Restless legs syndrome: update on pathogenesis

Evaluation of the relationship between idiopathic restless legs syndrome and serum hepcidin levels

INTRODUCTION

The relationship between restless legs syndrome (RLS) and iron deficiency is a well-known topic. However, the etiology of the disease has not been determined. As the central iron deficiency is the most critical biological abnormality for RLS, we planned a study examining the relationship between RLS and hepcidin, which is the only regulatory hormone of iron metabolism known so far.

METHODS

International Restless Legs Syndrome Study Group diagnostic criteria (2014) were taken as a basis. A total of 40 RLS patients and 40 healthy controls were included in the study. To avoid the potential variables that might cause secondary RLS, all the participants were asked to provide hemogram, ferritin, iron, thyroid function tests, and sedimentation analysis. The hepcidin levels were measured with a Human Hepcidin (Hepc 25) ELISA kit (MyBioSource).

RESULTS

The statistically significant results of our analysis show that the red blood cell count, the neutrophil count, the percentage of lymphocytes and neutrophils, and, more distinctively, hepcidin levels were higher in RLS patients in comparison with the control group.

CONCLUSION

In this study, no differences were found in iron and ferritin values. High levels of hepcidin, the main regulator of iron metabolism, in those with primary RLS support the possibility that hepcidin may play a role in the pathogenesis of RLS. We think that larger studies on this subject can give clearer ideas.

Restless legs syndrome: From clinic to personalized medicine

Restless legs syndrome (RLS) is a common neurological sensorimotor disorder that impairs sleep, mood and quality of life. RLS is defined by an urge to move the legs at rest that increases in the evening and at night, and is frequently associated with metabolic and cardiovascular diseases. Symptoms frequency, age at RLS onset, severity, familial history and consequences of RLS vary widely between patients. A genetic susceptibility, iron deficiency, dopamine deregulation, and possible hypo-adenosinergic state may play a role in the pathophysiology of RLS. Polysomnographic recordings found often periodic leg movements during sleep and wakefulness in patients with RLS. RLS can be classified as primary or comorbid with major diseases: iron deficiency, renal, neurological, rheumatological and lung diseases. First-line treatments are low-dose dopamine agonists, and alpha-2-delta ligands depending on the clinical context, and second/third line opiates for pharmacoresistant forms of RLS. Augmentation syndrome is a serious complication of dopamine agonists and should be prevented by using the recommended low dose. Despite an increase in knowledge, RLS is still underdiagnosed, poorly recognized, resulting in substantial individual health burden and socioeconomic coast, and education is urgently needed to increase awareness of this disabling disorder.

Advancements in Restless Leg Syndrome Management: A Review of Physiotherapeutic Modalities and Their Efficacy

The goal of this review is to compile information on the use of physiotherapeutic treatments for the treatment of restless leg syndrome (RLS) and to classify the effectiveness of conservative methods in relieving the discomfort due to RLS. English literature found on PubMed, Google Scholar, and Scopus was used in the present review. According to the titles and matters of the abstracts, each literature item connected to RLS was retrieved, analyzed, and reviewed. The 24 papers that were considered admissible were those that included manual approaches, exercises, and alternative RLS management, which were then analyzed for data by the authors. A consistent trend in the data demonstrated benefits in lessening RLS symptom severity across the 24 papers that met the selection criteria. Patients were chosen based on clinical diagnostic standards, and the effectiveness of stretching, exercise therapy, yoga, vibration therapy, reflexology and massage, muscular relaxation techniques, and electrical stimulation was determined. Our findings indicated that each type of therapy significantly affected the manifestations of the illness. Stretching, fitness training, and reflexology were very beneficial, with no side effects and shorter intervention periods.

Effectiveness of exercise and pramipexole in the treatment of restless leg syndrome: Implications on the dopaminergic system and PTPRD

OBJECTIVE

Dopaminergic dysfunction, iron reduction and variations in the PTPRD gene (protein tyrosine phosphatase receptor type delta) may be associated with restless leg syndrome (RLS). Here, we evaluate the effect of pramipexole (PPX) and exercise on genes and proteins associated with RLS and on sleep patterns in spontaneously hypertensive rats (SHR).

METHODS

Animals were distributed into 4 groups: 1) Control (CTRL); 2) Exercise (EX); 3) Exercise and pramipexole (EX + PPX); and 4) Pramipexole (PPX). PPX treatment was performed daily (0.125 mg/kg), while exercise was conducted over 5 sessions per week, both for 4 weeks.

RESULTS

EX + PPX increased the protein levels of PTPRD, reduced the protein levels of the enzyme tyrosine hydroxylase (TH) and improved sleep parameters in both cycles; on the other hand, the use of PPX reduced mRNA and protein levels of PTPRD and TH but improved the sleep pattern in the light cycle. However, in the dark cycle, pramipexole caused the worsening of symptoms.

CONCLUSIONS

We suggest that the improvement in sleep pattern by EX + PPX may be associated with the increased protein levels of PTPRD and that EX + PPX can reverse the negative effects of PPX.

Exploring the causes of augmentation in restless legs syndrome

Long-term drug treatment for Restless Legs Syndrome (RLS) patients can frequently result in augmentation, which is the deterioration of symptoms with an increased drug dose. The cause of augmentation, especially derived from dopamine therapy, remains elusive. Here, we review recent research and clinical progress on the possible mechanism underlying RLS augmentation. Dysfunction of the dopamine system highly possibly plays a role in the development of RLS augmentation, as dopamine agonists improve desensitization of dopamine receptors, disturb receptor interactions within or outside the dopamine receptor family, and interfere with the natural regulation of dopamine synthesis and release in the neural system. Iron deficiency is also indicated to contribute to RLS augmentation, as low iron levels can affect the function of the dopamine system. Furthermore, genetic risk factors, such as variations in the BTBD9 and MEIS1 genes, have been linked to an increased risk of RLS initiation and augmentation. Additionally, circadian rhythm, which controls the sleep-wake cycle, may also contribute to the worsening of RLS symptoms and the development of augmentation. Recently, Vitamin D deficiency has been suggested to be involved in RLS augmentation. Based on these findings, we propose that the progressive reduction of selective receptors, influenced by various pathological factors, reverses the overcompensation of the dopamine intensity promoted by short-term, low-dose dopaminergic therapy in the development of augmentation. More research is needed to uncover a deeper understanding of the mechanisms underlying the RLS symptom and to develop effective RLS augmentation treatments.

