To examine the relative influence of speed of information processing
versus working memory ability, CFS participants with
psychiatric comorbidity (CFS–Psych) and CFS without a psychiatric
history (CFS–noPsych) were examined on tests of visual and
auditory processing speed and visual and auditory working memory.
Compared to healthy controls (HC) and a group of participants with
rheumatoid arthritis (RA), the CFS–noPsych group displayed
significantly reduced performance on tests of information processing
speed, but not on tests of working memory. No significant differences
were observed between the CFS–Psych group and any other group in
the study. The implications of group heterogeneity on the understanding
of cognitive impairment in CFS are discussed. (JINS, 2004,
10, 101–109.)