A new study of brain activity in depressed and anxious people indicates that some of the ill effects of depression are modified—for better or for worse—by anxiety.
Using functional magnetic resonance imaging (fMRI), researchers looked at depression and two types of anxiety: anxious arousal, the fearful vigilance that sometimes turns into panic, and anxious apprehension, better known as worry.
“Although we think of depression and anxiety as separate things, they often co-occur,” says U of I psychology professor Gregory A. Miller, who led the research with Illinois psychology professor Wendy Heller. “In a national study of the prevalence of psychiatric disorders, three-quarters of those diagnosed with major depression had at least one other diagnosis. In many cases, those with depression also had anxiety, and vice versa.”
Previous studies have generally focused on people who were depressed or anxious, Miller says. Or they looked at both depression and anxiety, but lumped all types of anxiety together.
Miller and Heller have long argued against combining these symptoms. In an earlier fMRI study, they found that the two types of anxiety produce very different patterns of activity in the brain. In the new study, 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. And the combination of depression with different forms of anxiety can give different brain results.
Most surprising was that 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 was higher in the depressed and worried-but-not-fearful subjects.
Despite their depression, the worriers also did better on the emotional word task they were given than did depressed individuals 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 says.
“It could be that having a particular type of anxiety will help processing in one part of the brain while at the same time hurt processing in another part of the brain,” he says. “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 upside to these things.”