Protein tyrosine phosphatase receptor type delta (PTPRD) gene in an animal model of restless legs syndrome

The pathophysiology of the restless legs syndrome (RLS) is related to dopaminergic dysfunction, reduced iron and variations in gene expression, such as the protein tyrosine phosphatase receptor type delta gene (PTPRD). Animal models could be key to achieving a mechanistic understanding of RLS and to facilitate efficient platforms for evaluating new therapeutics. Thus, the aim of this study was to evaluate the expression of PTPRD, of genes and proteins associated with RLS, the sleep patterns and the cardiovascular parameters in an animal model of RLS (spontaneously hypertensive rat [SHR]). Rats were divided into two groups: (i) Wistar-Kyoto and (ii) SHR. Cardiovascular parameters were assessed by tail plethysmography. Polysomnography was used to analyse the sleep pattern (24 h). For the PTPRD analyses, quantitative polymerase chain reaction (qPCR) and indirect enzyme-linked immunosorbent assay (ELISA) techniques were used. To evaluate the tyrosine hydroxylase enzyme, dopamine transporter (DAT) and type 2 dopaminergic receptor, qPCR and Western Blotting techniques were used. For the quantification of iron, ferritin and transferrin, the ELISA method was used. SHRs had higher blood pressure, alterations in sleep pattern, lower expression of protein content of PTPRD, lower expression of DAT, and lower serum concentrations of ferritin. These data suggest that the behavioural, physiological, and molecular changes observed in SHRs provide a useful animal model of RLS, reinforcing the importance of this strain as an animal model of this sleep disorder.

Association between Inflammatory Bowel Disease and Subsequent Development of Restless Legs Syndrome and Parkinson’s Disease: A Retrospective Cohort Study of 35,988 Primary Care Patients in Germany

Background: In addition to the gastrointestinal symptoms, inflammatory bowel disease (IBD), which includes Crohn’s disease (CD) and ulcerative colitis (UC), is associated with extraintestinal manifestations, including neurological disorders, which are gaining increasing attention due to a recently increased focus on the gut–brain axis. Here we aim to evaluate the association between IBD and restless legs syndrome (RLS) as well as Parkinson’s disease (PD) in a cohort of primary care patients in Germany. Methods: The study included 17,994 individuals with a diagnosis of IBD (7544 with CD and 10,450 with UC) and 17,994 propensity-score-matched individuals without IBD from the Disease Analyzer database (IQVIA). An initial diagnosis of RLS or PD was assessed as a function of IBD. Associations between CD and UC with RLS and PD were analyzed using Cox regression models. Results: During the 10-year observation period, 3.6% of CD patients vs. 1.9% of matched non-IBD pairs (p < 0.001) and 3.2% of UC patients vs. 2.7% of matched pairs (p < 0.001) were diagnosed with RLS. The results were confirmed by Cox regression analysis, which showed a significant association between UC (HR: 1.26; 95% CI: 1.02–1.55) and CD (HR: 1.60; 95% CI: 1.23–2.09) and subsequent RLS. The incidence of PD in IBD patients was not significantly increased. However, we observed a non-significant trend towards a higher incidence of PD in male patients with CD but not UC (HR: 1.55; 95%CI: 0.98–2.45, p = 0.064). Conclusions: The present analysis suggests a significant association between IBD and the subsequent development of RLS. These findings should stimulate further pathophysiological research and may eventually lead to specific screening measures in patients with IBD.

Restless Leg Syndrome in Hemodialysis Patients: A Narrative Review

BACKGROUND

Restless legs syndrome (RLS) is a clinical entity characterized by sensory-motor manifestations commonly observed in end-stage renal illness. Evidence suggests that RLS is a multifactorial phenomenon that can be influenced by many critical factors, including genetic predisposition, dietary patterns, and deficiency in some vitamins. Iron metabolism disorders and metabolic derangements have been generally accepted as predisposing elements in RLS. Furthermore, both pharmacological and neuroimaging studies demonstrated dopamine deficiency and dopamine receptors decrease in basal ganglia during RLS.

REVIEW SUMMARY

A literature search was done in three databases (PubMed, Google Scholar, and Cochrane) to identify the pertinent articles discussing the epidemiology, pathogenesis, and management of RLS in hemodialysis patients. RLS can affect the morbidity and mortality of patients treated with dialysis. It also has significant impacts on the quality of life since it can lead to insomnia, increased fatigue, mental health troubles, and other movement problems. Appropriate measures should be considered in this particular population so to prevent and treat RLS. Many drugs and other nonpharmacological methods have been investigated to attenuate the disease's severity. No treatment, however, could offer long-term effects.

CONCLUSION

Further efforts are still required to improve the understanding of RLS pathogenic trends to find more specific and efficient therapies. A wide range of treatment options is available. However, it can be individualized according to the patients' several factors.

Overlapping features of restless legs syndrome and growing pains in Turkish children and adolescents

BACKGROUND

Restless legs syndrome (RLS) and growing pains (GPs) share many common features and are sometimes overlapping diagnoses. The present study aims to investigate the shared features of patients with RLS, classified based on the 2013 diagnostic criteria of International Restless Legs Syndrome Study group and of patients with GPs, diagnosed based on the combined criteria proposed in 2013.

