Caffeine (pronounced ka-feen, kaf-een or kaf-ee-in)
A white,
crystalline, bitter alkaloid with the chemical compound C8H10N4O2.
1830: From the French caféine, the construct being café (coffee) + ine (the chemical suffix). The earlier German was kaffein, from kaffee (coffee); the adjective is caffeinic. Technically, caffeine is a trimethyl-derivative of xanthine, a coining as Kaffein in 1830, from German Kaffein, by German analytical chemist Friedlieb Ferdinand Runge (1794–1867). He chose the name because the alkaloid was found in coffee beans; its presence accounting for the stimulating effect of coffee and tea. The noun caffeinism was coined as medical jargon in 1880 to describe the "morbid state produced by prolonged or excessive exposure to caffeine" although the condition had for centuries been noted by doctors and others.
Of coffee
Methyltheobromine (or caffeine) is a central nervous system stimulant and the most widely consumed psychoactive drug which works, inter alia, by reversibly blocking the action of adenosine on its receptor and consequently prevents the onset of adenosine-induced drowsiness. Caffeine is a bitter, white crystalline purine, a methylxanthine alkaloid, chemically related to the adenine and guanine bases of DNA and ribonucleic acid RNA.
Human caffeine consumption is said to date from circa 3000 BC when, according to Chinese legend, the mythological Emperor Shennong (Divine Farmer) serendipitously invented tea, a story derived from an early book on the history of tea. Coffee drinking first became common in the mid-fifteenth century in the Sufi monasteries of Yemenin Arabia and it spread first to North Africa and by the sixteenth century was widely consumed throughout the Middle East, Persia and Asia Minor. The first European coffee houses were in Italy and they soon became common throughout the continent.
In its pure form, caffeine can be fatal in tiny quantities although in the form usually enjoyed, coffee, one would need to drink over a hundred cups in a day to approach toxicity. Voltaire (1694–1778), often at the Café de Procope in Paris, drank sometimes as many as forty cups a day, enjoying it so much he ignored the advice of his doctors to stop. He lived to eighty-four but there’s no evidence the often attributed quotation: “It may be poison, but I have been drinking it for sixty-five years, and I am not dead yet” was his. The more likely source is French author Bernard Le Bovier de Fontenelle (1657–1757) whose actual words were: “I think it must be [a slow poison], for I’ve been drinking it for eighty-five years and am not dead yet.” Fontenelle died a month short of his hundredth birthday.
Whatever the concern about coffee the drink, the coffee house the place attracted its own concerns. There’s some evidence coffee houses were welcomed by the authorities when first they became popular in seventeenth century London because they seemed a desirable alternative to the ale house where men would drink beer and later gin, leading to all the notorious social ills. However, it seemed soon to kings and ministers that while having drunken men brawl or beat their wives was hardly good, it was a more manageable problem than having them cluster, share the newly available cheap newspapers and pamphlets, talk and think. Men taking and thinking might lead to them getting ideas which was worse than them fighting in the street and government made repeated attempts to suppress the coffee shops. Ultimately, caffeine prevailed.
On the continent, the Habsburgs were no more impressed than the Stuarts in England, the government there encouraging the idea of coffee was a subversive societal vice and there was something of a minor moral panic among good citizens disturbed at the corrupting influences of such places. This didn’t amuse a German composer famously associated with the late Baroque, JS Bach (1685–1750) who was fond of taking his frequent shots in his favorite coffee shops and, although never noted for his light-heartedness, he took an amusing poem mocking the public’s concerns, written by his frequent collaborator Christian Friedrich Henrici (1700–1764; pen name Picander), and set it to music as Schweigt stille, plaudert nicht (Be still, stop chattering). Composed between 1732-1735, it’s usually called the Coffee Cantata, although, it’s really a comic operetta. A satirical commentary, the work makes fun of the concerns respectable folk had about coffee and coffee houses. In Vienna as in London, caffeine triumphed.
Despite the joys of a Bach cantata and the persuasive (if misattributed) endorsement of Voltaire, the killjoy editors of the Diagnostic and Statistical Manual of Mental Disorders (DSM) weren’t sure ordinary folk could be trusted to decide how many cups of coffee daily to enjoy and declared more research was needed. They often conclude more research is needed. Strangely, the DSM’s editors appear to be less trusting than most clergy, caffeine a drug to which even normally condemnatory priests, rabbis and mullahs don’t object, the only famously abstemious among the major faiths being the Church of Latter-Day Saints (the Mormons), the Seventh-Day Adventists and the Rastafarians, the last perhaps a surprise given how well a long black complements some good weed.
