People with a history of traumatic brain injury are 30 percent more likely to develop stroke than those who haven't had a brain injury, according to a new study.

"Both stroke and traumatic brain injury are common, costly, and leading causes of severe disability in adults, and approximately 20 percent of strokes occur in adults under age 65. A large proportion of stroke risk is unexplained, especially in the young, so if we can identify new risk factors, we have the potential to prevent more strokes and improve outcomes," said study author James F. Burke, MD, University of Michigan and a member of the American Academy of Neurology.

Even Mild injuries to the brain or concussions during sports can damage parts that take a while to recover. People who have had repeated concussions have been known to have severe brain damage. Centers for Disease Control and Prevention (CDC) says that each year about 1.7 million people sustain a traumatic brain injury and about 75% of TBIs that occur each year are concussions or other forms of mild TBI.

The study was based on data of 435,630 people with traumatic brain injury and another 736,723 people with trauma but no brain injury. These people were followed for about 28 months during which 11,229 people, or 1 percent, had an ischemic stroke in which blood flow to the brain is blocked. In the study, about 1.1 percent of people with brain injuries suffered from stroke compared with 0.9 percent of the non-brain injury group.

The risk for people with brain injuries suffering from a stroke was about 30 percent higher than the non-brain injury group, even after the researchers accounted for other factors such as age, high blood pressure and cholesterol.

The study is published in the journal Neurology®.