Post-exertion Malaise In Me/cfs

Abstract

Myalgic Encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating illness characterized by a host of symptoms including pain, fatigue and cognitive problems. One of the most debilitating aspects of ME/CFS is post-exertion malaise (PEM), a phenomenon described as a worsening of the entire ME/CFS symptom complex. Exercise has been used as a model to induce PEM, yet little is known beyond symptom exacerbation. PURPOSE: To determine symptoms, brain function and cognitive performance during PEM in ME/CFS. METHODS: Fourteen ME/CFS patients and 13 healthy controls completed baseline symptom assessment (e.g. pain, fatigue, memory, concentration) and functional neuroimaging (3.0Tesla) while performing both non-fatiguing (finger tapping and number recognition) and fatiguing (paced auditory serial addition) tasks. Participants returned one-week later, filled out symptom questionnaires and completed 30 minutes of cycling at 70% of age-predicted peak heart rate. Twenty-four hours later they returned and completed the same symptom assessment and neuroimaging protocols as baseline. Repeated measures ANOVAs were used to determine symptom and cognitive performance changes pre- to post-exercise. Linear mixed-effects analyses were conducted using Analysis of Functional Neuroimaging’ 3dLME program to determine within and between groups differences in brain responses. Data were thresholded at p<0.05 with a cluster extent of 65 voxels. RESULTS: There was significant Group by Time interaction (p<0.05) indicating that the ME/CFS patients reported greater symptom changes than controls. There was also a significant Group by Time interaction (p<0.05) for cognitive performance characterized by a worsening of performance for ME/CFS and improved performance for controls. There was a significant Group by Time interaction (p<0.05) showing that ME/CFS patient’s had greater changes in brain activity during fatiguing cognition in the mid-cingulate, inferior frontal cortex and left hippocampus compared to controls. These changes were significantly related to fatigue (p<0.05). CONCLUSIONS: ME/CFS patients experience symptom exacerbation following acute exercise that is accompanied by both augmented neural responses during fatiguing cognition and a worsening of cognitive performance. Supported by the Solve ME/CFS Initiative