METHODS

A cross-sectional population study was conducted in 7 Istanbul schools, which were selected randomly. A total of 4565 (56.1% female) children aged 9 to 18 years were included. In the first stage, candidates of RLS and GPs were identified based on 2 separate questionnaires, whose diagnoses were confirmed by a second survey applied to them under parental supervision.

RESULTS

Out of 192 children (65.6% female) diagnosed as definite RLS (yearly prevalence: 4.2%), 30 (15.6%) reported bilateral leg muscle pain localized typical regions for GPs, which started <13 years of age in 17 children. An urge to move the legs to relieve unpleasant sensations or pain was present in 39.3% of 140 children (64.3% female) classified as GPs (yearly prevalence: 3.1%). Occurrence of symptoms at rest or when lying down was present in 36.4% of GPs children and relief by gross movements was in 21.4% children. Only 12 patients (9 with definite RLS and 3 with GPs) (0.03% of total cohort) were eligible for overlapping diagnosis of GPs and RLS.

CONCLUSION

Although a considerable number of patients with RLS and GPs share some clinical features, a combined phenotype is very rare.

Periodic limb movements during sleep: a narrative review

Objective

Using narrative review techniques, this paper evaluates the evidence for separable underlying patho-mechanisms of periodic limb movements (PLMs) to separable PLM motor patterns and phenotypes, in order to elucidate potential new treatment modalities.

Background

Periodic limb movement disorder (PLMD) is estimated to occur in 5–8% of the paediatric population and 4–11% of the general adult population. Due to significant sleep fragmentation, PLMD can lead to functional impairment, including hyperactivity and delayed language development in children, and poor concentration and work performance in adults. Longitudinal data demonstrate that those with PLMD are at greater risk of depression and anxiety, and a 4-fold greater risk of developing dementia. PLMD has been extensively studied over the past two decades, and several key insights into the genetic, pathophysiological, and neural correlates have been proposed. Amongst these proposals is the concept of separable PLM phenotypes, proposed on the basis of nocturnal features such as the ratio of limb movements and distribution throughout the night. PLM phenotype and presentation, however, varies significantly depending on the scoring utilized and the nocturnal features examined, across age, and co-morbid clinical conditions. Furthermore, associations between these phenotypes with major neurologic and psychiatric disorders remain controversial.

Methods

In order to elucidate potential divergent biological pathways that may help clarify important new treatment modalities, this paper utilizes narrative review and evaluates the evidence linking PLM motor patterns and phenotypes with hypothesised underlying patho-mechanisms. Distinctive, underlying patho-mechanisms include: a pure motor mechanism originating in the spinal cord, iron deficiency, dopamine system dysfunction, thalamic glutamatergic hyperactivity, and a more cortical-subcortical interplay. In support of the latter hypothesis, PLM rhythmicity appears tightly linked to the microarchitecture of sleep, not dissimilarly to the apnoeic/hypopneic events seen in obstructive sleep apnea (OSA).

Conclusions

This review closes with a proposal for greater investigation into the identification of potential, divergent biological pathways. To do so would require prospective, multimodal imaging clinical studies which may delineate differential responses to treatment in restless legs syndrome (RLS) without PLMS and PLMS without RLS. This could pave the way toward important new treatment modalities.

Practitioner's review: medication for children and adolescents with autism spectrum disorder (ASD) and comorbid conditions

Alleviating the multiple problems of children with autism spectrum disorder (ASD) and its comorbid conditions presents major challenges for the affected children, parents, and therapists. Because of a complex psychopathology, structured therapy and parent training are not always sufficient, especially for those patients with intellectual disability (ID) and multiple comorbidities. Moreover, structured therapy is not available for a large number of patients, and pharmacological support is often needed, especially in those children with additional attention deficit/hyperactivity and oppositional defiant, conduct, and sleep disorders.

Management of Restless Legs Syndrome in Pregnancy and Lactation

Restless legs syndrome (RLS) affects about 20% of all pregnant women. RLS symptoms are usually moderate to severe in intensity during pregnancy and can result in insomnia, depression, and other adverse outcomes. Although iron deficiency has been implicated as a potential etiological factor, other mechanisms can also play a role. Nonpharmacologic methods are the primary recommended form of treatment for RLS in pregnancy and lactation. Iron supplementation may be considered when the serum ferritin is low; however, several patients are unable to tolerate iron or have severe symptoms despite oral iron replacement. Here, we describe a case of severe RLS in pregnancy and illustrate the dilemmas in diagnosis and management. We review the literature on the prevalence, diagnosis, course, possible underlying pathophysiologic mechanisms and complications of RLS in pregnancy. We describe current best evidence on the efficacy, and safety of nonpharmacologic therapies, oral and intravenous iron supplementation, as well as other medication treatments for RLS in pregnancy and lactation. We highlight gaps in the literature and provide a practical guide for the clinical management of RLS in pregnancy and during breastfeeding.

Is restless legs syndrome in Parkinson disease patients associated with any specific factor?

BACKGROUND

Restless legs syndrome or Willis-Ekbom disease is a disorder characterized by unpleasant sensations associated with the need to mobilize the lower limbs. In Parkinson disease patients, restless legs syndrome is associated with worse quality of life and excessive sleepiness. Regarding other factors, results of different studies are controversial.

OBJECTIVE

To determine the factors associated with the restless legs syndrome presence in Parkinson disease patients.

METHODS

A cross-sectional study was conducted in 88 consecutive Parkinson disease patients from the outpatient clinic for 21 months. Participants underwent a clinical interview, assessment based on standardized scales (Epworth Sleepiness Scale, Parkinson Disease Questionnaire - 39, Pittsburgh Sleep Quality Index, International Restless Legs Syndrome Study Group rating scale), and video-polysomnography.

