Depression May Not Be Associated With Low Serotonin Levels, New Research Review Suggests
There is so much nuance (and frankly, confusion) when it comes to mental health—still, experts are continuing to uncover new insights, to shed some light on this complex topic.
This week, a new research review published in Molecular Psychiatry calls into question the common belief that chemical imbalance is the root of depression (also known as "serotonin hypothesis of depression"). And their findings are certainly rocking the boat in the psychology and mental health space.
What did the review find?
First and foremost, the review revealed that 80% or more of the population are under the impression that depression is caused by a chemical imbalance in the brain—and this theory has been influential for decades. This is one reason so many people are prescribed selective serotonin reuptake inhibitors, or SSRIs, intended to regulate serotonin levels and treat depression and anxiety.
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Still, despite the influential scope of this theory, "no comprehensive review has yet synthesised the relevant evidence," the researchers share. That is, until now.
Based on data from 17 different studies on serotonin, the researchers found "there is no convincing evidence that depression is associated with, or caused by, lower serotonin concentrations or activity."
The authors went on to state, “Most studies found no evidence of reduced serotonin activity in people with depression compared to people without, and methods to reduce serotonin availability using tryptophan depletion do not consistently lower mood in volunteers."
It's worth noting that in some studies, there was minor evidence that pointed toward a tie between increased serotonin activity and depression, but the researchers believe these results were likely "influenced by prior use of antidepressants and its effects on the serotonin system."
All this to say, while this study doesn't definitively disprove a link, based on the data points from thousands of people, the researchers don't believe there is strong evidence depression and serotonin are connected.
Where does this leave us?
If depression is not, in fact, caused by low levels of serotonin, this also calls into question the efficacy of antidepressant medications.
The review reveals that there is evidence that people who are taking antidepressants may actually have lower levels of serotonin in their blood, contrary to the intention. "These findings suggest that in the long-term antidepressants might produce compensatory changes that are opposite to their acute effects," the authors note.
As for individuals who have benefited from this type of medication, the review posits, "Other explanations for the effects of antidepressants have been put forward, however, including the idea that they work via an amplified placebo effect or through their ability to restrict or blunt emotions in general."
Whatever the case, if you're currently taking SSRIs, this data shouldn't be a cue to stop taking the medication. Instead, this may be a good time to check with your doctor or mental health care professional to discuss a future plan of action and determine the best care.
Caring for your mental health is incredibly important. If you're dealing with depression, a chemical imbalance may not be to blame, but it's still important to seek help and determine the best course of treatment. While these types of findings may seem frustrating (particularly if you're taking antidepressants at this time), just remember that more research is necessary, and speaking with a health care professional is the best route to finding individualized care to fit your particular needs.