Abstract

Andrew P. Smith*

ABSTRACT

Background: Memory problems are frequently reported by Chronic Fatigue Syndrome (CFS) patients. These self-reports are often not confirmed using objective memory tests. Indeed, conflicting results have been obtained in previous studies examining the performance of CFS patients on a variety of memory tasks. Results have shown that CFS patients perform working and semantic memory more slowly but show no decrease in accuracy. The present study examined whether sleep disturbances, depression, age and intelligence may modify the effects of CFS on memory. Methods: CFS patients were recruited from a specialist clinic and compared with healthy controls. Three experiments were carried out. The first used memory tasks designed to examine the different components of working memory. The second used working memory and semantic memory tasks and also examined psychomotor speed. The third used the "Doors and People" task, which measures immediate recall and forgetting of names and visual shapes. Measures of intelligence, insomnia and depression were also recorded. Results: The CFS patients reported frequent memory problems and showed a trend of impaired memory performance. However, only the differences in speed scores and the recall of shapes were significant. Depression, insomnia, age and intelligence did not significantly modify the performance of the CFS patients. Conclusions: CFS patients reported frequent memory problems, but objective testing largely failed to confirm this. The CFS patients were slower at several tasks (Digit-Symbol Substitution; Semantic Processing; writing and simple reaction time), and this slowing may be involved in the poorer immediate recall of shapes. Depression, insomnia, age and intelligence did not change the CFS effects. Future research should use large sample sizes as the effect sizes of being in the CFS group were small.