RESULTS

Out of the 88 participants, 25 had restless legs syndrome. In the multivariate analysis, restless legs syndrome in Parkinson disease has been associated with the symptom of smell loss and quality of sleep and life. In the univariate analysis, restless legs syndrome in Parkinson disease has occurred more frequently in women with higher frequency of insomnia, constipation, and anosmia than in the group without restless legs syndrome.

CONCLUSION

Restless legs syndrome is a prevalent condition in patients with Parkinson disease and is associated with specific characteristics in this group of patients.

[Restless legs syndrome]

Restless legs syndrome (RLS) is seen widely in clinical practice. RLS commonly occurs at night time and presents with unpleasant or uncomfortable sensations in the legs that causes an urge to move them. This article describes the epidemiology, risk factors and pathophysiology of RLS. There is a detailed description of clinical presentations, diagnostic criteria and also management of RLS.

Grey matter alterations in restless legs syndrome: A coordinate-based meta-analysis

Brain structural abnormalities in idiopathic restless legs syndrome have long been debated. Voxel-based morphometry is an objective structural magnetic resonance imaging technique to investigate regional grey matter volume or density differences between groups. In the last decade, voxel-based morphometry studies have exhibited inconsistent and conflicting findings regarding the presence and localization of brain grey matter alterations in restless legs syndrome. We therefore conducted a coordinate-based meta-analysis to quantitatively examine whether there were consistent grey matter findings in restless legs syndrome using the latest algorithms, seed-based d mapping with permutation of subject images. We included 12 voxel-based morphometry studies (13 datasets, 375 patients and 385 healthy controls). Our coordinate-based meta-analysis did not identify evidence of consistent grey matter alterations in restless legs syndrome. Grey matter alterations via voxel-based morphometry analysis are not therefore recommended to be used as a reliable surrogate neuroimaging marker for restless legs syndrome. This lack of consistency may be attributed to differences in sample size, genetics, gender distribution and age at onset, clinical heterogeneity (clinical course, anatomical distribution of symptoms, disease severity, disease duration, abnormal sensory profiles and comorbidity), and variations in imaging acquisition, data processing and statistical strategies. Longitudinal studies with multimodal neuroimaging techniques are needed to determine whether structural changes are dynamic and secondary to functional abnormalities.

Searching for Novel Candidate Biomarkers of RLS in Blood by Proteomic Analysis

PURPOSE

We performed comparative proteomic analyses of blood of patients with RLS and healthy individuals aiming to identify potential biomarker and therapeutic target candidate for RLS.

PATIENTS AND METHODS

Blood serum samples from 12 patients with a clinical diagnosis of RLS (8 females and 4 males, with a mean age of 68.52 years) and 10 healthy controls (5 females and 5 males, with a mean age of 67.61 years) underwent proteomic profiling by liquid chromatography coupled with tandem mass spectrometry. Pathway analysis incorporating protein-protein interaction networks was carried out to identify pathological processes linked to the differentially expressed proteins.

RESULTS

We quantified 272 proteins in patients with RLS and healthy controls, of which 243 were shared. Five proteins - apolipoprotein C-II, leucine-rich alpha-2-glycoprotein 1, FLJ92374, extracellular matrix protein 1, and FLJ93143 - were substantially increased in RLS patients, whereas nine proteins - vitamin D-binding protein, FLJ78071, alpha-1-antitrypsin, CD5 antigen-like, haptoglobin, fibrinogen alpha chain, complement factor H-related protein 1, platelet factor 4, and plasma protease C1 inhibitor - were decreased. Bioinformatics analyses revealed that these proteins were linked to 1) inflammatory and immune response, and complement activation, 2) brain-related development, cell aging, and memory disorders, 3) pregnancy and associated complications, 4) myocardial infarction, and 5) reactive oxygen species generation and subsequent diabetes mellitus.

CONCLUSION

Our findings shed light on the multifactorial nature of RLS and identified a set of circulating proteins that may have clinical importance as biomarkers and therapeutic targets.

Hepcidin and ferritin levels in restless legs syndrome: a case-control study

The association between restless legs syndrome (RLS) and iron homeostasis remains unclear. We compared serum hepcidin and ferritin levels in patients with RLS and controls, and assessed their relationships with RLS phenotype, drug intake, and history of augmentation syndrome. 102 drug-free RLS patients (age 58.9 [24.5–77.2], 63 females) and 73 controls (age 56.8 [23.46–76.6], 45 females) underwent a polysomnography recording. Hepcidin levels were quantified by ELISA. 34 RLS patients had a second assessment after starting dopaminergic drugs. Ferritin level was low (< 50 µg/l) in 14.7% of patients and 25% of controls, with no between-group differences in the mean values. Hepcidin levels were higher in patients even after adjustment for confounding factors, and excluding participants with low ferritin levels. Ferritin and hepcidin levels were comparable before and after treatment, and between patients with (n = 17) and without history of augmentation. Ferritin and hepcidin levels correlated with age, body mass index, and periodic leg movements. Higher hepcidin levels were associated with older age, older age at RLS onset, less daytime sleepiness and familial RLS. In conclusion, serum hepcidin levels but not ferritin were higher in RLS patients regardless of treatment and history of augmentation. Serum hepcidin may be a more relevant biomarker of RLS than ferritin.

Restless legs syndrome and iron deficiency in adults with attention-deficit/hyperactivity disorder

STUDY OBJECTIVE

The association between restless legs syndrome (RLS), periodic leg movements during sleep (PLMS) and iron deficiency has been reported in children with attention-deficit/hyperactivity disorder (ADHD); however little is known in adults. The aim of this study was to assess frequencies of RLS, PLMS and other leg movements (LM) and iron deficiency and their relationships with ADHD phenotype in adults with ADHD.

METHODS

Two hundred adults with ADHD (112 males, median age 31 years) were evaluated on lifetime ADHD symptoms and sleep characteristics. RLS was diagnosed according to standard criteria. Serum ferritin levels were measured, with iron deficiency defined as <50 ng/mL. A subgroup of 48 ADHD patients with RLS, 48 ADHD without RLS and 48 controls underwent a polysomnography to record sleep, LM, and PLMS.

