The worldwide incidence and mortality rates for stroke decreased slightly from 1990 to 2019, but the overall numbers are still high, especially in high- and middle-income countries, according to a study published in the December 15, 2021, online issue of Neurology, the medical journal of the American Academy of Neurology. The study focused on ischemic stroke, which is caused by blood clots and makes up 85% of stroke cases.