How antidepressants work


Mental health issues have been the centre of talks in society especially since the emergence of Covid-19. There has been an increased number of people getting psychological aid through calls and hospital visits as more people are aware that mental health is important to be taken care of. Such aid can be in forms of talks, physical activity, therapy and medicine. In this DoctorOnCall article, we will be focusing on a widely used medicine for mental disorders called antidepressants and how it works.

 As the name suggests, antidepressants are mainly used to treat a wide range of depression disorders, to name a few: major depressive disorder (MDD), persistent depressive disorder (dysthymia) and premenstrual dysphoric disorder.  Although it is called such a name, it is also used to treat other mental disorders such as anxiety disorder, obsessive-compulsive disorder (OCD) and post-traumatic stress disorder (PTSD). Antidepressants have also shown effectiveness to reduce pain in patients with chronic diseases such as arthritis and peripheral neuropathy associated with diabetes.

 Although depressive symptoms are usually said to be associated with chemical imbalance or serotonin deficiency, the exact cause of depression is not that simple and may also be due to other illness or genetic factors. With that being said, the way the brain works has been believed by researchers to play roles in mental disorders. Antidepressant works by boosting certain brain chemicals such as noradrenaline and serotonin or causing the chemical to last longer. These brain chemicals are also called neurotransmitters which act as chemical messengers to carry signals between nerve cells in the brain or nerves to other organs in the body. Noradrenaline and serotonin play a big role in regulating the mood. Hence, presence of these mood regulators in big amounts helps to improve the brain chemistry and improve mood overall. Take multivitamins for better health.

Antidepressants exist in many types such as selective serotonin reuptake inhibitors (SSRIs), serotonin and noradrenaline reuptake inhibitors (SNRIs), norepinephrine and dopamine reuptake inhibitors (NDRIs), tricyclics and monoamine oxidase inhibitors (MAOIs). Generally, SSRIs are the most commonly prescribed because it causes the least adverse effect. Basically, these drugs work (except MAOIs) by preventing the reuptake process (reabsorption of neurotransmitters into nerve cells in the brain that initially released the neurotransmitter). By using SSRIs, the serotonin can stay longer in the brain and body. Meanwhile, SNRIs, NDRIs and tricyclics make serotonin and noradrenaline to act longer in the brain and body. MAOIs work by preventing an enzyme called monoamine oxidase to break down noradrenaline and serotonin. However, MAOIs usage has been avoided due to many side effects and possible interactions with food and other drugs. Specialists may prescribe MAOIs in cases that any other antidepressants did not work for the patient.

Examples of antidepressants:

  • SSRIs- escitalopram, citalopram, fluoxetine, sertraline, paroxetine, fluvoxamine
  • SNRIs- duloxetine, venlafaxine, desvenlafaxine, levomilnacipran, milnacipran
  • Tricyclics- amitriptyline, clomipramine, imipramine, nortriptyline, doxepin, desipramine
  • MAOIs- selegiline
  • NDRIs- bupropion

 Antidepressants may not work immediately to help reduce the depressive symptoms once consumed. Thus, it is important for patients to take it accordingly for at least 2 to 4 weeks before letting your doctor know that the current antidepressant does not work and helps you to switch to other possible effective antidepressants. If you feel your symptoms getting worse rapidly, speak to your doctor urgently. It is important to note that an antidepressant that works for others, might not work for you or vice versa.

Antidepressants are usually prescribed for people with moderate or severe depression as studies show more effectiveness. In mild depression, doctors are likely to offer other treatments such as talking therapy or cognitive behavioural therapy (CBT) before offering antidepressants.


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