FRIDAY, Nov. 2 (HealthDay News) -- Migraines may harm children's school performance, a new study finds.

Researchers looked at more than 5,600 Brazilian children, aged 5 to 12, and found that 0.6 percent had chronic migraines (15 or more headache days per month), 9 percent had episodic migraines and 17.6 percent had probable migraines.

Overall, children with migraines were 30 percent more likely to have below-average school performance compared to those with no headaches, according to the study, which was published in the Oct. 30 issue of the journal Neurology.

The link between migraines and poorer school performance was strongest among children with chronic migraines, those whose migraines were more severe and lasted longer, and those who also had emotional or behavioral problems.

"Studies have looked at the burden of migraine for adolescents, but less work has been done to determine the effect of migraine on younger children," study author Dr. Marcelo Bigal, of the pharmaceuticals maker Merck & Co. in Whitehouse Station, N.J., said in a journal news release.

"With approximately one-fourth of school-age children having headaches with migraine features, this is a serious problem, especially for those with frequent, severe attacks that do not subside quickly," he said. "Parents and teachers need to take these headaches seriously and make sure children get appropriate medical attention and treatment."

According to the U.S. National Headache Foundation, about 20 percent of U.S. children aged 5 to 17 experience headaches. Of those kids, approximately 5 percent suffer from migraines.

More information

The American Headache Society offers teachers and school nurses guidance for dealing with children's migraines.