Cognition in Restless Legs Syndrome

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.

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.

Working memory deficits in patients with idiopathic restless legs syndrome are associated with abnormal theta-band neural synchrony

Cognitive impairment, particularly prefrontal function, has been reported in patients with restless legs syndrome. However, working memory performance in patients with restless legs syndrome remains uncertain. The present study aimed to examine working memory performance in patients with restless legs syndrome by investigating electroencephalography theta-band oscillations within task-relevant brain regions and the synchronization among oscillations during a working memory task. Twelve female idiopathic patients with restless legs syndrome and 12 female healthy controls participated in this study. Nineteen-channel electroencephalography data were recorded while participants performed a Sternberg working memory task. We analysed event-related theta-band activity and interregional theta-band phase synchrony during the memory retrieval phase. The spatial pattern of theta-band phase synchrony was quantified using graph theory measures, including the clustering coefficient, characteristic path length, and small-world propensity. Considerable increases in theta-band activity and theta-band phase synchrony were observed at 600-700 ms in controls and at 650-750 ms in restless legs syndrome subjects after the probe item was presented. During this period, induced theta-band activity showed lower with borderline significance in the restless legs syndrome subjects than in the controls regardless of channel location (F_4,88  = 3.92, p = .06). Theta-band phase synchrony between the frontal and posterior regions was significantly reduced in the restless legs syndrome subjects. Inefficiency in both global and local networks in the restless legs syndrome subjects was revealed by the decreased small-world propensity (t₂₂  = 2.26, p = .03). Small-world propensity was negatively correlated with restless legs syndrome severity (r = -.65, p = .02). Our findings suggest that patients with restless legs syndrome have multiple deficits in cognitive processes, including attentional allocation, evaluation of incoming stimuli, and memory manipulation of encoded information during a working memory task. Abnormal local theta-band neural synchrony and global theta-band neural synchrony may underlie the neurophysiological mechanism of the working memory dysfunction associated with restless legs syndrome.

Association between Restless Legs Syndrome Symptoms and Self-Reported Hypertension: a Nationwide Questionnaire Study in Korea

BACKGROUND

The association between restless legs syndrome (RLS) and hypertension remains controversial. We investigated the relationship between RLS and hypertension in a nationwide sample of the Korean adult population.

METHODS

This was a cross-sectional questionnaire-based study including 2,740 adults aged 19 years or more. Subjects who met the four essential International RLS Study Group criteria and reported symptoms occurring at least once a week were defined as the RLS group. The presence of hypertension was defined as a self-reported history of physician-diagnosed hypertension. We conducted multiple logistic regression analysis to determine the independent association between RLS symptoms and self-reported hypertension after adjusting for potential confounding factors.

RESULTS

Among the 2,740 subjects, 68 (2.5%; 95% confidence interval [CI], 1.9%-3.1%) were found to have RLS with a symptom frequency of at least once a week. The prevalence of self-reported hypertension was 30.9% (95% CI, 20.5%-42.0%) in the RLS group, which was significantly higher than that in controls (12.4%; 95% CI, 11.2%-13.6%; P < 0.001). Multiple logistic regression analysis showed that the adjusted odds ratio for self-reported hypertension in the RLS group was 2.10 (95% CI, 1.12-3.93) compared to controls. In addition to RLS symptoms, old age, being overweight, low education level, diabetes mellitus, and short sleep duration were significantly associated with self-reported hypertension.

CONCLUSION

RLS symptoms occurring at least once a week is independently associated with a higher prevalence of self-reported hypertension in the adult Korean population. Further research will confirm the clinical implication of the present results and the causal relationship between RLS and hypertension.

Abnormal Sleep Delta Rhythm and Interregional Phase Synchrony in Patients with Restless Legs Syndrome and Their Reversal by Dopamine Agonist Treatment

Background and Purpose

The purpose of this study was to characterize abnormal cortical activity during sleep in restless legs syndrome (RLS) patients and to determine the effects of treatment with a dopamine agonist. Based on whole-brain electroencephalograms, we attempted to verify alterations in the functional network as well as the spectral power of neural activities during sleep in RLS patients and to determine whether the changes are reversed by treatment with pramipexole.

Methods

Twelve drug-naïve RLS patients participated in the study. Overnight polysomnography was performed before and after treatment: the first recording was made immediately prior to administering the first dose of pramipexole, and the second recording was made 12–16 weeks after commencing pramipexole administration. Sixteen age-matched healthy participants served as a control group. The spectral power and interregional phase synchrony were analyzed in 30-s epochs. The functional characteristics of the cortical network were quantified using graph-theory measures.

Results

The delta-band power was significantly increased and the small-world network characteristics in the delta band were disrupted in RLS patients compared to the healthy controls. These abnormalities were successfully treated by dopaminergic medication. The delta-band power was significantly correlated with the RLS severity score in the RLS patients prior to treatment.

Conclusions

Our findings suggest that the spectral and functional network characteristics of neural activities during sleep become abnormal in RLS patients, and these abnormalities can be successfully treated by a dopamine agonist.