Many people start the day with a good cup of coffee . This substance has reached a very high level of popularity throughout history, being taken by around 80% of the adult population and being an element widely present in everyday life, its consumption being used even as a pretext at the time of socialising.

Coffee helps to clear the mind, increase the level of activation and improve attention span. But, how can coffee affect us in this way? What happens in your brain when you drink coffee?

Caffeine, an excitatory substance

Caffeine, one of the main components of coffee, has, as we already know, psychoactive effects on our brain. Due to the effect they produce on the nervous system, they are part of the psycho-stimulant or psycho-analytic substances, substances characterized by producing an increase in the activation and the brain metabolism, generally managing to increase the level of activity of the organism.

However, within this group caffeine is considered a minor activator, forming together with theophylline and theobromine the group of substances known as xanthines. This group, although it presents activating effects in the organism, has a much less powerful performance than other excitatory substances and much less side effects, not often presenting serious adverse effects.

Caffeine takes a few minutes to reach the brain, and its effects tend to last about four to six hours . It is not uncommon for it to be consumed several times a day, without this having to be dangerous due to its low addictive potential. In spite of this, its habitual consumption ends up producing certain levels of tolerance, with a greater quantity or frequency of the substance being necessary to provoke the same effects as at first.

Action at the brain level: mechanisms of action

About five minutes after drinking a cup of coffee, caffeine begins to exert its effects on the nervous system. This substance acts differently throughout the nervous system, interacting and causing effects on different types of neurotransmitters.

The activating effect of coffee is mainly due to the action on a hormone called adenosine, a hormone that contributes to maintaining a state of calm and relaxation by inciting the suppression of brain activity as well as maintaining medium or low levels of other hormones such as dopamine and noradrenaline. Caffeine acts as an antagonist to adenosine receptors, affecting its absorption in a way that inhibits its reuptake by neurons. This action results in an increase in brain activity and intensity of transmission of nerve signals by allowing greater action by other hormones such as dopamine.

Brain reward system

In addition to its effect on adenosine, caffeine also interacts with other neurotransmitters. Another major effect of caffeine on the brain is the increased release of dopamine, which activates the brain’s reward mechanisms to induce a state of well-being.

However, while other substances such as cocaine activate the entire system (facilitating its enormous addictive potential), caffeine and xanthines often cause increased dopaminergic release in more specific areas such as the caudate nucleus and prefrontal cortex. In this way, a sense of activation is achieved that is somewhat pleasant, but without activating the entire brain’s reward system.

Caffeine stimulates in turn the noradrenergic and cholinergic systems, producing an increase in activation and an improvement in the capacity of concentration and information processing.

Finally, it is important to note that caffeine consumption causes an increase in levels of cortisol, the so-called stress hormone, and adrenaline. This effect helps to induce a state of activation at a physiological level that allows one to remain alert and vigilant. However, it can also cause distress or negative stress that can lead to maladaptive behavior, heart racing or anxiety.

Beneficial effects

Coffee consumption can bring many benefits as long as it is done wisely and without excess. Some of the positive effects that coffee has on the organism are the following .

1. Increases wakefulness and decreases the level of fatigue

The fact that caffeine inhibits the action of adenosine and enhances an increase in cortisol and other excitatory hormones causes the level of consciousness to remain high, thereby causing the levels of fatigue and tiredness the body may be experiencing to be reduced.

2. Promotes attention span and learning ability

By maintaining the level of consciousness and reducing the sensations of fatigue and tiredness, the subject’s attention span also increases, enabling him to use and distribute his physical and cognitive resources more efficiently and for longer.

In addition, it allows nerve impulses to be transmitted with great intensity, which can favour the acquisition of new learning and the reinforcement of existing ones.

3. It has a protective effect against certain dementias

Recent research has investigated the possible role that caffeine consumption may have in contributing to the prevention of certain dementias.

