New research shows that migraines may not be as benign as we once thought.

People who experience migraine headaches have a greater risk of developing brain lesions and other problems, according to a new study appearing in the journal Neurology.

“Traditionally, migraine has been considered a benign disorder without long-term consequences for the brain,” study author Dr. Messoud Ashina of the University of Copenhagen in Denmark, said in a press release. “Our review and meta-analysis study suggests that the disorder may permanently alter brain structure in multiple ways.”

Migraines are severe headaches characterized by throbbing pain as well as nausea and other symptoms. Women are twice as likely as men to experience migraines, according to the U.S. Centers for Disease Control and Prevention.

In the study, researchers used six population-based studies and 13 clinical studies to compare migraines’ long-term effects.

“Migraine affects about 10 to 15 percent of the general population and can cause a substantial personal, occupational, and social burden,” Ashina said.

The researchers found that people with migraines ran a higher risk of brain lesions, abnormalities in brain white matter, and altered brain volume. The latter two have been associated with numerous conditions, including multiple sclerosis and obsessive-compulsive disorder.

Researchers say people who experience migraines with aura—blind spots, flashes of light, or tingling in the hands or face immediately preceding the headache—have an even greater risk of complications. Specifically, migraine with aura puts people at a 68 percent higher risk of brain lesions and other abnormalities. Aura-deficient migraines only increase the risk by 34 percent.

Auras are also linked to a 44 percent increase in abnormalities similar to cell death, which is caused by lack of oxygen to the brain.

Medical experts were already aware that people who experience migraines with aura are at a greater risk of stroke. Women who smoke or use birth control and have migraines with aura are at the highest risk, according to the Mayo Clinic.

“We hope that through more study, we can clarify the association of brain structure changes to attack frequency and length of the disease,” Ashina said. “We also want to find out how these lesions may influence brain function.”