What are SSRIs?

Serotonin’s action in the synapse is controlled by its reuptake by the pre-synaptic cell. In fact, an increase in the reuptake of serotonin can lead to the termination of its action (Ho 1999). The problem is that this “termination” is considered as one of the factors that trigger the development of depression because serotonin is associated with emotional control (Ho 1999). However, drugs, such as the selective serotonin reuptake inhibitor or SSRIs, which control this reuptake of serotonin on the pre-synaptic neuron, had been developed. These act by blocking some of the serotonin transporter in the pre-synaptic cell to decrease the reuptake of serotonin (Windle 2011). This causes an increase in the number of serotonin in the synaptic cleft, which can then lead to an increase serotonergic action and a reduction of depression symptoms (Ho 1999).
Figure 7. SSRI blocks serotonin transporters in the pre-synaptic cell to decrease serotonin reuptake.
There are a lot of studies and researches that showed the effectiveness of these antidepressant drugs. Some studies even provided strong evidences on how these SSRI drugs greatly reduced symptoms of depression (Ho 1999). For example, a group of smokers with a history of depression had reduced symptoms of depression after being treated with Fluoxetine (Ho 1999). As of now, there are a number of different prescribed SSRIs that are used to reduce symptoms of depression such as Sertraline, Paroxetine, Fluvoxamine, and Citalopram (Windle 2011).

Video 3. Selective Serotonin Reuptake Inhibitors
Usually, antidepressant drugs are the first choice treatment for symptoms of depression (Black Dog Institute 2009). But, non-drug therapies, such as psychotherapy, counselling and electrochemotherapy (ECT), are also worth considering. But, it is important to note that drug therapy is still needed to maintain remission (Pharmaceutical Society of Australia 2011). It is also important to note that different types of depression usually respond to different kinds of treatment. Usually, non-melancholic depression responds to almost all types of treatments while melancholic depression, though it responds to non-medical ones, still mainly respond to drug therapy (Fry, Ryan 2011). On the other hand, psychotic depression only responds to physical treatments such as the administration of antidepressant drugs (Black Dog Institute 2009).

Conflicting Theories

Figure 8. Structural-functional changes in the brain can lead to the development of depression.

The main problem is that the main antidepressant drugs are selective serotonin reuptake inhibitors (SSRIs), which increases the extracellular serotonin concentration by means of inhibiting the serotonin reuptake in the pre-synapticcell (Ho 1999). This indicates that an increase in serotonin reuptake may lead to depression. This is contradicting with other theories, which showed that depression is associated with a decrease in serotonin reuptake. The bad thing is that this paradox is still unresolved but some explanations have been made. Firstly, if a gene lowers serotonin reuptake in the early age of development, this could lead to changes in the brain development, which can then lead to depression (Wurtman 2005). On the other hand, SSRIs drugs depresses serotonin reuptake only when it is being administered, which is usually in adulthood when the brain is fully developed, thus there is a lower chance for it to undergo any structural-functional changes (Wurtman 2005).

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