Addiction Treatment Blog

While the bubbling and loud hissing urn
Throws up a steamy column, and the cups,
That cheer but do not inebriate, wait on each,
So let us welcome peaceful evening in.

William Cowper (1731-1800), ‘The Task’.

History

Caffeine addiction is one of the most common addiction types.

Caffeine is an important constituent of several plants that are cultivated for widespread consumption in the West. The most popular of these are listed in the table below, together with their caffeine content. The tea plant is native to Southeast Asia. It has been consumed in China as a hot infusion for many centuries. The Chinese character for tea is pronounced ‘tay‘ or ‘cha‘ depending upon the dialect. Tea was introduced into Europe in the early 1600s and in Britain was originally termed ‘tay’; the modern pronounciation ‘tea‘ originated in the 18th century.

The coffee plant is native to Ethiopia and local legend relates that the first human use was by a holy man who prepared an infusion of the seeds in water so that he might stay awake at night to pray. The plant was first cultivated by man in the vicinity of Mocha in Yemen, the plants having been originally taken from Kefa in Ethiopia. Until the end of the 17th century, this region supplied most of the world’s coffee. From the mid-17th century onwards, coffeehouses in London became important centres for political, literary and business dealings. Coffee and tea consumption and cultivation spread rapidly once Europeans acquired a taste for them. European nations, especially the British and Dutch, subsequently encouraged their colonies to grow the plants.

Chocolate is a relatively minor source of caffeine. It is prepared from the seeds of the cacao tree (Theobroma cacao) which is native to South America. A drink prepared from the seeds by the Aztecs was ‘chocalatl’ (bitter), and was described as the food of the gods.

Major dietary sources of caffeine

Effects Sought

Caffeine is taken primarily for its stimulant effect on the central nervous system (CNS). It is the most widely used psychoactive substance in the world. Caffeine produces increased alertness, decreased fatigue, clear-headedness, intellectual stamina and enhanced physical endurance. In those habituated to caffeine, administration gives rise to a contentment, possibly related to the avoidance of withdrawal symptoms but also influenced by the social ease associated with the drinking of caffeinated drinks and the personal expectation of CNS stimulation. Recent work suggest that to some extent negative reinforcement drives the daily consumption of caffeinated drinks. Thos habituated to caffeine show a strong preference for caffeinated drinks as opposed to caffeine-free varieties, even when the caffeine content is not known to the consumer. The effect is particularly apparent in the morning because enforced overnight caffeine abstinence produces dysphoria which is alleviated by ingestion of caffeine. It has been further proposed that a liking for the taste and the smell of caffeinated beverages is driven by Pavlovian-like conditioning: taste and smell alerting the brain that a stimulating caffeine ‘reward’ is about to arrive. As with other psychotropic substances, many of the effects are at least partly determined by the expectation of the user.

Administration

Caffeine intake has been arbitrarily classified according to the following values for daily consumption:

• low: 0 to 250 mg per day;
• moderate: 250 to 750 mg per day;
• high: in excess of 750 mg per day.

The amount of caffeine consumed by the average person is difficult to estimate because of the various forms of each beverage and the different methods of preparing them. For example, percolated coffee usually contains more caffeine than instant varieties. If the coffee grounds are boiled during preparation – a method popular in many Scandinavian countries – the caffeine content can be as high as 500 mg per cup. Tea brewed directly from the crushed leaf releases more caffeine into the infusate than tea bags. The various strains of coffee and tea plants also differ in their caffeine content.

Plain chocolate contains more caffeine than milk chocolate. Chocolate also contains large amounts of theobromine, a methylxanthine with approximately 10 per cent of the pharmacological activity of caffeine. Products flavoured with chocolate contain only small amounts of caffeine (e.g. chocolate ice cream has 2 to 5 mg of caffeine per 50 g).

A variety of other preparations also contain caffeine. These include OTC stimulants (e.g. Pro-Plus), analgesic medicines (e.g. Anadin, Solpadeine) and herbal products (e.g. Guarana).

Pharmacokinetics and Pharmacology

Caffeine is a member of the group of compounds known as methylxanthines, which also includes theophylline. Many of the effects of methylxanthines are thought to be mediated via competitive antagonism of adenosine. Adenosine is a neurotransmitter with largely inhibitory actions in the CNS. Benzodiazepines are thought to act as adenosine agonists and it is therefore not surprising that methylxanthines and benzodiazepines have opposing CNS actions.

