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, according to a study published in the May issue of the Journal of Nuclear Medicine.

The report provides evidence of a long-suspected biological cause for social phobia.

Comparing densities of elements of the serotonin and dopamine neurotransmitter systems, researchers examined 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 brain’s serotonin and dopamine systems. A radiotracer then revealed functional alterations in these systems by measuring the radioactive binding in the thalamus, midbrain and pons, which is 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.