Background: Cognitive problems are commonly reported in persons with chronic fatigue syndrome (CFS) and are one of the most disabling symptoms of this condition. A number of cognitive deficits have been identified, although the findings are inconsistent and hindered by methodological differences. The current study therefore conducted a meta-analysis of research examining cognitive functioning in persons with CFS in order to identify the pattern and magnitude of any deficits that are associated with this condition.
Method: A comprehensive search of the PubMed and PsycINFO databases for studies that examined cognitive functioning in CFS between 1988 and 2008 identified 50 eligible studies. Weighted Cohen's d effect sizes, 95% confidence intervals and fail-safe Ns were calculated for each cognitive score.
• Evidence of cognitive deficits in persons with CFS was found primarily in the domains of attention, memory and reaction time.
• Deficits were not apparent on tests of fine motor speed, vocabulary, reasoning and global functioning.
Persons with CFS demonstrate moderate to large impairments:
• In simple and complex information processing speed,
• And in tasks requiring working memory over a sustained period of time.
Source: Psychological Medicine, August 2010. PMID: 20047703, by Cockshell SJ, Mathias JL. School of Psychology, University of Adelaide, South Australia, Australia.