It is clear that scientists have little hard data on which to base conclusions about the prevalence of caffeine intoxication. The uncertainty is exacerbated by the failure of some researchers to distinguish between chronic high caffeine consumption and caffeine intoxication, or similarly, the failure to distinguish between an isolated episode of caffeine intoxication and chronic intoxication. Because caffeine is the most widely used drug on earth, we can be sure that, sooner or later, both the prevalence and incidence of caffeine intoxication will be better characterized by applying the rigorous criteria for diagnosis, standardized assessments, and representative sampling techniques that have been applied to intoxicants such as alcohol, cocaine, and morphine.
Really heavy caffeine consumption has often been observed among institutionalized schizophrenics, as this curious letter, captioned “Coffee Eating in Chronic Schizophrenics,” from two psychiatrists to the American Journal of Psychiatry (July 1986) vividly attests:
Caffeinism, a psychophysiologic syndrome in DSM-III, is a clinically important syndrome per se, and as a co-diagnosis it may complicate the course of affective, anxiety, and thought disorders. The methylxanthines are the major pharmacoactive ingredient in many readily available caffeinated foods, beverages, and over-the-counter medications. To highlight a possibly important pattern of pathological consumption behavior that may produce caffeinism, we report three observations of coffee eating that occurred among chronic schizophrenic inpatients of a large state psychiatric hospital.
Mr. A, age 27, was frequently seen carrying around nearly empty jars of instant coffee, at which times he had an observable brown “mustache.” When asked, he volunteered that he and another patient pooled their money on Friday “paydays” to buy instant coffee, usually 6–10 oz. jars. Then, over several hours they would consume the coffee “for kicks” using plastic spoons. Nurses stated that they could tell when these patients had eaten coffee because they were more irritable and prone to “act up”; they also required more medications.
Ms. B, age 53, presented her physician with an obviously heart-felt and generous gift: a paper cup filled with instant coffee and plastic spoon “to help eat it.” She stated that she ate instant coffee when she could afford it and that she shared it with fellow patients. She said she “enjoyed the feeling” it gave her.
A third observation was of an incident in the breezeway between wards. A patient dropped a large jar of instant coffee. Despite the broken glass and the objections of staff, patients immediately crowded around and knelt down to scoop up the apparently precious powder, eating it directly off the floor.
These cases are not unique. Patients attest to the wide popularity of coffee eating in the hospital, where it seemed to be a shared social activity. Coffee eating is one of several examples of psychopharmacologically potent consumption behaviors that alter the clinical management of the psychotic patient. Such aberrant behaviors include excess coffee and tea ingestions, tobacco and marijuana abuse, and ethanol and self-induced water intoxication.19 Patients have co-abused coffee and trihexylphenidyl, a combination that produces hallucinations and euphoria.
These incidents are of clinical concern because caffeine is reported to exacerbate the clinical course of schizophrenia. Caffeine products may alter psychopharmacologic management by several mechanisms. First, the methylxanthines induce hepatic microsomal enzymes, which results in faster neuroleptic degradation. Second, patients may use caffeine to reverse the sedative side effects of antipsychotic drugs. Third, coffee (as a complex compound) forms insoluble precipitates with some antipsychotic medications, thus reducing their absorption. Fourth, the methylxanthines are adenosine antagonists that modulate CNS norepinephrine, serotonin, dopamine, and other neurotransmitters. Caffeine may thereby alter antipsychotic action at the neurotransmitter level. Coffee eating may represent a potentially malignant cause of caffeinism. Four ounces of instant coffee typically contain 5 g of caffeine, which in toxicological terms is about one-half the median lethal dose. The more general problem is that caffeinism among chronic hospitalized patients may be a widespread and clinically important problem.
Given the potent opiate receptor binding activity of coffee, we wonder whether naloxone might be worth investigation as a blocker of this aberrant consumption behavior.
