Review of the role of the endogenous opioid and melanocortin systems in the restless legs syndrome.

Restless legs syndrome (RLS) is responsive to opioid, dopaminergic and iron-based treatments. Receptor blocker studies in RLS patients suggest that the therapeutic efficacy of opioids is specific to the opioid receptor and mediated indirectly through the dopaminergic system. An RLS autopsy study reveals decreases in endogenous opioids, ß-endorphin and perhaps Met-enkephalin in the thalamus of RLS patients. A total opioid receptor knock-out (mu, delta and kappa) and a mu-opioid receptor knock-out mouse model of RLS show circadian motor changes akin to RLS and, although both models show sensory changes, the mu-opioid receptor knock mouse shows circadian sensory changes closest to those seen in idiopathic RLS. Both models show changes in striatal dopamine, anaemia and low serum iron. However, only in the total receptor knock-out mouse do we see the decreases in serum ferritin that are normally found in RLS. There are also decreases in serum iron when wild-type mice are administered a mu-opioid receptor blocker. In addition, the mu-opioid receptor knock-out mouse also shows increases in striatal zinc paralleling similar changes in RLS. Adrenocorticotropic hormone and α-melanocyte stimulating hormone are derived from pro-opiomelanocortin as is ß-endorphin. However, they cause RLS-like symptoms and periodic limb movements when injected intraventricularly into rats. These results collectively suggest that an endogenous opioid deficiency is pathogenetic to RLS and that an altered melanocortin system may be causal to RLS as well.

Perceptions of exercise and restless legs syndrome: Results from a nationwide survey.

Restless legs syndrome is a prevalent, sensorimotor sleep disorder temporarily relieved by movement, with evidence of symptomatic improvement with regular exercise. The present study describes perceptions of the effects of exercise on symptoms of restless legs syndrome. Participants (N = 528) completed a mixed-methods (i.e. numerical and narrative), nationwide survey including items assessing personal experiences with exercise and restless legs syndrome (both positive and negative), as well as restless legs syndrome diagnosis, restless legs syndrome severity, and demographic and clinical characteristics. Responses varied widely on specific experiences with exercise, but a higher percentage of participants indicated positive experiences with exercise than those who reported negative experiences (72%-40%, respectively) with exercise. Further, 54% of respondents reported that exercise only improves restless legs syndrome, while 24% reported exercise only worsens symptoms. Participants described that any abrupt change in exercise routine would almost always elicit restless legs syndrome symptoms (e.g. hiking for a long time, stopping an exercise routine), and that a consistent pattern of exercise improved restless legs syndrome symptoms with an overall beneficial effect on the frequency of symptomatic bouts. Participants further described time of day as impactful for their exercise experience, with > 50% indicating morning exercise improves symptoms and evening exercise worsens symptoms. Participants described several questions that they wanted answered regarding the evidence for exercise in restless legs syndrome and specific exercise prescription recommendations. The present study describes information crucial to the creation of stakeholder-informed health promotion programs for individuals with restless legs syndrome to optimize personalized treatment plans that could prevent and manage symptoms.

Alterations in functional brain connectivity following treatment for restless legs syndrome: The role of symptom improvement in restoring functional connectivity.

The pathophysiology of restless legs syndrome (RLS) remains incompletely understood. Although several studies have investigated the alterations of brain connectivity as one of the pathophysiological mechanisms of RLS, there are only few reports on functional connectivity changes after RLS treatment. Forty-nine patients with newly diagnosed RLS and 50 healthy controls were prospectively enrolled. The patients underwent resting-state functional magnetic resonance imaging (rs-fMRI) at baseline, and 39 patients underwent follow-up rs-fMRI, 3 months after treatment with pramipexole or pregabalin. Patients were divided into good or poor medication response groups. Functional brain connectivity was analysed using rs-fMRI and graph theoretical analysis. Significant differences in functional connectivity were observed between the RLS patients and healthy controls. The average path length, clustering coefficient, transitivity, and local efficiency were lower (2.02 vs. 2.30, p < 0.001; 0.45 vs. 0.56, p < 0.001; 3.08 vs. 4.21, p < 0.001; and 0.71 vs. 0.76, p < 0.001, respectively) and the global efficiency was higher (0.53 vs. 0.50, p < 0.001) in patients with RLS than in healthy controls. Differences in functional connectivity at the global level were also observed between post- and pre-treatment RLS patients who showed a good medication response. Transitivity in the post-treatment group was higher than that in the pre-treatment group (3.22 vs. 3.04, p = 0.007). Global efficiency was positively correlated with RLS severity (r = 0.377, p = 0.007). This study demonstrates that RLS is associated with distinct alterations in brain connectivity, which can be partially normalised following symptom management. These findings suggest that therapeutic interventions for RLS modulate brain function, emphasising the importance of symptom-focussed treatment in managing RLS.

