18 June 2015

High serotonin may increase social phobia

Serotonin can increase anxiety, and not decrease it as was previously often assumed, according to researchers at a Swedish university.


Levels of the brain chemical serotonin are too high in people with social phobia, rather than too low as previously believed, a new study says.

Oversensitive fear centre

Researchers at Uppsala University in Sweden conducted brain scans on volunteers and found that those with social phobia – also called social anxiety disorder – produced too much serotonin in the amygdala, which is part of the brain's fear centre.

The more serotonin their brains produced, the more anxious they were in social situations, the investigators found.

"Serotonin can increase anxiety, and not decrease it as was previously often assumed," researcher Andreas Frick, a doctoral student in the psychology department at Uppsala, said in a university news release.

Read: Anxiety disorders

The study was published in the journal JAMA Psychiatry.

Serotonin, which is produced by nerve cells, helps to relay messages from one area of the brain to another.

Previous research showed that nerve activity in the amygdala is higher in people with social phobia and that the fear centre in their brain is oversensitive. These new findings suggest that too much serotonin plays a role.

Social phobia is often treated with drugs called selective serotonin reuptake inhibitors (SSRIs), which increase the amount of available serotonin in the brain.

Read more:

What is social anxiety disorder?

Stranger anxiety

Fine-tuning treatments for depression

Image: Social phobia from Shutterstock


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Michael Simpson has been a senior psychiatric academic, researcher, and Professor in several countries, having worked at London University in the UK; McMaster University in Canada; Temple University in Philadelphia, USA.; and the University of Natal in South Africa.

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