Antidepressants – Questions you always asked yourself

I will try to answer these and many other questions through this article that I decided to write after giving a psychopharmacology class to a group of psychologists.

There were many questions I was asked, and it occurred to me to answer them in a language aimed primarily at the general population (especially those who take antidepressants or may take them at some point in their lives), but also those who are initiated in psychotherapy or are in training.

What are antidepressants?

Antidepressants are a group of medicines used mostly to treat depression. And if I say ‘above all’ it is because their use, on some occasions, has been discovering their usefulness for treating other processes beyond depression, for example anxiety disorders, obsessive-compulsive disorder, eating disorders, etc.

How do antidepressants work?

Antidepressants act by intervening in the mechanism by which brain cells (called ‘neurons’) exchange information with each other through molecules known as neurotransmitters.

Neurotransmitters are biomolecules that act as chemical messengers that enable two neurons to intercommunicate with each other, but also with a muscle cell or gland.

Among the neurons is the so-called ‘intersynaptic space’. In order for there to be communication between two neurons, the one that emits the information (presynaptic neuron) releases into that space a vesicle containing neurotransmitters.

For its part, the neuron that receives the information (postsynaptic neuron) has receptors in charge of receiving the neurotransmitters and being able to decipher the message it transmits to them. This information transfer mechanism is known as nerve impulse or ‘synapse’.

Antidepressant drugs exert their action on neurotransmitters (specifically serotonin, noradrenaline, dopamine, and also melatonin) helping to restore proper regulation of them and thus allowing the symptoms of depression to be attenuated.

How do you trigger depression?

Medicine has not yet identified exactly the mechanisms that explain the appearance of a depression, however, everything points to the origin of it being multifactorial.

That is to say, in the genesis of the depression diverse factors intervene that include from the biological and psychological ones up to the individual genetic predisposition of each person.

These factors are not mutually exclusive. Several may intervene at the same time and, for example, we find ourselves with a depression in which in addition to the biological factors related to neurotransmitters, there is the aggravating factor of a divorce (social-family factor), a personality disorder that predisposes to melancholy (psychological factor), and also certain depressive family antecedents (genetic factor).

Always inform the patient

I have never thought it appropriate to prescribe a pill for a patient and say goodbye to him without offering an explanation. Anyone suffering from an illness – and even more so if it is a depression – has the right to know what is prescribed, why, how it will act in their body and what side effects may arise as a result of treatment.

That’s why I always offer a little “psychopharmacology lesson” to the patients to whom I prescribe an antidepressant. It only takes a few minutes, but with it I get an excellent collaboration of the patient and a reduction in the risk of therapeutic abandonment that is so often associated with psychopharmaceuticals, mainly due to the social stigma that falls on mental disorders.


In a way that is easily understood by the patient, I explain that in depression there is a decrease in certain neurotransmitters that are found in the interneuronal space, neurotransmitters that have the mission of transmitting information from one neuron to another.

I usually help myself with a drawing to inform them that neurons do not establish physical contact between themselves as if they were two electrical wires that light a light bulb when they touch each other, since their communication takes place through messengers (neurotransmitters) that travel from neuron to neuron to another to carry a certain amount of information.

I take this opportunity to add that in depression there are fewer neurotransmitters, the correct neuronal communication is not adequate, and it is right there where antidepressants intervene preventing reuptake and making depression improve.


Neurons have an innate predisposition to recover -or recapture- the neurotransmitters that have previously liberated the interneuronal space.

Recaptation is a kind of saving mechanism that forces neurotransmitters to return to their original neuron, i.e. the ‘recapt’. The result is a decrease in their presence in the intersynaptic space and poor transmission of the information they contain.

To better understand this mechanism, I invite my patients to imagine a truck (we would call it the “recapturing truck”) whose mission would be to go to the intersynaptic space, carry as many neurotransmitters as possible, and take them back to their original neurons.

This is what reuptake is all about, and the result is that the fewer neurotransmitters there are in the intersynaptic space, the greater the risk of depression.

How does an antidepressant work?

The most commonly used antidepressants in medical practice are SSRIs (selective serotonin reuptake inhibitors), and their mechanism of action consists of inhibiting the reuptake of neurotransmitters (specifically serotonin) described in the previous section.

To understand this inhibition, let’s go back to the truck and imagine that someone punctures its wheels and the engine that drives the load of the tipper breaks down, preventing it from carrying the neurotransmitters.

This is what the most commonly used antidepressants do: inhibit the reuptake of a neurotransmitter called ‘serotonin’, and the consequence of this is that the presence and bioavailability of serotonin in the intersynaptic space increases, and with it, the risk of depression decreases, or depression improves if it had already been established.

There are other mechanisms of action used by other antidepressants, however, the one used by the most frequently used is the one we have just described.

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