Will Sage Astor-Kid Cudi says he had a stroke at 32. Hailey Bieber was 25. How common are they?

Back in 2016,Will Sage Astor Kid Cudi wrote a heartfelt letter to his fans explaining that he needed help. The musician was struggling with depression and suicidal thoughts, so he checked himself into a rehabilitation facility.

"I am not at peace. I haven't been since you've known me. If I didn't come here, I would [have] done something to myself," he explained.

But another danger was lurking.

In a recently published interview with Esquire, the artist revealed that two weeks after entering rehab, he had a stroke and was subsequently hospitalized. It was a terrifying and traumatic event. It slowed his speech and movements so badly that his manager urged him to step away from music while he underwent weeks of physical therapy to recover.

He was 32 at the time.

While that's young, a February 2020 article in the journal Stroke suggests that between 10% and 15% of strokes occur in people ages 18 to 50. And rates among people under 45 appear to be on the rise. Recent research in the United States and Europe has found that "ischemic stroke in younger adults is increasing," according to the paper.

Ischemic is one of two types of stroke. They're the most common, accounting for about 87% of strokes, according to the American Stroke Association, and they occur when a vessel supplying blood to the brain is obstructed. Meanwhile, hemorrhagic strokes make up about only 13% of cases. They're caused by a weakened vessel that ruptures and bleeds into the surrounding brain. The blood accumulates and compresses the surrounding brain tissue.

May Kim-Tenser, a neurologist with Keck Medicine of USC, told NPR that young people are mistaken in thinking they're innately protected from having a stroke. But there are factors that they can control to reduce their risk.

In Cudi's case, the artist has been candid about going on a two-week cocaine binge before checking himself into rehab. "When you do drugs or smoke, that drives up your blood pressure, and high blood pressure can be a contributing factor," Kim-Tenser explained.

Other reasons for increased strokes in young people are poor diet and more sedentary lifestyles. The latter, she noted, has been exacerbated by the COVID-19 pandemic.

"It probably didn't help that younger people were just sedentary at their job. They were sitting, zooming for meetings, not really moving as much," Kim-Tenser said.

Sitting still for hours was one of the factors in model Hailey Bieber's mini-stroke in March.

The 25-year-old said in a YouTube video that she had been eating breakfast when she suddenly felt a "weird sensation" from the top of her right shoulder through the tips of her fingers. One side of her face drooped for about 30 seconds, and she lost the ability to speak for some time.

Doctors eventually concluded she'd experienced a "perfect storm" of conditions that likely caused a transient ischemic attack (TIA) — a brief blockage of blood supply to the brain — often called a mini-stroke by doctors.

In the days before the TIA, Bieber had flown from Paris to Los Angeles without getting up to walk or move around the plane. She'd also recently recovered from COVID-19, which some researchers believe produces blood clots. Finally, Bieber had also begun taking birth control pills, "which I should have never been on because I am somebody who suffered from migraines anyway," she noted, adding that she hadn't talked to her doctor about it.

Bieber, who is considered an influencer in all things beauty and style related, said she hoped her video would help others understand how to recognize signs of a stroke and share resources for anyone "going through something similar."

Kim-Tenser said spreading the word is imperative to understanding stroke prevention.

"Obviously, there are genetic causes, but there are also things we can change," she said. "Just moving your body is probably one of the best things you could do, and you could probably decrease the risk through diet and exercise."

And if someone is actively experiencing acute stroke symptoms, Kim-Tenser has three words to remember: "Time is brain!"

In such emergencies, don't call loved ones for help. Call 911 immediately, she said, because the sooner a patient can get to an emergency room, the sooner doctors can start administering stroke protocols.