Functional recovery after ischemic stroke: Impact of different sleep health parameters.

Sleep disturbances after ischaemic stroke include alterations of sleep architecture, obstructive sleep apnea, restless legs syndrome, daytime sleepiness and insomnia. Our aim was to explore their impacts on functional outcomes at month 3 after stroke, and to assess the benefit of continuous positive airway pressure in patients with severe obstructive sleep apnea. Ninety patients with supra-tentorial ischaemic stroke underwent clinical screening for sleep disorders and polysomnography at day 15 ± 4 after stroke in a multisite study. Patients with severe obstructive apnea (apnea-hypopnea index ≥ 30 per hr) were randomized into two groups: continuous positive airway pressure-treated and sham (1:1 ratio). Functional independence was assessed with the Barthel Index at month 3 after stroke in function of apnea-hypopnea index severity and treatment group. Secondary objectives were disability (modified Rankin score) and National Institute of Health Stroke Scale according to apnea-hypopnea index. Sixty-one patients (71.8 years, 42.6% men) completed the study: 51 (83.6%) had obstructive apnea (21.3% severe apnea), 10 (16.7%) daytime sleepiness, 13 (24.1%) insomnia, 3 (5.7%) depression, and 20 (34.5%) restless legs syndrome. Barthel Index, modified Rankin score and Stroke Scale were similar at baseline and 3 months post-stroke in the different obstructive sleep apnea groups. Changes at 3 months in those three scores were similar in continuous positive airway pressure versus sham-continuous positive airway pressure patients. In patients with worse clinical outcomes at month 3, mean nocturnal oxygen saturation was lower whereas there was no association with apnea-hypopnea index. Poorer outcomes at 3 months were also associated with insomnia, restless legs syndrome, depressive symptoms, and decreased total sleep time and rapid eye movement sleep.

Transcutaneous electrical nerve stimulation in the management of restless legs syndrome symptoms: A single-blind, parallel-group clinical study.

The aim of this study was to investigate the additional effect of transcutaneous electrical nerve stimulation (TENS) on the control of the symptoms of restless legs syndrome (RLS). A total of 46 randomly selected patients diagnosed with RLS were divided into two groups in a single-blind study to either receive pramipexole (0.25 mg daily) plus 10 sessions of TENS or only pramipexole (0.25 mg daily) for 4 weeks. The severity of the symptoms was determined according to the International Restless Legs Syndrome Rating Scale (IRLSRS) and the Pittsburgh sleep quality index (PSQI) at the beginning of the treatment, post-treatment, and at an 8 week follow-up. A significant time interaction was observed between the groups for all measurement outcomes, revealing differences in favour of the experimental group's IRLSRS and PSQI scores. A notable improvement was also observed in the IRLSRS and PSQI scores in both groups at the end of treatment and during the 8 week follow-up period. In comparison with pramipexole monotherapy, the results of this study showed that the use of TENS therapy combined with a low dose of pramipexole (0.25 mg daily) is therapeutically beneficial in the treatment of RLS over an 8 week follow-up period.

Sex-based disparities in dopamine agonist response in patients with restless legs syndrome.

This study aimed to investigate sex-related differences in the response to ropinirole and pramipexole in patients with restless legs syndrome (RLS). By analysing clinical parameters and polysomnographic (PSG) findings, we sought to elucidate the potential factors related to sex disparities modulating treatment responses and sleep quality in RLS. A total of 41 drug-free patients with RLS, aged ≥18 years, underwent two consecutive nocturnal PSG recordings, without medication at baseline; before the second night, 26 patients received an oral dose of 0.25 mg pramipexole whereas 15 received 0.5 mg ropinirole. After each PSG recording, patients self-evaluated the severity of their previous night symptoms by means of an ad hoc visual analogue scale (VAS). At baseline, sleep efficiency and percentage of Stage N2 tended to be higher in females while wakefulness after sleep onset was significantly higher in males. After treatment, total leg movements during sleep (LMS), periodic LMS (PLMS), and periodicity indexes were significantly lower in females than in males. The VAS score was lower after treatment in all patients, without differences between the two sexes. This study demonstrates a higher acute responsiveness of PLMS to dopamine agonists (pramipexole and ropinirole) in females than in males with RLS. These findings might be explained by differential sex-related expression of dopamine receptors, especially D3, within the central nervous system. In addition, our findings provide translational hints toward a better tailored and sex-specific approach to the treatment of RLS associated with PLMS, with dopamine agonist possibly associated with a better outcome in females than in males.

