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Stress-Related Disorders Affect Brain's Processing of Memory

Wednesday, December 3, 2008 General News J E 4
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CHICAGO, Dec. 3 Researchers using functionalMRI (fMRI) have determined that the circuitry in the area of the brainresponsible for suppressing memory is dysfunctional in patients suffering fromstress-related psychiatric disorders. Results of the study will be presentedtoday at the annual meeting of the Radiological Society of North America(RSNA).

"For patients with major depression and other stress-related disorders,traumatic memories are a source of anxiety," said Nivedita Agarwal, M.D.,radiology resident at the University of Udine in Italy, where the study isbeing conducted, and research fellow at the Brain Imaging Center of McLeanHospital, Department of Psychiatry at Harvard Medical School in Boston."Because traumatic memories are not adequately suppressed by the brain, theycontinue to interfere with the patient's life."

Dr. Agarwal and colleagues used brain fMRI to explore alterations in theneural circuitry that links the prefrontal cortex to the hippocampus, whilestudy participants performed a memory task. Participants included 11 patientswith major depression, 13 with generalized anxiety disorder, nine with panicattack disorders, five with borderline personality disorder and 21 healthyindividuals. All patients reported suffering varying degrees of stressfultraumatic events, such as sexual or physical abuse, difficult relationships or"mobbing" - a type of bullying or harassment - at some point in their lives.

After reviewing a list of neutral word pairs, each participant underwentfMRI. During imaging, they were presented with one of the words and asked toeither recall or to suppress the memory of its associated word.

The fMRI images revealed that the prefrontal cortex, which controls thesuppression and retrieval of memories processed by the hippocampus, showedabnormal activation in the patients with stress-related disorders compared tothe healthy controls. During the memory suppression phase of the test,patients with stress-related disorders showed greater activation in thehippocampus, suggesting that insufficient activation of the prefrontal cortexcould be the basis for inadequate suppression of unwanted traumatic memoriesstored in the hippocampus.

"These data suggest that the mechanism for memory suppression isdysfunctional in patients with stress-related disorders primarily because ofan alteration of the prefrontal cortex," Dr. Agarwal said. "These patientsoften complain of poor memory, which might in part be attributed to thisaltered circuitry," she added.

According to Dr. Agarwal, fMRI is an important tool in understanding theneurobiological basis of psychiatric disorders and in identifying imagingmarkers to psychiatric disease, helping clinicians target specific parts ofthe brain for treatment.

The study's principal investigator is Paolo Brambilla, M.D., Ph.D. Co-authors are Monica Baiano, M.D., Ph.D., Massimo Bazzocchi, M.D., GiuseppeComo, M.D., and Marta Maieron, Ph.D.

Note: Copies of RSNA 2008 news releases and electronic images will beavailable online at RSNA.org/press08 beginning Monday, Dec. 1.

RSNA is an association of more than 42,000 radiologists, radiationoncologists, medical physicists and related scientists committed to excellencein patient care through education and research. The Society is based in OakBrook, Ill. (RSNA.org)

Editor's note: The data in these releases may differ from those in theprinted abstract and those actually presented at the meeting, as researcherscontinue to update their data right up until the meeting. To ensure you areusing the most up-to-date information, please call the RSNA Newsroom at 1-312-949-3233.

For patient-friendly information on fMRI, visit RadiologyInfo.org.AT A GLANCE -- Researchers using fMRI have found that people with stress- related psychiatric disorders have difficulty suppressing traumatic memories. -- The brain's prefrontal cortex, which controls processing of memories, is dysfunctional in patients with stress-related psychiatric disorders. -- fMRI is an important tool in understanding psychiatric disorders.

SOURCE Radiological Society of North America (RSNA)
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