Neurocognitive impairment in patients with Fibromyalgia and Chronic Fatigue Syndrome

Background: Fibromyalgia (FM) and chronic fatigue syndrome (CFS), two diseases that are frequently associated, are known to share many symptoms, which include pain - usually more pronounced in FM - and fatigue, together with mood, sleep and neurocognitive disorders. Symptoms as clouded mentation, forgetfulness and difficulty concentrating are very common and contribute to the disability of the disorders. These complaints are termed “fibrofog” and suggest that the central nervous system may be involved in the pathophysiology of the syndroms. Coexisting psychological distress or a psychiatric disorder also may contribute to neurocognitive deficits. Moreover literature data suggest that the peptide β amyloid, major constituent of amyloid plaques, is involved in neurodegenerative and psychiatric disorders as Alzheimer and depression. Objective: The aim of the study was to investigate neurocognitive disorders in FMS and CFS patients also examining the influence of many clinical variables (i.e. pain, fatigue, mood and sleep disorders, drug assumption). Secondary objective was to evaluate the levels of β amyloid to better understand neurodegenerative impairments in these syndromes. Methods: Forty patients with a diagnosis of fibromyalgia and 45 patients with a diagnosis of chronic fatigue syndrome were consecutively recruited. All patients were asked to complete a set of questionnaires on paper and perform a battery of neurocognitive computerized (CNS Vital Signs©). Subsequently in a subgroup of 25 FMS, 25 CFS patients and 25 healthy subjects we evaluated the levels of beta amyloid (isoforms Aβ 40 and Aβ 42 and their ratio) using a commercial ELISA kit. Results: Patients with fibromyalgia were compared to chronic fatigue syndrome, and in the first group female sex was prevalent (97.5% vs 51.1%). Moreover, they were different for duration of illness and pain perception. Although patients from both groups similarly complained about neurocognitive problems of concentration or/and attention, thanks to the use of CNS Vital Signs© test battery we found that fibromyalgia patients resulted to have more compromised neurocognitive function and neurocognitive impairments were found to correlate with pain and illness duration. Concerning beta amyloid no difference in Aβ 40 and Aβ 42 and their ratio was found between patient and control, moreover we did not find any correlation between Aβ40 and Aβ42 levels and cognitive impairment. In the FM group we found a statistically significant negative correlation between Aβ40/42 ratio and disease duration (p=0.0056; r= -0.53) and a statistically significant negative correlation between Aβ40 levels and FIQ values (p=0.037; r=-0.42) and FACIT scores (p=0.0069; r=-0.52). Moreover in FM we found a negative correlation between Aβ42 levels and age (p=0,03, r= -0,43) Conclusion: In patient affected by fibromyalgia or/and chronic fatigue syndrome, neurocognitive impairments should never be underestimated, because they could disclose a more severe condition affecting the central nervous system. The cognitive impairment referred by FM and CFS patients and evaluated by CNS vital signs© don’t correlate with the Aβ levels. These observation suggest that the cognitive impairment referred by the patients, was probably related to the health status, instead of a damage of central nervous system.