Caffeine is a white, bitter crystalline alkaloid derived from coffee or tea. It belongs to a class of compounds called xanthines, its chemical formula being 1,3,7-trimethylxanthine. Caffeine is classified together with cocaine and amphetamines as an analeptic, or central nervous system stimulant. Coffee is the most abundant source of caffeine, although caffeine is also found in tea, cocoa, and cola beverages as well as in over-the-counter and prescription medications for pain relief.
In the clinician's handbook for diagnosing mental disorders (the Diagnostic and Statistical Manual of Mental Disorders, known as the DSM-IV-TR), caffeine-related disorders are classified under the rubric of substance-related disorders. DSM-IV-TR specifies four caffeine-related disorders: caffeine intoxication, caffeine-induced anxiety disorder, caffeine-induced sleep disorder, and caffeine-related disorder not otherwise specified. A fifth, caffeine withdrawal, is listed under the heading of "Criteria Sets and Axes Provided for Further Study."
Caffeine-related disorders are often unrecognized for a number of reasons:
• Caffeine has a "low profile" as a drug of abuse. Consumption of drinks containing caffeine is unregulated by law and is nearly universal in the United States; one well-known textbook of pharmacology refers to caffeine as "the most widely used psychoac-tive drug in the world." In many countries, coffee is a social lubricant as well as a stimulant; the "coffee break" is a common office ritual, and many people find it difficult to imagine eating a meal in a fine restaurant without having coffee at some point during the meal. It is estimated that 10-12 billion pounds of coffee are consumed worldwide each year.
• People often underestimate the amount of caffeine they consume on a daily basis because they think of caffeine only in connection with coffee as a beverage. Tea, cocoa, and some types of soft drink, including root beer and orange soda as well as cola beverages, also contain significant amounts of caffeine. In one British case study, a teenager who was hospitalized with muscle weakness, nausea, vomiting, diarrhea, and weight loss was found to suffer from caffeine intoxication caused by drinking 8 liters (about 2 gallons) of cola on a daily basis for the previous two years. She had been consuming over a gram of caffeine per day. Chocolate bars and coffee-flavored yogurt or ice cream are additional sources of measurable amounts of caffeine.
• Caffeine has some legitimate medical uses in athletic training and in the relief of tension-type headaches. It is available in over-the-counter (OTC) preparations containing aspirin or acetaminophen for pain relief as well as in such OTC stimulants as NoDoz and Vivarin.
• Caffeine is less likely to produce the same degree of physical or psychological dependence as other drugs of abuse. Few coffee or tea drinkers report loss of control over caffeine intake, or significant difficulty in reducing or stopping consumption of beverages and food items containing caffeine.
• The symptoms of caffeine intoxication are easy to confuse with those of an anxiety disorder.
The DSM-TR-IV states that it is unclear as of 2000 whether the tolerance, withdrawal symptoms, and "some aspects of dependence on caffeine" seen in some people who drink large amounts of coffee "are associated with clinically significant impairment that meets the criteria for Substance Abuse or Substance Dependence." On the other hand, a research team at Johns Hopkins regards caffeine as a model drug for understanding substance abuse and dependence. The team maintains that 9%-30% of caffeine consumers in the United States may be caffeine-dependent according to DSM criteria for substance dependency.
la el r
e in ei feaf
£ Adenosine—A compound that serves to modulate the activities of nerve cells (neurons) and to produce a mild sedative effect when it activates certain types of adenosine receptors. Caffeine is thought to produce its stimulating effect by competing with adenosine for activation of these receptors.
Analeptic—A substance that acts as a stimulant of the central nervous system. Caffeine is classified as an analeptic.
Caffeinism—A disorder caused by ingesting very high doses of caffeine (10g or more per day) and characterized by seizures and respiratory failure.
Dependence—The adaptation of neurons and other physical processes to the use of a drug, followed by withdrawal symptoms when the drug is removed; physiological and/ or psychological addiction.
Hematemesis—Vomiting blood. Hematemesis is a symptom that sometimes occurs with gastrointestinal ulcers made worse by high levels of caffeine consumption.
Norepinephrine—A catecholamine neurotransmitter that acts to constrict blood vessels, raise blood pressure, and dilate the bronchi of the respiratory system. Caffeine increases the secretion of norepinephrine.
Reinforcement—A term that refers to the ability of a drug or substance to produce effects that will make the user want to take it again.
Tolerance—Progressive decrease in the effectiveness of a drug with long-term use.
Withdrawal—Symptoms experienced by a person who has become physically dependent on a drug, experienced when the drug use is discontinued.
Xanthine—A class of crystalline nitrogenous compounds that includes caffeine, which is 1,3,7-trimethylxanthine.
Was this article helpful?