PHILADELPHIA (CBS) — A new study shows that girls take longer to recover from concussions than boys.

Researchers found that girls suffered with symptoms for 28 days on average, while boys suffered for 11.

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Experts believe the extended recovery time is due to underlying conditions like migraines, depression and anxiety, all of which are more common in girls.

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“You have your concussion and then you have your stress and your stress symptoms and they can overlap,” said Dr. Joelle Rehberg of Atlantic Neurological Specialists. “Very often the concussion symptoms have resolved, but you’re still dealing with stress headaches.”

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Doctors say concussions can also make those underlying conditions, like depression and anxiety, worse.