08/24/2013 AT 09:00 AM EDT
, the smooth-voiced singer who racked up 11 Grammy awards during a decades-long career, just revealed she "can't sing a note" due to Parkinson's disease.
Ronstadt, 67, received the diagnosis eight months ago, but showed signs of the disease as long as eight years ago – although she initially dismissed them as related to a tick-borne illness and shoulder surgery, she tells aarp.org
in a story to be published on their website next week.
"I couldn't sing," she says in the interview, "and I couldn't figure out why. I knew it was mechanical. I knew it had to do with the muscles, but I thought it might have also had something to do with the tick disease that I had. And it didn't occur to me to go to a neurologist. I think I've had it for seven or eight years already, because of the symptoms that I've had. Then I had a shoulder operation, so I thought that’s why my hands were trembling."
When she finally did see a neurologist, his diagnosis floored her.
"When ... he said, 'Oh, you have Parkinson's disease,' I was completely shocked. I wouldn't have suspected that in a million, billion years," she says.
Now, she walks with the aids of poles on uneven ground and uses a wheelchair while traveling.
Singing, she says, is out of the question.
"No one can sing with Parkinson's disease," Ronstadt says. "No matter how hard you try."
That means she can't perform the many hits she has released since beginning her career in the 1960s – when she became lead singer of folk-rock trio The Stone Poneys before going solo – including "Blue Bayou" and "Don't Know Much" (her popular duet with Aaron Neville).
Yet fans can still relive the highlights of her life in her upcoming memoir, Simple Dreams
, out Sept. 17. The book does not include details of her diagnosis, but apparently touches on her high-profile relationships with men including George Lucas and former California Gov. Jerry Brown.
Ronstadt has kept a low profile for the last decade, but made news in 2004 when she was booted from a Las Vegas hotel
for praising filmmaker Michael Moore during a performance.
Yet the Wall Street Journal
couldn't help but praise her vocal abilities
at the time. "She doesn't need the kind of publicity to drive her career," said a review. "As a musician, she still has the goods."