In vitro, methylxanthines inhibit phosphodiesterase, the enzyme which causes breakdown of cyclic AMP. This group of drugs also has effects on the intracellular movement of calcium ions. However, neither of these actions is likely to occur to a significant extent in humans except at very high doses. Caffeine can also increase the concentration of circulating catecholamines but the mechanism of this and its importance to methylxanthine pharmacology is uncertain.

The average half-life of caffeine in adults is five hours but with considerable variation between individuals (range: 2 to 12 hours). The main metabolite is paraxanthine which is inactive but small amounts of theobromine and theophylline are also produced. Each of these metabolites is subject to further enzymatic degradation before elimination. Following oral administration, caffeine is almost 100 per cent bioavailable and reaches peak plasma concentration 15 to 45 minutes after ingestion. Like theophylline, the clearance of caffeine is accelerated by drugs which induce cytochrome P450 metabolism. Thus, for example, tobacco smoking will increase caffeine clearance but metabolism is appreciably slowed in women taking oral contraceptives.

Adverse Effects of Caffeine

On being told that coffee was a slow-acting poison, Voltaire is said to have remarked: ‘I think it must be so, for I have been drinking it for 65 years and I am not dead yet.‘ There is no proven association between caffeine intake and any fatal illness at normal levels of consumption. However, caffeine is pharmacologically active and can produce a range of effect in man. It is difficult to specify the dose of caffeine required to produce particular effects, because the amount that individuals ingest is rarely known. In addition, the sensitivity to methylxanthines and the pharmacokinetic profile varies markedly between individuals; dose-related effects are also affected by tolerance, which can develop quickly.

Caffeine-related adverse effects are often wrongly attributed to other causes through ignorance. Recurrent headaches, persistent anxiety, inability to concentrate, muscular tremor/tension and chronic insomnia are probably the commonest of these reactions. The psychostimulant action of caffeine upon the CNS is dose-related but in individuals who do not regularly consume it, even quite small amounts can cause irritability, insomnia and nerveousness. The escalation of stimulant effects with increasing dose is illustrated in the table below.

Severe psychiatric upset and convulsions are the ultimate, if rarely observed, sequelae of high-dose usage. Some of the other pharmacological effects of caffeine are also shown in the table below. At regular daily doses above 0.5 to 1 g, the condition known as ‘caffeinism’ may develop. This frequently has a presentation akin to anxiety neurosis because the CNS effects predominate. Other symptoms are given in the table below.

High, regular caffeine intake can exacarbate the symptoms of pre-existing psychiatric illness such as anxiety, depression and schizophrenia. The stimulant effect of caffeine may encourage patients to consume large quantities in order to overcome the sedative effects of psychiatric medication. If this resulted simply in the reversal of unacceptable sedation then it would be helpful but caffeine can also antagonise the therapeutic actions of benzodiazepines and phenothiazines. High caffeine consumers who are taking these medications require larger doses of drug to control their symptoms. In the case of benzodiazepines, this is probably due to the opposing pharmacological action of caffeine on adenosine.

Caffeine-containing drinks may cause phenothiazines to precipitate when the two are mixed. The tannic acid content may be responsible. Tea may be more potent than coffee in causing precipitation, although the effect is not related to the caffeine content of these beverages. Stomach acid reserves the precipitation in vitro but in some animal studies the absorption of phenothiazines has still been impaired. The practice of mixing phenothiazines has still been impaired. The practice of mixing phenothiazines with tea or coffee should not be encouraged because of the following:

• If only a proportion of the drink consumed it is impossible to ascertain how much drug has been taken. The precipitate may discourage a patient from finishing a drink due to unpalatibility.
• The precipitate might settle in the cup or stick to the sides of it so that the drug is not ingested even if a substantial proportion of the drink is consumed.
• In patients taking antacids or drugs which reduce acid secretion from the stomach, the reversal of precipitation cannot occur.
• Precipitation in a drink and its potential reversal in the stomach introduces unnecessary uncertainty into drug therapy. The response to phenothiazines could vary from day to day in the same patient because of this practice.

