Restless Legs Syndrome and Cognitive Function: A Population-based Cross-sectional Study

Longitudinal Cognitive Trajectories in Older Adults with Restless Legs Syndrome or Willis-Ekbom Disease

Background: Restless legs syndrome/Willis-Ekbom disease (RLS/WED) has occasionally but not consistently been associated with cognitive and most notably language and executive impairment. The present study was conducted to investigate the cognitive trajectories of older individuals with RLS/WED. Methods: Participants were drawn from the randomly selected, older (>64 years), population-based HELIAD cohort. Individuals without dementia and with available neuropsychological evaluations at baseline and follow-up were considered for potential eligibility. A comprehensive assessment examining five principal components of cognition (memory, visuo-spatial ability, attention, executive function, and language) was administered to the participants. Generalized estimating equation analyses were used to examine the unadjusted and adjusted (for critical factors and covariates) effects of RLS/WED on cognition over time. Results: A total of 1003 predominantly female (59.5%), older (72.9 ± 4.9 years) participants with follow-up evaluations after a mean of 3.09 ± 0.85 years and without dementia at baseline and follow-up were included in the present study. Among them, 81 were diagnosed with RLS/WED at baseline. Global cognition, memory, attention, and executive and visuo-perceptual skills did not differ between those with and without RLS/WED. However, the RLS/WED group performed worse on language at baseline by a standard deviation of 0.249, while demonstrating a mitigated language decline over time, by a standard deviation of 0.063. The unadjusted models yielded similar results. Conclusions: Our findings were indicative of a baseline language disadvantage among older individuals with RLS/WED, but the initial discrepancy tends to dissolve over time.

Daytime impulsiveness, attention, and learning in the restless legs syndrome

INTRODUCTION

Restless legs syndrome (RLS) is a sensorimotor condition characterized by disturbing sensations and the desire to move, often localized in the legs. Cognitive changes and impulsivity can be present in RLS, although the potential effect of commonly co-occurring attention-deficit/hyperactivity disorders (ADHD) or dopamine agonist (DA) use on these are unclear.

METHOD

Twenty-three RLS patients and 22 healthy controls were included. Rey Auditory Verbal Learning Test (RAVLT), Continuous Performance Test (CPT), Beck Depression Inventory (BDI), Epworth Sleepiness Scale (ESS), State and Trait Anxiety Inventory (STAI), and Adult Attention Deficit Self-Evaluation Scale (ASRS) were administered. Performance was compared between RLS patients and controls accounting for the presence of attention-deficit/hyperactivity disorder (ADHD) and DA use.

RESULTS

Age, education, BDI, ESS, STAI, and ASRS scores were similar for control and RLS groups. Control and RLS groups performed similarly on auditory verbal learning and general attention tests. In the CPT, commission error was significantly higher and response time was significantly shorter in the RLS group compared to controls (p = .014 and p = .010, respectively). These significant differences persisted after adjusting for ADHD and DA usage.

CONCLUSION

In this study, RLS patients were more impulsive than the healthy individuals independent of ADHD and DA use. However, learning and attention performances of the patients are not affected.

A study on the prevalence of RLS in OSA and the consequences of co-occurrence

Background

Restless leg syndrome (RLS) is common among patients with obstructive sleep apnoea (OSA) but the prognostic importance of this is not studied. We have called OSA and RLS coexistence as ComOSAR.

Materials and Methods

A prospective observational study was done on patients referred for polysomnography (PSG) with the aims to evaluate 1) the prevalence of RLS in OSA and comparing it with RLS in non-OSA, 2) the prevalence of insomnia, psychiatric, metabolic and cognitive disorders in ComOSAR versus OSA alone, 3) chronic obstructive airway disease (COAD) in ComOSAR versus OSA alone. OSA, RLS and insomnia were diagnosed as per respective guidelines. They were evaluated for psychiatric disorders, metabolic disorders, cognitive disorders and COAD.

