More than 75 percent of U.S. states have experienced stalling in the rapid decline of stroke-related deaths, opening the country to excess mortality, according to new data from the CDC.

Though stroke death rates have been declining steadily since the 1960s, that downward trend has stalled in recent years, according to a study by Quahne Yang, PhD, and colleagues for the CDC. Yang pulled death data from the U.S. National Vital Statistics System from 2000-2015 and examined death trends in the most stroke-prone demographic: adults over 35 years old, who made up 99 percent of stroke patients in 2015 and typically share common risk factors, the study stated.

Researchers found results fell under one of three categories—stroke death rates have either been slowed, stalled or reversed in recent years. Blacks experienced the most stroke deaths after a stalling of the rate decline in 2012. Not far behind, Hispanics saw a reversal in the falling trend, jumping from a 3.6 percent decline per year from 2000 to 2013 to a 5.8 percent increase between 2013 and 2015. The study’s south region saw a similar reversal, with a 4.2 percent increase during those same years.

“[The] report is distressing, but unfortunately not unexpected based on our previous projections,” American Stroke Association (ASA) CEO Nancy Brown said in a press release. “After more than four decades of decline, progress in preventing stroke deaths has slowed across most states and demographic groups. We’ve especially lost ground in the battle to save lives among Hispanics and those living in the South, despite our ongoing efforts.”

Eight of nine states in the northeast saw a stalling, slowing or reversing of stroke death rates between 2000 and 2015, according to Yang’s data. Seven of 12 states in the Midwest, 14 of 17 in the South and nine of 13 in the West saw the same results. Florida’s decline reversed between 2013 and 2015, eventually jumping to a 10.8 percent increase in stroke deaths per year.

In 2013, stroke dropped from the third leading cause of death in the country to the fourth, marking an era that was expected to see continuously falling numbers. Even so, Yang notes in his work that one in 20 deaths is still attributed to stroke, making it a leading cause of long-term disability that strikes more than 800,000 American citizens a year.

Yang et al. estimated 32,593 excess stroke deaths that would have been avoided were it not for the stalled decline. Yang said 32 percent of those deaths would have occurred among adults between 35 and 64 years old.

Though his findings are consistent with other recent studies in the U.S., Yang notes there isn’t a known reason for the abrupt stalling and reversing trends in stroke death rates. Possibilities include increased prevalence of risk factors like obesity, inactivity, diabetes, poor diet, bad flu seasons or mismanagement of stroke risk symptoms.

According to the study, the past 15 years have seen an uptick in strokes in younger adults, and research suggests a large portion of the U.S. population with risk factors like high blood pressure mismanage their symptoms, leading to further complications. While millions of Americans suffer from strokes, around 80 percent of those instances are preventable.

“Recognizing the signs and symptoms of a stroke and knowing the importance of calling 9-1-1 is critical to ensuring that stroke patients receive the best care as quickly as possible,” Yang and colleagues wrote. “Stroke symptoms tend to occur suddenly and include sudden onset of weakness and numbness on one side of the body, sudden confusion, trouble speaking or understanding, sudden trouble seeing in one or both eyes, sudden trouble walking, dizziness or loss of balance or a sudden, severe headache.” The study cites reducing sodium intake and tobacco use, increasing physical activity and controlling blood pressure and cholesterol as a handful of ways to prevent heart disease.

“Back in 2010, the (American Heart) Association set an aggressive goal to reduce stroke deaths by 20 percent by 2020,” Brown said in the ASA release. “This report gives us even more reason to aggressively continue our efforts, especially in multicultural communities, and to reach people at younger ages.”