for National Geographic Magazine
Question: What do heroin addicts who receive a daily dose of methadone have in common with people who feel they cannot function without that morning cup of caffeine?
Answer: They are tending to their addiction—keeping the physical devils of drug withdrawal at bay.
As writer T.R. Reid pointed out in his January 2005 National Geographic article, "Caffeine,"researchers agree that regular caffeine use triggers a physical dependence, a mild form of addiction.
The article describes how some heavy caffeine users grow irritable, get headaches, or feel lethargic when they can't get that coffee, soft drink, energy drink, or cup of tea. (See a photo gallery of the many forms of caffeine.)
But should those effects of caffeine withdrawal be classified as a definite psychological disorder?
Yes, contends Roland Griffiths, a professor of behavioral biology and neuroscience at the Johns Hopkins School of Medicine in Baltimore, Maryland.
Griffiths, who helped review the caffeine article in National Geographic, is a principal author of a comprehensive caffeine-withdrawal study. He hopes the report presents a strong case to include caffeine withdrawal in the next edition of theDiagnostic and Statistical Manual of Mental Disorders.
Known as the DSM, the manual is published by the American Psychiatric Association. Mental-health practitioners use it to help identify conditions and treatment strategies. The next edition will be published in 2010.
In addition, Griffiths believes that the diagnosis criteria for caffeine withdrawal should be updated in the International Statistical Classification of Diseases and Related Health Problems, a medical manual used by the World Health Organization.
His conclusions are based on a review of more than 170 years' worth of scientific research and published medical observations on the physiological affects of caffeine and its withdrawal symptoms.
The researchers cited 57 experimental studies and 9 survey studies to support their recommendations for including caffeine withdrawal in the DSM. Their study was reported in the October 2004 issue of the journal Psychopharmacology.
"Doctors and other health professionals have had no scientifically based framework for diagnosing the syndrome," said Griffiths, explaining why he undertook the research project.
In an interview, Griffiths said that the studies had demonstrated that people who take in as little as a hundred milligrams of caffeine per day—about the amount in half a cup of coffee—can acquire a physical dependence that would trigger withdrawal symptoms.
"Although most regular caffeine users know that caffeine is a mild stimulant, many are not aware that abrupt cessation can sometimes produce unpleasant withdrawal symptoms," Griffiths said.
The studies suggested five clusters of common withdrawal symptoms:
• Fatigue or drowsiness
• Depression or irritability
• Difficulty in concentrating
• Flulike symptoms including nausea, muscle pain, and stiffness
Griffiths said that the studies consistently indicated that at least half of regular caffeine consumers would experience withdrawal symptoms if they abstained. And, he added, that the research showed that symptoms could flare up regardless of what type of caffeine product was used.
"With regard to severity, 13 percent of people had clinically significant distress or functional impairment," Griffiths added. "At its worst, caffeine withdrawal involved missing work, canceling social functions, and going to bed with the belief that they had the flu."
The onset of symptoms, research indicated, occurred within 12 to 24 hours after stopping caffeine intake. Peak unpleasantness occurred within the first two days, but other symptoms could continue for as long as nine days.
An interesting finding of the research, Griffiths said, is that regular caffeine consumers may use it more to stave off withdrawal symptoms than to simply enjoy the product.