Reston, Va.Using single-photon emission computed tomography (SPECT), researchers in The Netherlands were able to detect biochemical differences in the brains of individuals with generalized social anxiety disorder (also known as social phobia), providing evidence of a long-suspected biological cause for the dysfunction.
The study, which was reported in the May issue of the Journal of Nuclear Medicine, compared densities of elements of the serotonin and dopamine neurotransmitter systems in the brains of 12 people diagnosed with social anxiety disorder, but who had not taken medication to treat it, and a control group of 12 healthy people who were matched by sex and age.
Both groups were injected with a radioactive compound that binds with elements of the brains serotonin and dopamine systems. Once administered, the radiotracer revealed functional alterations in these systems by measuring the radioactive binding in the thalamus, midbrain and pons (known to be acted upon by serotonin) and in the striatum (known to be acted upon by dopamine). The altered uptake activity in these regions indicated a greater level of disordered function.
Our study provides direct evidence for the involvement of the brains dopaminergic system in social anxiety disorder in patients who had no prior exposure to medication, said Dr. van der Wee, M.D., Ph.D., at the department of psychiatry and the Leiden Institute for Brain and Cognition at the Leiden University Medical Center, Leiden (and previously at the Rudolf Magnus Institute of Neuroscience, University Medical Center in Utrecht, The Netherlands). It demonstrates that social anxiety has a physical, brain dependent component.
Serotonin and dopamine (neurotransmitters, or substances responsible for transferring signals from one neuron to another) act upon receptors in the brain. If the neurotransmitters are out of balance, messages cannot get through the brain properly. This can alter the way the brain
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Society of Nuclear Medicine