Is caffeine the cause or cure of headaches?

That morning cup of coffee might clear your mental cobwebs – or cause you unwanted headaches.

Dr. James Bibb, an associate professor at UT Southwestern Medical Center, calls caffeine the oldest stimulant known to man. But he also warns that it can exacerbate medical conditions or cause headaches through withdrawal or other effects on the brain.

“Caffeine has proven to be a useful drug,” says Dr. Bibb, who holds dual appointments in psychiatry and in neurology and neurotherapeutics at UT Southwestern. “But, as with all things, moderation is required so that we receive its benefits.”

Caffeine stimulates people in two ways, Dr. Bibb says. It ultimately facilitates the release of acetylcholine, a chemical compound that prevents drowsiness. Caffeine also blocks a type of adenosine receptor located in the part of the brain that controls reward-based learning. By blocking those receptors and keeping the brain primed for rewards, caffeine keeps people alert.

Caffeine also has well-documented negative effects, Dr. Bibb says. It can raise the heart rate, cause motor or muscle tremors, increase blood pressure and act as a diuretic that reduces water content in the blood. This might affect sensory neurons in the dura, the thin envelop of tissue that surrounds the brain and may be the source of headaches.

“A small amount of caffeine can be very helpful, allowing us to work with focus and attention and stay aroused and awake,” Dr. Bibb says. “But too much of it can be unhealthy.”

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