WebMD Medical News
Laura J. Martin, MD
Aug. 3, 2011 -- A study that compared the brains of suicide victims to those of people who died suddenly from other causes found key differences in specific brain cells in the white matter of the brain.
The finding lends support to the idea that inflammation within the brain plays a key role in depression, says lead researcher Naguib Mechawar, PhD, of McGill University’s Group for Suicide Studies in Montreal.
Mechawar and colleagues have been studying the brains of suicide victims for close to a decade in an effort to better understand why some people with major depression take their own lives.
A major goal has been to identify what is happening at the cellular and molecular level in the brains of people just before they commit suicide, Mechawar tells WebMD.
“We are using different approaches to study the neurobiology of suicide and brain disorder, including comparing the brains of suicides to those of people who died suddenly without any known neurological illness,” he says.
In the newly published study, the Canadian research team analyzed the expression of cells known as astrocytes in both the gray and white matter of brains from 10 suicides with established depression and 10 people with no history of depression who died of other causes.
Astrocytes have been shown to be altered in people with depression in several studies.
The researchers identified the cells in a key region of the brain involved in emotion regulation using a century-old staining process known as silver impregnation. They then reconstructed the astrocytes in a 3D model using state-of-the-art computer software, Mechawar says.
Although cell expression was the same in brain gray matter regardless of cause of death, astrocytes were much larger with longer branches in the brain white matter of suicide victims compared to people who died from other causes.
The study was published online today in the Nature Publishing Group journal Neuropsychopharmacology.
Astrocytes are involved in many aspects of brain function, including immune regulation and inflammation.
The researchers hypothesize that the enlarged, branched astrocytes seen in the brain white matter of the suicides resulted from inflammation.
There is wide support for the idea that inflammation within the brain plays a role in depression.
The newly published study suggests that inflammation associated with depression may be confined to the white matter, but Mechawar says the findings must be confirmed.
“This study supports, but does not prove, the hypothesis that inflammation plays a role in major depression,” he says.
SOURCES:Tores-Platas, S.G., Neuropsychopharmacology, published online Aug. 3, 2011.Naguib Mechawar, PhD, assistant professor, department of psychiatry; McGill Group for Suicide Studies, department of psychiatry, Douglas Mental Health University Institute, McGill University, Montreal, Canada.News release, Nature Publishing.
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