[Cognition and perception deficits in fibromyalgia and rheumatoid arthritis]

A Comparative Analysis of Cognitive Deficits in Rheumatoid Arthritis and Fibromyalgia: Impact of Symptoms Severity and Its Clinical Implications

Purpose

Fibromyalgia syndrome (FMS) and rheumatoid arthritis (RA) are chronic pain disorders, with clearly distinct pathogenetic mechanisms, frequently accompanied by symptoms like depression, fatigue, insomnia and cognitive problems. This study compared performance in various cognitive domains between patients with FMS and RA. The role of clinical symptoms severity in determine the differences in cognitive performance was also investigated.

Patients and Methods

A cross-sectional study was conducted according to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement. In total, 64 FMS patients, 34 RA patients and 32 healthy controls participated, all women. Using factor analysis, questionnaire scores were combined to yield a symptom severity factor, which was used as a control variable in the group comparisons.

Results

Without controlling for symptom severity, both patient groups performed worse than controls in all the cognitive domains assessed (visuospatial memory; verbal memory; strategic planning and self-regulation; processing speed, attention and cognitive flexibility; and planning and organizational abilities); overall deficits were greater in FMS than in RA patients. FMS patients reported more severe clinical symptoms (current pain intensity, total pain, state anxiety, depression, fatigue and insomnia) than RA patients. After controlling for symptom severity, a large proportion of the cognitive test parameters no longer differed between FMS and RA patients.

Conclusion

The study confirmed significant impairments in attention, memory, and higher cognitive functions in both FMS and RA. The greater deficits seen in FMS patients may at least partly be explained by more severe pain and secondary symptoms. Cognitive screening may facilitate the development of personalized treatment plans to optimize the quality of life of FMS and RA patients.

Revealing the Role of Social Support on Cognitive Deficits in Fibromyalgia Syndrome

Despite the relevance of cognitive deficits in fibromyalgia syndrome (FMS) and the attempts to elucidate the influence of the disorder symptoms in the cognitive decline reported by patients, no studies have explored the specific role of social support on cognition in FMS. Social support has been shown to be an essential modulator factor on cognitive performance in other diseases. Sixty-four women with FMS and 32 healthy women participated in the study and completed questionnaires pertaining to anxiety, depression, fatigue, insomnia, clinical pain, and social support, along with a neuropsychological battery assessing verbal memory, organization, strategic and planning abilities, self-regulation, processing speed, attention, and cognitive flexibility. Results showed that FMS patients exhibited lower values in all social support dimensions in comparison with healthy individuals, especially in the socializing dimension. Despite the lower social support observed in FMS, all social support dimensions showed a positive impact on verbal memory, organization and planning abilities, strategic planning, self-regulation, processing speed, attention, and cognitive flexibility in these patients. In fact, social support was associated with greater correct responses and processing speed and minor number of errors in all the neuropsychological battery tests. Socializing was the main predictor of organization and planning abilities, strategic planning, and self-regulation. In sum, results suggest that social support may be a key factor in buffering the cognitive decline observed in FMS. Designing psychoeducation programs and intervention programs directed not only to FMS patients but also relatives, health care workers, and the general population might be essential to improve the social support of FMS patients and positively impact on patient's cognitive status.

Fibromyalgia Syndrome and Cognitive Decline: The Role of Body Mass Index and Clinical Symptoms

The high prevalence of obesity and overweight in fibromyalgia (FM) may be an important factor in the well-known cognitive deficits seen in the disorder. This study analyzed the influence of body mass index (BMI) and primary clinical symptoms of FM (pain, fatigue, insomnia, anxiety, and depression) on attention, memory, and processing speed in FM. Fifty-two FM patients and thirty-two healthy participants completed cognitive tasks assessing selective, sustained, and divided attention; visuospatial and verbal memory; and information processing speed. Furthermore, they were evaluated in terms of the main clinical symptoms of the disorder. FM patients showed a marked reduction of cognitive performance in terms of selective, sustained, and divided attention; visuospatial memory; and processing speed, but no group differences were observed in verbal memory. BMI negatively affects sustained and selective attention, verbal memory, and processing speed and is the main predictor of performance in these basic cognitive domains. Our findings confirm the presence of cognitive deficits with respect to attention and visual memory, as well as slower processing speed, in FM. Moreover, the results support a role of BMI in the observed cognitive deficits. Interventions increasing physical activity and promoting cognitive stimulation could be useful for strengthening cognitive function in FM patients.

