Is caffeine the pick-me-up cause?

• Position: Headaches - Brief article

That morning cup of coffee might clear your mental cobwebs--or cause unwanted headaches. James Bibb, associate professor at the University of Texas Southwestern Medical Center, Dallas, calls caffeine the oldest stimulant known to man, but he 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," notes Bibb, who holds dual appointments in psychiatry and neurology and neurotherapeutics, "but, as with all things, moderation is required so that we receive its benefits."

Caffeine stimulates people in two ways, he explains. 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...