Neuropsychology of chronic fatigue syndrome: a critical review.
Tiersky, L A, Johnson, S K, Lange, G et al.·Journal of clinical and experimental neuropsychology·1997
This review examined research on thinking and memory problems in ME/CFS patients. The clearest finding was that people with ME/CFS struggle with processing information quickly and efficiently, similar to when your brain feels sluggish. However, overall intelligence and complex thinking skills remain normal. Emotional factors like anxiety or depression can make cognitive problems feel worse, though it's unclear if they directly affect actual thinking performance.