Evidence of Brain Changes in MS-Related Depression

Megan Brooks

February 06, 2014

Using a novel automated imaging technique, researchers have identified shrinkage in the hippocampus in a large group of women with multiple sclerosis (MS) and depressed mood.

The results suggest that "regionally clustered reductions in hippocampal thickness can be detected by automated surface mesh modeling and may be a biological substrate of MS depression in female patients," the researchers write.

"We were able to see local differences in the hippocampus related to symptoms specific to depression in patient with MS," Nancy Sicotte, MD, neurologist at Cedars-Sinai Medical Center in Los Angeles, California, told Medscape Medical News. "This helps to reproduce work we have done previously using a manual segmenting technique."

Potential for Therapeutic Monitoring

The advantage of automated surface mesh modeling, Dr. Sicotte explained, is that it is fully automated and can be derived from relatively standard MRI examinations done routinely for clinical purposes. "This allows us to more easily monitor changes over time in these hippocampal regions and more readily determine the effects of therapies aimed at treating depression and/or MS," she said.

The study was published in the January 2014 issue of Human Brain Mapping.

Depression in MS Common

Depression is common in MS, but the neuroanatomic correlates of MS depression are poorly understood. The hippocampus plays a key role in mood regulation and is implicated in the development of depression.

Dr. Sicotte and colleagues performed volumetric and shape analyses of the hippocampus in 109 women with MS and depressive symptoms. Bilateral hippocampi were segmented from T1-weighted MRI scans by using automated tools, and shape analysis was performed by using surface mesh modeling.

Of the 109 women, 83 were classified as having low depression on the Center for Epidemiologic Studies-Depression scale (score of 0 to 20) and 26 as high depression (score of 21 or greater).

The high-depression group had significantly smaller right hippocampal volume (P = .04) compared with the low-depression group. There was no significant between-group difference in left hippocampal volume (P = .67) or total hippocampal volume (P = .19).

"Importantly," the researchers write, "global volume as measured by brain percentage was similar in the 2 groups, indicating that brain volume differences were specific to the hippocampus."

Surface rendering analysis showed that hippocampal shape changes were clustered in the right hippocampus. Smaller hippocampal volume was associated with depressed affect but not the somatic/vegetative or interpersonal components of depression.

These findings support earlier research by Dr. Sicotte and colleagues and reported by Medscape Medical News suggesting that the hippocampus may contribute to MS-related depression.

Dr. Sicotte and colleagues are enrolling participants for an ongoing study of MS and depression.

"In the new study, we will compare the manual and automated hippocampal imaging techniques directly and will also assess individuals who have major depression, along with MS patients with and without depression. We hope to determine if MS-related depression is associated with the same pattern of hippocampal changes as major depression alone and to pinpoint the subregions that are responsible for the surface changes we can detect with the automated approach," Dr. Sicotte explained.

She said automated surface-based morphometric analyses "could be used to study a variety of neurological and psychiatric disorders."

Funding for the study was provided by the National Institutes of Health, the Cousins Center for Psychoneuroimmunology, the National Institute on Aging, a Marie Curie grant from the European Union, the Skirball Foundation, and the Department of Defense. The authors have disclosed no relevant financial relationships.

Hum Brain Mapp. 2014;35:30-37. Full text

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