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The Neuroscience Behind Depression


Donna Tsai (text)

/ (graphics)

Depression: a word that is tossed around lightly but also carries the heavy burden of its stigma.

It’s often dismissed as “feeling sad”, and there’s a common misconception that depression is purely psychological, merely a period of negative emotions that one should be able to “snap out of”. In reality, the changes of certain structures of the brain and the neurochemistry plays a major role in the causes of depression.

(Get ready for some nerdy science lingo.)

Most people might have learned that depression is simply due to a decrease in the neurotransmitter serotonin, which helps regulate sleep, appetite, and mood. This is why the most common antidepressants are known as SSRIs, or Selective Serotonin Reuptake Inhibitors. To explain it simply, this type of drug will prevent the serotonin molecules from being absorbed back by the presynaptic nerve, allowing more serotonin to be available in the synapse.

SSRIs block the reabsorption of serotonin very quickly. However, it normally takes the drug around 4-6 weeks to have any positive effects on the patient. This is a clue that the causes of depression are actually far more complicated than a decrease in the amount of a single neurotransmitter, and perhaps mainly due to the structure of the brain.

There are many possible physiological changes of the brain that can lead to depression. Although more research is needed, here is a summary of the results comparing the brains of people with depression and people without.

1. A smaller hippocampus: The hippocampus, a structure known to be involved in learning and memory, is found to be smaller in some depressed people. The hypothesis is that stress, a major contributor for depression, can actually hinder the growth of new neurons (a process called neurogenesis) in the hippocampus.

2. Hyperactivity in the amygdala and anterior cingulate cortex: Both of these structures have a role in emotions (among other functions). Although findings have been inconsistent, activity of the amygdala and the ACC is generally higher in depressed patients. These studies have led researchers to suggest that emotional valence, an intrinsic attraction or aversion to an event, may have an important role in the emotional dysfunction of depression.

The best way to describe the brain abnormality in depressed patients is perhaps a dysfunction in the frontal-limbic communication. These two areas of the brain are responsible for higher-order thinking, feeling, and actions. Some people might be born with brains that are more prone to having depression, and when combined with a genetic predisposition as well as traumatic or stress-inducing life events, the possibility of them developing depression can be extremely high.

Of course, there is always treatment. Even though brain structure can affect the likelihood of getting depression, there are still treatments that can help with alleviating the symptoms. Anti-depressants might not work for everyone, but other types of medication, therapy, exercise, and lifestyle changes can all help in the process of treating depression.

For those that may be suffering from depression, I highly recommend reading the book “The Upward Spiral” by Dr. Alex Korb, which offers a different point of view to break the loop of the downward spiral that depression may cause.

Remember that it’s always important to reach out for help if you feel like you need it, and know that it’s okay to put your mental health first.

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Haru Sukegawa

a thing about Lisa