Working Memory Performance, Pain and Associated Clinical Variables in Women With Fibromyalgia

Working memory (WM) is a critical process for cognitive functioning in which fibromyalgia (FM) patients could show cognitive disturbances. Dyscognition in FM has been explained by interference from pain processing, which shares the neural substrates involved in cognition and may capture neural resources required to perform cognitive tasks. However, there is not yet data about how pain is related to WM performance, neither the role that other clinical variables could have. The objectives of this study were (1) to clarify the WM status of patients with FM and its relationship with nociception, and (2) to determine the clinical variables associated to FM that best predict WM performance. To this end, 132 women with FM undertook a neuropsychological assessment of WM functioning (Digit span, Spatial span, ACT tests and a 2-Back task) and a complete clinical assessment (FSQ, FIQ-R, BDI-1A, HADS, PSQI, MFE-30 questionnaires), including determination of pain thresholds and tolerance by pressure algometry. Patients with FM seem to preserve their WM span and ability to maintain and manipulate information online for both visuospatial and verbal domains. However, up to one-third of patients showed impairment in tasks requiring more short-term memory load, divided attention, and information processing ability (measured by the ACT task). Cognitive performance was spuriously related to the level of pain experienced, finding only that pain measures are related to the ACT task. The results of the linear regression analyses suggest that sleep problems and fatigue were the variables that best predicted WM performance in FM patients. Future research should take these variables into account when evaluating dyscognition in FM and should include dynamic measures of pain modulation.

Cognitive impairment in patients with rheumatoid arthritis: A systematic review and meta-analysis

OBJECTIVE

An increasing number of studies have demonstrated cognitive impairment in patients with rheumatoid arthritis (RA). The literature indicates many factors play an important role in this clinical problem, such as the severity of depressive symptoms and the treatment used. The aim of this study was to systematically review studies comparing cognitive functioning between healthy participants and RA patients and to determine both the severity and potential moderators of cognitive impairment.

METHODS

For this purpose, 16 studies that fulfilled all selection criteria were carefully selected. Altogether, 921 patients with RA (812 women and 109 men) and 700 controls participated in these studies. Due to the inability to perform a network meta-analysis, it was decided to determine the effect sizes for studies which used the same measurement methods.

RESULTS

The analysis demonstrated greater impairment of cognitive functioning in patients with RA than in healthy controls, with effect sizes ranging from small to large, depending on the assessment method used in the study.

CONCLUSIONS

The study pinpoints potential biases, lack of replication, and inconsistencies in reporting data as possible confounding factors and suggests further recommendations for assessment methods, research directions and clinical implications.

CLINICAL TRIAL REGISTRATION

Not applicable.

Altered sub-processes of working memory in fibromyalgia patients: An ERP study using N-back task

OBJECTIVE

Cognitive dysfunction in fibromyalgia has become a key symptom considered by patients as more disabling than pain itself. Experimental evidence from neuropsychological and neuroimaging studies indicates that such cognitive impairments are especially robust when patients need to set in motion working memory processes, suggesting the existence of an altered functioning underlying the cerebral cortices of the frontoparietal memory network. However, the temporal dynamics of working memory sub-processes have not yet been explored in fibromyalgia.

SUBJECTS

Thirty-six right-handed women participated in the experiment: comprising eighteen patients with fibromyalgia and eighteen healthy controls.

METHODS

Event-related potentials (ERPs) and behavioural responses were recorded while participants were engaged in a 2-back working memory task. Principal Component Analyses (PCA) were used to define and quantify the ERP components associated with working memory processes.

RESULTS

Fibromyalgia patients exhibited worse performance than the control group, as revealed by their number of errors in the working memory task. Moreover, both scalp parieto-occipital P2 and parieto-occipital P3 amplitudes were lower for patients than for healthy control participants. Regression analyses revealed that lower P3 amplitudes were observed in those patients with fibromyalgia reporting higher pain ratings.