Cerebral blood flow changes in maintenance hemodialysis patients with restless legs syndrome and their clinical significance:a cross-sectional case-control study.

OBJECTIVE: Restless legs syndrome (RLS) stands as a prevalent neurological complication within maintenance hemodialysis (MHD) patients. However, the alterations in cerebral blood flow (CBF) among MHD-RLS patients remain uncharted. Through the utilization of the arterial spin labeling (ASL) technique, we evaluated the fluctuations in CBF within distinct brain regions and analyzed the risk factors for the development of RLS in MHD patients in the context of the clinic. METHODS: Thirty-one MHD patients with concomitant RLS (MHD-RLS group) and thirty-one non-RLS patients matched based on age, gender, as well as cognitive function (MHD-nRLS group) were included. Through image preprocessing and data analysis, the changes in CBF values in distinct brain regions were obtained, and the CBF values of brain regions with substantial differences between the two groups were correlated with the RLS scores. Furthermore, the differences in baseline data were compared, and through the utilization of multifactorial logistic regression, the independent risk factors for the development of RLS were examined. RESULTS: Compared with the MHD-nRLS group, the MHD-RLS group had increased CBF in the right superior temporal gyrus, reduced CBF in the right hippocampus, left middle frontal gyrus, inferior frontal gyrus of right triangle, middle frontal gyrus of left orbit, left precentral gyrus, and left precuneus. Only left precentral gyrus CBF were negatively correlated with RLS scores after correction for dialysis duration(r = -0.436, P = 0.016). Accordingly, multifactorial regression analysis by stepwise method yielded that the left precentral gyrus CBF values(OR: 0.968, 95%CI: 0.944-0.993, P = 0.012) remained an independent risk factor for RLS in MHD patients. In addition, the results showed that hemodialysis duration (OR: 1.055, 95%CI: 1.014-1.098, P = 0.008) and serum iron levels (OR: 0.685, 95%CI: 0.551-0.852, P = 0.001) were also risk factors for the development of RLS. CONCLUSION: Patients afflicted with MHD-RLS exhibit alterations in CBF across several brain regions. Notably, the left precentral gyrus might serve as a pivotal region influencing the onset of RLS among MHD patients. Furthermore, extended hemodialysis duration and a relative insufficiency in serum iron levels independently contribute as risk factors for RLS development within the MHD patient population.

Risk of Suicidal Ideation and Behavior Following Early-Onset Idiopathic Restless Legs Syndrome Treatment.

PURPOSE: To estimate incidence rates of suicidal ideation and behavior following treatment initiation with gabapentinoids or dopamine agonists (DAs) in patients with newly diagnosed early-onset idiopathic restless legs syndrome (RLS) and to examine suicidal behavior risk, comparing between those receiving gabapentinoids and DAs. METHODS: A new user retrospective cohort study using MarketScan claims data from 2012 to 2019 was conducted. Exposures were monotherapy gabapentinoids or DAs initiated within 60 days of new RLS diagnosis. Three varying outcome measures of suicidality were examined and incidence rates were calculated for each. A log-binomial regression model the estimated relative risk (RR) of the outcomes with gabapentinoids. Propensity score weighting adjusted for baseline covariates, including age, substance use disorders, hyperlipidemia, antipsychotic use, hypnotic/sedative use, and mood stabilizer use, which were most imbalanced before weighting. RESULTS: The cohort included 6672 patients, with 4986 (74.7%) initiating a DA and 1686 (25.3%) initiating a gabapentinoid. Incidence rates for all outcome measures were higher in the gabapentinoid group (suicidality: 21.6 vs. 10.7 per 1000 person-years; suicidality with self-harm: 23.0 vs. 11.1 per 1000 person-years; overdose- and suicide-related events: 30.0 vs. 15.5 person-years). Associated risk of suicidality (adjusted RR, 1.27 [95% CI, 0.86-1.88]); suicidality with self-harm (adjusted RR, 1.30 [95% CI, 0.89-1.90]); or overdose- and suicide-related events (adjusted RR, 1.30 [95% CI, 0.93-1.80]) was not significant with gabapentinoids. CONCLUSIONS: Incidence rates for suicidal ideation and behavior were higher among the gabapentinoid group, although increased risk was not detected after adjustment. A possible signal cannot be ruled out given limitations of the data and rarity of the outcome.

