Yet despite its prevalence, the cause of this depression is not understood. It's not related to how severe one's MS is, and it can occur at any stage of the disease. That suggests it is not simply a psychological reaction that comes from dealing with the burden of a serious neurologic disorder.
Now, in the first such study in living humans, researchers at UCLA suggest a cause, and it's not psychological, but physical: atrophy of a specific region of the hippocampus, a critical part of the brain involved in mood and memory, among other functions.
Reporting in the early online edition of the journal Biological Psychiatry, senior study author Dr. Nancy Sicotte, a UCLA associate professor of neurology, Stefan Gold, lead author and a postdoctoral fellow in the UCLA Multiple Sclerosis Program, and colleagues used high-resolution magnetic resonance imaging to identify three key sub-regions of the hippocampus that were found to be smaller in people with MS when compared with the brains of healthy individuals.
The researchers also found a relationship between this atrophy and hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis, a complex set of interactions among three glands. The HPA axis is part of the neuroendocrine system that controls reactions to stress and regulates many physiological processes. It's thought that this dysregulation may play a role in the atrophy of the hippocampus and the development of depression.
"Depression is one of the most common symptoms in patients with multiple sclerosis," Gold said. "It impacts cognitive function, quality of life, work performance and treatment compliance. Worst of all, it's also one of the strongest predictors of suicide."
The researchers examined three sub-regions of the hippocampus region ¯ CA1, CA3 and the dentate gyrus area of the hippocampal region called CA23DG (CA stands for cornu ammonis). They imaged 29 patients with relapsing remitting multiple sclerosis and compared them with 20 healthy control subjects who did not have MS. They also measured participants' cortisol level three times a day; cortisol is a major stress hormone produced by the HPA axis that affects many tissues in the body, including the brain.
In addition to the difference between MS patients and healthy controls, the researchers found that the multiple sclerosis patients diagnosed with depression showed a smaller CA23DG sub-region of the hippocampus, along with excessive release of cortisol from the HPA axis.
"Interestingly, this idea of a link between excessive activity of the HPA axis and reduced brain volume in the hippocampus hasn't received a lot of attention, despite the fact that the most consistently reproduced findings in psychiatric patients with depression (but without MS) include hyperactivity of the HPA axis and smaller volumes of the hippocampus," Sicotte said.
"So the next step is to compare MS patients with depression to psychiatric patients with depression to see how the disease progresses in each," she said.
Other authors of the study included Kyle C. Kern, Mary-Frances O'Connor, Michael J. Montag, Aileen Kim, Ye S. Yoo and Barbara S. Giesser, all of UCLA.
Funding was provided by the National Multiple Sclerosis Society, the National Institutes of Health, the UCLA Cousins Center for Psychoneuroimmunology, and Claire and William Vaughn.
The authors report no conflicts of interest.
The UCLA Department of Neurology encompasses more than a dozen research, clinical and teaching programs that cover brain mapping and neuroimaging, movement disorders, Alzheimer's disease, multiple sclerosis, neurogenetics, nerve and muscle disorders, epilepsy, neuro-oncology, neurotology, neuropsychology, headaches and migraines, neurorehabilitation, and neurovascular disorders. The department ranks first among its peers nationwide in National Institutes of Health funding.
For more news, visit the UCLA Newsroom and follow us on Twitter
Mark Wheeler | EurekAlert!
Antimicrobial substances identified in Komodo dragon blood
23.02.2017 | American Chemical Society
New Mechanisms of Gene Inactivation may prevent Aging and Cancer
23.02.2017 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
23.02.2017 | Physics and Astronomy
23.02.2017 | Earth Sciences
23.02.2017 | Life Sciences