For the study, researchers analyzed medical data from more than 1 million veterans who served in Iraq and Afghanistan. They ranged in age from 18 to 60 years and two-thirds were white.
Of those, 29% had been diagnosed with PTSD. None had previously suffered a stroke or mini-stroke (also known as a transient ischemic attack, or "TIA").
During 13 years of follow-up, 766 vets had a TIA and 1,877 had an ischemic stroke, which is caused by blocked blood flow to the brain.
Veterans with PTSD were 62% more likely to have a stroke, raising the risk more than known risk factors such as obesity and smoking. They were also twice as likely to have a TIA, increasing the risk more than diabetes and sleep apnea.
Even after accounting for known stroke risk factors, mental health disorders (such as depression and anxiety) and drug and alcohol abuse, the investigators found that veterans with PTSD were still 61% more likely to have a TIA and 36% more likely to have a stroke than vets without PTSD.
The link between PTSD and stroke was stronger in men than in women. In addition, vets with PTSD were more likely to have unhealthy habits -- such as smoking and inactivity -- that increase stroke risk, according to the study published Oct. 17 in the journal Stroke.
Previous studies have shown that PTSD increases heart disease and stroke risk for older adults, but the researchers said this is the first study to identify a link between PTSD and the risk of TIA and stroke in young and middle-aged adults. These groups have had a large increase in strokes over the past decade, the study authors noted.
"Stroke has a devastating impact on young patients and their families, many of whom struggle to cope with long-term disability, depression and economic loss during their most productive years," said lead author Lindsey Rosman. She's an assistant professor in the cardiology division at the University of North Carolina School of Medicine in Chapel Hill.
"Ten to 14% of ischemic strokes occur in adults ages 18 to 45, and we don't really have a good understanding of the risk factors for stroke in this age group," she explained in a journal news release.
PTSD affects about 30% of U.S. veterans. While this study focused on veterans, about 8 million U.S. adults have PTSD, which can develop when someone sees or experiences a traumatic event, such as sexual assault, gun violence, military combat or a natural disaster.
"PTSD is not just a veteran issue, it's a serious public health problem," Rosman said.
Clinicians should be aware that mental health conditions like PTSD are increasingly common among young people and may affect their risk of stroke, she added.
"Our findings raise important questions about whether early recognition and successful treatment of PTSD can prevent or decrease the likelihood of developing stroke in those exposed to violence, trauma and severe adversity," Rosman said.