People with generalized anxiety disorder (GAD) are less able to respond to any negative emotions they may feel, concludes a new Stanford University School of Medicine study.
The research is published online in this month's American Journal of Psychiatry.
GAD in particular is marked by extreme feelings of fear and uncertainty; people with the disorder live in a state of non-stop worry and often struggle getting through their daily lives.
"Patients experience anxiety and worry and respond excessively to emotionally negative stimuli, but it's never been clear really why," said Amit Etkin, MD, PhD, acting assistant professor of psychiatry and behavioral sciences and first author of the study.
Etkin said clinical data have suggested that adult GAD patients initially register negative stimuli in a largely normal way, but have deficits in how they then control negative emotions.
To reach the conclusion, Etkin recruited 17 people with GAD and 24 healthy participants and used functional magnetic resonance imaging and a behavioral marker to compare what happened when the two groups performed an emotion-based task. The task involved viewing images of happy or fearful faces, overlaid with the words "fear" or "happy," and using a button box to identify the expression of each face. Not all the words matched up - some happy faces featured the word "fear," and vice versa - which created an emotional conflict for participants.
After analyses, Etkin and his colleagues found that both healthy participants and GAD patients were able to identify the expressions. Healthy participants, as was expected, reacted more quickly to incongruent images when the previous image was also incongruent. When later asked if they were aware of any pattern that might have helped or hindered their performance, the volunteers said they were not; Etkin said this demonstrated that this process was carried out unconsciously.
However, the researchers found that in the GAD patients, the reaction-time effect seen in healthy patients was absent - and in the most anxious patients, reaction time actually worsened when there were two incongruent images in a row.
"GAD patients had decreased ability to use emotional content from previous stimuli to help them with the task," said Etkin.