Dr. William Reeves from the CDC conducted a study to test measured deficits in working memory and motor response in ME/CFS that is not associated with psychiatric and psychological problems.
The objective of the study was to examine the neuropsychological function characterized in subjects with chronic fatigue syndrome at the same time controlling for relevant confounding factors. Neuropsychology addresses relationships between brain structure & function, information processing, behavior.
http://www.fightingfatigue.org/?p=1601