Three short divulgation essays – 1 The neuroscience of coffee

©

Leandro Castelluccio

 

Cover image taken from link

 

Introduction

Coffee is a widely consumed beverage in the world. It belongs to the group of psycho-stimulants for its caffeine content, a compound with stimulating properties at the brain level, although coffee is a beverage with multiple chemical compounds with different effects at the biological level. It is usually consumed at different times of the day, usually at breakfast, or after certain meals, and is associated with improvements in mood and certain cognitive abilities, since caffeine stimulates noradrenergic and cholinergic systems, producing an increase of activation and an improvement in the capacity for concentration and information processing (see in link). 

Levels of action

Caffeine acts mainly as an antagonist at the level of adenosine receptors in the brain, blocking their action without generating an active effect on them. Adenosine levels regulate certain states of relaxation and induce sleep, when these are high one feels more tired or sleepy. But with the blocking action of caffeine, the person can remain alert and activated for longer, thanks to the activity of neurotransmitters such as dopamine and noradrenaline. In turn, caffeine seems to have an effect on the increase in dopamine release, which activates the brain’s reward mechanisms to induce a state of well-being. While other substances such as cocaine activate the whole system, caffeine usually causes an increase in dopaminergic release in more specific areas such as the caudate nucleus and the prefrontal cortex. This could imply lower addictive levels, although it is suggested that it still has a potential as a drug that can generate dependence and addiction (see in link).  However, as indicated by Nehlig, Armspach and Namer (2010), caffeine activates some regions mainly involved in the control of vigilance, anxiety and cardiovascular regulation, but does not affect the areas involved in reinforcement and reward, which may mean less power of dependence.

However, the effects of caffeine do not just stay there. Apparently, regular caffeine consumption decreases norepinephrine receptors, along with serotonin, a mood enhancer. Some studies have also seen changes in different adenosine receptors when caffeine becomes normal, although caffeine is probably not directly responsible for all these changes (see in link). In turn, the consumption of caffeine causes an increase in the levels of cortisol, known as stress hormone, and adrenaline. This effect helps induce a state of activation at a physiological level that allows one to remain alert and attentive. However, it can cause negative stress that can lead to maladaptive behaviors, heart accelerations and anxiety(see in link).

A hidden addition?

As with many substances, the body develops tolerance to caffeine. As one consumes coffee regularly, increasing doses are required to obtain the same effect. Exactly how that tolerance develops is not so clear, although many studies have suggested that the creation of more adenosine receptors is involved in the process. The tolerance is such that after a fairly regular intake, drinking several cups of coffee a day seems to have no stimulating effect, but if the consumption is abandoned, one begins to feel symptoms of withdrawal fairly quickly. This happens because the brain gets used to operating with caffeine, and the neurochemistry changes depending on this. Headaches are the almost universal effect of eliminating caffeine, but depression, fatigue, lethargy, irritability, nausea and vomiting can also be part of these withdrawal effects. In any case, in general, the symptoms disappear after a couple of days (see in link).

From the individual experiences, we can associate the regular use of coffee more than with a particularly pleasant long-term effect, with a way to avoid the lethargy and the natural fatigue that it generates, since with time the effect of coffee is not the same, it is eventually consumed to neutralize the negative effects of its absence. This may be associated to some extent with the hedonic-allostatic theory of addiction, which proposes that the initial use of drugs is mainly controlled by the rewarding effects of the addiction, but that chronic use leads to a reduction of its rewarding effects and recruitment of systems related to stress (Badiani, Belin, Epstein, Calu, & Shaham, 2011). This introduces an interesting idea, which could tell us a lot about motivation and why we could use drugs in general, which is to avoid negative states, in simple terms, avoid suffering or disgust.

cerebro3fases_LegendasImage taken from link

According to an study, certain participants (consumers accustomed to a daily average amount of caffeine of 650 mg), before consuming their usual dose of caffeine, presented low levels of visual and auditory activity in the brain (indicated by the bright colors in the images above). After ingesting 250mg of caffeine, activity increased, but only to levels identical to occasional consumers who had not consumed caffeine. According to the researcher Paul Laurienti, the regular consumption of high amounts of caffeine means that we will need it in order for the brain to function normally, so without it, the brain will function at a reduced level, so to speak (see in link).

