Prescriber Update Articles

 

Information about Caffeine Dependence

<LEFT>USE AND COMMON SOURCES OF CAFFEINE

CAFFEINE AND HEALTH

MOOD ALTERING AND REINFORCING EFFECTS OF CAFFEINE

ANXIETY AND CAFFEINE

SLEEP AND CAFFEINE

CAFFEINE TOLERANCE

CAFFEINE WITHDRAWAL

CAFFEINE ADDICTION (i.e. CAFFEINE DEPENDENCE)

CAFFEINE INTOXICATION

Caffeine research study at Johns Hopkins University

USE AND COMMON SOURCES OF CAFFEINE

Caffeine is the most commonly used mood-altering drug in the world. Caffeine is found in numerous plants, the most widely consumed being coffee, tea, cola nut, cocao pod, guarana, and maté. It is estimated that in North America between 80 and 90 percent of adults and children habitually consume caffeine. About 15% of the general population report having stopped caffeine use completely, citing concern about health and unpleasant side effects.

In the United States the average per capita daily intake among adult caffeine consumers is 280 milligrams (the equivalent of 17 ounces of brewed coffee or 84 ounces of soft drink). Studies show that 30 milligrams or less of caffeine can alter self-reports of mood and affect behavior and 100 mg per day can lead to physical dependence and withdrawal symptoms upon abstinence.

Coffee is the leading dietary source of caffeine among adults in the United States, while soft drinks represent the largest source of caffeine for children. Caffeine consumption from soft drinks has dramatically increased over the last few decades and 70% of all soft drinks contain caffeine.

The table below shows the range of caffeine contents from common foods and medications as well as estimated "typical" caffeine contents. Of the three major dietary sources of caffeine, servings of tea and soft drinks usually contain about one-half to one-third the amount of caffeine in a serving of coffee.

Although most people are aware that coffee, tea and most cola beverages contain caffeine, there several sources of caffeine about which there is less awareness. In the United States, about 70% of all soft drinks consumed contain caffeine. A number of non-cola drinks such as root beer, orange soda, cream soda, and lemon-lime drinks contain caffeine in amounts similar to those in the cola drinks. Some, but not all, coffee ice creams and yogurts deliver a significant dose of caffeine. Although chocolate milk, cocoa, and milk chocolate candy also contain caffeine, the dose delivered in a usual serving is generally below the threshold for readily detectable mood and behavioral effects (<10 mg). The one exception is that a serving of dark chocolate candy may contain about 30 mg of caffeine.

Medicinal products also often contain significant amounts of caffeine. Over-the-counter stimulant medications such as NoDoz and Vivarin contain between 100-200 milligrams per tablet, while caffeine-containing analgesics such as Anacin, Excedrin, and Midol deliver 64 to 130 milligrams per two tablet dose.

Typical Caffeine Content of Common Foods and Medications

Substance	Serving Size	Caffeine Content	Caffeine Content
	(volume or weight)	(range)	(typical)
Coffee
Brewed/Drip	6 oz	77-150 mg	100 mg
Instant	6 oz	20-130 mg	70 mg
Espresso	1 oz	30-50 mg	40 mg
Decaffeinated	6 oz	2-9 mg	4 mg
Tea
Brewed	6 oz	30-90 mg	40 mg
Instant	6 oz	10-35 mg	30 mg
Canned or Bottled	12 oz	8-32 mg	20 mg
Caffeinated Soft Drinks	12 oz	22-71 mg	40 mg
Caffeinated Water	16.9 oz	50-125 mg	100 mg
Cocoa/Hot Chocolate	6 oz	2-10 mg	7 mg
Chocolate Milk	6 oz	2-7 mg	4 mg
Coffee Ice Cream or Yogurt	1 cup (8 oz)	8-85 mg	50 mg
Chocolate Bar
Milk Chocolate	1.5 oz	2-10 mg	10 mg
Dark Chocolate	1.5 oz	5-35 mg	30 mg
Caffeinated Gum	1 stick	50 mg	50 mg
Caffeine-Containing OTC Products
Analgesics	2 tablets	64-130 mg	64 or 130 mg
Stimulants	1 tablet	75-350 mg	100 or 200 mg
Weight-loss products	2-3 tablets	80-200 mg	80-200 mg
Sports Nutrition	2 tablets	200 mg	200 mg

As shown in the table above, it can be difficult for a person to accurately estimate his/her caffeine consumption because of the wide differences in the amount of caffeine delivered in common foods as well as large differences in common serving sizes. For instance, the amount of caffeine in a serving of coffee can vary over a 10-fold range, from as little as 20 mg for a small 5 oz cup of instant coffee to 300 mg for a large 12 oz. cup of strong drip coffee. A similar 10-fold variation can occur with soft drinks, with a small glass of one of the weaker cola drinks containing as little as 12 mg of caffeine in contrast to about 120 mg from a 20 oz bottle one of the stronger colas.

