Depression is produced due to the decreased level of neurotransmitters such as serotonin, noradrenaline, and dopamine. Neurotransmitters are chemical messengers that help with signal transmission between neurons. The major neurotransmitter concerned with depression is 5HT/serotonin. Neurotransmitters play a vital role in regulating mood, emotions, and various physiological processes.
Antidepressants are classified into 2 categories:
- Typical Antidepressants
- A Typical Antidepressants
1. Typical Antidepressants
Typical antidepressants are effective in severe depression. These mainly increase levels of serotonin and noradrenaline and slightly elevate dopamine.
Tricyclic Antidepressants (TCAs)
TCAs inhibit the reuptake of serotonin and noradrenaline from the postganglionic junction to the synaptic recycles. They also have an effect on other neurotransmitter systems, including histamine and acetylcholine. TCAs are not the primary option in depression. Generally, TCAs are used when other treatments have not been effective, due to their potential for more side effects.
Selective Serotonin Reuptake Inhibitors (SSRIs)
SSRIs are widely used in depression. SSRIs inhibit the reuptake of serotonin in the synaptic vesicles, which helps increase serotonin levels in the body and improve mood. They also help reduce other symptoms of depression.
Monoamine Oxidase Inhibitors (MAOIs)
MAOIs act by inhibiting the enzyme Monoamine oxidase. The action of MAO is the breakdown of neurotransmitters like serotonin, noradrenaline, and dopamine. Inhibition of this enzyme increases the levels of neurotransmitters in the brain. MAOIs have some dietary restrictions because they can react with other medications and foods like cheese.
Selective Noradrenaline Reuptake Inhibitors (SNRIs)
SNRIs inhibit the reuptake of serotonin and noradrenaline. Noradrenaline is responsible for the fight-or-flight response and is associated with energy and alertness. SNRIs increase the levels of serotonin and noradrenaline, which has a significant impact on improving the mood of depressed patients. SNRIs are commonly used if the patient does not respond to SSRIs alone.
2. Atypical Antidepressants:
These inhibit the reuptake of noradrenaline and dopamine predominantly and slightly inhibit the reuptake of serotonin. These antidepressants have different mechanisms of action for each medicine. For example, bupropion acts by increasing the levels of norepinephrine and dopamine, while mirtazapine affects both norepinephrine and serotonin through different mechanisms.
The actual mechanism of antidepressants is very complex in nature. Self-medication with antidepressants is not recommended because it can lead to more complications. The use of these drugs is strictly under the control of healthcare professionals.