CONCLUSIONS

Current results suggest that both encoding of information (as reflected by P2) and subsequently, context updating and the replacement (as seen in lower P3 amplitudes), as a part of working memory sub-processes, are impaired in fibromyalgia. Studying the temporal dynamics of working memory using ERP methodology is a helpful approach to detect specific cognitive impaired mechanisms in this chronic pain syndrome. These new data could be used to develop more specific treatments adapted for each patient.

Pain-dependent learning in healthy volunteers

A state-dependent learning paradigm was studied in which healthy adult volunteers studied/encoded and recalled information from short passages, neutral in their content, in one of the following conditions: (1) Pain during study-Pain during both recall sessions; (2) Pain during study-No Pain during both recall sessions; (3) No Pain during study-Pain during both recall sessions; and (4) No Pain during study-No Pain during both recall sessions. Pain was experimentally induced using the cold pressor technique. In this study, we looked at evidence for state-dependent learning when the context of learning is not emotionally driven, but neutral. The memory task consisted of encoding detailed information about short stories, then recalling as many details as possible 20 min and 48 hr later. The results indicated no occurrence of a state-dependent learning and retrieval effect in this sample: Participants in the pain-no pain and no pain-pain conditions did not significantly perform differently than participants in the pain-pain and no pain-no pain conditions. However, a main effect of the state during study/encoding was significant, suggesting that being in pain during study had a detrimental effect on performance on the memory tests regardless of the state at retrieval. These results oppose previous studies' findings and shed new light on possible implications in various research areas.

Effects of COMT Genotypes on Working Memory Performance in Fibromyalgia Patients

Growing research has reported the presence of a clear impairment of working memory functioning in fibromyalgia. Although different genetic factors involving dopamine availability (i.e, the COMT gene) have been associated with the more severe presentation of key symptoms in fibromyalgia, scientific evidence regarding the influence of COMT genotypes on cognitive impairment in these patients is still lacking. To this end, 167 participants took part in the present investigation. Working memory performance was assessed by the application of the SST (Spatial Span Test) and LNST (Letter and Number Sequence Test) belonging to the Weschler Memory Scale III. Significant working memory impairment was shown by the fibromyalgia patients. Remarkably, our results suggest that performance according to different working memory measures might be influenced by different genotypes of the COMT gene. Specifically, fibromyalgia patients carrying the Val/Val genotype exhibited significantly worse outcomes for the span of SST backward, SST backward score, SST total score and the Working Memory Index (WMI) than the Val/Val healthy carriers. Furthermore, the Val/Val patients performed worse on the SST backward and SST score than heterozygotes. Our findings are the first to show a link between the COMT gene and working memory dysfunction in fibromyalgia, supporting the idea that higher COMT enzyme activity would contribute to more severe working memory impairment in fibromyalgia.

Neuropsychological Changes in Complex Regional Pain Syndrome (CRPS)

Complex Regional Pain Syndrome (CRPS) is a poorly understood chronic pain condition of multifactorial origin. CRPS involves sensory, motor, and autonomic symptoms primarily affecting one extremity. Patients can also present with neuropsychological changes such as reduced attention to the CRPS-affected extremity, reminiscent of hemispatial neglect, yet in the absence of any brain lesions. However, this "neglect-like" framework is not sufficient to characterise the range of higher cognitive functions that can be altered in CRPS. This comprehensive literature review synthesises evidence of neuropsychological changes in CRPS in the context of potential central mechanisms of the disorder. The affected neuropsychological functions constitute three distinct but not independent groups: distorted body representation, deficits in lateralised spatial cognition, and impairment of non-spatially-lateralised higher cognitive functions. We suggest that many of these symptoms appear to be consistent with a broader disruption to parietal function beyond merely what could be considered "neglect-like." Moreover, the extent of neuropsychological symptoms might be related to the clinical signs of CRPS, and rehabilitation methods that target the neuropsychological changes can improve clinical outcomes in CRPS and other chronic pain conditions. Based on the limitations and gaps in the reviewed literature, we provide several suggestions to improve further research on neuropsychological changes in chronic pain.