John I.Benson, M.D., Augusta, GA
Joseph J.David, M.D., Charlottesville, VA
Another psychiatric problem associated with excessive caffeine consumption is delirium, which is sometimes present in cases of extreme caffeine intoxication. For example, caffeine-induced delirium has been reported in a man who chugged down large amounts of coffee, cola, and 800 mg of caffeine tablets while competing in the Iditarod sled dog race held between Anchorage and Nome, Alaska. He experienced tremor and alteration in his level of consciousness, anxiety, visual illusions and hallucinations, vertigo, and impaired memory consistent with an episode of delirium. While in this case and others delirium has been attributed to excessive caffeine use, the degree to which factors such as fatigue and sleep deprivation may have contributed to the delirium is not readily determinable. However, even though the redoubtable DSM-IV, the bible of psychiatric diagnosis, does not yet officially recognize caffeine as one of the agents that can produce a “substance intoxication delirium,” it seems probable that caffeine, like other psychoactive substances, should produce delirium if taken in sufficiently high doses.
Can Caffeine Kill?
If you take enough caffeine, it can kill you. The value generally accepted for a fatal overdose, and one given by pharmacology texts for fifty years, is about 10 grams for the average adult, about as much as in one hundred cups of coffee. In more precise clinical terms, the LD-50 of caffeine, that is, the lethal dosage for 50 percent of the population, is estimated at 10 grams for oral administration. However, the lethal dosage for any individual varies directly with body weight, and about 150 mg/kg to 200 mg/kg of caffeine is the usual estimate for the LD-50 for adult human beings. That is, those who weigh 150 pounds will have an LD-50 of at least 10 grams. However, because fatalities are very rare, and deaths have occurred at 5 to 50 grams, it is impossible to have confidence in this exact figure.
Acute toxic symptoms occur at levels as low as 50 mg/kg, equivalent to about 3.5 grams for a 150-pound person, about as much as in 35 cups of coffee. Even these levels are not usually attainable from dietary sources.20 Milder caffeine intoxication symptoms, including anxiety, insomnia, and gastrointestinal disturbances, can occur after a 150-pound man ingests as little as 250 mg, or about 3 mg/kg.
Researcher Jack James cites what may be the first account of caffeine poisoning, dating from 1883. In this description, a sixty-three-year-old man “survived an oral overdose of caffeine after developing various cardiovascular, CNS, and gastrointestinal symptoms.”21 Others have not been so fortunate. An account published in 1959 of a thirty-five-year-old woman who, after arriving at the hospital in a state of insulin shock, was accidentally injected with a caffeine solution instead of glucose,22 died after experiencing convulsions and respiratory arrest. Subsequent investigation determined that she had received 3.2 grams, raising her serum concentration of caffeine to 57 mg/kg.
Most of the cases where caffeine was the cause of death were the result of the accidental administration of caffeine by hospital staff. Typical examples are those of a fifteen-month-old boy and a sixty-one-year-old man, each given about 18 grams of caffeine orally. Another is a forty-five-year-old woman who was given 50 grams of caffeine instead of 50 grams of glucose.
In “A Fatal Ingestion of Caffeine,” a 1977 article in Clinical Toxicology, written by J.E.Turner and R.H.Cravey, of the Office of the Sheriff-Coroner, Toxicology Laboratory, Santa Ana, presents one of the rare caffeine-associated deaths. According to the authors, the thirty-four-year-old woman who was to die from a massive overdose of caffeine
complained of weakness and experienced episodes of vomiting. Upon retiring, her breathing became progressively labored, and she began to suffer con
vulsions. A rescue unit found her in coma. Upon arrival at the hospital, there was no audible heart beat, pulse, or breath sounds. She was in a state of acidosis (pH 6.8, arterial blood) with cyanosis about the neck and mouth. She had assumed an opisthotonic posture [a severe muscle spasm, in which the back arches and head and heels bend back, such as occurs in the final stages of tetanus]. Resuscitative efforts lasted one hour....
Autopsy revealed general congestion, particularly of the lungs, liver, and brain stem. Direct cause of death was attributed to pulmonary edema.23
Toxicological Findings after a Fatal Caffeine Overdose
Specimen Caffeine Content
Blood 10.6 mg/100 ml
Liver 11.6 mg/100 g
Kidney 12.4 mg/100 g
Brain 10.8 mg/100 g
Gastric 43 mg total, plus three partially undissolved tablets
Turner and Cravey, “A Fatal Ingestion of Caffeine,” Clinical Toxicology 10 (3): 341–44 (1977).