CAFFEINE AND HEALTH

Caffeine use can be associated with several distinct psychiatric syndromes: caffeine intoxication, caffeine withdrawal, caffeine dependence, caffeine-induced sleep disorder, and caffeine-induced anxiety disorder. Studies have not proven that caffeine produces significant life-threatening health risks such as cancer, heart disease, and human reproduction abnormalities. Nevertheless, individuals with various conditions such as generalized anxiety disorder, panic disorder, primary insomnia, gastroesophageal reflux, pregnancy and urinary incontinence are often advised to reduce or eliminate regular caffeine use. With regard to cardiovascular health, caffeine produces modest increases in blood pressure and studies have established that unfiltered caffeinated and decaffeinated coffee (including espresso and French Press) contain lipids which raise serum cholesterol. In addition, concerns have been raised about a role of caffeine in cardiovascular disease. Finally, studies suggest that there may be an association between high daily caffeine consumption and delayed conception and lower birth weight.

MOOD ALTERING AND REINFORCING EFFECTS OF CAFFEINE

Mood Altering Effects: The mood altering effects of caffeine depend on the amount of caffeine consumed and whether the individual is physically dependent on or tolerant to caffeine. In caffeine non-users or intermittent users, low dietary doses of caffeine (20-200 mg) generally produce positive mood effects such as increased well-being, happiness, energetic arousal, alertness, and sociability. Among daily caffeine consumers, much of the positive mood effect experienced with consumption of caffeine in the morning after overnight abstinence is due to suppression of a low grade withdrawal symptoms such as sleepiness and lethargy (see section on Caffeine Withdrawal). Large caffeine doses (200 mg or greater) may produce negative mood effects. Although generally mild and brief, these effects include increased anxiety, nervousness, jitteriness, and upset stomach. However, individual differences in sensitivity and tolerance affect the severity and likelihood of experiencing negative effects.

Reinforcing Effects: Drug reinforcement refers to the ability of a drug to sustain regular self-administration (i.e. drug-taking). As the most widely consumed mood altering drug in the world, it is clear that caffeine is a reinforcer. Furthermore, historical efforts to restrict or eliminate use of caffeine containing foods in various cultures have invariably met with failure. Contemporary research has shown that caffeine functions as a reinforcer when it is delivered in coffee, soft drinks, tea, or capsules. For regular caffeine users, the avoidance of low grade withdrawal symptoms, such as drowsiness after overnight abstinence, has been identified as a central mechanism underlying the reinforcing effects of caffeine.

ANXIETY AND CAFFEINE

Studies have shown that high dietary doses of caffeine (200 mg or more) increase anxiety ratings and induce panic attacks in the general population. Individuals with panic and anxiety disorders are especially sensitive to the effects of caffeine. Although highly anxious individuals tend to be more likely to limit their caffeine use, not all individuals with anxiety problems naturally avoid caffeine, and some may fail to recognize the role that caffeine is playing in their anxiety symptoms.

SLEEP AND CAFFEINE

Studies have demonstrated that caffeine disrupts sleep. When caffeine is consumed immediately before bedtime or continuously throughout the day, sleep onset may be delayed, total sleep time reduced, normal stages of sleep altered, and the quality of sleep decreased. Because of its ability to cause insomnia, sleep researchers have used caffeine as a challenge agent in order to study insomnia in healthy volunteers. Caffeine’s effects on sleep appear to be determined by a variety of factors including dose, the time between caffeine ingestion and attempted sleep, and individual differences in sensitivity and/or tolerance to caffeine. The effects of caffeine on sleep are dose-dependent with higher doses showing greater disruption on a number of sleep quality measures. Caffeine administered immediately prior to bedtime or throughout the day has been shown to delay sleep onset, reduce total sleep time, alter the normal stages of sleep, and decrease the reported quality of sleep. There is some evidence to suggest that caffeine taken early in the day also negatively affects nighttime sleep. Caffeine-induced sleep disturbance is greatest among individuals who are not regular caffeine users. Although there is evidence for some tolerance to the sleep disrupting effects of caffeine, complete tolerance may not occur and thus habitual caffeine consumers are still vulnerable to caffeine-induced sleep problems.

CAFFEINE TOLERANCE

Tolerance refers to a decrease in responsiveness to a drug after repeated drug exposure. High doses of caffeine (750 to 1200 mg/day spread throughout the day) administered daily, have been shown to produce "complete" tolerance (i.e., caffeine effects are no longer different from baseline or placebo) to some, but not all of the effects of caffeine. However, lower or typical dietary doses of caffeine produce incomplete tolerance. For example, sleep may continue to be disrupted in regular caffeine users.