Widely consumed, caffeine is a psychoactive drug which produces its psychomotor stimulant and reinforcing effects through antagonism at adenosine receptors and indirect effects on dopaminergic neurotransmission. The editors of DSM-5 (2013) were prepared to concede consumption of caffeine at recommended dietary doses is usually at least harmless and may even have some benefits such as the enhancement of analgesia but do caution some may experience caffeine-related health effects and functional impairment and that this can manifest in different people at different levels of consumption. Higher doses can produce dysphoric subjective effects and caffeine intoxication, including restlessness, nervousness, insomnia and an irregular heartbeat. It’s also associated in some with gastrointestinal problems, urinary incontinence and anxiety, use during pregnancy said to be associated with especially poor outcomes.
Cold turkey may not be the solution either, the editors documenting withdrawal symptoms which some may experience if abruptly discontinuing regular use, including headaches, fatigue, irritability, a depressed mood, difficulty concentrating, and even flu-like symptoms, the DSM-5 codifying the conditions as (1) caffeine intoxication, (2) caffeine withdrawal, (3) caffeine-induced anxiety disorder and (4), caffeine-induced insomnia. These are listed as the potential diagnoses when symptoms cause clinically significant distress or impairment and, because some individuals report an inability to reduce their consumption despite clinically significant problems even after seeking treatment, caffeine consumption can be said to lead to substance dependence.
Thus the DSM-5 proposed three necessary diagnostic criteria for caffeine use disorder: (1) a persistent desire or unsuccessful efforts to reduce or control caffeine use, (2) continued caffeine use despite knowledge of (it’s not specified if an explicit acknowledgment is needed) having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by caffeine and (3), withdrawal, as manifested by the characteristic withdrawal syndrome for caffeine, or caffeine or a closely related substance being taken to relieve or avoid withdrawal symptoms. Six additional diagnostic criteria included in other substance use disorders, such as craving, tolerance, and taking caffeine in larger amounts or over a longer period of time than intended, were also included as markers for greater severity beyond the three key criteria for caffeine use disorder. Because caffeine is so widely consumed, to reduce any potential for over-diagnosis, the proposed diagnostic strategy for caffeine, despite sounding onerous, is actually more conservative than for other substances.
The editors did note the paucity of data relating to the prevalence and clinical significance of caffeine use disorder and the suspicion is the interest may have been triggered not the usual suspect, coffee, but the newer generation of energy drinks and diet supplements. Previous research was apparently too focused on specific, small-subsets rather than the general populations, some of the studies so specialized as to be thought unrepresentative of the general population. One (very small) study of caffeine use disorder in the United States (reported in the DSM-IV (1994)) found that 30% of caffeine consumers fulfilled the generic DSM-IV criteria for substance dependence as applied to caffeine but this fell to 10% under (the supposedly more realistic) DSM-5 criteria, a hint the concerns of clinical over-diagnosis do need to be taken seriously. Again, the point was made that more research is required, the extent to which caffeine use disorder is associated with markers of clinical significance such as self-reported caffeine-related distress or impairment, psychological distress, sleep problems, or other drug use is wholly unknown.
The documented study the editors reviewed was the most thorough evaluation yet conducted of the prevalence, clinical significance and correlates of meeting proposed criteria for caffeine use disorder yet it was extensive enough only to inform future research and considerations regarding risk and differential diagnosis, technical points about the parameters of control group populations especially noted. Despite the apparent lack of robustness, the editors were persuaded the findings did support the inclusion of caffeine use disorder in future editions of the DSM. Although only a small percentage of sampled caffeine consumers met the proposed key diagnostic criteria, where the standards were met, there were clinically meaningful effects.
Caffeine has become more interesting as a drug because of the late twentieth-century phenomenon of the energy drink, the interest not so much in the caffeine content which, can be much more or much less than a cup of coffee but because the pattern of consumption is, in certain sub-groups, so associated with strong alcohol, often on a 1:1 (ie 30-60 ml spirits to 250 ml energy drink) basis, a pattern well known with long-established mixers like Coca-Cola but now in both much greater volume and a much higher caffeine content. It’s difficult to tell whether a problem has emerged because while the deaths associated with the combination attract attention, the aggregate numbers, impressionistically, seem small and may not be statistically significant. There's even been the suggestion extreme variations in ambient temperature may have been an at least contributory factor in some deaths.
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