RESULTS

RLS was diagnosed in 33.0%, associated with earlier onset of ADHD, hyperactive presentation and more severe lifetime ADHD symptoms. Iron deficiency was found in 35.5% with higher frequency in patients with RLS. LM were more frequent in ADHD patients, with higher LM periodicity levels in those with comorbid RLS in comparison to controls. However, PLMS index did not differ between groups. Patients with ADHD and RLS had higher frequency of iron deficiency than other groups.

CONCLUSIONS

In a large sample of adults with ADHD, we individualized a subgroup characterized by earlier and severe ADHD symptoms, RLS, higher LM during sleep and iron deficiency. This endophenotype may reflect a different neurobiological mechanism that remains to be further studied.

Randomized pilot trial for the efficacy of the MMF07 foot massager and heat therapy for restless legs syndrome

Background

Restless Legs Syndrome (RLS) is a sensorimotor condition with a wide range of severity. Symptoms negatively affect sleep and quality of life. Pharmacologic options are not universally effective and side effects are common. Objective data regarding non-pharmacologic treatment is limited. The study objective was to evaluate the efficacy of the MMF07 foot massager and heat therapy on the severity of RLS symptoms.

Methods

In this pilot randomized controlled trial, twenty-eight patients with diagnosed, bothersome RLS were randomized to four treatment arms: no active intervention (n = 7), foot massager (n = 8), heat therapy (n = 6), and foot massager plus heat therapy (n = 7). Participants completed the RLS Severity Scale, RLS Quality of Life questionnaire, and the Medical Outcomes Study Sleep scale at the baseline visit and at the 4-week follow up visit.

Results

Four weeks post randomization, participants in the massager group had significant improvement in the RLS severity score (average difference: -9.0, 95% CI: -16.3, -1.7, p = 0.017) and sleep scale (average difference: -22.0, 95% CI: -36.5, -7.5, p = 0.005) compared to the no intervention group. The heat alone group had a significant improvement in the sleep scale compared to the no-intervention group (average difference: -17.4, 95% CI: -32.5, -2.3, p = 0.026). Quality of life improved in the massage only group compared to control (average difference 25.3, 95% CI: -2.4, 53.0, p = 0.072).

Conclusions

Results suggest that the MMF07 foot massage device and heat therapy may be feasible and effective treatment options to improve RSL symptoms.

The Prevalence of Insomnia and the Link between Iron Metabolism Genes Polymorphisms, TF rs1049296 C>T, TF rs3811647 G>A, TFR rs7385804 A>C, HAMP rs10421768 A>G and Sleep Disorders in Polish Individuals with ASD

Iron deficiency have been found to be linked to sleep disorders. Both genetic and environmental factors are risk factors for skewed iron metabolism, thus sleep disruptions in autism spectrum disorders (ASD). The aim of our study was to assess the prevalence of single nucleotide polymorphisms (SNPs) within transferrin gene (TF) rs1049296 C>T, rs3811647 G>A, transferrin receptor gene (TFR) rs7385804 A>C, and hepcidin antimicrobial peptide gene (HAMP) rs10421768 A>G in Polish individuals with ASD and their impact on sleep pattern. There were 61 Caucasian participants with ASD and 57 non-ASD controls enrolled. Genotypes were determined by real-time PCR using TaqMan SNP assays. The Athens Insomnia Scale (AIS) was used to identify sleep disruptions. There were 32 cases (57.14%) with insomnia identified. In the ASD group, the defined counts of genotypes were as follows: TF rs1049296, C/C n = 41 and C/T n = 20; TF rs3811647, G/G n = 22, G/A n = 34, and A/A n = 5; TFR rs7385804, A/A n = 22, A/C n = 29, and C/C n = 10; and HAMP rs10421768, A/A n = 34, A/G n = 23, and G/G n = 4. There were no homozygous carriers of the TF rs1049296 C>T minor allele in the ASD group. All analyzed SNPs were not found to be linked to insomnia. The investigated polymorphisms are not predictors of sleep disorders in the analyzed cohort of individuals with ASD.

Mobility Deficits Assessed With Mobile Technology: What Can We Learn From Brain Iron-Altered Animal Models?

Background: Recent developments in mobile technology have enabled the investigation of human movements and mobility under natural conditions, i.e., in the home environment. Iron accumulation in the basal ganglia is deleterious in Parkinson's disease (i.e., iron accumulation with lower striatal level of dopamine). The effect of iron chelation (i.e., re-deployment of iron) in Parkinson's disease patients is currently tested in a large investigator-initiated multicenter study. Conversely, restless legs syndrome (RLS) is associated with iron depletion and higher striatal level of dopamine. To determine from animal models which movement and mobility parameters might be associated with iron content modulation and the potential effect of therapeutic chelation inhuman.

Methods: We recapitulated pathophysiological aspects of the association between iron, dopamine, and neuronal dysfunction and deterioration in the basal ganglia, and systematically searched PubMed to identify original articles reporting about quantitatively assessed mobility deficits in animal models of brain iron dyshomeostasis.

Results: We found six original studies using murine and fly models fulfilling the inclusion criteria. Especially postural and trunk stability were altered in animal models with iron overload. Animal models with lowered basal ganglia iron suffered from alterations in physical activity, mobility, and sleep fragmentation.

Conclusion: From preclinical investigations in the animal model, we can deduce that possibly also in humans with iron accumulation in the basal ganglia undergoing therapeutic chelation may primarily show changes in physical activity (such as daily “motor activity”), postural and trunk stability and sleep fragmentation. These changes can readily be monitored with currently available mobile technology.

