The Serotonin Mystery: How Does Too Much Make You Anxious?

Serotonin and Social Phobia

A lot of the treatments for anxiety and depression have sought to raise levels of serotonin – the chemical in the brain linked mostly to happiness and relaxation.

Because of that, research has tended towards finding physical ways to reverse low levels of the neurotransmitter such as antidepressant medications called SSRIs, diet (everything from bananas and walnuts, to vitamins B and C have been linked to increased levels of serotonin), regular exercise and general healthy eating.

But research at Uppsala University (a venerable old institution in Sweden which was established in 1477) is turning some of that thinking on its head.

The study, which was published in the scientific journal JAMA Psychiatry, revealed that the more serotonin they produce, the more anxious they feel in trigger situations.

One of the most difficult aspects of tracking serotonin levels has been finding a reliable method to measure brain activity – it’s all very well saying that the region of the brain called the amygdala is more active in certain patients but since that region is involved in fear responses, anger and sexual arousal, it’s difficult to understand the whole picture.

The new research uses a PET (positron emission tomography) camera and tracer to give researchers the ability to measure chemical signal transmission by serotonin in the brains of 36 people (18 people with Social Anxiety Disorder and 18 control patients) between March 2013 and August 2014 – they also acquired PET camera images for 26 extra SAD patients and 26 more control patients taken between 2002 and 2012.

They found that patients with social phobia produced more serotonin in the region of the brain called the amygdala which controls our fear responses.

“Not only did individuals with social phobia make more serotonin than people without such a disorder, they also pump back more serotonin. We were able to show this in another group of patients using a different tracer which itself measures the pump mechanism. We believe that this is an attempt to compensate for the excess serotonin active in transmitting signals”, says Andreas Frick, a doctoral student at Uppsala University Department of Psychology.

This reaction – combined with the knowledge that activity in the amygdala is higher in people who live with social anxiety – is a big step in understanding not only the brain’s chemical makeup in social anxiety, but also creates a large question mark over treatments.

Of course, it’s still important to realise that low serotonin levels are not the only cause of anxiety and it’s important to look at health, lifestyle, environment and thought patterns through a course or system of appropriate therapy.

What are your thoughts on the results of the study above? I’d love to hear from you.

All the best, Kyle

  • Thanks for sharing information from this interesting study! I agree with you in that low serotonin levels are not the only cause of anxiety but can definitely contribute.


  • Mary

    There seems to be a contradiction in your brief article. Are high serotonin levels and low serotonin levels both related to anxiety according to the research?

    • There is still plenty of contradiction in the research, SSRI medication is still frequently a front line treatment for anxiety mixed depression, and while it works for some, it is also true that they don’t help everyone. This research throws up some interesting ideas, and suggests that for some, too much serotonin can be a problem. I suspect, and some of the more general emotion research confirms this, is that some anxiety is caused by the serotonin mood “circuits”, and some anxiety is caused by other “circuits”, hence the difference and apparent contradiction.


  • Knockout Ned

    check out raypeat if you wanna learn more about how too much serotonin is bad.

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