Stroke!
In males and females ages 5-14, the number of ischemic stroke hospitalizations increased 31% and 36%, respectively, from 1994 to 2007. For ages 15-34 the increase was 51% for males and 17% for females. For ages 35-44, the increase was 47% for men and 36% for females. The increase in obesity seems to be the primary cause.
CDC, February 2011