Social phobia linked to surplus serotonin, not deficit

Researchers has refuted a previous study by claiming that individuals with social anxiety disorder/ social phobia have too much levels of the neurotransmitter serotonin, not too little.

Uppsala University study shows that the more serotonin produce produce, the more anxious they are in social situations.

The research team, led by professors Mats Fredrikson and Tomas Furmark, used a so-called PET camera and a special tracer to measure chemical signal transmission by serotonin in the brain.

They found that patients with social phobia produced too much serotonin in a part of the brain's fear centre, the amygdala. The more serotonin produced, the more anxious the patients were in social situations.

A nerve cell, which sends signals using serotonin, first releases serotonin into the space between the nerve cells. The nerve signal arises when serotonin attaches itself to the receptor cell. The serotonin is then released from the receptor and pumped back to the original cell.

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, said researcher Andreas Frick.

Frick added that they believe that this is an attempt to compensate for the excess serotonin active in transmitting signals.

Serotonin can increase anxiety and not decrease it as was previously often assumed, noted Frick.

The study is published in the scientific journal JAMA Psychiatry.