West Orange, NJ. November 1, 2013. A new study by Kessler Foundation scientists sheds light on the mechanisms underlying cognitive fatigue in individuals with multiple sclerosis. Cognitive fatigue is fatigue resulting from mental work rather than from physical labor. Genova H et al: Examination of cognitive fatigue in multiple sclerosis using functional magnetic resonance imaging and diffusion tensor imaging" was published on Nov. 1 in PlosOne. This is the first study to use neuroimaging to investigate aspects of cognitive fatigue. The study was funded by grants from the National MS Society and Kessler Foundation.
The study investigated the neural correlates of cognitive fatigue in MS utilizing three neuroimaging approaches: functional magnetic resonance imaging (fMRI), which allows researchers to look at where in the brain activation is associated with a task or an experience; diffusion tensor imaging (DTI), which allows researchers to look at the health of the brain's white matter; and voxel-based morphometry (VBM), which allows researchers to investigate structural changes in the brain. These three approaches were used to examine how likely it is for an individual to report fatigue ("trait" fatigue), as well as the fatigue an individual feels in the moment ("state" fatigue). This study is the first to use neuroimaging to investigate these two, separable aspects of fatigue.
"We looked specifically at the relationship between individuals 'self-reported fatigue and objective measures of cognitive fatigue using state-of-the-art neuroimaging," explained Helen M. Genova, Ph.D., research scientist in Neuropsychology & Neuroscience Research at Kessler Foundation. "The importance of this work lies in the fact that it demonstrates that the subjective feeling of fatigue can be related to brain activation in specific brain regions. This provides us with an objective measure of fatigue, which will have incalculable value as we begin to test interventions designed to alleviate fatigue."
In Experiment 1, patients were scanned during performance of a task designed to induce cognitive fatigue. Investigators looked at the brain activation associated with "state" fatigue. In Experiment 2, DTI was used to examine where in the brain white matter damage correlated with increased "trait" fatigue in individuals with MS, as assessed by the Fatigue Severity Scale (FSS). The findings of Experiments 1 and 2 support the role of a striato-thalamic-frontal cortical system in fatigue, suggesting a "fatigue-network" in MS.
"Identifying a network of fatigue-related brain regions could reframe the current construct of cognitive fatigue and help define the pathophysiology of this multifaceted yet elusive symptom of MS," said John DeLuca, Ph.D., VP of Research & Training at Kessler Foundation. "Replication of these findings with larger sample sizes will be an important next step."
Kessler Foundation co-investigators are Venkateswaran Rajagopalan, D.Eng, John DeLuca, Ph.D., VP for Research & Training, Abhijit Das, MD, DM (now director of Institute of Neurosciences in Kolkata, India), Allison Binder, B.A., Aparna Arjunan, B.A. (now at Suffolk University, Boston, MA), Nancy Chiaravalloti, Ph.D., director of Neuropsychology & Neuroscience Research, and Glenn Wylie, D.Phil., associate director of Neuroscience Research and the Center for Neuroimaging Research @ Kessler Foundation. Foundation scientists also have faculty appointments at Rutgers New Jersey Medical School.
Recent publication: Dobryakova E, DeLuca J, Genova HM, Wylie GR. Neural correlates of cognitive fatigue: cortico-striatal circuitry and effort-reward imbalance. Int Neuropsychol Soc. 2013 Sep;19(8):849-53.
About MS Research at Kessler Foundation
Kessler Foundation's cognitive rehabilitation research in MS is funded by grants from the National Institutes of Health, National MS Society, NJ Commission of Brain Injury Research, Consortium of MS Centers, and Kessler Foundation. Under the leadership of Dr. DeLuca and Nancy Chiaravalloti, PhD, director of Neuropsychology & Neuroscience Research, scientists have made important contributions to the knowledge of cognitive decline in MS. Clinical studies span new learning, memory, executive function, attention and processing speed, emotional processing and cognitive fatigue. Research tools include innovative applications of neuroimaging, iPADs, and virtual reality. Among recent findings are the benefits of cognitive reserve; correlation between cognitive performance and outdoor temperatures; the efficacy of short-term cognitive rehabilitation using modified story technique; and the correlation between memory improvement and cerebral activation on fMRI.
About Kessler Foundation
Kessler Foundation, a major nonprofit organization in the field of disability, is a global leader in rehabilitation research that seeks to improve cognition, mobility and long-term outcomes, including employment, for people with neurological disabilities caused by diseases and injuries of the brain and spinal cord. Kessler Foundation leads the nation in funding innovative programs that expand opportunities for employment for people with disabilities. For more information, visit KesslerFoundation.org.
Carolann Murphy, PA
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