Results

Of 326 patients enrolled, 249 were OSA and 77 were non-OSA. 61/249 OSA patients, i.e. 24.4% had comorbid RLS, i.e. ComOSAR. RLS in non-OSA patients was similar (22/77, i.e. 28.5%); P = 0.41. ComOSAR had a significantly higher prevalence of insomnia (26% versus 10.1%; P = 0.016), psychiatric disorders (73.7% versus 48.4%; P = 0.00026) and cognitive deficits (72.1% versus 54.7%, P = 0.016) compared to OSA alone. Metabolic disorders like metabolic syndrome, diabetes mellitus, hypertension and coronary artery disease were also observed in a significantly higher number of patients with ComOSAR versus OSA alone (57% versus 34%; P = 0.0015). COAD was also seen in a significantly higher number of patients with ComOSAR compared to OSA alone (49% versus 19% respectively; P = 0.00001).

Conclusion

It is essential to look for RLS in patients with OSA as it leads to a significantly higher prevalence of insomnia, and cognitive, metabolic and psychiatric disorders. COAD is also more common in ComOSAR compared to OSA alone.

Restless leg syndrome and risk of all-cause dementia: a nationwide retrospective cohort study

BACKGROUND

Restless leg syndrome (RLS) is associated with poor sleep quality, depression or anxiety, poor dietary patterns, microvasculopathy, and hypoxia, all of which are known risk factors for dementia. However, the relationship between RLS and incident dementia remains unclear. This retrospective cohort study aimed to explore the possibility that RLS could be deemed as a non-cognitive prodromal feature of dementia.

METHODS

This was a retrospective cohort study using the Korean National Health Insurance Service-Elderly Cohort (aged ≥ 60). The subjects were observed for 12 years, from 2002 to 2013. Identifying patients with RLS and dementia was based on the 10th revised code of the International Classification of Diseases (ICD-10). We compared the risk of all-cause dementia, Alzheimer's disease (AD), and vascular dementia (VaD) in 2501 subjects with newly diagnosed RLS and 9977 matched controls based on age, sex, and index date. The association between RLS and the risk of dementia was assessed using Cox regression hazard regression models. The effect of dopamine agonists on the risk of dementia among RLS patients was also explored.

RESULTS

The baseline mean age was 73.4, and the subjects were predominantly females (63.4%). The incidence of all-cause dementia was higher in the RLS group than that in the control group (10.4% vs 6.2%). A baseline diagnosis of RLS was associated with an increased risk of incident all-cause dementia (adjusted hazard ratio [aHR] 1.46, 95% confidence interval [CI] 1.24-1.72). The risk of developing VaD (aHR 1.81, 95% CI 1.30-2.53) was higher than that of AD (aHR 1.38, 95% CI 1.11-1.72). The use of dopamine agonists was not associated with the risk of subsequent dementia among patients with RLS (aHR 1.00, 95% CI 0.76-1.32).

CONCLUSIONS

This retrospective cohort study suggests that RLS is associated with an increased risk of incident all-cause dementia in older adults, providing some evidence that requires confirmation through prospective studies in the future. Awareness of cognitive decline in patients with RLS may have clinical implications for the early detection of dementia.

Restless legs syndrome and cognitive function among adults: a systematic review and meta-analysis

BACKGROUND

Changes in the cognitive function of patients with restless legs syndrome is a growing area of research. Although several studies have been performed to investigate the association between restless legs syndrome (RLS) and cognitive function, the outcomes are still controversial. The meta-analysis aimed to elucidate the relationship between RLS and cognition, including global cognition and various cognitive domains including memory, attention, executive function, and spatial cognition.

METHODS

We searched the MEDLINE, EMBASE, and Web of Science databases from inception to November 2022 to screen eligible records. The means and standard deviations of cognitive test scores were obtained to calculate the standard mean difference and 95% confidence intervals.

RESULTS

A total of 1437 records were collected from the initial search and 16 records involving 4635 individuals were ultimately included in the systematic review and meta-analysis. Our data suggest negative associations between RLS and global cognition (SMD, - 0.42; 95% CI - 0.72 to - 0.11; I² = 76.6%) and attention (SMD, - 0.43; 95% CI - 0.73 to - 0.12; I² = 85.3%). No significant differences in memory (SMD, - 0.01; 95% CI - 0.31 to 0.28; I² = 68.0%), executive function (SMD, - 0.10; 95% CI, - 0.30 to 0.11; I² = 52.1%), or spatial cognition (SMD, - 0.17; 95% CI - 0.38 to 0.03; I² = 58.5%) were observed between the RLS and control groups. Moreover, the strength of the results was modified by age but not by sex or region.