Genetic Association Studies in Restless Legs Syndrome: Risk Variants & Ethnic Differences.

BACKGROUND: Genetic association studies have not produced consistent results in restless legs syndrome (RLS). OBJECTIVES: To conduct a systematic review on genetic association studies in RLS to highlight the common gene variants and ethnic differences. METHODOLOGY: We conducted Pubmed, Embase, and Cochrane search using terms "Genetic association studies" and "restless legs syndrome" for candidate gene-based studies. Out of the initial 43 studies, 18 case control studies (from 2012 to 2022) were included. Thirteen studies including 10794 Caucasian subjects (4984 RLS cases and 5810 controls) and five studies involving 2009 Asian subjects (796 RLS cases and 1213 controls) were tabulated and analyzed. In addition, three Genome-Wide Association Studies (GWAS) in Asians and Europeans/Caucasians were included for comparisons. RESULTS: In the Asian population, gene variants in BST1, SNCA Rep1, IL1B, BTBD9, and MAP2K5/SKOR1 increased the risk of RLS (odds ratio range 1.2-2.8). In Caucasian populations, examples of variants that were associated with an increased risk of RLS (odds ratio range 1.1-1.9) include those in GABRR3 TOX3, ADH1B, HMOX1, GLO1, DCDC2C, BTBD9, SKOR1, and SETBP1. Based on the meta-analysis of GWAS studies, the rs9390170 variant in UTRN gene was identified to be a novel genetic marker for RLS in Asian cohorts, whereas rs113851554 in MEIS1 gene was a strong genetic factor among the >20 identified gene variants for RLS in Caucasian populations. CONCLUSION: Our systemic review demonstrates that multiple genetic variants modulate risk of RLS in Caucasians (such as MEIS1 BTBD9, MAP2K5) and in Asians (such as BTBD9, MAP2K5, and UTRN).

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.

Association between inflammatory cytokines and disease severity in restless legs syndrome.

BACKGROUND: This study aims to evaluate serum cytokine levels in individuals with primary Restless Legs Syndrome (RLS) and analyze their correlation with RLS symptom severity, sleep disturbances, anxiety, and depression. METHODS: A case-control study was conducted involving 87 primary RLS patients and 100 healthy individuals undergoing health check-ups. Serum cytokine levels were assessed, and RLS severity was evaluated using the International Restless Legs Syndrome Study Group (IRLSSG) rating scale. Additionally, the Pittsburgh Sleep Quality Index (PSQI), 24-item Hamilton Depression Rating Scale (HAMD24), and 14-item Hamilton Anxiety Rating Scale (HAMA14) were utilized to assess symptom severity, sleep disturbances, and emotional states in RLS patients. RESULTS: Serum cytokine levels, including IL-6 and TNF-α, were significantly higher in RLS patients compared to controls (P < 0.05). Adjustment for disease duration, sex, age, BMI, SBP, and DBP revealed an independent association between serum IL-6 and RLS (OR = 1.46; 95% CI = 1.02-1.93; P = 0.003). Linear regression analysis demonstrated a significant correlation between IL-6 levels and IRLS scores (ß = 0.123, P = 0.008). CONCLUSION: Elevated circulating levels of inflammatory cytokines in RLS patients suggest a potential role of inflammation in the pathogenesis of primary RLS. Additionally, serum cytokine levels correlate closely with disease severity.

Effect of dairy products fortified with vitamin d3 on restless legs syndrome in women with premenstrual syndrome, abdominal obesity and vitamin d deficiency: a pilot study.

