Jun 17, 2015 11:40 AM By Susan Scutti
Levels of the neurotransmitter serotonin in people with social anxiety disorder may be too high, not too low, as previously believed. Lili Vieira de Carvalho
Anxiety disorders affect more than 25 million Americans. In particular, those with social phobia feel embarrassed, inferior, and uncomfortable when they are in public situations. A new study from Uppsala University gets to the root of this mental disorder. The researchers say that levels of serotonin, a neurotransmitter, in people with social anxiety disorder are not too low as previously believed — instead, these anxious people produce too much serotonin. And, the higher the level of this neurotransmitter, the more anxious they feel.
“Our study provides better insight as to how serotonin contributes to anxiety,” Dr. Tomas Furmark, a psychology professor at Sweden’s Uppsala University, told Medical Daily in an email, further noting the importance of understanding the etiology of anxiety disorders.
A very recent small-scale study of social anxiety found more than three quarters of sufferers first developed their symptoms before the age of 18. Compared to those whose symptoms first appeared later in life, the early-onset group had higher scores on anxiety and depression tests, and lower scores on global functioning tests. For those with early anxiety, their depression and other symptoms are more severe and so more difficult to treat.
Commonly, psychiatrists treat social phobia with medications known as selective serotonin reuptake inhibitors or SSRIs, a type of drug which changes the amount of the neurotransmitter serotonin in the brain.
Furmark and Dr. Mats Fredrikson, another professor of psychology at Uppsala University, questioned the underlying hypothesis of treating patients with SSRIs: What molecular role, exactly, does serotonin play in social phobia?
Overly-Sensitive to Fear
To discover the truth, they used brain scanning technology, PET scans, to measure serotonin in the brains of volunteers with social phobia. Essentially, then, they tracked the chemical signals transferred between cells in the brain.
Communication within the brain works like this: Nerve cells release serotonin into the space between nerve cells. Then, serotonin attaches itself to receptor cells. Following this, serotonin is released from the receptor and returns to the original cell.
The researchers discovered patients with social phobia were producing too much serotonin in the amygdala. This brain region, tucked deep inside our skulls, is the seat of our most primitive emotions, including fear. The more serotonin produced in this area, then, the more anxious people feel in social situations.
This new finding does not entirely challenge past research. Previous scientific studies proved people with social phobia have higher nerve activity in the amygdala — for anxious people, the fear center of the brain is overly sensitive. This new research fleshes out the prior work with its suggestion that a surplus of serotonin may be (at least part of) the underlying reason for this.
Serotonin, then, does not decrease anxiety as previously assumed, it increases it. Further research into the underlying chemical processes of anxiety should help scientists investigate familiar treatments and possibly develop new ones for what amounts to a debilitating condition for some people.
“We may have to rethink how anxiety-reducing drugs, like serotonin reuptake inhibitors (SSRIs), actually exert their beneficial effects in anxiety disordered patients,” Furmark said.
Source: Frick A, Åhs F, Engman J, et al. Serotonin Synthesis and Reuptake in Social Anxiety Disorder: A Positron Emission Tomography Study. JAMA Psychiatry. 2015.
Quotes from Dr. Furmark were added in following the original posting of this article.