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What did the right brain say to the left brain? "Don’t worry, that’s my job."
That, oversimplified, is the conclusion of research presented at the annual meeting of the Society for Neuroscience in New Orleans in October by Johns Hopkins University psychiatrist Rudolf Hoehn-Saric, M.D. Hoehn-Saric and colleagues used brain scans that measure blood flow to conclude that anxious thoughts—or, simply put, worries—are localized among several structures in the right brain. The research was funded by the National Institutes of Health.
Ten volunteers made short tapes describing their worries such as recent family problems, workplace stress, and financial and other concerns. Scientists scanned their brains using position emission tomography (PET) to detect differences in blood flow immediately after the volunteers listened to either the worry tapes or neutral tapes about flowers.
"They spoke into a tape for two minutes as if they would be worrying" rather than in a normal conversational tone, explained Hoehn-Saric, director of Hopkins’ anxiety disorders unit. They then listened for two minutes and were told to continue worrying, so that the tape would trigger anxiety.
During worry, there was increased blood flow to the right frontal lobe, which is involved in planning and decision making; the cerebellum, which stores routine patterns of thought and movement; the basal ganglia, which coordinate and process messages from various parts of the brain; and the pontine nuclei, which regulate arousal.
Prior studies have indicated that the left brain is the primary site of analytical, rational thought, while the right brain is the main site of emotional, intuitive processes.
The current study of normal volunteers has helped establish a baseline, so that further research can compare regional blood flow in normal subjects with that in subjects with an anxiety disorder, said Hoehn-Saric. This was a pilot "to see if anything happens or not," he noted.
If future studies using PET reveal clear differences between normals and subjects with anxiety disorders, it will be possible to see whether the differences are qualitative, quantitative, or both, said Hoehn-Saric. "It could be that the same regions are activated but in the anxiety disorders much more. Or it could be that in those with anxiety disorders other regions of the brain are activated."
The sample was very small and not designed to identify possible gender differences, which need to be investigated in future studies, Hoehn-Saric said.
For psychiatric clinicians, such research holds the promise of more site-specific pharmacological therapies. "If you identify regions, then you may be able to determine if there are medications that are specifically effective in those regions," said Hoehn-Saric.
Mark George, M.D., is director of the functional neuroimaging division of the Medical University of South Carolina in Charleston and an associate professor of psychiatry, radiology, and neurology.
"These results are quite intriguing, and the method a very powerful one," remarked George. The work "fits nicely into an existing body of literature on the brain and anxiety." It adds credence to the notion that structures of the right brain are involved in anxiety.
"Some of those same regions are consistently hyperactive in patients with OCD," George observed. Although drawn from a small sample, Hoehn-Saric’s results "help to give us another piece of the jigsaw puzzle in understanding both normal and pathologic anxiety in relationship to regional neuroanatomy," George added.
Based on work such as Hoehn-Saric’s, George and colleagues are experimenting with rTMS (repetitive transcranial magnetic brain stimulation) in right brain regions to see whether they can induce anxiety.