Mariah Carey, the superstar singer who has lived in the public eye for three decades, has acknowledged that, in 2001, she learned that she had bipolar disorder.

Ms. Carey disclosed the diagnosis in an interview with People magazine’s editor in chief, Jess Cagle. A preview of the magazine’s cover story was published online Wednesday. The full interview will be available Friday.

The interview marks one of the first instances in which a celebrity of Ms. Carey’s stature has acknowledged her struggles with mental illness. In the interview, she explained why she had not previously revealed the diagnosis.

“I didn’t want to carry around the stigma of a lifelong disease that would define me and potentially end my career,” she said. “I was so terrified of losing everything.”

Ms. Carey said that she had lived in “denial and isolation and in constant fear someone would expose me,” and that she had come forward after the burden became too heavy to bear. She is in therapy and taking medication for bipolar II disorder, a disease that can cause sudden and extreme shifts in mood, among other symptoms.

People magazine declined to explain how the interview had come about, saying only that Ms. Carey had trusted Mr. Cagle to tell her story. A publicist for Ms. Carey did not immediately respond to a request for comment.

Ms. Carey was a teenager in the late 1980s when she was recruited by Tommy Mottola, the president of what was then CBS Records, to become a pop star. Her fame was swift with the backing of the label, and that placed enormous pressure on her from the beginning.

(Excerpt) Read More in: The New York Times

Mariah Carey Opens Up About Bipolar Disorder