Other physiological effects of coffee

In spite of the above, many studies relate the consumption of coffee with many health benefits. As mentioned by Dr. Michael Greger, the mortality rate of coffee consumers is lower. This may be because coffee might have beneficial effects on inflammation, lung function, insulin sensitivity and depression. This may be due, in part, to a class of polyphenol phytonutrients found in coffee beans called chlorogenic acids, which have been shown to have favorable effects, such as a reduction in acute blood pressure. However, chlorogenic acid levels vary between different types of coffee. In addition, adding milk to coffee seems to block its beneficial effects. This does not happen if it is taken with soymilk for example (see in link). But in turn, there is another problem with coffee, and it is its ability to increase cholesterol, a factor present due to the fatty substances in the oil of coffee beans. The component cafestol is involved in this, and it has been shown that even filtered coffee cannot stop the small particles that transport the compound to enter our body and raise cholesterol levels (see in link).

So is coffee good or bad?

As Dr. Michael Greger points out, coffee can cause heartburn and worsen osteoporosis, but it can protect against diabetes, Parkinson’s and Alzheimer’s. (see in link). The worsening effects on anxiety could also be a problem. Therefore, there are positive and negative effects. However, as Greger mentions, there is something much healthier that one can drink than coffee, and that is tea, which has the beneficial effects without the negative side effects of coffee (see in link 1, link 2). The best thing would be green tea compared to other preparations of it. Also worth mentioning, tea contains lower amounts of caffeine than coffee (Bunker & McWilliams, 1979).

References

Badiani, A., Belin, D., Epstein, D., Calu, D., & Shaham, Y. (2011). Opiate versus psychostimulant addiction: the differences do matter. Nature Reviews Neuroscience12(11), 685.

Bunker, M. L., & McWilliams, M. (1979). Caffeine content of common beverages. Journal of the American Dietetic Association74(1), 28-32.

Geographic, N. (n.d.). Ninguém vive sem cafeína. Retrieved from https://nationalgeographic.sapo.pt/ciencia/grandes-reportagens/1040-cafeina-jan2005?showall=&start=2

Greger, M. (n.d.). Coffee & Mortality. Retrieved from https://nutritionfacts.org/video/coffee-and-mortality/

Greger, M. (n.d.). Does Adding Milk Block the Benefits of Coffee? Retrieved from https://nutritionfacts.org/video/does-adding-milk-block-the-benefits-of-coffee/

Greger, M. (n.d.). Does Coffee Affect Cholesterol? Retrieved from https://nutritionfacts.org/video/does-coffee-affect-cholesterol/

Greger, M. (n.d.). Is Coffee Bad For You? Retrieved from https://nutritionfacts.org/video/is-coffee-bad-for-you/

Greger, M. (n.d.). Update on Coffee. Retrieved from https://nutritionfacts.org/video/update-on-coffee/

Mimenza, C., Barcelona, (2018). ​¿Qué ocurre en tu cerebro cuando tomas café? Retrieved from https://psicologiaymente.com/neurociencias/que-ocurre-cerebro-cafe

Nehlig, A., Armspach, J. P., & Namer, I. J. (2010). SPECT assessment of brain activation induced by caffeine: no effect on areas involved in dependence. Dialogues in clinical neuroscience12(2), 255.

Purdy, K. (2013). What Caffeine Actually Does to Your Brain. Retrieved from https://lifehacker.com/5585217/what-caffeine-actually-does-to-your-brain?utm_medium=sharefromsite&utm_source=lifehacker_copy&utm_campaign=top

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