BACKGROUNDS: Restless legs syndrome (RLS) is an unpleasant condition that affects the quality of life of patients. Its prevalence in increased in women with premenstrual syndrome (PMS). Vitamin D plays a key role in female reproduction through its impact on calcium homeostasis and neurotransmitters. We aimed to evaluate the effect of dairy products fortified with Vitamin D3 on RLS in women with PMS. MATERIALS AND METHODS: We conducted a 2.5-month, randomized, total-blinded clinical trial to evaluate the effectiveness of low-fat milk and yogurt fortified with vitamin D on RLS in women with PMS. Among 141 middle-aged women with abdominal obesity, 71 and 70 cases received fortified and non-fortified low-fat dairy products, respectively. All subjects completed a Symptoms Screening Tool (PSST) and RLS questionnaires. RESULTS: The results showed that in the women with severe PMS (PSST > 28), serum levels of vitamin D increased significantly following vitamin D fortification. The mean restless legs score in the severe PMS subgroup (PSST > 28) was significantly lower after the intervention (p < 0.05. Serum Vitamin D levels significantly differed between intervention and control groups in all individuals (PSST < 19, PSST 19-28, and PSST > 28) (p < 0.05), but no significant differences were found between RLS scores of the intervention and control groups in the three PMS subgroups (p > 0.05). CONCLUSION: Fortifying dairy products with vitamin D3 can increase the serum levels of vitamin D and reduce the RLS severity in women with severe PMS, but not in other groups.

The ethos brief index-validation of a brief questionnaire to evaluate wellness based on a holistic perspective in patients with restless legs syndrome.

PURPOSE: The aim of this study was to validate the Ethos Brief Index (EBI) in patients with Restless Legs Syndrome (RLS). METHODS: A cross-sectional design, including 788 subjects with RLS (65% women, 70.8 years, SD 11.3) from the Swedish RLS Association, was used. A postal survey was sent out to collect data regarding socio demographics, comorbidities, and RLS-related treatment data. Questionnaires included were EBI, the Restless Legs Syndrome-6 Scale (RLS-6), Restless Legs Syndrome-Quality of Life questionnaire (RLSQoL), the Insomnia Severity Index (ISI), and the Epworth Sleepiness Scale (ESS). The validity and reliability of the EBI were investigated using Rasch and confirmatory factor analysis (CFA) models. Measurement invariance, unidimensionality, and differential item functioning (DIF) across age and gender groups, as well as insomnia, daytime sleepiness, RLS-related QoL and RLS severity were assessed. RESULTS: The results supported the unidimensionality of the EBI in the CFA (i.e., explaining 61.5% of the variance) and the Rasch model. The reliability of the EBI was confirmed using composite reliability and Cronbach's alpha. No DIF was identified for gender, age, insomnia, daytime sleepiness, RLS severity or RLS-related QoL. CONCLUSION: The EBI showed good validity and reliability and operated equivalently for male and female patients with RLS. Accordingly, healthcare professionals can use the EBI as a psychometrically sound tool to explore and identify patient-centered problems related to the whole life situation.

Unfolding the role of exercise in the management of sleep disorders.

Sleep disorders are prevalent among the general population and even more in individuals suffering from chronic diseases. Recent data reveal promising effects of physical exercise as a non-pharmacological approach for improving sleep and managing various sleep disorders. However, more studies with proper design and methodology should be conducted in the future to obtain a clearer understanding of the subject. The role of exercise in preventing and improving sleep disorders is probably much higher than what is currently exploited. To fully exploit the potential benefit of physical activity on sleep disorders in the future, it is necessary to identify the relevant tools to assess sleep-wake disorders and establish specific exercise protocols tailored to different sleep disorders. The present manuscript aims to review the literature on the use of exercise in managing selected sleep disorders. Regular exercise, including short-term aerobic activity, resistance training, and mind-body exercises, can effectively improve sleep quality, particularly in cases of insomnia and sleep-disordered breathing. Additionally, increasing evidence supports the effectiveness of aerobic and strength training, and body-mind exercises such as yoga in managing sleep-related movement disorders. Exercise can be a safe, affordable, and efficient tool in enhancing sleep quality and improving sleep disorders. Per se, regular exercise could play an adjuvant role alongside with established therapies, or a valid alternative when the pharmacological approach is limited by side effects, interactions, or inefficacy. More research is needed to define how exercise affects the physiology of sleep, and consequently how to use exercise in patients with sleep disorders.

Prevalence of restless legs syndrome during pregnancy and postpartum period.

