Caffeine-Related Disorders

Caffeine-related disorders are a group of psychiatric disorders defined by DSM-5 * that are caused by taking in large amounts of caffeine in foods, drinks, or over-the-counter medications. Caffeine is a stimulant * that also affects the muscles and the digestive tract. Some doctors include digestive problems caused by caffeine in the category of caffeine-related disorders.

Keith's Story

Keith, a high school student in Chicago, got into the habit of drinking Redline, a caffeinated energy drink that his friends recommended as a way of boosting his energy and endurance before basketball practice. Keith thought of Redline as much like a soft drink: a drink to quench thirst as well as to improve sports performance. Before long he was drinking two or three cans per day.

One afternoon Keith felt sick after his basketball game. He could feel his heart beating, he was sweating heavily, and he could not stop vomiting. He was also very anxious. The coach took him to the emergency room of a nearby hospital, where the doctor diagnosed Keith with caffeine intoxication. Keith was surprised to learn how much caffeine he had been taking on a daily basis and how quickly it could affect his health.

What Is Caffeine?

Caffeine is a naturally occurring chemical compound that is classified as a xanthine (ZAN-theen). Xanthines are nitrogen-based compounds that are found in both plant and animal tissue and have a stimulating effect on the nervous system. Caffeine itself is found in various amounts in the stems, leaves, and berries or beans of some plants, particularly the coffee plant and the leaves of tea bushes. Other natural sources of caffeine used by humans to make beverages include yerba maté, a shrub in the holly family that grows in South America; guarana, a climbing plant found in the Amazon rain forest; kola nuts, used to flavor cola beverages; and cacao pods, the source of cocoa and chocolate. The caffeine in all these plants acts as a natural pesticide that paralyzes and kills insects that would otherwise feed on their leaves and berries.

Caffeine is the most widely consumed psychoactive * substance in the world, although most people do not think of it as a drug. Unlike most other psychoactive substances, caffeine is legal and unregulated in almost all countries. The U.S. Food and Drug Administration (FDA) first defined caffeine as a “multiple purpose generally recognized as safe food substance.” Now, the FDA describes caffeine as being “both a drug and a food additive.” This change in wording reflects a growing awareness around the world that caffeine can be addictive when it is overused and that it can have toxic side effects in people who take very high doses of it or who are unusually sensitive to its effects.

How Does Caffeine Affect Humans?

Human use of caffeine

Humans have known for centuries about the effects of caffeine in improving alertness, fighting off drowsiness, and increasing physical endurance and muscular coordination. There is evidence from Stone Age burial sites that early humans (possibly as early as 10,000 BcE) knew that chewing the leaves of plants containing caffeine relieved fatigue, enabled people to do hard physical work for longer periods of time, and helped to lift depressed moods. It was not until about 3000 BcE that the Chinese discovered that soaking tea leaves in hot water produced a beverage containing more caffeine than the fresh tea leaves themselves. Brewed coffee appeared in the Arab world around the 9th century CE but did not reach Europe until the 17th century.

Approximate amounts of caffeine in popular products

Approximate amounts of caffeine in popular products
Table by PreMediaGlobal. © 2016 Cengage Learning®.

Cacao beans were used for their caffeine content by the Maya in southern Mexico as early as 600 BCE. The cacao beans were ground and flavored with vanilla and chili peppers to make a spicy drink to relieve tiredness. When the Spanish conquistadors came to Mexico in the 16th century CE, they adopted the chocolate-flavored drink (minus the chili peppers), and brought it back to Europe. They planted cacao trees in the West Indies and the Philippines to supply the new European craving for chocolate.

In the 20th century, kola nuts were used by the Coca-Cola Company to flavor its well-known soft drink. Although most cola-flavored soft drinks use artificial flavoring, some energy drinks use kola nuts as well as guarana berries to increase their caffeine content.

Caffeine in the body

Caffeine is classified as a central nervous system * stimulant because it reduces drowsiness and increases alertness and the ability to focus. It is also a diuretic * , which means that it increases the loss of body water in the urine.

Caffeine usually enters the body through the mouth and is absorbed by the stomach and small intestine within 45 minutes. The half-life of caffeine—that is, the time it takes for the body to eliminate half the caffeine taken at one time—varies according to age, sex, the healthiness of a person's liver, and other medications the person may be taking. In general, the half-life of caffeine in a healthy adult is three to four hours. In pregnant women, the half-life of caffeine is 9 to 11 hours; in young children, it is as long as 30 hours; and in elderly adults with liver disease, it can be as long as 96 hours.

After being absorbed from the digestive tract, caffeine passes rapidly into other body tissues. It can affect the brain because it is able to cross the blood-brain barrier * . Once in the brain, caffeine acts primarily as an antagonist * of a brain chemical called adenosine (ah-DEN-oh-seen), a chemical that occurs naturally in the body and among its other functions promotes sleep and suppresses arousal. It is also involved in the sleep-wake cycle. Caffeine's ability to increase alertness and physical endurance is largely due to its role as an adenosine antagonist.

In the digestive tract, caffeine stimulates the stomach to produce more gastric acid and reduces muscle tone in the (lower esophageal) esophago-gastric sphincter (the muscle ring that closes off the esophagus from the stomach during digestion), which is the reason why some people experience heartburn after drinking tea or coffee. Caffeine is metabolized (broken down) in the liver into three simpler compounds. One of these compounds is a diuretic; it increases the person's urine output. This pattern of caffeine metabolism *

Other effects of caffeine on the digestive tract include stimulation of the gallbladder * and the colon * . In addition, caffeine relaxes the muscles of the anal * sphincter (SFINK-ter), the ring of muscles surrounding the anus that holds fecal matter inside the body. The effects of caffeine on the colon and anal sphincter help to explain why people with fecal incontinence * should not drink coffee or tea.

Tolerance and withdrawal

People who drink large quantities of coffee, tea, or energy drinks develop a tolerance to the psychological and physical effects of caffeine. This means that people get used to the stimulant effects of caffeine and are not kept awake at night even after consuming several cups of tea or coffee. Tolerance to caffeine builds up quite rapidly; one study found that test subjects who took 400 mg of caffeine three times per day for seven days did not have any problems with sleep. Another study found that subjects who took in 300 mg of caffeine three times per day for 18 days developed complete tolerance to the psychological effects of caffeine.

The other side of caffeine tolerance is caffeine withdrawal * . Withdrawal refers to the symptoms experienced by heavy caffeine users when they suddenly stop taking large amounts of caffeine. The most common symptoms of caffeine withdrawal are headache, nausea, drowsiness or difficulty sleeping, irritability, difficulty concentrating, and pain in the stomach, upper body, or joints. Some people may experience psychological depression. Caffeine withdrawal begins within 12 to 24 hours after the last dose of caffeine and lasts anywhere from one to five days.

Medical uses of caffeine

Although most people think of caffeine simply as an ingredient in certain foods and beverages it is used in some medications to improve the effectiveness of aspirin and other pain relievers, to treat migraine headaches, or to counteract the drowsiness caused by antihistamines * . A number of over-the-counter medications taken to relieve menstrual cramps or to help dieters control their appetite contain caffeine.

What Are Caffeine-Related Disorders?

Caffeine-related disorders are a group of four mental disorders defined by DSM-5. Some doctors also use the term loosely to refer to physical problems caused or made worse by consuming large amounts of caffeine.

Psychiatric disorders

DSM-5 defines four caffeine-related psychiatric disorders:

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)