Meta-analysis of cognitive performance in fibromyalgia.

Introduction: Fibromyalgia is a condition with symptoms of pain, physical function difficulties, and emotional problems, but is also characterized by complaints of poor cognition (often called "FibroFog"). Over the last two decades, a number of studies have examined cognitive differences between individuals with and without fibromyalgia. The purpose of the current study was to conduct a quantitative synthesis of these differences across multiple cognitive domains.

Method: Following Cochrane guidelines, we identified 37 eligible studies for analysis where persons with fibromyalgia (total n = 964) were compared to participants from age-matched control groups without fibromyalgia (total n = 1025) on a range of neuropsychological measures. Group differences between persons with fibromyalgia and healthy controls were examined for cognitive domains including processing speed, long- and short-term memory, and executive functions (inhibitory control, set shifting, updating, and accessing). Random-effect meta-analyses were conducted to determine effect sizes for these differences in cognitive performance.

Results: Fibromyalgia was significantly and negatively associated with performance on all domains of cognitive function. The largest effect size was found for inhibitory control (g = 0.61), followed by memory (g = 0.51 for short-term, 0.50 for long-term memory). The smallest cognitive difference between those with fibromyalgia and controls was for set shifting (g = 0.30).

Conclusion: These findings support the hypothesis that the self-reported cognitive impact of fibromyalgia is also found in objective neuropsychological measures. Routine screening for cognitive dysfunction in those with fibromyalgia may be warranted in addition to assessment of the traditional fibromyalgia symptoms.