CONCLUSIONS

Our findings suggest that RLS is negatively correlated with cognitive function, particularly global cognition and attention. However, the causal relationship, considering more confounders, is worthy of further exploration.

Worldwide estimation of restless legs syndrome: a systematic review and meta-analysis of prevalence in the general adult population

This systematic review, meta-analysis and meta-regression assessed the prevalence of restless legs syndrome (RLS) in the general adult population. Studies identified in Scopus, PubMed, Web of Science, and PsycInfo between January 2000 and February 2022 were included if they used a case-control or cross-sectional design and reported data regarding the prevalence of RLS. The protocol was pre-registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42022300709). A total of 97 studies including 483,079 participants from 33 different countries met the eligibility criteria. The Newcastle Ottawa Scale was used to evaluate the methodological quality, and the fill-and-trim method was used to correct probable publication bias, while the jack-knife method was performed to assess small study effect. The corrected overall pooled prevalence of RLS was 3% (95% confidence interval [CI] 1.4%-3.8%). The pooled prevalence of RLS syndrome was affected by methodological quality (no data from non-respondents in the included studies), gender (higher among women), study design (lower prevalence in case-control versus cohort and cross-sectional studies). The figures for corrected pooled prevalence among men, women, alcohol consumers and smokers were 2.8% (95% CI 2%-3.7%); 4.7% (95% CI 3.2%-6.3%); 1.4% (95% CI 0%-4.2%); and 2.7% (95% CI 0%-5.3%), respectively. The prevalence among male and female participants was lower in community-based versus non-community-based studies. Moreover, the prevalence was higher in developed versus developing countries and among elders versus adults. In conclusion, RLS is a common disorder in the general adult population, with a higher prevalence in women; however, prevalence data are affected by study design and quality.

Objective Measures of Cognitive Performance in Sleep Disorder Research

Neurocognitive tests offer objective and reliable assessment of patients' status and progress. However, there is no consensus on how to use neurocognitive assessment in sleep disorder research. An effective use of neurocognitive assessment must be based on standardized practices and have a firm theoretic basis. The aim of this review is to offer an overview of how different tests have been used in the field, mapping each test onto a corresponding cognitive domain and propose how to move forward with a suggested cognitive battery of tests covering all major cognitive domains.

Language analysis of spontaneous descriptions of restless legs syndrome: Gender differences?

Patients with restless legs syndrome (RLS) use various terms when describing their symptoms. Whether gender might influence this has not been investigated so far. The aim of this study was to evaluate possible gender differences in spontaneous descriptions of RLS symptoms. This prospective study, conducted in 100 consecutive German‐speaking RLS patients, used a single standardized question. Answers were digitally recorded and transcribed. A content‐related linguistic analysis of the transcripts was performed by two independent blinded raters. The lengths of the answers and content‐related linguistic features were compared between women and men. Ninety‐eight patients were included in the final analysis, 59 women (60.2%) and 39 men (39.8%), with a median age of 62 (23–94) and 63 (31–82) years, respectively (p = 0.602). Demographic and clinical features, including educational level and RLS treatment class, did not differ between genders (p > 0.05). Total word or sentence count showed no gender differences (p = 0.159 and 0.259, respectively), although men used more words per sentence than women (p = 0.018). More men than women described quiescegenic (i.e., triggered by rest or inactivity) symptoms (p = 0.006) and successful attempts at relief (p = 0.039). There was a non‐significant trend toward a more frequent use of the first‐person perspective in men (median times used = 5 [0–10.5] vs. 3.8 [0–17.5], p = 0.068). The more frequent mention of quiescegenic symptoms and successful attempts at relief in men could indicate differences in phenotypic presentation of RLS between genders, a more precise description of RLS symptoms or a higher experience of self‐efficacy in men compared to women.