Sleep disorder-related headaches

Migraine with and without aura, cluster headache, hypnic headache, and paroxysmal hemicranias are each reported as intrinsically related to sleep. Chronic migraine, chronic tension-type headache, and medication overuse headache may cause sleep disturbance. Otherwise, both headache and sleep disorder may be manifestations of a same systemic dysfunction. There is a vicious cycle linking sleep disorders and migraine. The poor quality or poor duration of sleep could be a trigger of migraine attack and migraineurs with poor sleep reported a higher headache frequency. Moreover, coping behaviors of migraineurs (e.g., going to sleep early to relieve migraine attacks) can be factors precipitating and perpetuating sleep disturbances themselves. During cluster headache, patients report a poor quality of sleep correlated with the amount of daylight. In particular, it was demonstrated that melatonin levels have influences on cluster headache attacks. Concerning the pathophysiology of hypnic headache, it has been hypothesized a possible role of obstructive sleep apnea in triggering nocturnal attacks: an increased number of apnea episodes has been reported in hypnic headache patients, but a lack of a temporal correlation of headache attacks with the drop of oxygen saturation has been observed. Tension-type headache is the most common headache with sleep dysregulation (lack of sleep or oversleeping) frequently reported as a triggering factor for acute attacks: management of sleep disturbances seems crucial in this form of headache.

Restless legs syndrome, periodic limb movements during sleep and cardiovascular risk

Multiple mechanisms may modulate an association between restless legs syndrome/Willis-Ekbom disease (RLS/WED) and cardiovascular disease (CVD), including chronic sleep deprivation, intermittent, periodic limb movements in sleep (PLMS)-related autonomic fluctuations and possible autonomic dysfunction intrinsically associated with RLS per se. The purpose of this paper is to review the existing RLS/WED literature focusing on the pathophysiologic evidence for possible associations between RLS/WED and PLMS with CVD and events (CVE). Specific intrinsic dysautonomic aspects of the disease, which may contribute to generating CVD, are separately discussed. The association between RLS/WED and both CV risk factors and CVD still remains elusive. Although several shared pathophysiological causes could explain these possible relationships, the emerging body of literature focusing on these disorders remains controversial. Not only longitudinal population-based studies and meta-analyses, but also more animal models and therapeutic interventions are needed in order to build a sufficiently robust body of evidence on this topic.

Spinal Cord Stimulation for Restless Legs Syndrome: Case Series and Mechanistic Hypothesis

BACKGROUND

Spinal cord stimulation (SCS) is a well-established therapy for chronic pain syndromes, with growing applicability to other conditions. Restless legs syndrome (RLS) is a widespread, chronic movement disorder managed primarily and incompletely by medication, and its etiology can be classified as idiopathic or secondary.

METHODS

Three patients underwent SCS implantation for chronic back and/or leg pain with concomitant targeting of RLS: (1) a 34-year-old man with sporadic RLS symptoms that strongly intensified after military-related spinal fractures, (2) a 54-year-old man with RLS likely secondary to meralgia paresthetica, and (3) a 42-year-old man with low back and right lower extremity pain after a military motor vehicle accident.

RESULTS

Continuing through 40-month, 2-month, and 28-month follow-ups, respectively, the patients experienced exemplary relief of their RLS symptoms. Notably in the case of patient 1, this benefit appears separate from his pain relief, as during the 5-month period directly after surgery but before adjusted targeting, he only experienced pain alleviation.

CONCLUSIONS

To our knowledge, this is the first reported case of using SCS as a potentially long-lasting, safe, and highly effective therapy for RLS of mixed etiology. Additionally, 2 patients with RLS possibly secondary to chronic pain also benefited from the therapy. This success may be due to increased inhibition from hypothalamic cells controlling dopaminergic input to the spine.

Caenorhabditis elegans and its applicability to studies on restless legs syndrome

Restless legs syndrome (RLS) is a common neurological disorder in the United States. This disorder is characterized by an irresistible urge to move the legs, although the symptoms vary in a wide range. The pathobiology of RLS has been linked to iron (Fe) deficiency and dopaminergic (DAergic) dysfunction. Several genetic factors have been reported to increase the risk of RLS. Caenorhabditis elegans (C. elegans) is a well-established animal model with a fully sequenced genome, which is highly conserved with mammals. Given the detailed knowledge of its genomic architecture, ease of genetic manipulation and conserved biosynthetic and metabolic pathways, as well as its small size, ease of maintenance, speedy generation time and large brood size, C. elegans provides numerous advantages in studying RLS-associated gene-environment interactions. Here we will review current knowledge about RLS symptoms, pathology and treatments, and discuss the application of C. elegans in RLS study, including the worm homologous genes and methods that could be performed to advance the pathophysiology RLS.

The heterotetrameric structure of the adenosine A1-dopamine D1 receptor complex: Pharmacological implication for restless legs syndrome

Dopaminergic and purinergic signaling play a pivotal role in neurological diseases associated with motor symptoms, including Parkinson's disease (PD), multiple sclerosis, amyotrophic lateral sclerosis, Huntington disease, Restless Legs Syndrome (RLS), spinal cord injury (SCI), and ataxias. Extracellular dopamine and adenosine exert their functions interacting with specific dopamine (DR) or adenosine (AR) receptors, respectively, expressed on the surface of target cells. These receptors are members of the family A of G protein-coupled receptors (GPCRs), which is the largest protein superfamily in mammalian genomes. GPCRs are target of about 40% of all current marketed drugs, highlighting their importance in clinical medicine. The striatum receives the densest dopamine innervations and contains the highest density of dopamine receptors. The modulatory role of adenosine on dopaminergic transmission depends largely on the existence of antagonistic interactions mediated by specific subtypes of DRs and ARs, the so-called A_2AR-D₂R and A₁R-D₁R interactions. Due to the dopamine/adenosine antagonism in the CNS, it was proposed that ARs and DRs could form heteromers in the neuronal cell surface. Therefore, adenosine can affect dopaminergic signaling through receptor-receptor interactions and by modulations in their shared intracellular pathways in the striatum and spinal cord. In this work we describe the allosteric modulations between GPCR protomers, focusing in those of adenosine and dopamine within the A₁R-D₁R heteromeric complex, which is involved in RLS. We also propose that the knowledge about the intricate allosteric interactions within the A₁R-D₁R heterotetramer, may facilitate the treatment of motor alterations, not only when the dopamine pathway is hyperactivated (RLS, chorea, etc.) but also when motor function is decreased (SCI, aging, PD, etc.).