To comprehend the blood values of the deceased, consider that a 300 mg dose of caffeine, about as much as in two strong cups of coffee, result in a maximum blood concentration of about .5 mg/100 ml in a 200-pound adult, or less than 5 percent of the level found in this autopsy.
The survivor of what is probably the largest dose of caffeine on record is a twenty-one-year-old woman, estimated to have ingested a total of 106 grams, taken in the form of more than four hundred tablets, each containing 250 mg of caffeine. Despite an astonishing serum caffeine concentration of nearly 300 mg/100 ml, the patient was said to have shown “no residual neurological deficit” when discharged from the hospital four days later.24
Although people who consume caffeine are less likely to commit suicide than nonconsumers, there are outstandingly rare suicide attempts utilizing high doses of the drug, which, under extreme circumstances, may in fact prove fatal, and there have been at least two reports of suicides by caffeine overdose.25 Caffeine may be used to commit suicide so infrequently partially because few people know if it could kill them or how much it would take to kill them. The infrequency of accidental death may be a result of the emetic (purgative) effect of the drug. If there is evidence that a patient has significantly overdosed on caffeine, it should be treated as a medical emergency requiring intensive monitoring, symptomatic treatment for rapid or irregular heartbeat and seizures, aspiration of the stomach, and assessment of the serum caffeine level. Serum readings of more than 1 milligram per milliliter are generally considered toxic. Caffeine overdose has also been treated successfully with hemoperfusion, or flushing the blood supply clean with fluids.
Because infants and young children are much more vulnerable to the toxic effects of caffeine than adults, even when the discrepancies in their body weights have been factored out, researchers say that in infants 40 mg/ml is probably toxic.26 There is a case of a child who died from orally ingesting less than 5.5 grams, or the equivalent of about five cups of coffee.27
Finally, the habit of smoking cigarettes must be mentioned again in relation to caffeine toxicity. There is an unholy bond between the habits of smoking cigarettes and drinking coffee. Although the precise figures vary, every survey indicates that a higher percentage of smokers drink coffee regularly than do non-smokers and that of regular coffee drinkers, smokers drink more of it than do non-smokers. We have noted repeatedly how variable the kinetic profile, or speed of metabolic passage, of caffeine can be among different people or in the same person at different times. Most people do not realize, however, that giving up cigarettes causes a profound slowing of caffeine’s half-life, creating a toxic hazard for people who continue their previous levels of caffeine intake, unaware that, if they are no longer smoking, their coffee or tea will have a greater and more sustained effect on them than they had become accustomed to.
epilogue
A Toast to the Future
In the course of its relatively brief history, caffeine has become the world’s most popular drug. Its most common sources, coffee, tea, and chocolate, have been celebrated and promoted as productive of health, stamina, and creativity and have been condemned and banned as the corrupters of the body and mind and subverters of social propriety and civil order. Through coffee and the coffeehouse, caffeine has altered society and culture from the Middle East to Europe, America, and beyond, justifying the fears of Islamic clerics and sultans and Western kings and police chiefs that the institutions purveying caffeine would undermine the stability and insularity of social and political order and religious practice. Through tea, teaism, and the afternoon tea, caffeine has subtly shaped the spiritual and aesthetic ideals of the Orient and given the British Empire, the most extensive imperial realm the world has ever seen, a universal symbol of civility, restraint, refinement, and social order. Through caffeinated soft drinks, caffeine has perfected its conquest of humanity, extending its community of users to children.
What powers or properties of caffeine have enabled it to exert such a broad influence on human history?
For one thing, caffeine is an intoxicant. As Freud observes in Civilization and Its Discontents (1930), man averts suffering by means of the enjoyment of four things: the enjoyment of illusions, or what Coleridge called “the willing suspension of disbelief”; the enjoyment of beauty, which beauty, we have been told by Keats, is “a joy forever”; the enjoyment of what we can have instead of the pursuit of the unattainable, which is called “displacement”; and, lastly, the enjoyment of intoxicants, or chemical intoxication. Freud might therefore have responded to the question “Why do people take drugs?” with the reply “Why not?” For it should come as no surprise that if caffeine, as an intoxicant, answers essentially to man’s quest for happiness, it should be among the general pleasures of mankind.