Cognitive profile in Restless Legs Syndrome: A signal-to-noise ratio account

Restless legs syndrome (RLS) is a common neurological disorder characterized by a sensorimotor condition, where patients feel an uncontrollable urge to move the lower limbs in the evening and/or during the night. RLS does not only have a profound impact on quality of life due to the disturbed night-time sleep, but there is growing evidence that untreated or insufficiently managed RLS might also cause cognitive changes in patients affected by this syndrome. It has been proposed that RLS is caused by alterations in the signal-to-noise ratio (SNR) and in dopamine (DA) neurotransmission in the nervous system. Based on this evidence, we propose the “SNR-DA hypothesis” as an explanation of how RLS could affect cognitive performance. According to this hypothesis, variations/reductions in the SNR underlie RLS-associated cognitive deficits, which follow an inverted U-shaped function: In unmedicated patients, low dopamine levels worsen the SNR, which eventually impairs cognition. Pharmacological treatment enhances DA levels in medicated patients, which likely improves/normalizes the SNR in case of optimal doses, thus restoring cognition to a normal level. However, overmedication might push patients past the optimal point on the inverted U-shaped curve, where an exaggerated SNR potentially impairs cognitive performance relying on cortical noise such as cognitive flexibility. Based on these assumptions of SNR alterations, we propose to directly measure neural noise via “1/f noise” and related metrics to use transcranial random noise stimulation (tRNS), a noninvasive brain stimulation method which manipulates the SNR, as a research tool and potential treatment option for RLS.

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Restless legs syndrome (RLS) is a common neurological disorder.

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RLS is caused by alterations in the SNR ratio and in DA neurotransmission.

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The SNR- DA hypothesis how RLS affects cognitive performance is presented.

Convergence of psychiatric symptoms and restless legs syndrome: A cross-sectional study in an elderly French population

OBJECTIVE

The objective was to evaluate the association between restless legs syndrome (RLS) with generalized anxiety disorder (GAD), major depression disorder (MDD), dysthymia, and GAD-depression comorbidity. Secondary aims were to examine the association between RLS with the cognitive-affective and somatic-vegetative disturbances experienced as part of depression and GAD.

METHODS

This was a cross-sectional study of 1493 elderly participants (median age 80.6 years, 64% women) from Dijon, France. Probable RLS was assessed using the minimal diagnostic criteria of the International Restless Legs Study Group and RLS symptom frequency and treatment. Participants underwent structured interviews for MDD, dysthymia, and GAD. Participants also completed the Center for Epidemiological Studies-Depression scale (CES-D). The association between RLS and psychiatric disorders, their criterion symptoms, or symptom factors was examined using logistic regression.

RESULTS

The point prevalence of probable RLS in this sample was 8.2%. Probable RLS was associated with isolated GAD (odds ratio [OR] 2.17, 95% confidence interval [CI] 1.01-4.68) and comorbid GAD-any depression disorder (OR 3.26, 95% CI 1.14-9.29), but not MDD or dysthymia. Probable RLS was also associated with the GAD criterion worry most days and feeling tense, and the CES-D factors representing depressed affect, somatic symptoms, and positive affect.

CONCLUSIONS

Probable RLS was associated with GAD-depression comorbidity as well as isolated GAD. The findings challenge previous reports linking RLS solely with MDD, suggesting the association is partly driven by GAD-depression comorbidity.

Among substance-abusing traffic offenders, poor sleep and poor general health predict lower driving skills but not slower reaction times

Background

Traffic accidents are a significant health issue in Iran. Explanations for such accidents have included single consideration of the role of poor sleep and negative psychological trait and state variables. In this study, we examined whether and to what extent sleep, general health, and aggression can concomitantly predict driving behavior.

Methods

A total of 360 male traffic offenders (driving under substance use; mean age: 31 years) participated in this study. They completed the questionnaires covering sociodemographic, sleep-related, and behavior-related variables. In addition, their visual and acoustic reaction times were objectively tested.

Results

Poor sleep, poor general health, and higher aggression scores were associated with self-rated poor driving behavior. Poor sleep was directly associated with poor driving behavior and indirectly via poor general health and aggression. In contrast, visual and acoustic reaction times were unrelated to sleep, general health, aggression, or self-rated driving behavior.

Conclusion

To our knowledge, this is the first study in Iran to assess concomitantly poor sleep, poor general health, and higher aggression scores as independent predictors of poor driving behavior among a larger sample of substance-abusing traffic offenders. Furthermore, visual and acoustic reaction times were unrelated to sleep, general health, aggression, and driving behavior. Finally, importantly, poor sleep predicted both directly and indirectly poor driving behavior.

Executive and Visuospatial Dysfunction in Patients With Primary Restless Legs Syndrome/Willis-Ekbom Disease: Study of a Chinese Population

STUDY OBJECTIVES

The aim of the study was to investigate the cognitive function of patients with primary restless legs syndrome/Willis-Ekbom disease (RLS/ WED) in a Chinese population.

