Cognitive impairment in fibromyalgia: A meta-analysis of case-control studies

Objective Cognitive dysfunction has been reported in individuals with fibromyalgia. However, findings regarding cognitive function examined using neuropsychological tests have been inconsistent. The aim of the study was to determine domain-specific cognitive impairment in patients with fibromyalgia compared with healthy controls. Methods We conducted a meta-analysis that systematically searched six databases (PubMed, Ovid MEDLINE, Embase, CINAHL, PsycINFO, and Web of Science) for articles published before September 2017. Results Twenty-three case-control studies with a total of 2096 participants were included in the meta-analysis. Cognitive function was significantly lower (g = 0.87, 95% confidence interval [CI] = 0.60-1.15) in individuals with fibromyalgia than in healthy controls. Large effect sizes were found in learning/memory and attention/psychomotor speed (g = 0.94, p =.013; g = 1.22, p <.001, respectively); medium effect sizes were reported in executive function and working memory (g = 0.72, p <.001; g = 0.75, p <.001, respectively). Depression and anxiety scores were associated with the effect size of group differences in cognitive function (B = 0.11, p <.001, 95% CI = 0.09-0.13; B = 0.02, p <.001, 95% CI = 0.01-0.02, respectively). Conclusions Cognitive impairment across different cognitive domains was found in individuals with fibromyalgia compared with healthy controls. Mood states (depression and anxiety) may explain the heterogeneity across studies.