In July 2005, the Center for Science in the Public Interest, a Washington-based consumer advocacy group, called for the Food and Drug Administration (FDA) to mandate warning labels on caffeinated soda. The group raised the usual concerns about childhood obesity, but also took things a step further, treating caffeine itself as a potentially dangerous substance. "[C]affeinated drinks," they argued, "should bear a notice that reads 'This drink contains x grams of caffeine, which is a mildly addictive stimulant drug. Not appropriate for children.'"
On the long list of public health concerns, caffeine rates a footnote. Indeed, there are no blue laws associated with the Starbucks or Cosis or Caribou cafes on every corner precisely because there are hardly any medically harmful effects or socially disruptive behaviors associated with normal use of caffeine.
Yes, a minority of people are hypersensitive to its effects--and for that reason don't drink it much. And those who drink large amounts of caffeine can experience anxiety and insomnia severe enough to require clinical attention.
But these are direct effects of the substance itself. They do not provide evidence of a compulsion to consume, which is what we normally mean by the term "addiction."
Yes, people do talk about needing their Starbucks "fix." But what they mean is that they like it. They seek its warmth, flavor, and aroma. They welcome the invigoration. Also, they may recognize when they don't have caffeine for many hours that they experience a kind of "withdrawal." This is not metaphorical; there is a well-documented caffeine withdrawal, or discontinuation, syndrome that can occur after abrupt cessation.
When researchers bring coffee drinkers into the laboratory, they observe that discontinuation of a moderate amount (generally at least 3 cups of coffee per day; 6 cans of soft drink per day) can lead to bothersome symptoms, most notably headache and lethargy, in some but not all people.
The withdrawal phenomenon reflects the fact that the user's central nervous system has adapted to regular exposure to the substance. Effects include headache, lethargy, irritability, mental fuzzy-headedness. The cure? A cup of coffee. A person who wants to stop drinking coffee altogether (e.g., perhaps because of gastric irritation) need simply drink a little less each day or gradually substitute decaffeinated coffee.
If caffeine were a powerfully addictive agent like, say, cocaine, heroin, or alcohol, we would expect to find people popping excessive or escalating numbers of caffeine pills (available in 200 mg pills — less than double the caffeine in a cup of coffee — from nutrition stores and on the internet, or at your local CVS). Yet a search of the medical literature reveals no reports of use that bear analogy to binge-drinking or chain-smoking.
Another difference: Caffeine does not affect the brain the same way as standard agents of abuse. From the standpoint of addiction biology, caffeine is exceptional. Astrid Nehlig, a physiologist and research director at the French National Institute for Health and Medical Research in Strasbourg, has found that caffeine levels approximating levels of human consumption do not activate reward circuits in the brain as do classic stimulants, such as cocaine and methamphetamine, and other drugs of abuse. (See Nehlig, Astrid. (1999) Does Caffeine Lead to Psychological Dependence? Chemtech 29, 30-35.)
The American Psychiatric Association does not have a designation for caffeine withdrawal (as it does for opiates, stimulants, alcohol, and nicotine) in its diagnostic manual, the DSM IV. For years, however, neuroscientist Roland Griffiths at Johns Hopkins University School of Medicine has been advocating for its addition to the list.
Right now, psychiatrists are busy working on the fifth edition of the DSM, due out in about four years. It remains to be seen whether or not Dr. Griffiths will prevail.
The main virtue of psychiatrists knowing about caffeine is that they can discriminate between its effects and an underlying psychiatric condition such as significant agitation, irritability, or panic attacks. It is important to know, as well, that caffeine can worsen those conditions if already present and that it might interfere with antipsychotic medications. The latter is relevant because people with schizophrenia typically consume large amounts of caffeine.
In medical settings physicians should ask about marked caffeine intake to isolate the source of headache, marked fatigue or drowsiness, marked anxiety or depression, and nausea or vomiting — all of which can result from rapid cessation of high caffeine intake. Something as innocent as an elective surgical procedure or a diagnostic test which requires no intake of fluids for many hours might be the culprit in unleashing such symptoms, though in most cases they will be relatively mild.
The term addiction as popularly understood — a self-destructive compulsion to use a substance in the face of harm brought on by doing so — rarely applies to caffeine. Caffeine consumption in coffee, tea, or soda can more properly be considered a dedicated habit.
Sally Satel is a Resident Scholar at the American Enterprise Institute and a practicing psychiatrist. This essay is based on her recent peer-reviewed paper, "Is Caffeine Addictive?—A Review of the Literature," which appeared in the American Journal of Drug and Alcohol Abuse. The research was supported by a grant from the American Beverage Association.
Image credit: ""coffee" by Flickr user cygnoir