Fear Factor

"Get over it!"

Those who fear not are fond of telling the overwrought amongst us to face our fears and move on. If you're a hot reactor who barely copes with scary movies or prefers to watch TV's "24" through slits between your fingers, here's some interesting news. You may, in fact, be genetically wired to startle and gasp and burst into tears.

Anxiety is a good thing, an unpleasant emotion that warns us against potential danger. Anxiety run amok can be a show-stopper--ask anyone who suffers from phobias and struggles with fear of crowds, riding in cars, flying in airplanes, visiting the doctor, or other situations that most people plunge through with nary a second thought. Neuroscientists are hot on the trail of the biological bases for various behaviors and the genetic codes that determine why we act the way we do.

Investigators at Weill School of Medicine in New York noted that mice with a small change in the gene sequence for a brain chemical called brain-derived neurotrophic factor (BDNF) are wimpy little things. BDNF is an important protein in mice and humans alike that supports brain cells to thrive and multiply especially in the brain regions responsible for learning and memory. These scaredy mice have DNA coding for BDNF that is just one molecule different from that of their intrepid colleagues. The cringing rodents with genetically skewed BDNF are not only anxious but known to have difficulty overcoming their fears and are resistant to treatments such as Prozac that decrease anxiety.

Dr. Fatima Solimon and her fellow psychobiologists at Cornell brought human and mouse volunteers with both normal and variant BDNF down to their lab for a psychological workout. Fear responses are prone to 'extinction' when subjects are repeatedly exposed to the threatening stimuli without any consequences. Psychologists use such exposure therapy to help people overcome phobias. Mice freeze and humans sweat when fearful, and the researchers checked how long it took subjects to quit freezing and sweating as correlated with their genetic type. In addition, the humans underwent functional MRI scans looking for high activity in brain regions known to be associated with both fear as well as the ability to master emotions through conditioning.

Their experiments confirmed that humans with variant BDNF coding have no problem learning that which is threatening but have a terrible time unlearning the cues that first signified danger. The people kept sweating and the mice kept freezing in their tracks long after the fearless subjects with the hardy BDNF were dry, calm, or scampering about their cages. And MRI scanning confirmed that those with the anxious variety of BDNF had trouble turning off their fear centers and turning on their learning centers.

Solimon and company whose findings appeared in a January, 2010 issue of Science Magazine are hopeful that their findings may ultimately translate into better understanding and treatment of persons with anxiety disorders, phobias, and PTSD. Those who suffer so are indeed eager to get over it.