A new study, published in the Journal of the American Medical Association, looked at the trends in the incidence of and mortality from stroke in the U.S. between 1987 and 2011. The researchers note that this is one of the first studies to have long-term trend data that is broken down by race. Overall, the study found decreases in both the incidence of stroke, as well as mortality. This trend was prevalent across races, though the level of decrease varied.

According to an analysis of the study in Bloomberg Businessweek, the majority of the decline was seen in the segment of the population that is 65 years and older. In this group, the number of strokes dropped by 31 percent per decade. Meanwhile, in other age groups, the number of strokes dropped three percent per decade. Still, public health officials remain cautious about stroke.

At present, nearly 800,000 Americans have a stroke yearly and 130,000 die, making stroke the fourth highest cause of the death in the U.S. Additionally, with obesity and diabetes on the rise, the concern is the declines will be reversed. Other studies have shown higher rates of stroke and upward trends in stroke prevalence in younger groups, which may be attributable to these risk factors that are on the rise.

The American Stroke Association states that a stroke occurs when a blood vessel that carries oxygen and nutrients to the brain is either blocked by a clot or ruptures, killing brain cells.  It is the fourth highest cause of death and a leading cause of disability in the U.S. Exercise, diet, alcohol, cigarettes, and stress are all factors that are strongly associated with stroke risks.