METHODS

A total of 40 patients with RLS/WED who were drug naïve and 40 controls, matched by age, sex, and educational level, were evaluated by cognitive function assessments, including the Chinese version of the Mini-Mental State Examination (MMSE-C), clock drawing test (CDT), Auditory Verbal Learning Test (AVLT), Rey-Osterrieth Complex Figure Test (CFT), and Stroop Color Word Test (SCWT).

RESULTS

Patients with RLS/WED showed worse performance on the SCWT (Stroop Card C time: 102.36 ± 17.12 versus 87.08 ± 7.73 seconds, P = .033; Interference Index: 3.39 ± 0.38 versus 2.90 ± 0.15, P < .0001), CFT (24.05 ± 9.28 versus 33.74 ± 1.59, P = .008), and CDT than controls (16-score method: 10.13 ± 3.94 versus 13.98 ± 1.79, P = .0002) after adjusting for Hamilton Anxiety Scale score, Hamilton Depression Scale score, Epworth Sleepiness Scale score, and Pittsburgh Sleep Quality Index total score to eliminate the confounders of concomitant sleep disturbances, anxiety, and depression.

CONCLUSIONS

Our study suggested that cognitive functions involving executive and visuospatial domains might be disturbed in Chinese patients with primary RLS/WED.

Further Evidence of the Zero-Association Between Symptoms of Insomnia and Facial Emotion Recognition-Results From a Sample of Adults in Their Late 30s

Background: Restoring sleep is associated with favorable cognitive, emotional, and behavioral adaptations. As regards the association between sleep duration and facial emotion recognition (FER), results are conflicting, and as regards the association between symptoms of insomnia and FER, no study has been performed so far. Accordingly, the aim of the present study was to investigate whether subjective sleep was associated with FER, along with perceived stress and mental toughness. Method: A total of 201 police officers (mean age = 38.5 years, 64.2% males) took part in the present cross-sectional study. They completed questionnaires covering socio-demographic data, subjective symptoms of insomnia, perceived stress, and mental toughness. Further, they underwent a computerized FER test, consisting of facial emotion labeling and facial emotion matching. Results: Performance of FER (accuracy, speed) was unrelated to subjective symptoms of insomnia. Lower FER was associated with higher age, but not to perceived stress or mental toughness. No gender differences were observed. Higher symptoms of insomnia were associated with higher stress scores and lower scores of mental toughness. Conclusions: The pattern of results suggests that FER was not associated with symptoms of insomnia, understood as a proxy of sleep quality, among adults. This observation replicates those studies showing a zero-association between sleep and FER.

Impact of restless legs syndrome in patients with inflammatory bowel disease on sleep, fatigue, and quality of life

PURPOSE

Inflammatory bowel disease has been associated with neurological symptoms including restless legs syndrome. Here, we investigated the impact of restless legs syndrome in patients with inflammatory bowel disease on sleep, fatigue, mood, cognition, and quality of life.

METHODS

Two groups of inflammatory bowel disease patients, with and without restless legs syndrome, were prospectively evaluated for sleep disorders, fatigue, daytime sleepiness, depression, anxiety, and health-related quality of life. Furthermore, global cognitive function, executive function, attention, and concentration were assessed in both groups. Disease activity and duration of inflammatory bowel disease as well as current medication were assessed by interview. Inflammatory bowel disease patients with and without restless legs syndrome were matched for age, education, severity, and duration of their inflammatory bowel disease.

RESULTS

Patients with inflammatory bowel disease and clinically relevant restless leg syndrome suffered significantly more frequent from sleep disturbances including sleep latency and duration, more fatigue, and worse health-related quality of life as compared to inflammatory bowel disease patients without restless legs syndrome. Affect and cognitive function including cognitive flexibility, attention, and concentration showed no significant differences among groups, indicating to be not related to restless legs syndrome.

CONCLUSIONS

Sleep disorders including longer sleep latency, shorter sleep duration, and fatigue are characteristic symptoms of restless legs syndrome in inflammatory bowel disease patients, resulting in worse health-related quality of life. Therefore, clinicians treating patients with inflammatory bowel disease should be alert for restless legs syndrome.