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New Results Show that Magnetic Stimulation of Brain May Improve Working Memory and Brain Connectivity in People with MS

Summary

  • People with MS, but not healthy controls, showed improvements in working memory, brain activity, and “connectivity” (how parts of the brain interact with one another), after treatment with Repetitive Transcranial Magnet Stimulation (rTMS). This device generates electromagnet pulses that stimulate brain activity.
  • rTMS may have a future role in cognitive rehabilitation in people with MS, but further, larger studies are necessary to confirm the safety and effectiveness of this intervention and its long-term effects.
  • The team (Hanneke Hulst, MD, of VU Medical Center in Amsterdam, and others) has published results in Journal of Neurology, Neurosurgery, and Psychiatry (Published Online First: 14 December 2016).

Background: Repetitive Transcranial Magnet Stimulation (rTMS) was approved by the FDA as a treatment for major depression. A device that generates electromagnet pulses is placed on the scalp with the idea of stimulating specific brain activity. Studies have shown that people with MS who received rTMS showed significant decreases in depression. This team looked at whether rTMS improved working memory (short-term memory needed for tasks such as mental arithmetic), which can be affected in people with MS.

The Study: Investigators administered rTMS – or a “sham” version of lower intensity – to an area of the brain associated with working memory in17 people with MS and 11 healthy controls. None of the participants showed signs of impaired memory at the outset of the study. A potential adverse event of rTMS is seizures, so participants were excluded if they were taking medicine that put them at risk for seizures, or had MS brain lesions in particular areas. Before and after, participants underwent imaging and extensive neuropsychological testing aimed at investigating memory. They also completed a working memory task while undergoing functional MRI, which measures brain activity during tasks.

At the beginning of the study, there were no differences in working memory between people with MS and controls. After treatment, the results suggested improvements among people with MS in working memory, brain activity, and “connectivity” (how parts of the brain interact with one another). These changes were not seen in controls.

The team (Hanneke Hulst, MD, of VU Medical Center in Amsterdam, and others) has published results in Journal of Neurology, Neurosurgery, and Psychiatry

Next Steps: The authors comment that this small study implies that rTMS may play a future role in cognitive rehabilitation in people with MS. However, the study is limited by the small sample size and the fact that participants did not have obvious cognitive problems. Further studies that address these factors are necessary to confirm the safety and effectiveness of this intervention for people with MS and its long-term impact on day to day activities.

Read more about cognitive changes that affect people with MS

 

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Study reveals brain network responsible for cognitive changes in multiple sclerosis

An estimated 2.3 million individuals are living with multiple sclerosis (MS) worldwide. Approximately half of all individuals with MS experience changes in cognition such as impaired concentration, attention, memory, and judgment. The underlying brain basis for these deleterious effects has been largely elusive. New findings published yesterday in Neuropsychology reveal that decreased connectivity between network-specific brain regions are to blame for the central deficit common to the various cognitive changes associated with MS, slowed cognitive speed.
In the first study of its kind, researchers at the Center for BrainHealth at The University of Texas at Dallas and The University of Texas Southwestern Medical Center found that, compared to healthy controls, individuals with MS exhibit weaker brain connections between the dorsolateral prefrontal cortex and posterior brain regions. The change amounts to a breakdown in communication between the part of the brain responsible for executing goal-directed thought and action and the regions responsible for carrying out tasks related to cognitive speed such as visual processing, motor execution, and object recognition. The researchers believe that the diminished connections are likely the result of decreased white matter surrounding the neurons in the brain.

“Our study is the first to really zero in on the physiology of cognitive speed, the central cognitive deficit in MS,” explained Center for BrainHealth principal investigator Bart Rypma, Ph.D., who also holds the Meadows Foundation Chair at UT Dallas. “While white matter is essential to efficient network communication, white matter degradation is symptomatic of MS. This study really highlights how tightly coupled connectivity is to performance and illuminates the larger, emerging picture of white matter’s importance in human cognitive performance.”

Collaborating with Elliot Frohman, M.D., Ph.D., director of the Multiple Sclerosis Program and Clinical Center at UT Southwestern, the study recruited 29 participants with relapsing-remitting MS and 23 age- and sex- matched healthy controls. Participants underwent functional magnetic resonance imaging (fMRI) while completing a measure of cognitive processing speed. Participants were given 4 seconds to view a nine-item key of number and symbol pairs (for example ‘+’ above the number 3) and one number-symbol pair probe. Participants were asked to indicate with a left or right thumb button press whether or not the probe appeared in the key.

While accuracy was similar for both healthy controls and individuals with MS, response times for individuals with MS were much slower. Analysis of the fMRI data revealed that while completing this measure, MS patients showed weaker functional connections with dorsolateral prefrontal cortex.

“These findings reveal a diffuse pattern of disconnectivity with executive areas of the brain,” explained the study’s lead author, Nicholas Hubbard, a doctoral candidate at the Center for BrainHealth working with Dr. Rypma. “Importantly, these decreases in connectivity predicted MS-related cognitive slowing both in and out of the fMRI environment suggesting that these results were not specific to our task, but rather were able to generalize to other situations where cognitive speed is required.”

This research supports the need for therapies that target white matter structures and white matter proliferation. Rypma and Hubbard are currently conducting research to further explore the physiology of white matter to better understand cognitive speed reductions not only in MS, but also in healthy aging individuals.

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