Specifically, its regular consumption may serve as a protective factor against Parkinson’s and Alzheimer’s by stimulating the dopaminergic, cholinergic and noradrenergic systems and having antioxidant effects that reduce the number of free radicals present in the system.

4. Accelerates metabolism

The increased activity that caffeine produces usually translates into a state of physiological excitement accelerating the metabolism not only of the brain but of the whole body. It has been demonstrated that the consumption of coffee before physical exercise helps to decompose the fat of our body.

In addition, this acceleration usually leads to an increase in physical activity, which, in addition to facilitating the burning of fat, predisposes the body to activities that allow it to be lost

5. Diuretic effect

Caffeine also has an important diuretic effect. It has been shown to stimulate urine production, helping to excrete elements that are harmful to the body.

It also has antiemetic effects if consumed in moderation, preventing the occurrence of vomiting and reducing the level of nausea,

Possible damages

One or several cups of coffee a day can positively affect our brain, but as with most substances and foods consumed, an excess can have adverse effects .

1. Sleep problems

As mentioned above, caffeine causes a decrease in the feeling of fatigue or tiredness.

Although it may increase the alertness in people with daytime sleepiness, depending on how, when and how much is consumed it may cause the individual to be unable to fall asleep , conciliation insomnia being the most frequent effect.

2. Anxiety disorders

The elevation of the amount of cortisol and adrenaline produced by coffee causes an increase in the excitability of the subject who has consumed it. Although in some circumstances it can be beneficial for learning or acting efficiently, on other occasions this increase generates a higher stress than the individual is capable of handling , and anxiety reactions can appear.

In fact, caffeine consumption is not recommended for stressed individuals or those with anxiety disorders.

3. Agitation, tachypsique and logorrhea

While the increased activation produced by coffee may be desirable in low doses, in higher amounts caffeine can cause the presence of agitation, tremors (and even seizures) .

Cognitively, there may also be tachypsychia or accelerated thinking, in which there is often a flight of ideas or a loss of the train of thought. Another common symptom is logorrhea.

4. Stress and irritability

The increase in activation of the nervous system and the slightly more expansive mood than usual , as well as the increase in the level of stress generated by coffee, mean that sometimes the person who has consumed caffeine tends to be aggressive or irritable when faced with stimuli that would not generally be aversive.

5. Cardiac effects

Neither is the consumption of caffeine usually recommended for people with cardiac disorders , given that it can induce tachycardia and arrhythmia that in people with a certain standard of living and with certain pathologies could lead to a heart attack or even cardiorespiratory arrest.

6. Risk of death

Although a high quantity is usually necessary, the consumption of quantities exceeding ten grams of caffeine can induce epileptic seizures, or cardiorespiratory problems that could culminate in the patient’s death .

7. Withdrawal syndrome

It has also been discussed that caffeine can, with prolonged and frequent consumption over time, lead to withdrawal . This syndrome is translated into the presence of excessive sleepiness, nausea and vomiting, anxiety and/or depression after abandoning or abruptly reducing consumption.

8. Other aspects

The elevation of the state of mind and the high level of activity that can produce in some people the consumption of caffeine makes it not suitable for people with certain characteristics . For example, in mood disorders (for example, during manic episodes in the case of bipolar disorder) or in psychotic disorders.

Bibliographic references:

  • American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders. Fifth edition. DSM-V. Masson, Barcelona.
  • Glade, M. J. (2010). Caffeine – not just a stimulant. Nutrition, 26(10), 932-938.
  • Macedo, J. (n.d.). Drinking coffee: advantages and disadvantages of its consumption. Online] Available at: https://psicologiaymente.com/neurociencias/beber-cafe-ventajas-desventajas
  • Salazar, M.; Peralta, C.; Pastor, J. (2006). Manual of Psychopharmacology. Madrid, Editorial Médica Panamericana.
  • Smith, A. (2002). Effects of caffeine on human behavior. Food and chemical toxicology, 40(9), 1243-1255.