Prevalence of sleep disorders and sleep problems in an elite super rugby union team

The aim of this study was to determine the prevalence of sleep disorders in an elite rugby union team using in-laboratory polysomnography (PSG) and sleep questionnaires. Twenty-five elite rugby union players underwent a night of PSG during the "off-season" of the Super Rugby competition to assess their sleep. Of interest were measurements that detected the presence of obstructive sleep apnea (OSA; apnea-hypopnea index ≥5 events/hr) and the presence of moderate-severe periodic leg movements during sleep (PLMs; ≥15 events/hr). Players completed sleep-related questionnaires to assess daytime sleepiness, perception of insomnia, risk of OSA, and the presence of restless legs syndrome (RLS) and underwent basic anthropometric assessments including body mass index and neck circumference. OSA was present in 24% (n=6) of players and PLMs ≥15 events/hr in 12% (n=3). Questionnaire responses showed that all players had insomnia defined subthreshold insomnia and excessive daytime sleepiness, two players were identified as being at risk for OSA and none were classified as having RLS. In conclusion, sleep disorders and excessive sleepiness are common in elite rugby union players. A process to identify and manage sleep disorders should be considered by teams to optimise their physical recovery, athletic performance and to safeguard their health.

Restless Legs Syndrome in Chinese Patients With Sporadic Amyotrophic Lateral Sclerosis

Objective: To evaluate the frequency and clinical features of restless legs syndrome (RLS) in a group of Chinese patients with amyotrophic lateral sclerosis (ALS). Methods: 109 Patients included in this study fulfilled the revised El Escorial diagnostic criteria for clinically definite, probable and lab-supported probable ALS, and a group of 109 control subjects was matched for age and sex to the ALS group. Disease severity was assessed by the revised ALS functional rating scale (ALSFRS-R). The diagnosis of RLS was made according to the criteria of the International RLS Study Group. Other characteristics including sleep quality, excessive daytime sleepiness (EDS), REM sleep behavior disorder (RBD), depression and anxiety were also evaluated in ALS patients. Results: RLS was significantly more frequent in ALS patients than in control subjects (14.6 vs. 0.9%; P < 0.05). Compared to those without RLS, ALS patients with RLS reported a higher frequency of anxiety and EDS. ALS patients with RLS showed more severe legs dysfunction. EDS and legs function scores of the ALSFRS-R were independent factors significantly associated with RLS in ALS patients. Conclusions: Our findings suggest that Chinese ALS patients exhibit a high frequency of RLS symptoms and that these patients may benefit from recognition of the condition and optimized management of its symptoms. Moreover, ALS patients might cause circadian rhythms disturbance and our study further supports that ALS is a heterogeneous disorder involving multiple systems; further studies are needed to confirm these preliminary findings.

Differential Dopamine D1 and D3 Receptor Modulation and Expression in the Spinal Cord of Two Mouse Models of Restless Legs Syndrome

Restless Legs Syndrome (RLS) is often and successfully treated with dopamine receptor agonists that target the inhibitory D3 receptor subtype, however there is no clinical evidence of a D3 receptor dysfunction in RLS patients. In contrast, genome-wide association studies in RLS patients have established that a mutation of the MEIS1 gene is associated with an increased risk in developing RLS, but the effect of MEIS1 dysfunction on sensorimotor function remain unknown. Mouse models for a dysfunctional D3 receptor (D3KO) and Meis1 (Meis1KO) were developed independently, and each animal expresses some features associated with RLS in the clinic, but they have not been compared in their responsiveness to treatment options used in the clinic. We here confirm that D3KO and Meis1KO animals show increased locomotor activities, but that only D3KO show an increased sensory excitability to thermal stimuli. Next we compared the effects of dopaminergics and opioids in both animal models, and we assessed D1 and D3 dopamine receptor expression in the spinal cord, the gateway for sensorimotor processing. We found that Meis1KO share most of the tested behavioral properties with their wild type (WT) controls, including the modulation of the thermal pain withdrawal reflex by morphine, L-DOPA and D3 receptor (D3R) agonists and antagonists. However, Meis1KO and D3KO were behaviorally more similar to each other than to WT when tested with D1 receptor (D1R) agonists and antagonists. Subsequent Western blot analyses of D1R and D3R protein expression in the spinal cord revealed a significant increase in D1R but not D3R expression in Meis1KO and D3KO over WT controls. As the D3R is mostly present in the dorsal spinal cord where it has been shown to modulate sensory pathways, while activation of the D1Rs can activate motoneurons in the ventral spinal cord, we speculate that D3KO and Meis1KO represent two complementary animal models for RLS, in which the mechanisms of sensory (D3R-mediated) and motor (D1R-mediated) dysfunctions can be differentially explored.

French consensus: Pharmacoresistant restless legs syndrome

Dopaminergic agonists, α2δ ligands and opioids are, as single-drug therapy, the first line treatment for restless legs syndrome (RLS/Willis-Ekbom disease). However, despite treatment efficacy, exacerbations of RLS may occur with overall worsening in symptoms severity, development of pain and symptoms spreading to other parts of the body, without meeting augmentation syndrome criteria. This development of "drug-resistant" RLS can cause pain, severe insomnia and psychiatric disorders that affect considerably patients' quality of life. The lack of French recommendations for this form of RLS leave physicians with few options to help patients with physical and emotional distress. Our group of neurological experts and sleep specialists proposes a diagnostic and therapeutic strategy to provide better care and appropriate treatment through searching for the organic, psychiatric and/or iatrogenic causes of drug resistance. Once a drug-resistant RLS diagnosis has been confirmed, we recommend an obligatory work-up including: a video-polysomnogram, a biological evaluation including iron status, standard numeration and C-reactive protein level. Treatment will be comorbidity-dependent: dopaminergic agonist would be recommended in case of depression or associated periodic leg movements, α2δ ligand in case of insomnia, complaint of pain, or general anxiety, in association with low-dose opioids if necessary. Strong opioids should be preferred for multiresistant RLS.

