Those who live by the gun, die by the gun.
Those who live by empiricism, die by empiricism.
For as long as I started looking into what the causes of depression are, either as a patient of the disease or as a student of the disorder, one neurotransmitter was implicated over and over again. Serotonin. Every book, blog or article I could find would mention that depression is caused by lower serotonin levels and increasing those levels would help with the disease. The relationship between the two was solid and long-term.
Until it wasn’t.
The Affair
The linkage between serotonin levels and depression is more controversial than the articles and books would have you believe. While most of the people familiar with the subject have heard of the relationship, the studies that go behind it are actually largely inconclusive or have weak evidence.
The origins of the serotonin hypothesis of depression can be found in the 1960s but it was only in the 1990s that the hypothesis started becoming a part of pop culture and then general usage. This was when SSRIs were first invented and promised to improve mood by increasing the levels of serotonin in the brain. This hypothesis meant that depression was a result of a chemical imbalance in the brain.
Cynics believe that the chemical imbalance theory was fuelled by pharma companies to sell as many antidepressants as possible. According to them, something with so little empirical support could only become so popular with a marketing campaign. While we don’t know the role pharma companies played in the popularization of SSRIs, we do know that today they are the frontline pills prescribed to tackle depression. Although, other types of pills which focus on different parts of the brain exist as well.
The Break-Up
Just a few weeks back, an umbrella review (considered high-quality evidence in the scientific community) found that the past studies did not have any conclusive evidence that low levels of serotonin always lead to depression.
Here are some of the things the researchers found.
Healthy people whose serotonin levels are artificially lowered don’t always develop depression
People who have depression don’t have significantly lower serotonin levels than healthy individuals.
The authors conclude that the chemical imbalance theory of depression is not empirically substantiated and that comes as quite a shock for many practitioners and patients.
I have been using antidepressants, specifically SSRIs for about 7 years now. I know they help me stay normal and not fall into the pit of depression but it’s unsettling to know, now, that we don’t know how these SSRIs work.
I don’t think this study will make doctors stop prescribing these medicines. I don’t think it will stop me from using them as I try to maintain a semblance of normalcy in my life. It will raise some interesting questions about the mechanism of antidepressants though. I am excited about how neuropsychiatry takes this forward.
The Aftermath
It has been quite fun to see how professionals have responded to the publication of this study though.
Some have questioned the legitimacy of depression as an illness if it doesn’t have a biological basis.
Others have questioned the ideology of the authors of this study and their motivations behind conducting this study. This one was particularly funny to me because I am pretty sure their motivations would not be questioned if they were debunking NLP or homoeopathy.
But there are some misguided claims being made by the authors and others on the basis of this study though. So I should clear some things out.
Low serotonin was not found to be the sole determinant of depression
Depression may have a biological basis but it is more complex than a single neurotransmitter
Antidepressants work for a large group of people but we still don’t know how or why they work
What do you think about the separation of serotonin and depression? Do you think its good it happened and we can now focus on other determinants of mental health or do you think it will make people more resistant to accepting depression as an actual illness?
Let me know in the comments :)
And that is it for the week! Hope you liked it. I am trying to experiment with the length of my articles on Substack. Let me know which length you would prefer by voting in the poll below.
See you next time!
Arjun.
🛣🖊🎯
Hey Arjun check this out promising research using psychedelics against treatment resistant depression. Also currently a phase three clinical trial by MAPs.org in progress. : https://hopkinspsychedelic.org/