CAFFEINE WITHDRAWAL

The caffeine withdrawal syndrome has been well-characterized in numerous rigorous double-blind studies. The potential for caffeine withdrawal to cause clinically significant distress or impairment in functioning is reflected by the inclusion of caffeine withdrawal as an official diagnosis in ICD-10 (World Health Organization) and as a proposed diagnosis in DSM-IV (American Psychiatric Association). Although most research on withdrawal has been performed with adults, there is also evidence that children experience withdrawal effects during caffeine abstinence.

Signs and symptoms. The most commonly reported withdrawal symptoms are listed below:

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Headache �?(often described as being gradual in development and diffuse, and sometimes throbbing and severe)

Fatigue -- (e.g., fatigue, tiredness, lethargy, sluggishness)

Sleepiness/drowsiness -- (e.g., sleepy, drowsy, yawning)

Difficulty concentrating -- (e.g., muzzy)

Work difficulty -- (e.g., decreased motivation for tasks/work)

Irritability -- (e.g., irritable, cross, miserable, decreased well-being/contentedness)

Depression -- (e.g., depressed mood)

Anxiety -- (e.g., anxious, nervous)

Flu-like symptoms -- (e.g., nausea/vomiting, muscle aches/stiffness, hot and cold spells, heavy feelings in arms or legs)

Impairment in psychomotor, vigilance and cognitive performances

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Dosing parameters. The incidence and severity of caffeine withdrawal is an increasing function of daily self-reported caffeine dose. Significant caffeine withdrawal has been shown to occur after abstinence from a dose as low as 100 mg/day, which is the caffeine equivalent of one 6 oz. cup of brewed coffee or two to three 12 oz. servings of caffeinated soft-drink. Caffeine withdrawal has also been shown to occur after stopping regular once-a-day consumption of caffeine (e.g. daily consumption of a single cup of coffee).

Incidence of caffeine withdrawal. Blind experimental studies in healthy normal caffeine consumers who abstain for �?24 hours indicate that the incidence of withdrawal headache is about 50%. When all withdrawal symptoms are considered, the incidence of caffeine withdrawal is higher. In a population-based random digit dial telephone survey study, 40 to 70% of individuals who tried to quit caffeine use reported experiencing withdrawal symptoms.

Many caffeine consumers may be unaware of their physical dependence on caffeine because their frequent habitual consumption precludes a period of sustained abstinence (e.g. 2 days). Furthermore, relatively low doses of caffeine (e.g. as little as 25 mg) can partially suppress withdrawal symptoms. Thus, some people may report never experiencing withdrawal because they unknowingly consumed small amounts of caffeine on days they thought they had been caffeine free. Finally, caffeine withdrawal symptoms (e.g., headache, nausea, muscle aches) may be misattributed to other causes or ailments (e.g., viral infection).

Severity of caffeine withdrawal. When signs or symptoms of caffeine withdrawal occur, the severity can vary from mild to extreme. At its worst, caffeine withdrawal has been repeatedly documented to produce clinically significant distress or impairment in daily functioning and, on rare occasions, to be totally incapacitating. For example, in a double-blind caffeine-withdrawal evaluation, 73% of individuals who met criteria for DSM-IV substance dependence on caffeine reported functional impairment in normal activities during an experimental withdrawal phase. The table below gives some examples of the types of functional impairments experienced during caffeine withdrawal. The proportion of regular caffeine consumers who are at risk for experiencing such functional impairment during caffeine withdrawal is difficult to estimate. In one double-blind study with individuals from the general community, 52% of individuals from the general community with an average caffeine intake of 260 mg/day reported moderate to severe headache, and 8-11% showed abnormally high scores on standardized depression, anxiety and fatigue scales. In another double-blind study, 45% of individuals experienced a diffuse, throbbing headache, with almost a third also reporting nausea and sickness.

Individual differences in caffeine withdrawal. There are substantial differences within and across individuals with regard to incidence and/or severity of caffeine withdrawal. As discussed above, only about 50% of regular caffeine consumers report headache after any single episode of caffeine abstinence. One study that examined repeated abstinence trials clearly showed differences within and across subjects: one individual never showed caffeine withdrawal headache, some showed consistent headaches, while others reported headaches on some trials but not other trials. Little is known about the determinants of these differences within and across individuals.

Time course of caffeine withdrawal. The caffeine withdrawal syndrome follows an orderly time course. Onset usually occurs 12 to 24 hours after terminating caffeine intake, although onset as late as 36 hours has been documented. Peak withdrawal intensity has generally been described as occurring 20 to 48 hours after abstinence. The duration of withdrawal has most often been described as ranging between 2 days and 1 week, although longer durations have been occasionally noted.

Examples of functional impairment observed during a double-blind caffeine withdrawal trial in eleven individuals who fulfilled DSM-IV criteria for substance dependence on caffeine.

