One day, when actor and comedian Rosie O’Donnell was in her 50s, her body ached and her arms felt sore, but she pushed through the pain, not realizing she was having a massive heart attack. She had surgery to put in a stent that saved her life.

Shortly after her 2012 heart attack, O’Donnell shared her experience on her blog. During her 2015 television standup special, she spoke about how the experience changed her life. The segment included a heart attack acronym the comedian coined: HEPPP (hot, exhausted, pain, pale, puke).

O’Donnell’s candidness about her heart attack helped spread awareness about how it can present differently in women. She’s one of countless celebrities over the years who have opened up about their health conditions, including breast cancer, HIV, depression, heart disease and stroke. When celebrities reveal and discuss their health issues, the impact can be far-reaching. It not only helps to educate the public, but it also can reduce stigma and inspire others.

“Health disclosures by celebrities do matter, and we know this from decades of research across a lot of different health conditions and public figures,” said Dr. Jessica Gall Myrick, a professor of health communication at Pennsylvania State University in University Park. “They absolutely do influence people.”

Some of the earliest celebrity health disclosures happened in the 1970s and 1980s with U.S. presidents and first ladies. When first lady Betty Ford was diagnosed with breast cancer just weeks after Gerald Ford became president in 1974, she spoke openly about her diagnosis, inviting photographers into the White House and helping make talk of cancer less taboo. In 1987, first lady Nancy Reagan used her breast cancer diagnosis as a chance to advocate for women to get mammograms. Her disclosure came two years after President Ronald Reagan’s colon cancer diagnosis, about which the couple was equally as vocal.

“Individuals throughout the country have been calling cancer physicians and information services in record numbers,” the Los Angeles Times reported after Nancy Reagan’s widely publicized surgery. The public showed a similar interest years earlier following Betty Ford’s mastectomy.

Another major milestone in celebrity health disclosures came in 1991, when 32-year-old NBA superstar Earvin “Magic” Johnson revealed he had tested positive for HIV, the virus that causes AIDS. “Life is going to go on for me, and I’m going to be a happy man,” Johnson assured fans during a news conference. He immediately retired, only to return to the Los Angeles Lakers in 1996. His disclosure, along with his work as an advocate for safe sex, helped shatter stigmas around HIV and AIDS.

Calls to testing centers increased significantly in the days and weeks after Johnson’s announcement. “That celebrity disclosure really helped people see there was a wider susceptibly to HIV,” Gall Myrick said. “People were more likely to say, ‘I need to think about my own risks.’ It was very powerful.”