Background Many fibromyalgia (FM) patients experience a deteriorated cognitive function. This is one of the reasons why FM diagnosis has been moved from a pain-focused classification to a more encompassing diagnosis including cognitive difficulties. It is noteworthy that self-reported cognitive difficulties by FM patients are commonly inaccurate (1). Additionally, when cognitive function is measured by performance-based tests in FM patients, with some studies claiming the existence of cognitive deficits and other studies concluding a lack of such impairments. Finally, most of previous studies measuring performance-based memory was conducted in relatively small samples and did not examine gender differences.
Objectives The aim of the present study was to compare performance-based memory of FM patients and non-FM controls and to assess potential gender differences.
Methods A total of 507 FM patients (21 men) and 308 non-FM controls (57 men) participated in the present cross-sectional study. Four composite scores were obtained by means of the Rey Auditory Verbal Learning Test (RAVLT): learning rate, proactive and retroactive interference, and retention. Mixed-design analyses of covariance (ANCOVA) were performed on each of the RAVLT composite scores (within-subjects factor) with sample group (FM vs. non-FM controls) and gender as between-subjects factors, and education level as covariate.
Results Performance-based memory observed in FM and non-FM participants was similar in every single composite score of the RAVLT (all P>0.05). There were not gender differences in proactive interference, retroactive interference and retention (all P>0.05), although women had a higher learning rate (i.e. greater number of words recalled) than men (P<0.01).
Conclusions Our results do not support performance-based memory impairments in FM. Overall, gender differences were not observed in performance-based memory; except for learning rate, where women outperformed men regardless of sample group (i.e., FM or non-FM). Therefore, the gender differences observed seem to be an extension of the picture observed in general population rather than a disease-specific feature. Future research focusing on factors that are associated with the perception of memory deficits and the discrepancy between objective and subjective measures of memory performance is warranted.
Grace, GM; et al. (1999). Concentration and memory deficits in patients with fibromyalgia syndrome. J Clin Exp Neuropsychol; 21(4), 477–487.
Acknowledgement This study was funded by the Spanish Ministries of Economy and Competitiveness [I+D+I DEP2013–40908-R, I+D+I DEP2010–15639, BES-2014–067612, and BES-2011–047133] and Education [FPU12/00963; FPU14/12518, and FPU13/01088].
Disclosure of Interest None declared