Subject	Primary Vehicle	Caffeine Intake (mg/day)	Functional Impairment
1	Soft drink	231	Missed work; emesis
2	Soft drink	270	Failure to complete daily responsibilities, e.g., stopped doing errands, didn’t make child’s lunch, did not exercise
3	Coffee	295	None
4	Soft drink	302	Unable to complete schoolwork
5	Soft drink	342	Couldn’t perform work responsibilities; needed spouse to care for children, went to bed early
6	Soft drink	371	Data entry errors at work, went to bed early, unable to do normal recreational reading
7	Soft drink	430	Cancelled son’s birthday party, called spouse home early because could not care for children
8	Coffee	516	None
9	Coffee	642	None
10	Coffee	1029	Multiple costly mistakes at work, manufacturing wrong lenses for glasses, left work early, went to bed early
11	Coffee	2548	Screaming at his children

 

 

 

 

Caffeine, More Good Than Harm

• July 14th, 2006

Source: Jean Tang, Women’s Health

The cup of coffee that most of us use as a crutch to get going in the morning, or to make us sharper before concentrating on a task and that is so warm and smooth going down, must be bad for us right? Not necessarily.

Researchers have been analyzing caffeine for years and have not found substantial proof that it is bad for us. In fact, because it improves alertness and function, small amounts can actually be good for us.

Caffeine Increases Dopamine Levels in the Brain Which is Why it Feels Good

Caffeine is a natural stimulant which increases adrenaline in your bloodstream and increases your respiratory rate. In your brain, caffeine intercepts adenosine, the chemical that slows down our nerves and signals the need to sleep. It also increases dopamine levels, stimulating pleasure centers. That’s why people truly enjoy their caffeinated drinks.

Coffee has been found to improve cognitive functions by blocking that brain-slowing adenosine, says Joe Vinson, Ph.D., a food chemist at the University of Scranton. When given caffeine, severely sleep-deprived Navy Seal trainees improved their alertness, vigilance, learning, and memory by as much as 60%, according to Dr. Lieberman, who administered the test.

Smokers Are To Blame for Coffee’s Bad Rap

That myth the caffeine is bad for us exists in part because smokers tend to drink a lot of coffee and they have more health problems. But nicotine, not caffeine, is the culprit. Experts say as long as you don’t have high blood pressure, heart arrhythmia, or anxiety, drinking caffeinated beverages is not a health risk.

Caffeine Improves Exercise Performance

In terms of athletic performance, caffeine “might be the difference between first place and last,�?Dr. Vinson says. Without caffeine, not only are you a little slower mentally, you’re lagging physically. “Caffeine stimulates you to exercise 10% to 15% longer�?because it keeps you from getting as tired, explains Terry Graham, Ph.D., a nutritionist who specializes in caffeine at Ontario’s University of Guelph.

However, recent research advises strongly that people not drink a cup of coffee immediately before exercise. That consumption so close to a workout can cause problems.

It’s also a mild analgesic, so you can work out longer before you start to feel sore. However, a troubling new study published in the Journal of the American College of Cardiology shows that caffeine may decrease blood flow to the heart during exercise. More research is needed.

The Journal of the American Medical Association recently reported that caffeine doesn’t put you at risk for hypertension, although something else, unknown to scientists, in sugared and diet colas does.

In people with normal blood pressure, any change in heart rate is not only “too small to measure,�?Dr. Graham says, but it disappears within minutes of your first cup. If you already have high blood pressure, however, avoid excessive intake, says Lynne Shuster, M.D., director of the Mayo Clinic’s Women’s Health Clinic, because caffeine can exacerbate a pre-existing condition. The same goes for those who suffer from heart arrhythmia or anxiety - caffeine can trigger arrhythmia in those who are prone to it and can worsen anxiety.

However, Caffeine Can Be Addicting

Many people have experienced those headaches when they went off coffee for a couple of days. You develop a tolerance to caffeine over time, and when you no longer take any in, your body, expecting that daily dose, reacts with headaches and irritability. The more caffeine you consume, the more severe the withdrawal symptoms, but some people can get hooked on just a cup a day.

Everything in Moderation

A Greek study suggested that moderate to heavy coffee intake is associated with a higher level of inflammation. An immune system response, inflammation can be harmful because too much of it can produce chemicals in the body that have been linked to heart disease and diabetes. But just because coffee was associated with inflammation doesn’t necessarily mean it caused it.

These researchers don’t discourage caffeine consumption, but do warn against caffeine in excess. A safe limit, according to the American Journal of Clinical Nutrition, is around 400 milligrams - or four cups of coffee - a day.

But if you’re still worried about excess caffeine, try tea instead of coffee. Tea has so little caffeine (25 milligrams per cup compared to 125 milligrams per cup of coffee) that for most, it soothes rather than agitates.