Much has been written about the role serotonin plays in mental health, particularly in regard to its advantageous effects on depression. Yet for all its benefits, another effect, called serotonin syndrome, can also arise from an influx of the neurotransmitter. So, what is serotonin syndrome, what are its symptoms, and is there a serotonin syndrome treatment? Read on to find out.
Serotonin is a chemical secreted by nerve cells. As a neurotransmitter, it is secreted in the brain, and used to relay information within the central nervous system (CNS). It is also found in the blood, where it acts as a hormone that relays information throughout the peripheral nervous system (PNS).
While roughly 90% of all serotonin is created in the gut, only 1-2% is created and activated in the brain. Since serotonin cannot pass through the blood-brain barrier, only the serotonin manufactured in the brain can affect one’s emotional state; serotonin created in the intestines, on the other hand, affects the digestive system.
Serotonin was first isolated in 1948. It has since become a focus of much mental health research and debate: In the 1960s, the serotonin theory of depression came out, positing that low levels of active serotonin in the brain facilitate depressive symptoms. Based on this theory, in the 1980s selective serotonin reuptake inhibitors (SSRIs) were introduced, which prolong the activation period of serotonin. Since then, a great deal of research has identified the neurotransmitter as the key to combating depression, dubbing serotonin as the “feel-good hormone” for its ability to alleviate symptoms of this disorder.
Recently, however, the centrality of serotonin in the fight against depression has been called into question. Most notably, a 2022 study published in Nature stated there was no consistent evidence to link low levels of serotonin with depression, and no clear cut evidence that confirms the claims made by the serotonin theory of depression.
While many have found the above study’s claim to be astounding, it is worth mentioning that serotonin’s role in depression has been understood in more relative terms for some time. A key study from 2006 highlighted as much: Funded by the National Institute of Mental Health, the study found that only one-third of patients with depression achieved remission with an SSRI antidepressant. Its results show that a minority of those battling this disorder can expect a full recovery by simply increasing their levels of active serotonin, while the rest will need to incorporate another form of treatment, such as psychotherapy of transcranial magnetic stimulation (TMS) to reach true symptom relief. This is still enough for the FDA to identify SSRIs as a first-line treatment for depression, but it nevertheless warrants a closer examination of both this and other treatment options for this condition.
As the debate around serotonin-focused depression treatment continues, other worrying aspects of this neurotransmitter have also garnered research attention. Specifically, serotonin syndrome has raised concern among those being treated for depression.
Serotonin syndrome, also called serotonin toxicity, can occur when one begins a new medication, or increases the dosage of one they are already taking. Combining an SSRI type of antidepressant with a MAOI antidepressant poses the greatest risk for developing this condition. It should also be mentioned that nearly all types of antidepressants increase the brain’s levels of serotonin, in one way or another.
When too much serotonin is present within the central nervous system’s synapses, it can trigger an influx, essentially flooding the brain with too much of the neurotransmitter.
Serotonin syndrome symptoms include the following:
Twenty-eight percent of patients develop serotonin syndrome within one hour of ingesting the medication that caused their neurotransmitter’s levels to spike, and 61% develop the condition within six hours.
It should be noted that serotonin levels can be increased by many additional types of medication, beyond SSRIs or even antidepressants as a whole. Certain medications treating migraine headaches, for instance, can cause an increase in one’s serotonin levels. Dietary supplements or specific, illicit drugs may also increase the amount of active serotonin in the brain.
Safeguarding against too much serotonin in one’s system is preferable to alleviating the detrimental effects of serotonin syndrome once it has already developed. In order to do so, several precautions should be taken:
It is rather rare for a case of serotonin syndrome to require any hospitalization. Cases of mild serotonin syndrome tend to pass after a day or two. Treatment for serotonin symptoms whose severity does necessitate intervention can include ingesting a serotonin-blocking agent to promote faster and more effective patient recovery.