Executive Functions and Pain

Abstract. A growing body of literature suggests that chronic-pain patients suffer from problems in various neuropsychological domains, including executive functioning. In order to better understand which components of executive functioning (inhibition, shifting and/or updating) might be especially affected by pain and which mechanisms might underlie this association, we conducted a systematic review, including both chronic-pain studies as well as experimental-pain studies. The chronic-pain studies (N = 57) show that pain is associated with poorer executive functioning. The findings of experimental-pain studies (N = 28) suggest that this might be a bidirectional relationship: Pain can disrupt executive functioning, but poorer executive functioning might also be a risk factor for higher vulnerability to pain.

A comprehensive literature review of chronic pain and memory

Chronic pain patients often complain of their "poor memory" and numerous studies objectively confirmed such difficulties in reporting working memory (WM) and long-term memory (LTM) dysfunctions. This paper provides a comprehensive review of the literature on memory impairment in chronic pain (CP) patients. Twenty-four observational studies evaluating WM or/and LTM in a chronic pain group and a control group were included in this review. Results showed that studies consistently reported a moderate decline, in both WM and LTM performances in CP patients. Even if CP patients complained about forgetfulness, objective measurements did not permit to conclude to a long-term storage impairment. CP patients exhibited more specifically encoding or retrieving difficulties compared to controls. Results showed that chronic pain selectively impacted the most attention-demanding memory processes, such as working memory and recollection in long-term memory. Results also demonstrated that CP patients exhibited a memory bias directed towards painful events compared to control subjects. Several authors have suggested that CP could be a maladaptive consequence of memory mechanisms. The long-lasting presence of pain continuously reinforces aversive emotional associations with incidental events. The inability to extinguish this painful memory trace could explain the chronic persistence of pain even when the original injury has disappeared. A major concern is the need to extricate pain-related cognitive effects from those resulting from all the co-morbidities associated with CP which both have a deleterious effect on cognitive function.

Broad cognitive complaints but subtle objective working memory impairment in fibromyalgia patients

BACKGROUND

Cognitive dysfunction in fibromyalgia (FM) encompasses objective cognitive difficulties, as measured in neuropsychological tests, and self-reported cognitive complaints. Although it has been suggested that FM patients display problems in working memory, the data are inconsistent, and the overall working memory status of the patients is unclear. It is also not clear whether the working memory problems are related to cognitive complaints or how the dyscognition is affected by the characteristic clinical symptoms of FM.

METHODS

To clarify these aspects, we explored the neuropsychological performance for different components of working memory and the subjective self-perception of cognitive status in a sample of 38 women with FM. They were compared with a matched group of 32 healthy women.

RESULTS

Our findings suggested that the FM patients do not differ from healthy controls in their overall working memory functioning. Only a poor performance was found in a single task of visuospatial working memory, mediated by the presence of depressive symptoms, fatigue and pain. The FM patients also displayed a higher level of perception of cognitive difficulties than healthy controls, and this difference was mediated by depression and fatigue. Furthermore, cognitive complaints in FM patients were only associated with a lower verbal WM capacity.

DISCUSSION

FM patients have a subtle specific impairment in their working memory functioning, as well as elevated concern about their cognitive status. These findings suggest a disconnection between neuropsychological performance and subjective complaints. In FM patients, clinical variables such as pain, fatigue, and depression play an important role in dyscognition, as assessed by both objective and subjective measures, and should be taken into account in future research.

Cognitive deficits in fibromyalgia syndrome are associated with pain responses to low intensity pressure stimulation

Background

Fibromyalgia syndrome (FMS) is a chronic disorder characterized by widespread musculoskeletal pain and diffuse tenderness, accompanied by complaints including morning stiffness, fatigue, insomnia and affective symptoms. In addition, affected patients frequently experience cognitive impairments such as concentration difficulties, forgetfulness or problems in planning and decision-making. These deficits are commonly ascribed to interference between nociceptive and cognitive processing.

Method

The present study investigated the association of cognitive performance with (a) pain responses to low intensity pressure stimulation (0.45–2.25 kg/cm²), (b) responses to stronger (above-threshold) stimulation (2.70 kg/cm²), and (c) pain threshold and tolerance in 42 women with FMS. Tests of attention, memory, processing speed, and executive functions were applied.

