Progress in understanding drug dependence has been impeded by a host of non-scientific moral, emotional, and legal factors. Fear of lethal drugs of abuse, such as heroin and cocaine, has clouded what might otherwise have been a neutral and relatively straightforward evaluation of the nature and extent of the habit-forming properties of less dangerous agencies, such as marijuana and caffeine, engendering confusion and doing little to encourage much-needed studies.

The word "dependence" is used in scientific literature in at least two distinct ways. "Physical dependence" is defined by the occurrence of a withdrawal syndrome after cessation of the use of a substance. Opium, cigarettes, and coffee each contain a psychoactive drug producing physical dependence: morphine, nicotine, and caffeine, respectively. "Clinical dependence syndrome" usually includes physical dependence, but also involves a pattern of pathologic behavior. Drugs that can support a clinical dependence syndrome are usually considered drugs of abuse. A heroin addict, whose behavior is deleteriously conditioned by his need to acquire the drug, exhibits clinical dependence syndrome. In contrast, a cancer patient under extended treatment with opioids will demonstrate physical dependence, but would probably not display any other symptoms of clinical dependence.

Caffeine unquestionably supports a physical dependence, as proved by the withdrawal symptoms associated with its abrupt discontinuation. It also has several additional characteristics in common with drugs that support a clinical dependence syndrome. These characteristics include both caffeine's ability to improve people's moods, self-confidence, and energy and what researchers call its ability to act as a reinforcer, or what in laymen's terms might be phrased as "the more you get, the more you want" factor. Yet despite the reasonableness of the hypothesis and considerable anecdotal evidence, it has been demonstrated only recently that there actually are users whose pattern of caffeine consumption merits a diagnosis of clinical dependence syndrome.

Many consumers of coffee, tea, and cola, never having entertained an association between caffeine and drug use, may be surprised to learn that the massive modern catalogue of psychiatric problems, the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), includes an entry for "Caffeine Intoxication," which it describes either as an acute drug overdose condition, occurring after the ingestion of a large amount of caffeine, or as a chronic condition, otherwise known as "caffeinism" or "caffeism" associated with the regular consumption of large amounts of caffeine.

There is nothing new about the awareness of caffeine intoxication, for it has been well described as a psychiatric disorder for more than a hundred years. Yet despite long-standing recognition, which perhaps began with the coining of the Arabic word "marqaha," or "caffeine high," in the 16th century, there is, even today, little information available about its prevalence or incidence.

In 1896 J.T. Rugh reported the case of a traveling salesman who had resorted to excessive coffee consumption to maintain an intense pace of work and was troubled by nervousness, involuntary contractions in the arms and legs, a sense of impending danger, and sleep disturbance. Similar reports of caffeine intoxication first appear in medical literature from the middle of the 1800s, and the profile of common symptoms remains unchanged today. The most common are anxiety or nervousness, insomnia, gastrointestinal disturbances, irregular heartbeat, tremors, and psychomotor agitation. Other reported symptoms include excessive urination, headaches, diarrhea, irregular breathing.

An interesting and unusual case was reported to JAMA early in 1914 by Otis Orendorff, M.D., of Canon City, Colorado. "A young miss, 18, an office clerk, of a slight, frail physique, had ordinary symptoms of asthenopia [eyestrain] for four years," Orendorff wrote. She grew worse over a period of several months. Although tests were administered and full correction for her vision was provided, she experienced no relief. The patient was alternately exhilarated and depressed. She had memory lapses and maintained a "deportment with an indifference to the usual conventionalities and proprieties." She had intermittent headaches, apparently not caused by work, but that increased when she attempted to read. She had insomnia at night but fell asleep at work. Her condition was getting serious. The physician was at his wits' end, when the patient asked him "if there could be any danger in an overindulgence of Coca-Cola? stating that she drank from three to six glasses a day. In addition, she had two or three cups of strong coffee at mealtime, sometimes taking but little other nourishment." He reports prompt improvement on curtailing her daily caffeine ingestion, concluding, "I feel that such a case is of interest from an ophthalmologic point of view and also because it indicates that the profession should be more alive to the pernicious influence in habit formation of some of the popular beverages served to young persons at public 'slop' fountains."

Unknown to the typical coffee or tea drinker, there exists a subterranean culture of undetermined extent in which caffeine is consumed with the fixed intention of inducing intoxication. That is, many people across the country and around the world regularly use large doses of caffeine to get high. In doing so, they frequently encounter many of the symptoms of toxicity, somatic and psychological, that we discuss in this chapter.

Internet news groups are electronic confraternities in which people who have generally never met each other post public messages, photographs, and even sound files pertaining to a common interest. If you access such newsgroups as "alt.drugs.caffeine" or "alt.coffee" on any given day, you are certain to find questions, comments, confessions, misgivings, and boasts regarding the use of large amounts of caffeine. Here are quotations from Internet postings, which are rife with misinformation and misspellings:

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 50 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. 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 63-year-old man "survived an oral overdose of caffeine after developing various cardiovascular, CNS, and gastrointestinal symptoms." Others have not been so fortunate. An account published in 1959 of a 35-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, 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 15-month-old boy and a 61-year-old man, each given about 18 grams of caffeine orally. Another is a 45-year-old woman who was given 50 grams of caffeine instead of 50 grams of glucose. ...

ReconsiDer Tidbits