Although we think of depression and anxiety as separate things, they often co-occur
　　Anxiety may modify depression for better or for worse, indicating a link between the two, U.S. researchers suggest.
　　By using functional Magnetic Resonance Imaging (MRI), researchers at the University of Illinois looked at brain activity in subjects who were depressed and not anxious, anxious but not depressed, or who exhibited varying degrees of depression and one or both types of anxiety.
　　The researchers took into account two types of anxiety: anxious arousal, the fearful vigilance that sometimes turns into panic; and anxious apprehension, better known as worry.
　　In the 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.
　　They found that the two types of anxiety produce very different patterns of activity in the brain. Anxious arousal lights up a region of the right inferior temporal lobe (just behind the ear). Worry, on the other hand, activates a region in the left frontal lobe that is linked to speech production.
　　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, said lead author Gregory A. Millers, a psychology professor at the university.
　　"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."
　　"Although we think of depression and anxiety as separate things, they often co-occur," he said.
　　"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."
　　The study was published in the latest journal Cognitive, Affective & Behavioral Neuroscience.