- MONDAY, Aug. 11 (HealthDay News) — A gene variation may explain why
some people are more prone to anxiety disorders, such as post-traumatic
stress, a new study says.

People carrying two copies of the Met158 variation of the
catechol-O-methyltransferase (COMT) gene showed greater anxiety on a
standard personality test and also were significantly more startled than
others when shown a series of unpleasant pictures, according to findings
published in the August issue of Behavioral Neuroscience.

Depending on ethnicity, about a quarter of the population carries two
copies of Met158. The COMT gene produces an enzyme that breaks down the
brain chemical dopamine, weakening its signal.

The study's German and American authors said their finding offers a
biochemical explanation for why some people find it harder to regulate
emotional arousal. Their sensitivity, combined with other genetic and
environmental factors, may make them more likely to have anxiety
disorders.

This finding also confirms suspicions that variations in the gene that
regulates dopamine signaling may be linked to negative emotionality. The
Met158 variation, the authors speculated, may increase dopamine levels in
the brain's memory and emotional support systems, resulting in an
“inflexible attentional focus” on unpleasant stimuli. Essentially, people
with the Met158 carriers can't tear themselves away from something that's
arousing — even if it's bad.

A single gene variation, though, can explain only some anxious
behavior, said one of the researchers.

“This single gene variation is potentially only one of many factors
influencing such a complex trait as anxiety,” study co-author Christian
Montag said in a news release issued by the publication. “Still, to
identify the first candidates for genes associated with an anxiety-prone
personality is a step in the right direction.”

Montag said that if further research continues to back this finding,
one day “it might be possible to prescribe the right dose of the right
drug, relative to genetic makeup, to treat anxiety disorders.”

More information

The Center for Mental Health Services has more about anxiety disorders.