What this observation leaves unaddressed is why caffeine should have emerged so recently from the large, diverse collection of available intoxicants to become both the most popular drug on earth, used regularly by more than 90 percent of everyone alive, and the most inconspicuous as well. For caffeine is as unnoticed as it is ubiquitous, suffusing our systems unremarked, despite its presence in our bodies from birth (and even before birth) through childhood, adulthood, and old age.1
Because the nature and extent of caffeine’s effects are widely variable among different people and in the same person at different times, different people use caffeine for different reasons, and the same person uses caffeine for different reasons at different times. This diversity of effects and purposes may be one reason caffeine is the most popular drug on earth. But this same diversity also suggests that a complete understanding of caffeine will elude us until we have fully disentangled the complexities of human life itself.
Of course, caffeine comes to us accompanied by delights beyond its power to intoxicate: the sensual appeal of its most commonly enjoyed vehicles, coffee, tea, and chocolate. And caffeine itself should not be overlooked as an important component of their taste. The taste threshold for caffeine, that is, the minimum concentration at which it can be detected by the tongue (about .02 mM/L [millimole per liter]), is the same order of magnitude as actually found in a cup of coffee. However, caffeine’s contribution to the taste of coffee and other beverages is greater than this number suggests, because, at levels far below the threshold of perception, caffeine affects the taste of sweet, bitter, and salty foods or drinks, and therefore affects the overall taste mix of coffee’s and tea’s many flavoring components. In this book we have not discussed the art of beverage preparation, except as an aside, preferring to follow the disclaimer found in A Compleat History of DRUGGS, in which the early-eighteenth-century author, speaking of recipes for chocolate, explains:
I did not think it proper to give you the Composition here, since there are so many Books that treat of it, and the Compositions are so various, that every one is for pleasing his own Fancy.2
We have discussed what we think constitutes the most important reason for caffeine’s prominence in the modern world: It gives men the power to regulate th
eir biological systems so as to make them more conformable with the demands of exacting and highly integrated schedules. Perhaps another reason for caffeine’s enduring appeal is that, as compared with many other intoxicants, it is mild and benign. Although it can produce undesirable effects, from jitteriness and insomnia to withdrawal headaches and sleepiness, few people, as far as we know, find their health broken by caffeine use, and few lose their jobs, families, or fortunes because of excessive caffeine consumption. Of course part of the difference between caffeine and stronger, more dangerous drugs is simply a legal artifact. No one really knows to what extent caffeine use would follow the patterns of the abuse of other drugs if it were to join them as a controlled or illegal substance, or, conversely, to what extent the patterns of abuse of other drugs would abate if they, like caffeine, were obtainable legally.
What is the future of the coffeehouse? All we can be certain of is that it has one and will continue to have one. We recently read of two high school alumnae from Philadelphia’s Main Line who met, for the first time in a decade, by chance in the Pumpernickel Café in Kathmandu, Nepal. Can there be any doubt that, if and when there are settlements on Mars, coffeehouses will be among the first amenities available to the émigrés? The coffeehouse, which changes, adapts, and diversifies, merits recognition as the most protean institution in history. In coffeehouses, men met and plotted the American, French, Russian, and Chinese revolutions, dissected dolphins, invented and wrote newspapers, underwrote international commerce, conducted love affairs, and bandied and exchanged every sort of idea. In seventeenth- and eighteenthcentury London, quack doctors treated patients and sold patent medicines at the coffeehouses. In Los Angeles at the end of the millennium a young lawyer has opened a coffeehouse in hope of practicing law there. To the concept of the tabula rasa, the blank slate of the mind on which experience writes, an idea of Locke’s so favored by the generation of Addison and Steele, who worked and played in the coffeehouses, might be added the mensa rasa, the cleared table of the coffeehouse, across which every sort of opinion might be sounded and every sort of person faced.
The World of Caffeine Page 47
