Worry is one of the main features of generalized anxiety disorder (GAD), a condition which affects 5.7% of the English-speaking population in the U.S. and which can have dramatic effects on people's relationships, work and well-being. Little is known about what goes on in the brains of people with GAD. Researchers at the University of Wisconsin compared 14 people with GAD to 12 healthy controls who were chosen to be as good a match as possible to the worriers. They showed them unpleasant pictures, which were preceded by a minus sign, and neutral images which were preceded by a circle. The participants with GAD showed greater activity in a part of their brain called the bilateral dorsal amygdala before both the unpleasant and the neutral pictures. The participants with GAD were given 8 weeks of treatment with venlafaxine after the initial experiment and the researchers found that those who had more activity in a region of the brain called the anteriour cingulate cortex, which is believed to play a part in resolving emotional conflict, did better than those who had less activity in this region.
Nitschke, Jack B. ... [et al] - Anticipatory activation in the amygdala and anterior cingulate in generalized anxiety disorder and prediction of treatment response American Journal of Psychiatry March 2009, 166(3), 302-310