In the new study, brain scans were done while participants performed a task that involved naming the colors of words that had negative, positive, or neutral meanings. This allowed the researchers to observe which brain regions were activated in response to emotional words.
The researchers found that the fMRI signature of the brain of a worried and depressed person doing the emotional word task was very different from that of a vigilant or panicky depressed person.
"The combination of depression and anxiety, and which type of anxiety, give you different brain results," Miller said.
Perhaps most surprisingly, anxious arousal (vigilance, fear, panic) enhanced activity in that part of the right frontal lobe that is also active in depression, but only when a person's level of anxious apprehension, or worry, was low. Neural activity in a region of the left frontal lobe, an area known to be involved in speech production, was higher in the depressed and worried-but-not-fearful subjects.
Despite their depression, the worriers also did better on the emotional word task than those depressives who were fearful or vigilant. The worriers were better able to ignore the meaning of negative words and focus on the task, which was to identify the color not the emotional content of the words.
These results suggest that fearful vigilance sometimes heightens the brain activity associated with depression, whereas worry may actually counter it, thus reducing some of the negative effects of depression and fear, Miller said.
"It could be that having a particular type of anxiety will help processing in one part of the brain while at the same time hurting processing in another part of the brain," he said. "Sometimes worry is a good thing to do. Maybe it will get you to plan better. Maybe it will help you to focus better. There could be an up-side to these things."
|Contact: Diana Yates|
University of Illinois at Urbana-Champaign