Scheffers, M K, Johnson, R, Grafman, J et al. · Neurology · 1992 · DOI
This study compared brain activity and reaction times between 13 people with ME/CFS and 13 healthy volunteers using brain scans while they performed attention and memory tasks. The ME/CFS patients showed much slower and more variable reaction times, but their memory and thinking abilities appeared normal. The researchers found that the brain's basic attention and memory processes were working similarly in both groups, suggesting the slowness came from problems with how the brain signals muscles to respond.
This study provides objective neurophysiological evidence that ME/CFS-related cognitive difficulties may not stem from fundamental deficits in attention or memory, but rather from problems with translating thought into action. Understanding the specific nature of cognitive impairment in ME/CFS helps researchers and clinicians distinguish cognitive complaints from actual dysfunction and guides treatment development.
This study does not establish whether the response-related deficits are neurological, neuromuscular, or metabolic in origin. The small sample size (N=13 per group) and lack of post-exertion malaise (PEM) measurement limit generalizability. Cross-sectional design cannot determine whether these deficits are permanent traits or fluctuate with disease severity and fatigue levels.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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