Genes and Fear

Genetics alone do not determine whether you are carefree or a worry wart, but there is mounting evidence that a specific genetic variation may lead to higher levels of anxiety. Prior research identified two forms of the gene, dubbed "short" and "long" for the amount of DNA needed to encode them. The short version appears to produce less of a protein that helps regulate the mood-altering neurotransmitter serotonin. People with this version are more likely to rate as "fearful" or "anxious" on personality tests than are those with the longer version.

A team led by Daniel Weinberger, M.D. of the National Institute of Mental Health has found that this gene affects the amygdala, the region of the brain that determines when a situation is dangerous enough to warrant fear. In a study reported in the journal Science, Weinberger performed functional magnetic resonance imaging on 28 subjects as they examined pictures of frightened or angry people -- a process known to engage the amygdala. Subjects with the short gene had considerably more activity in this region than did those with the longer gene, indicating a stronger response to the emotions viewed.