Superimposing the adverse psychiatric effects of caffeine on top of an existing psychiatric disorder may change the clinical presentation. The new predominating symptoms may not be ameliorated by existing medication. A high caffeine intake is also undoubtedly the reason behind some prescriptions for hypnotics and anxiolytics. Persistent caffeine stimulation encourages those affected adversely to take a CNS depressant drug in order to try to restore the normal sleep/wake cycle of the body. In the elderly, in whom the sleep/wake cycle is naturally subject to increased disruption, caffeine may have more obvious sleep-disturbing properties. Unfortunately, many elderly patients find it difficult to believe that tea and coffee, which most have been drinking for several decades, could be part of the cause of their insomnia.

Many patients with a high intake of caffeine also take considerable quantities of a very common CNS depressant – alcohol. The role of caffeinism in fuelling alcoholism has not been adequately researched. Caffeine is also suspected of involvement in the aetiology of some cases of the restless legs syndrome.

Caffeine can cause mutagenesis in bacteria but studies in laboratory animals reveal no evidence of carcinogenicity. Despite initial concerns, epidemiological studies have not proved a link between caffeine consumption and any cancer in humans. Specifically, investigations have not revealed an association between caffeine intake and human cancer of the breast, pancreas, bladder, ovary or colon. However, such studies are complicated by the widescale use of caffeine and the difficulty of excluding all other confounding variables.

Similar arguments apply to studies of the relationship between caffeine intake and coronary heart disease. Small amounts of daily coffee do not seem to be associated with an increased risk but as the daily intake increases the likelihood of an association also increases. the overall risk associated with coffee drinking is probably small. However, high-dose methylxanthines do stimulate the myocardium so that it would seem wise for those with existing cardiovascular disease to avoid excessive intake. Large amounts of boiled unfiltered coffee have been known for some time to raise plasma cholesterol levels by 6 to 10 per cent (low density lipoprotein cholesterol by 9 to 14 per cent). This has been suggested to increase the risk of coronary heart disease by 12 to 20 per cent. The effect is thought to be due to two diterpenes in coffee – cafertol and kahweol – and is reversible upon cessation of cafetiere coffee intake. Plasma cholesterol levels are not raised after drinking amounts of filter coffee because the diterpenes are retained on the paper filter. The same study showed that cafetiere coffee raises serum alanine aminotransferase (which is a signal for liver damage) in all patients but that this only exceeded the upper limit of normal in 36 per cent. The clinical relevance of these findings to liver function is now known at present.

Caffeine can also stimulate the production of gastric acid, so potentially worsening the symptoms of acid-related gastrointestinal disease in susceptible individuals. Decaffeinated coffee is at least as detrimental in this respect as caffeine-containing varieties, suggesing that caffeine is not the culprit and that patients with acid-related gastrointestinal disease will not benefit by swapping from caffeinated to decaffeinated coffees.

Caffeine encourages urinary excretion of calcium but a link between caffeine intake and osteoporosis has not been demonstrated.

Some effects produced by caffeine-containing beverages are not due to the caffeine itself. For example, the high tannin content of tea can cause constipation wheras the essential oils in coffee may give rise to gastrointestinal upset and diarrhoea. The table below lists some of the known ingredients of coffee and tea.

Side effects of caffeine

Loe to moderate intake of caffeine

• Diuresis
• Increased gasteric acid secretion
• Fine tremor
• Increased skeletal muscle stamina
• Mild anxiety

High intake of caffeine

• Chronic insomnia
• Persistent anxiety, restlessness, tension, agitation, excitement, panic attacks, inability to concentrate
• Confusion, disorientation, paranoia, delirium
• Tremors, muscle twitching, muscle tension, convulsions
• Vertigo, dizziness, tinnitus, auditory and visual disturbance
• Facial flushing, increased body temperature, raised blood pressure
• Palpitations, arrhythmias
• Nausea, vomiting, abdominal discomfort
• Headaches
• Tachypnoea

Lethal acute adult dose: 5-10 g caffeine

Chemicals found in tea and coffee

Tea leaves

• Tannin (10-24 per cent)
• Caffeine (1-5 per cent)
• Various proteins
• Theobromine, theophylline
• Volatile oils
• Over 20 amino acids
• About 30 polyphenolic compounds (e.g. theaflavins, thearubigins)
• 12 sugars
• 6 organic acids (e.g. oxalic)
• Various B-group vitamins
• Minerals (e.g. manganese, fluoride)

