By Stephanie Stahl

PHILADELPHIA (CBS) —Mariah Carey reveals she has been impacted by her bipolar disorder diagnosis for nearly 20 years.

Bipolar disorder is marked by dramatic mood swings and it’s not known what causes it but it is often triggered by stressful events.

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Carey tweeted the following from her Twitter account: “I’m grateful to be sharing this part of my journey with you”

Her revelation about her bipolar disorder disorder came out via a People Magazine interview, in which she shares her battle.

The 48-year-old entertainer says she was first diagnosed in 2001 after she was hospitalized for a physical and mental breakdown.

Most people with bipolar experience more depression than manic side.

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Dr. George James, with The Council for Relationships in Philadelphia says people with bipolar disorder like Carey gradually go between feeling very high or low.

Lithium is the traditional drug used to treat someone with bipolar disorder. In combination with therapy, it can be very effective.

“They actually do really well and are able to cope and function at a high level,” Dr. James said.

Carey says she lived in denial and isolation, fearing she’d be exposed.

“Whether you’re an entertainer or someone in an everyday job, it’s something that people don’t often share their mental health struggles diagnosis because they don’t want to be treated in inappropriate or unfair way,” Dr. James said.

He also says there’s still a stigma attached to mental health issues but when famous people like Carey talk about it that helps break the stereotype.

“It allows people to see this is just an everyday thing that we do need to talk about and we do need treatment just like we’d get treatment for cancer or a heart attack or other illnesses,” Dr. James said.

Carey says she finally sought treatment just recently.

Now, she says she’s taking medication that’s not making her feel too tired or sluggish and she’s back to doing what she loves — writing songs and making music.

Many are applauding Carey’s bravery for being public about the disorder.