Migraines, blood clots in veins, kidney or liver disease, and cancer aren’t typically considered conditions that put a person at increased danger for stroke.

But these less-common risk factors can more than double the odds of having a stroke in folks younger than 50, a new study says.

“We were surprised by the role of non-traditional risk factors, especially migraine headaches, which seems to be one of the leading risk factors in the development of strokes in younger adults,” lead researcher Dr. Jukka Putaala, head of the stroke unit at Helsinki University Hospital in Finland, said in a news release.

Non-traditional risk factors were particularly important among people born with a heart defect called patent foramen ovale (PFO), which involves a hole in the upper chambers of the heart, researchers reported April 17 in the journal Stroke.

For the study, researchers analyzed data on more than 1,000 people between 18 and 49 years of age in Europe, about half of whom had suffered an ischemic (clot-caused) stroke for which there was no apparent explanation. These stroke victims were compared with healthy people.

The team analyzed the effect of 12 traditional stroke factors, 10 non-traditional risk factors, and five risk factors specific to women, to see if they could find a pattern among these unexplained stroke cases.

Traditional risk factors include high blood pressure, diabetes, elevated cholesterol, smoking, heart disease, smoking, obesity, unhealthy diet, physical inactivity, alcohol consumption, stress and depression.

Non-traditional factors included migraines with aura, kidney disease, liver disease, blood disorders, autoimmune diseases and cancer.

Results showed that:

• In people without the PFO heart defect, each additional non-traditional risk factor increased stroke risk by 70%, while each additional traditional risk factor increased stroke risk by 41%.

• In women without the heart defect, non-traditional risk factors increased their stroke risk by 70%.

• Among people with PFO, non-traditional risk factors more than doubled the odds of having a stroke.

“Recognizing specific risks that affect women and those not commonly seen, such as migraine with aura and pregnancy complications as significant contributors to stroke risk in younger women, could change our approach to screening for these risks and educating our patients throughout their lives,” Dr. Tracey Madsen, vice chair of research in emergency medicine with the University of Vermont, said in a news release. Madsen was not involved in the study.