What Really Causes Brain Freeze?

Brain freeze: a condition that occurs when quickly eating or drinking a cold item, resulting in a painful but temporary headache. Although almost anyone could tell you what brain freeze is and what causes it, no one knows exactly what happens biologically to link this shock of cold in your mouth to a pain in your head.

NPR recently set up its own experiment to illustrate how eating a Popsicle too fast may give you a pain at the front of your forehead. The experiment was hosted by Jorge Serrador with the War Related Illness and Injury Study Center, which is part of the Department of Veterans Affairs in East Orange, N.J., who studies brain freeze in order to gain better understanding about how headaches are caused in general.

Watch NPR's video of the experiment:

As Serrador explains in the report, there are several theories as to what causes brain freeze, including the fact that there is a nerve in the roof of your mouth leading to the brain that when over stimulated by the cold could send a painful message. It could also be caused by an increased blood flow to the brain that causes "localized pressure," which could result in a headache.

Earlier this year, CBS reported a study where Serrador and other scientists combined these two ideas:

[...] researchers induced brain freeze in 13 healthy adults by having them sip ice cold water with a straw on their upper palate. The researchers monitored participants' blood flow in their brains with a "transcranial Doppler test," and found the sudden headache seems to be triggered by an abrupt increase in blood flow on the brain's anterior cerebral artery. The pain disappears when that artery constricts, an effect researchers reproduced by having participants drink warm water.

 [...]

Why does this increase in blood flow occur? The researchers think the brain is adapting to the "freeze" through a self-defense mechanism.

"The brain is one of the relatively important organs in the body, and it needs to be working all the time," study co-author Dr. Jorge Serrador, a cardiovascular electronics researcher at Harvard Medical School in Boston, said in a written statement. "It's fairly sensitive to temperature, so vasodilation might be moving warm blood inside tissue to make sure the brain stays warm."

Food Republic takes on a slightly different theory, which is that the blood vessels in your mouth constrict in response to the drastic temperature drop and then quickly expand again. Upon expansion, which would allow blood flow again to warm up the mouth, the pain receptors in your mouth send a signal to the brain alerting it of pain.

Until we know exactly what causes the brain freeze, the condition can at least be prevented: eat cold foods and drink cold drinks slower.