Cognitive functioning is impaired in patients with chronic fatigue syndrome devoid of psychiatric disease.

OBJECTIVE To examine the effect of the presence or absence of psychiatric disease on cognitive functioning in chronic fatigue syndrome. METHODS Thirty six patients with chronic fatigue syndrome and 31 healthy controls who did not exercise regularly were studied. Subgroups within the chronic fatigue syndrome sample were formed based on the presence or absence of comorbid axis I psychiatric disorders. Patients with psychiatric disorders preceding the onset chronic fatigue syndrome were excluded. Subjects were administered a battery of standardised neuropsychological tests as well as a structured psychiatric interview. RESULTS Patients with chronic fatigue syndrome without psychiatric comorbidity were impaired relative to controls and patients with chronic fatigue syndrome with concurrent psychiatric disease on tests of memory, attention, and information processing. CONCLUSION Impaired cognition in chronic fatigue syndrome cannot be explained solely by the presence of a psychiatric condition.