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Black young adults are almost four times more likely than their white counterparts to have a stroke, according to new research. Yet regardless of race, the risk of having a stroke at a younger age increased as blood pressure rose.

High blood pressure is the leading cause of stroke. It adds to the heart's workload and over time damages arteries and organs. Experts already knew stroke rates among young adults have risen in recent decades, but little was known about which adults were at higher risk.

The new study, published Monday in the ÃÛÑ¿´«Ã½ journal , looked at the link between high blood pressure and stroke in a group of Black and white young adults in four U.S. cities.

More than 5,000 study participants were repeatedly tested for high blood pressure. Stage 1 hypertension is defined as a top number of at least 130 or a bottom number of at least 80, and stage 2 hypertension is a top number of 140 or higher or a bottom number of 90 or higher. The top (systolic) number indicates how much pressure the blood exerts against artery walls while the heart beats, while the bottom (diastolic) number gauges the pressure between beats.

During an average follow-up of 26 years, 100 strokes occurred in participants with and without high blood pressure. But while the overall stroke rate was similar between women and men, it was four times higher in Black people compared to white people.

"Four times is a significant and alarming number," said study co-author Dr. Jamal Rana, chief of cardiology at Kaiser Permanente's Oakland Medical Center in California. "We know there's more stroke in general among Black adults, but we didn't expect it to be this high. It was striking to see that the incidence of stroke increased rapidly around age 40, especially for Black adults."

For participants overall, the study found that compared to having normal blood pressure, stage 2 hypertension was "strongly and significantly" linked with stroke risk – more than four times the risk at age 30 and 5.6 times the risk at age 40. Elevated blood pressure and stage 1 hypertension were associated with "more modest increases in risk."

The findings call for more careful management of blood pressure among young adults, particularly Black adults, said the study's senior author Dr. Stephen Sidney, director of research clinics and a senior research scientist at Kaiser Permanente Northern California Division of Research in Oakland.

"Study participants were 18 to 30 years old" at the start of the study, he said. "Blood pressure exposure accumulates over time: Your risk increases the longer you have it, so it's extremely important to get hypertension under control as quickly as possible."

The study was limited by its small size, Sidney said. Both he and Rana called for future studies to see how high blood pressure and stroke rates among Black people might be impacted by environmental factors, such as a lack of access to affordable care, healthy foods and places to exercise.

"The next step is to better understand and address the social determinants that could be contributing toward this," Rana said.

Dr. Shawna Nesbitt, who was not involved in the research, called the study "a real call to arms for people to pay attention to stroke prevention, and to the lower spectrum of blood pressure."

"We need to let people know that blood pressure does respond to lowering your sodium intake and to losing even a small amount of weight, like 10 pounds," said Nesbitt, professor of internal medicine at UT Southwestern Medical Center and medical director of Parkland Hospital's Hypertension Clinic in Dallas.

"We also need to remind people how important exercise is for your cardiovascular health. During COVID, a lot of people were locked down in our homes, watching TV and eating more snacks. We have to aggressively motivate people to get back to exercising, or to start exercising if they weren't already physically active."

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