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What Do Antidepressants do to the Brain?

Nov 15, 2021

If you have been struggling with a major depressive disorder, chances are you have considered or already tried antidepressant medications. Antidepressants have helped many with depression, but the mechanisms of which they work are quite complex.

Many researchers still don’t actually know precisely how all antidepressants work. Though, we have been able to measure levels of neurotransmitters in the brain that are often associated with depression and other mood disorders. It has also been suggested that these medications can improve neuro-connectivity in the brain and promote neuronal growth.

How do Antidepressants Work?

Antidepressants boost one’s mood, helping people get over depression and get back to the things they love. As someone starts to enjoy these things again, they can make better decisions and create a positive feedback loop, rather than a negative one that may have led them to depression.

Antidepressant drugs act by balancing and replenishing neurotransmitters such as serotonin, dopamine, and noradrenaline.

Here are the general mechanisms at which antidepressants work:

  1. SNRI antidepressants inhibit the reuptake of monoamines (i.e. serotonin, dopamine, noradrenaline) at synapses where neurons connect;
  2. SSRI antidepressants inhibit the breakdown of monoamines. This keeps these happy chemicals in the brain longer and can compensate for deficiencies in serotonin, dopamine, and noradrenaline;
  3. And, tricyclic antidepressants increase the reuptake of serotonin and the release of serotonin. They also do the same for norepinephrine.

You should note that these three mechanisms may be applied differently depending on the medication used. And, the above is a general simplification.

Also, while these medications may immediately begin their mechanism of action, their antidepressant properties may not be felt for weeks after continuous administration.

As time allows for antidepressant drugs to have their antidepressant effect, they may improve the hardwiring of the brain via neuroplasticity. When these medications work, we can see changes in regions of the brain including the prefrontal cortex, the hippocampus, the amygdala, and other parts.

Other Implications of Antidepressants

As stated above, antidepressants can increase the levels of neurotransmitters in the brain and help improve brain function to alleviate symptoms of depression.

Though, one should be aware that these changes to the brain are not always the answer to depression. Doctors prescribe these medications to reverse structural changes in the brain caused by depression. But, everyone experiences depression uniquely, and they are not a one-size-fits-all solution.

Many people exploring antidepressants as a treatment for depression may need to try different antidepressants or classifications of antidepressants. This process typically takes months, as most medications are recommended to be tried for at least a month — considering no severe side effects are experienced.

When going through this process in depression treatment, it is important to communicate with your treating doctor. Share all of your positive progress and especially any side effects you may be experiencing.

When Antidepressants Don’t Work

Roughly a third of people taking antidepressants alone do not get the result they are looking for.

Continuing therapy is also an important part of treating depression. Therapists can talk you through past traumas and emotional damage that may be causing depression.

As with therapy and medications, it is important to consider all options when talking with your doctor about treating depression.

One lesser-known non-medication option that we provide here at Brain Therapy TMS is transcranial magnetic stimulation. This therapy is a non-invasive, non-drug option that stimulates nerves in the brain via magnetic frequency. It aims to do much of the same things antidepressants do but through different mechanisms.

If you have tried multiple medications to treat your depression and have not received the benefit you were looking for, talk to your doctor about TMS therapy.

Alternatively, you can contact Brain Therapy TMS directly at 619-419-0901 to schedule a free consultation to learn more about TMS treatment.


  1. Andrade, C., & Rao, N. S. (2010). How antidepressant drugs act: A primer on neuroplasticity as the eventual mediator of antidepressant efficacy. Indian journal of psychiatry, 52(4), 378–386.
  2. Richelson, E., M.D. (1990). Antidepressants and Brain Neurochemistry. Mayo Clinic Proceedings, 65(9), 1227-1236. doi:10.1016/s0025-6196(12)62747-5

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