OBJECTIVES: Restless legs syndrome (RLS) is a disease from the spectrum of movement disorders, the prevalence of which increases significantly during pregnancy and is associated with poor sleep, a drop in daytime energy, and the development of psychological disorders during pregnancy and the postpartum period. METHODS: The IRLSS scale was used to determine the presence of RLS symptoms. The total test sample that included the tested and control groups was (n=390) subjects. The examined group consisted of pregnant women (n=260), and the control group consisted of female students (n=130). In total, 260 pregnant women were monitored 6 months after pregnancy. Three measurements were performed, first in the third trimester of pregnancy, second two months after delivery, third 6 months after delivery, while one cross-sectional measurement was performed for the control group. RESULTS: The prevalence of RLS in pregnancy is highest in the third trimester and amounts to 26.5 %. In the postpartum period, a significant decrease in the prevalence of RLS was observed, measured two months after delivery (18.1 %). Postpartum, over time, a decrease in the prevalence of RLS was noticed, and six months after delivery it was (7.3 %), when it practically approached the prevalence of the control group (standard population) which was (6.2 %). CONCLUSIONS: The prevalence of RLS is highest during the third trimester of pregnancy and decreases after delivery so that 6 months after delivery it approaches the prevalence of the standard population.

[Gastrointestinal disorders in hyperkinetic movement disorders and ataxia]. / Gastrointestinale Störungen bei hyperkinetischen Bewegungsstörungen und Ataxien.

Disorders of the gastrointestinal tract in patients suffering from hypokinetic movement disorders, and in particular Parkinson's disease, have increasingly been the subject of more intensive neuromedical research. So far, few data are available for patients with hyperkinetic movement disorders and ataxias. This review article summarizes the currently available and relevant publications on this topic. The particular focus is on essential tremor, restless legs syndrome, Huntington's disease and the group of hereditary ataxias. Further intensive research will be necessary in the future to collect detailed information also for these disease symptoms about specific disturbance patterns, in order to understand the underlying pathological pathways and to derive specific treatment approaches.

Defect of the Endogenous Inhibitory Pain System in Idiopathic Restless Legs Syndrome: A Laser Evoked Potentials Study.

BACKGROUND: Restless legs syndrome (RLS) is a complex sensorimotor disorder. Symptoms worsen toward evening and at rest and are temporarily relieved by movement. Symptoms are perceived as painful in up to 45% of cases, and nociception system may be involved. OBJECTIVES: To assess the descending diffuse noxious inhibitory control in RLS patients. METHODS: Twenty-one RLS patients and twenty age and sex-matched healthy controls (HC) underwent a conditioned pain modulation protocol. Cutaneous heat stimuli were delivered via laser evoked potentials (LEPs) on the dorsum of the right hand (UL) and foot (LL). N2 and P2 latencies, N2/P2 amplitude and pain ratings (NRS) were recorded before (baseline), during, and after a heterotopic noxious conditioning stimulation (HNCS) application. The baseline/HNCS ratio was calculated for both UL and LL. RESULTS: N2 and P2 latencies did not vary between groups at each condition and limbs. Both groups showed a physiological N2/P2 amplitude and NRS reduction during the HNCS condition in UL and LL in comparison to baseline and post conditions (all, P < 0.003). Between-groups comparisons revealed a significant lower amplitude reduction in RLS at the N2/P2 amplitude during the HNCS condition only for LL (RLS, 13.6 µV; HC, 10.1 µV; P = 0.004). Such result was confirmed by the significant difference at the ratio (RLS, 69%, HC, 52.5%; P = 0.038). CONCLUSIONS: The lower physiological reduction during the HNCS condition at LL in RLS patients suggests a defect in the endogenous inhibitory pain system. Further studies should clarify the causal link of this finding, also investigating the circadian modulation of this paradigm. © 2023 International Parkinson and Movement Disorder Society.

Epigenetic Association Analyses and Risk Prediction of RLS.

