A study published in JAMA Psychiatry found that patients who use SSRI (selective serotonin reuptake inhibitor) medications to control depression and anxiety may actually suffer from too much serotonin in their brains, not too little as previously thought.
Millions of people suffering from depression and anxiety disorders take SSRIs. The common assumption used to be that the medications increased the amount of serotonin in the brain, which helped alleviate symptoms. Researchers used positron emission tomography (PET) scanners and a chemical tracer to measure the specific chemical signal associated with serotonin in the brains of people suffering from anxiety disorders. The researchers found that the participants’ brains produced too much serotonin, especially in the amygdala that is responsible for the fear response. The more serotonin produced in these people’s brains, the more intense their anxiety.
“SSRIs are effective for anxiety disorders, including social anxiety disorder that we have studied,” stated Thomas Furmark, study co-author and psychologist at Uppsala University. “However, the exact mechanisms whereby SSRIs exert their anxiety reducing effect is still not known. Clearly, it is not a simple matter of too little serotonin being produced when anxious, and more serotonin being produced during SSRI treatment. This story is often being presented for patients but, in fact, the opposite might be true.”
SSRIs are effective at treating anxiety because they tweak the amount of serotonin in the brain rather than flooding the brain with extra serotonin. The drugs also help modulate the interaction of serotonin with other neurotransmitters, such as dopamine.
Furmark stated, “We also need to understand how genetic variation, i.e. how certain gene variants, influence serotonin synthesis, emotional reactions and the susceptiblity for psychiatric disorders. It would also be interesting to test if psychosocial treatments like cognitive-behavior therapy have an effect on the brain’s serotonin synthesis capacity.”
Furmark added that although research points to SSRIs as an effective choice for treating anxiety disorders, there needs to be some rethinking about how the class of drugs actually works and how serotonin contributes to anxiety conditions.