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!
Opening the cavity floodgates
23.01.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
Incentive to Move
23.01.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
Physicists have developed a technique based on optical microscopy that can be used to create images of atoms on the nanoscale. In particular, the new method allows the imaging of quantum dots in a semiconductor chip. Together with colleagues from the University of Bochum, scientists from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute reported the findings in the journal Nature Photonics.
Microscopes allow us to see structures that are otherwise invisible to the human eye. However, conventional optical microscopes cannot be used to image...
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
23.01.2018 | Earth Sciences
23.01.2018 | Life Sciences
23.01.2018 | Materials Sciences