BACKGROUND: As opposed to other neurobehavioral disorders, epigenetic analyses and biomarkers are largely missing in the case of idiopathic restless legs syndrome (RLS). OBJECTIVES: Our aims were to develop a biomarker for RLS based on DNA methylation in blood and to examine DNA methylation in brain tissues for dissecting RLS pathophysiology. METHODS: Methylation of blood DNA from three independent cohorts (n = 2283) and post-mortem brain DNA from two cohorts (n = 61) was assessed by Infinium EPIC 850 K BeadChip. Epigenome-wide association study (EWAS) results of individual cohorts were combined by random-effect meta-analysis. A three-stage selection procedure (discovery, n = 884; testing, n = 520; validation, n = 879) established an epigenetic risk score including 30 CpG sites. Epigenetic age was assessed by Horvath's multi-tissue clock and Shireby's cortical clock. RESULTS: EWAS meta-analysis revealed 149 CpG sites linked to 136 genes (P < 0.05 after Bonferroni correction) in blood and 23 CpG linked to 18 genes in brain (false discovery rate [FDR] < 5%). Gene-set analyses of blood EWAS results suggested enrichments in brain tissue types and in subunits of the kainate-selective glutamate receptor complex. Individual candidate genes of the brain EWAS could be assigned to neurodevelopmental or metabolic traits. The blood epigenetic risk score achieved an area under the curve (AUC) of 0.70 (0.67-0.73) in the validation set, comparable to analogous scores in other neurobehavioral disorders. A significant difference in biological age in blood or brain of RLS patients was not detectable. CONCLUSIONS: DNA methylation supports the notion of altered neurodevelopment in RLS. Epigenetic risk scores are reliably associated with RLS but require even higher accuracy to be useful as biomarkers. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Validation of two brief instruments (the SURE and CollaboRATE) to measure shared decision-making in patients with restless legs syndrome.

Restless legs syndrome (RLS) is a common neurological disorder characterised by an urge to move arms and legs, usually associated with discomfort, pain, motor restlessness, and sleep disturbance. An individually adapted treatment is needed but difficult to optimise, which makes shared decision-making (SDM) important. However, brief validated instruments on how patients with RLS perceive their involvement in treatment decisions are lacking. Therefore, the aim was to validate two instruments, SURE (Sure of myself, Understand information, Risk-benefit ratio, Encouragement, i.e., to assess decisional conflict) and CollaboRATE (brief patient survey focused on SDM, i.e., to assess SDM), in patients with RLS. A cross-sectional design, including 788 participants with RLS (65% females, mean [SD] age 70.8 [11.4] years) from a national patient organisation for RLS, was used. A postal survey was sent out to collect data regarding weight, height, comorbidities, demographics, and RLS-related treatment data. The following instruments were included: the SURE, CollaboRATE, Restless Legs Syndrome-6 Scale, and eHealth Literacy Scale. Confirmatory factor analysis and Rasch models were used to assess the validity and reliability of the SURE and CollaboRATE. Measurement invariance, unidimensionality, and differential item functioning (DIF) across age, gender, and medication groups were assessed. The SURE and CollaboRATE were both identified as unidimensional instruments with satisfactory internal consistency. No DIF across age and gender was identified, while significant DIF was observed for both the SURE and CollaboRATE regarding medication use categories. However, both the SURE and CollaboRATE are potential instruments to be used in research, but also as reflection tools by healthcare professionals, patients, and students to explore and assess SDM, and support its development in clinical care.

Structural and functional multilayer network analysis in restless legs syndrome patients.

The combination of brain structural and functional connectivity offers complementary insights into its organisation. Multilayer network analysis explores various relationships across different layers within a single system. We aimed to investigate changes in the structural and functional multilayer network in 69 patients with primary restless legs syndrome (RLS) compared with 50 healthy controls. Participants underwent diffusion tensor imaging (DTI) and resting state-functional magnetic resonance imaging (rs-fMRI) using a three-tesla MRI scanner. We constructed a structural connectivity matrix derived from DTI using a DSI program and made a functional connectivity matrix based on rs-fMRI using an SPM program and CONN toolbox. A multilayer network analysis, using BRAPH program, was then conducted to assess the connectivity patterns in both groups. At the global level, significant differences there were between the patients with RLS and healthy controls. The average multiplex participation was lower in patients with RLS than in healthy controls (0.804 vs. 0.821, p = 0.042). Additionally, several regions showed significant differences in the nodal level in multiplex participation between patients with RLS and healthy controls, particularly the frontal and temporal lobes. The regions affected included the inferior frontal gyrus, medial orbital gyrus, precentral gyrus, rectus gyrus, insula, superior and inferior temporal gyrus, medial and lateral occipitotemporal gyrus, and temporal pole. These results represent evidence of diversity in interactions between structural and functional connectivity in patients with RLS, providing a more comprehensive understanding of the brain network in RLS. This may contribute to a precise diagnosis of RLS, and aid the development of a biomarker to track treatment effectiveness.