Anyone sufferingwith an anxiety-related condition will recognize the scenario where anxiety is so overwhelming they actively avoid certain situations. The fear of a panic attack, or of becoming embroiled in some negative situation, can be so intense that some people refuse to leave the security of their home. In nearly all cases the anticipation of a negative outcome far outweighs the reality of the situation. Therefore, wouldn't it be good if we could target and treat the region in our brain that causes the problem?
In the American Journal of Psychiatry, a study has been published into the role of an area of the brain known as the amygdala. The amygdala is involved in the processing and acquisition of emotional memories and reactions. Over the past few years a great deal of research has been conducted into the role of the amygdala in relation to anxiety, autism, depression and other psychological processes. In this latest study, high activity in the amygdala was noted in anticipation to adverse events. Of interest, high activity was also noted in a regulatory region known as the anterior cingulate cortex, in response to common antidepressant medication.
Jack B. Nitschke, Ph.D., an assistant professor and clinical psychologist at the University of Wisconsin-Madison School of Medicine and Public Health, and lead author of the study, reports that people with Generalized Anxiety Disorder (GAD) show very high levels of amygdala activity when exposed to situations that simulate some form of expectation of an outcome. These anticipatory signals were far higher than those shown by a control group of volunteers, when monitored by functional magnetic resonance imaging (fMRI) scans.
For the study, Dr. Nitschke asked volunteers to view sets of neutral and negative images. Several seconds before an image was shown, volunteers saw a circle if the image they were about to see was neutral, or a minus sign if the forthcoming image was aversive. When images were shown, volunteers with GAD reacted no more strongly than the control group. However, when aversive or neutral anticipatory cues were shown, volunteers with GAD showed remarkably high levels of activity in comparison to the control group. The findings point to a situation where volunteers with GAD are unable to discriminate between the anticipation of an event that might be aversive from one that isn't.
Volunteers with GAD were then put on an eight-week course of the anti-depressant venlafaxine (Effexor). Clinical improvement on the medication was associated with higher levels of pre-treatment brain activity.
"When you look within the GAD population that [brain] area is what predicts whether they respond to this treatment . . .using fMRI to predict treatment response," says Nitschke.
Because anxiety disorders are commonly associated with depression, Dr. Nitschke plans to extend his line of enquiry by examining GAD patients with and without major depressive disorder.