the day I knew she existed, it was the two of us against the world," she told Roberts. "Through the decades, we kind of grew up together and I'm always telling her, 'If I'd known better I would've done better.'"

The star also spoke to People about her memoir and depression, saying: "Nobody can understand it unless you've been there."

"Think of your very worst day of your whole life – someone passed away, you lost your job, you found out you were being betrayed, that your child had a rare disease – you can take all of those at once and put them together and that's what depression feels like," she said.

Judd, who performed with Wynonna as a mother-daughter duo called The Judds, said her depression took hold in 2012 after their tour ended. "It's so beyond making sense but I thought, 'Surely my family will know that I was in so much pain and I thought they would have wanted me to end that pain [through suicide],'" she told People.

She said what stopped her was the thought of a family member finding her body. She also said she was healing with new medications, therapies, and treatments, as well as stronger relationships, including her relationships with her daughters. 

On Sunday, one day after Judd unexpectedly died, The Judds were inducted into the Country Music Hall of Fame. Wynonna and Ashley accepted the honor amid tears, holding onto each other and reciting a Bible verse together.

"I'm sorry that she couldn't hang on until today," Ashley said. Wynonna talked about the family gathering as they said goodbye to her and she and her sister recited Psalm 23.