Psychoactive substances as per ICAO Doc 9645,considered in this document are: alcohol, opioids, cannabinoids, sedatives and hypnotics, cocaine, other stimulants, hallucinogens, and volatile solvents. The document does not consider tobacco or caffeine.1
1. In the ICD-10 classification of Mental and Behavioural Disorders, WHO, Geneva 1992, both tobacco and caffeine are listed as psychoactive substances.
Caffeine is the most widely used psychoactive drug in the world, found in coffee, tea, cocoa, chocolate candy, and soft drinks. While caffeine has several positive effects such as increasing energy and mental alertness, heavy use can cause symptoms such as anxiety and insomnia. Caffeine is physically addictive, and withdrawal symptoms can include headaches, fatigue, and irritability.
The use of psychoactive substances by individuals can give rise to significant problems. Not only are there potentially harmful effects from the substance use itself, but use can also lead to physical and psychical dependence. Whether or not this dependence is regarded as a “disease” per se, it is clear that the dependence and any attendant psychological or physiological pathology must be treated professionally. Only a trained specialist can determine whether a pathological condition is present, what the condition is, and what treatment is appropriate.
Caffeine: Cognitive and Physical Performance Enhancer or Psychoactive Drug?
The use of caffeine to stay awake and alert is a long-standing habit. Coffee is the most popular beverage after water and is consumed worldwide in daily amounts of approximately 1.6 billion cups, which is quite an impressive figure.
There is some uncertainty about the etymology of the word “coffee”. The botanical name of the plant from which coffee is derived is Coffea Arabica: it finds its origins in Ethiopia and is an exceptionally hardy self-pollinating plant. The Persian physician Rhazes was the first to mention it in his manuscripts. Yemen was the first country to cultivate the coffee plants, whilst Turkey was the first country to roast the green coffee beans. So it is not surprising that the word “coffee” finds its roots in Arabia, where it was called “qahwah”. Although there is no doubt about the origin of the word, researchers do not agree on how the language process led the English word “coffee”. It is likely that the latter found its way into European languages in the 17th century from the Italian word “caffé”, stemming, in turn, from the word “kahveh”, which was the Turkish way to pronounce “qahwah”. Over the centuries, the habit of drinking coffee spread from Arabia to all the world.
Caffeine is contained in more than sixty plants, which is a remarkable number, thus it has been hypothesized that caffeine was originally a minor nutrient, not essential for the plant, but extremely useful as a pesticide. In fact, caffeine is toxic for several insects and animals, especially herbivores. Through caffeine the plant may defend itself and have a better chance of survival: in this view, caffeine can be considered as a “co-evolutionary protecting agent”.
“The Canon of Medicine”, written in 1025 by the Persian physician Avicenna, is the first text mentioning coffee as a medication. At the time, coffee was used to “clean the skin, dry up the humidities that are under it, and give a better odor to the body”. In the 15th century, the diffusion of coffee, initially employed by Muslim dervishes for providing energy, had remarkably increased and countless coffee houses had opened in Arabia. In the late 17th and in the 18th century, as sea shipping had expanded, the use of coffee became common in Europe .
The stimulant effects of caffeine on the central nervous system have been known for centuries . In the 19th century a well-known consumer was Honoré De Balzac. Saying that he loved the coffee is not enough. He was completely dependent on it and in the period in which he wrote “The Human Comedy” he went on to drink up to 50 cups a day. In 1830, he published an article in a French magazine called “Pleasures and pains of coffee”, which recounted: “coffee slips into the stomach and you immediately feel a general commotion. Ideas begin to move like the battalions of the Grand Army on the field of the battle and the battle takes place. Memories come at a gallop, carried by the wind”. Nowadays, caffeine is believed to be the most frequently consumed psychostimulant worldwide, being ingested predominantly as coffee. Many other caffeine-containing beverages and products exist and contain significant amounts of the substance, for example, tea, chocolate, cocoa beverages, soft drinks, and energy drinks. Coffee and caffeinated beverages are part of the diet in all countries.
With regard to cognitive functions, caffeine’s properties have been investigated in both human and animal studies. In epidemiological reports, a link between chronic caffeine consumption and a significantly lower risk of developing neurodegenerative diseases, such as Alzheimer’s disease, has been described . Likewise, chronic treatment with caffeine has been shown to be effective in preventing β-amyloid (Aβ) production and memory deficits in experimental models of Alzheimer’s disease. While caffeine seems to prevent or restore memory impairment due to disturbances in brain homeostasis, its cognition-enhancing properties are still a matter of debate . Besides, moderate-to-high consumers develop tolerance to caffeine and only low or nonconsumers can eventually benefit from an acute administration .
In addition, in epidemiological reports and experimental models, caffeine has been found to have a role in the prevention of motor symptoms and loss of dopaminergic neurons in Parkinson’s disease.
With regard to physical activity, it should be noted that until 2004 the International Olympic Committee listed caffeine in its prohibited substances list. Professional athletes who tested positive for more than 12 μg/l of urine – which corresponds to drinking about 5-6 cups of coffee in a day – were banned from the Olympic games .
In the past years, a relationship between coffee consumption and several types of cancers, such as colon, bladder, and pancreatic ones, has been postulated. Yet, the recent literature has provided no evidence of this relationship.