Coffee beans

• Fixed coffee oil (15 per cent) including linoelic and oleic acids
• Various proteins (11 per cent)
• Sucrose and other sugars (8 per cent)
• Chlorogenic / caffeic acids (6 per cent)
• Caffeine (0.75 – 2.75 per cent)
• Trigonelline
• Volatile oils
• Oxalic and tannic acids
• Minerals (e.g. magnesium, potassium)
• Various B-group vitamins (especially nicotnic acid)
• Cafertol, Kahweol

Caffeine Dependence

Dependence on caffeine undoubtedly occurs and has both a psychological and physical aspect. The former is best characterised by the rituals, habits and beliefs associated with ingestion. For example, many people always take caffeine at certain times of the day (e.g. afternoon tea, coffee with breakfasts) and there is a strong desire to continue taking caffeinated substances to maintain/achieve a sense of well-being. Caffeinated drinks form an important part of many social occasions and are part of the cultural background to our society. ‘Tea time’ and ‘coffee breaks’ are terms used to describe points in the day when caffeine may be taken but these terms are used even by those that do not take caffeine at these times.

The physical aspects of caffeine dependence are most notably the apparent tolerance to some of its effects (e.g. diuresis) and the existence of a definite withdrawal syndrome. Withdrawal is typified by headache, irritability, restlessness, dysphoria, anxiety, depression, lethargy, fatigue, poor concentration and feeling antisocial. Less common symptoms include muscular tension and pains, sweating, rhinorrhoea and nausea. Some sufferers experience craving for caffeine. Hedache is the most common feature of withdrawal. Symptoms usually start within 24 hours of abstinence, peak during the next one or two days and last up to a week. In those who consume moderate amounts of caffeine each day, dysphoric symptoms can be observed every morning, after only overnight abstinence. Withdrawal reactions are seen only after chronic administration but is not limited to those with a high caffeine intake. Most users are aware, even if only subconsciously that the symptoms of withdrawal can be rapidly reversed by ingesting more caffeine. Negative reinforcement may therefore play a part in ensuring continued dependence.

Headaches that occur in many patients following surgery under general anaesthetic have been attributed to caffeine withdrawal caused by forced abstinence.

Tolerance to the stimulant effect of caffeine develops to some extent but, unlike many psychoactive substances, there generally seems to be no particular desire to increase the amount of caffeine consumed with time. Most consumers continue to drink caffeinated beverages at roughly the same intake for their lifetime.

The table below gives suggestions for making caffeine withdrawal less unpleasant.

Steps to help reduce caffeine intake

• Educate the subject regarding the potential adverse effects of caffeine and discuss how health may be improved by stopping or reducing caffeine intake. The individual should understand the nature and time course of withdrawal.
• It is important to identify all the current means of caffeine intake and the patterns of use (frequency, quantities). Ensure that one form of caffeine intake is not inadvertently swapped for another.
• Withdrawal is probably easier if it is not abrupt. Drinking tea or coffee which is gradually made weaker than usual may help. The frequency of ingestion and perhaps the volume of beverage can also be progressively reduced.
• Substitution of caffeinated drinks wholly or partly with deaffeinated varieties may help, especially as these have a similar taste and presentation to caffeinated varieties. Again, this may need to be a gradual changeover.
• In order not to disrupt the psychological aspect of the daily routine and to keep social rituals alive, the subject should be encouraged to drink something at the time of the day when caffeine was normally taken, e.g. herbal teas (but check that these do not contain caffeine)
• Non-caffeine containing analgesics may be helpful to treat withdrawal headache.
• If caffeine intake is to be reduced rather than stopped completely, the subject may find it helpful to limit consumption to certain fixed times of the day, e.g. one coffee with breakfast and one after lunch.

Are You Addicted to Caffeine?

If you are addicted to caffeine or are feeling stressed because of excessive caffeine intake, don’t forget that there is help available. The Causeway Retreat is Europe’s leading addiction treatment facility and it helps people with addiction. To find out more, give us a call on 0207 100 7260 or fill the form below. Please note that all of the information you supply to us remains confidential.