Results

While no significant correlations were seen for pain threshold and pain tolerance, inverse associations arose between pain intensity ratings during pressure stimulation and performance in all evaluated cognitive domains. The magnitude of the correlations increased with decreasing stimulus intensity.

Conclusions

It may be concluded that pain experience during somatosensory stimulation of low intensity is more closely related to attention, memory and executive functions in FMS than the traditional measures of pain threshold and pain tolerance. Considering that pain responses to low intensity stimulation reflect the hyperalgesia and allodynia phenomena characterizing FMS, it may be hypothesized that central nervous pain sensitization is involved in cognitive impairments in the disorder.

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.

Magnitude and variability of effect sizes for the associations between chronic pain and cognitive test performances: a meta-analysis

OBJECTIVES AND METHODS

A systematic review and meta-analysis were performed to estimate the size and variability of the association between chronic pain (CP) and poorer cognitive test performances as a function of individual tests, pain sub-types, and study sources on 22 studies having (1) a control group, (2) reported means and standard deviations (SDs) and (3) tests studied at least 3 times.

RESULTS

CP patients performed significantly poorer with small to moderate effects (d = -.31 to -.57) on Digit Span Backward; STROOP Word; Color and Color-Word; Digit Symbol; Trail Making A and B; Rey Auditory Learning Immediate and Delayed Recall and Recognition. For these 10 measures, single effects (no interaction) were supported (I(2) = 0%-8%) and Random and Fixed models yielded similar results. No group differences were found for Corsi Blocks Forward or Wisconsin Cart Sorting Test Categories Achieved, or Perseveration. Effects for the Rey Complex Figure Immediate and Delayed Recall were significant, but effect size was inconclusive, given moderate to high heterogeneity and lack of consistency between Random and Fixed models. For the Paced Auditory Serial Addition Test, there was a homogeneous (I(2) = 0%) and significantly lower performance in fibromyalgia (d = -.47), but no effect in diagnostically undifferentiated pain samples, and wide variability across studies of whiplash (d = -.15 to -1.04, I(2) = 60%).

CONCLUSION

The magnitude and consistency of the CP - cognition effect depended on the test, pain subgroup and study source.

SUMMARY POINTS

Among tests showing a chronic pain (CP) - cognition effect, the magnitude of this association was consistently small to moderate across tests.Effect size estimation was inconclusive for Digit Span Forwards, the Paced Auditory Serial Addition Test and the Rey Complex Figure Test.Variance was too heterogeneous for testing cognitive domain specificity of the CP - cognition effect.

Methods and Instruments to Evaluate Cognitive Function in Chronic Pain Patients: A Systematic Review

OBJECTIVE

We aimed to systematically review the methods and instruments used to evaluate cognitive function in chronic pain (CP) patients.

METHODS

A sensitive search strategy was designed using five databases. Based on the objectives and methodology, we selected cross-sectional studies on adults with chronic non-cancer pain in which cognitive function was assessed using validated instruments. The characteristics of the subjects, control groups, and other variables that might affect cognitive function, and the instruments used, were extracted from each article.

RESULTS

In the 42 articles identified, 53 instruments were used to assess cognitive function. Chronic pain criteria were defined in 83.3% of the articles and more than half (57.1%) included single diagnosis samples, with fibromyalgia being the most frequent studied (75%). Patients with prior cognitive impairment were excluded in 61.9% of the studies, and a control group was included in 64.3% of the studies. In most cases potential confounding variables were evaluated. More than 14% of the studies used self-report measures, and 73.8% used neuropsychological instruments, particularly for assessing attention (30%) and memory (27.5%). None of the instruments were specifically validated for pain patients and only five studies analyzed the psychometric properties of the instruments.

CONCLUSIONS

Various instruments and methods were used to assess cognitive function in CP patients, particularly fibromyalgia patients, but also other cohorts with well-defined CP. The instruments used had been validated, but not for pain populations, thus they require specific adaptation and validation to be used in CP patients. Certain recommendations are made in order to improve the evaluation of cognitive function in these patients.