Getting headaches? Feeling tired, moody, anxious or slightl depressed? Although these symptoms can stem from a variety of ills, new research shows they can be telltale signs of a caffeine addict going cold turkey.
In an almost subconscious ritual, most caffeine addicts avoid these symptoms by downing more coffee, tea, cola or chocolate any time they feel the slightest bit jittery or fatigued. Fueling the addiction can cause nervousness and insomnia, but probably nothing worse.
But some people are forced to swear off caffeine because of underlying health problems or a scheduled medical procedure -- and the consequences can be ugly.
Researchers at the Johns Hopkins School of Medicine didn't load the dice by recruiting society's worst caffeine fiends, the type who can drink a dozen cups just at the office. The 62 Maryland volunteers came into the study with an average daily caffeine intake of 235 milligrams, the amount found in two cups of strong coffee.
The findings bolstered a preliminary study two years ago at Hopkins. But that study involved only seven research subjects, all of them scientists involved in the project.
"There's no implication to our [latest] study that there's any risk to using caffeine except for the severe withdrawal if you stop abruptly," Dr. Roland R. Griffiths, professor of psychiatry and neuroscience, said yesterday. Results of the study appear in today's New England Journal of Medicine.
People at risk for caffeine withdrawal include those who are thrown off their normal routine when they take vacations or visit friends or family members who don't like to keep coffee and other caffeinated foods around.
Sometimes, doctors ask people to temporarily halt their caffeine before medical procedures such as a colonoscopy. Or they might have to stop permanently to lessen the chance of complicating a heart abnormality.
The result may be a cascading series of symptoms that make the patient feel lousy.
"If someone comes in reporting headache or fatigue, a caffeine history would be important to do," said Dr. Griffiths, one of several doctors involved in the study at the Francis Scott Key Medical Center. "Many physicians are aware of that. But there's evidence to believe that many are not."
A previous study showed that withdrawal symptoms emerge within 12 to 24 hours of a person's last drink, peak a day or two into denial, then decrease gradually over the course of a week.
Rather than subjecting oneself to this, said Dr. Griffiths recommends, people should gradually taper their caffeine intake over the course of several days.
The findings roughly confirm a 1990 Hopkins study in which the scientists themselves were the research subjects. They kept diaries, describing in sometimes testy language the creeping symptoms of fatigue, irritability, sluggishness, depression and even nausea after they were denied caffeine.
But in the latest study, volunteers weren't told they were in a caffeine study, lessening the possibility that they were braced for caffeine withdrawal symptoms.
Instead, they were asked to participate in research examining the effects of different chemicals in food and drink. They were instructed to drink only water, milk and fruit juice and -- confusing them further -- to swear off shellfish and artificial sweeteners.
The volunteers were given capsules containing either a placebo or caffeine in doses equal to the amount each one was used to consuming in a day.
Two days of caffeine denial caused 10 percent to experience fatigue, moodiness, anxiety and mild depression. Half experienced moderate to severe headaches, and 13 percent used over-the-counter or prescription drugs to kill the pain.
The symptoms were comparatively rare among the people getting their daily fix.
Volunteers denied caffeine also performed sluggishly in a finger-tapping test, a sign that caffeine denial also hinders coordination.
Claire Regan, nutrition director for an industry group called the International Food Information Council, said the study was well designed, but she found the results unimpressive.
"It's a known phenomenon that when people abruptly stop consuming caffeine, a regular user may get some of these symptoms," she said. "We think it is mild and transient in the general population."