Impact of Fatigue on Cognitive Functioning among Premenopausal Women with Fibromyalgia Syndrome and Rheumatoid Arthritis: The Controlled Study

Objective: The most common cognitive problem is attentional impairment in fibromyalgia syndrome [FMS]. We aimed to evaluate the physical, mental and psychological symptoms and to determine the predictor[s] of attentional impairment in premenopausal women with two chronic painful diseases [FMS and rheumatoid arthritis [RA]] and to compare them with healthy pain-free controls [HNCs]. Methods: This study was designed to involve patients with FMS or RA. Healthy normal controls [HNC] were recruited for comparison. Stroop color and word interference test was selected as cognitive measure. Questionnaires regarding FMS symptoms [100 mm visual analog scale], quality of life [Fibromyalgia Impact Questionnaire], sleep disorders [Pittsburgh Sleep Quality Index] and anxiety and depression [Hospital Anxiety and Depression Scale] were also applied to all groups. Results: Ninety-eight age- and education-matched premenopausal female patients were recruited. The evaluation groups were FMS [n = 40, mean age: 36.2 +/- 7.3 years], RA [n = 28, mean age: 37.3 +/- 6.0 years] and HNCs [n = 30, mean age: 33.7 +/- 8.0 years]. Scores of the Pittsburgh Sleep Quality Index, Fibromyalgia Impact Questionnaire and Hospital Anxiety and Depression Scale were worse in FMS than in RA and in HNCs [p = 0.001]. The completion times of the Stroop test were similar in patients with FMS and RA but both were worse than with HNCs [p = 0.035]. After the adjustment for age, education level and possible related factors, the Stroop test data were found to correlate with pain, fatigue, anxiety, depression, dizziness, forgetfulness and sleeplessness [p < 50.05]. Fatigue was the predictor of attentional impairment in stepwise regression analysis. Conclusion: Because of predictive role of fatigue on cognitive functioning, pharmacologic and non-pharmacologic interventions should be investigated to increase physical and mental endurance in FMS.