Are serum ferritin and transferrin saturation risk markers for restless legs syndrome in young adults? Longitudinal and cross-sectional data from the Western Australian Pregnancy Cohort (Raine) Study

Restless legs syndrome has been associated with serum iron deficiency in clinical studies. However, studies investigating this relationship have had inconsistent results and there are no studies in young adults. Therefore, we investigated the relationship between serum measures of iron stores and restless legs syndrome in young adults in the community. Participants in the Western Australian Pregnancy Cohort (Raine) Study answered questions on restless legs syndrome (n = 1,100, 54% female) at age 22 years, and provided serum measures of iron stores (ferritin and transferrin saturation) at ages 17 and 22 years. Restless legs syndrome was diagnosed when four International RLS Study Group criteria were met (urge to move, dysaesthesia, relief by movement, worsening during evening/night) and these symptoms occurred ≥5 times per month. Logistic regression was used to assess associations between serum iron stores and restless legs syndrome, adjusting for potential confounders. The prevalence of restless legs syndrome at age 22 years was 3.0% (n = 33, 70% female). Among those who provided restless legs syndrome and iron data at age 22 years (n = 865), the median (interquartile range) ferritin was not different between the restless legs syndrome (55 [29.5-103.5] µg L^-1 ) and the non-restless legs syndrome group (65.0 [35.0-103.3] µg L^-1 , p = 0.2), nor were there differences in iron deficiency prevalence (p = 0.36). There was no association between restless legs syndrome (22 years) and iron stores (17, 22 years) before or after adjustment for potential confounders. There was no association between restless legs syndrome at 22 years and iron stores at 17 or 22 years in this cohort. Serum iron stores may not be a useful indicator of restless legs syndrome risk in young adults in the community.

French Consensus: How to diagnose restless legs syndrome

Correct diagnosis of restless legs syndrome (RLS) is essential to patient care and treatment. Diagnosis is most often clinical and based on diagnostic criteria: the need to move the legs accompanied to varying degrees by unpleasant sensations, predominantly during the evening and improved by movement. In rare cases, clinical examination is insufficient and a polysomnography is necessary. Once a positive diagnosis has been made, a neurological examination and an assessment of iron status are required. The severity of the RLS must be evaluated to determine whether a specific treatment is necessary. Before treatment, it is essential to ensure that a definite diagnosis of RLS has been made and the phenotype characterised. This enables a personal treatment plan and limits the risk of augmentation syndrome.

French consensus: Augmentation syndrome in restless legs syndrome

Augmentation syndrome is one of the most severe complications of RLS. It is characterised by a worsening of treated symptoms; principally an increase in the severity of symptoms and an earlier onset time. Augmentation syndrome occurs primarily with dopaminergic treatments. It is crucial for the patient to be sufficiently well informed to prevent its occurrence and the prescription of too high doses of dopaminergic agonists avoided. In the presence of augmentation syndrome confirmed using the diagnostic criteria, the specialist treating the restless legs syndrome should quickly modify the patient's treatment. In this article, our expert group proposes a practical strategy for the diagnosis, prevention and treatment of augmentation syndrome.

Restless legs syndrome is a relevant comorbidity in patients with inflammatory bowel disease

BACKGROUND AND AIMS

In patients with inflammatory bowel disease (IBD), restless legs syndrome (RLS) may occur as an extraintestinal disease manifestation. Iron deficiency (ID) or folate deficiency/vitamin B₁₂ deficiency (FD/VB₁₂D) has previously been described to cause RLS. Here, we determined the prevalence and severity of RLS in IBD patients and evaluated the effect of iron and/or folic acid/vitamin B₁₂ supplementation.

METHODS

Patients were screened for ID and RLS by a gastroenterologist. If RLS was suspected, a neurologist was consulted for definitive diagnosis and severity. Patients with RLS and ID, FD, or VB₁₂D received supplementation and were followed-up at weeks 4 and 11 after starting supplementation.

RESULTS

A total of 353 IBD patients were included. Prevalence for RLS was 9.4% in Crohn's disease (CD) and 8% in ulcerative colitis (UC). Prevalence for the subgroup of clinically relevant RLS (symptoms ≥ twice/week with at least moderate distress) was 7.1% (n = 16) for CD and 4.8% (n = 6) for UC. 38.7% of RLS patients presented with ID, FD, and/or VB₁₂D. Most frequently ID was seen (25.8%; n = 8). Iron supplementation resulted in RLS improvement (p = 0.029) at week 4 in seven out of eight patients.

CONCLUSION

Although the overall prevalence of RLS in IBD did not differ to the general population, clinically relevant RLS was more frequent in IBD patients and, therefore, it is important for clinicians to be aware of RLS symptoms. Though for definite diagnosis and proper treatment of RLS, a neurologist must be consulted. Additionally, iron supplementation of IBD patients with ID can improve RLS symptoms.

TRIAL REGISTRATION

ClinicalTrials.gov No. NCT03457571.

Genetic Variations Associated with Sleep Disorders in Patients with Schizophrenia: A Systematic Review

Background: Schizophrenic patients commonly suffer from sleep disorders which are associated with acute disease severity, worsening prognoses and a poorer quality of life. Research is attempting to disentangle the complex interplay between schizophrenia and sleep disturbances by focusing not only on demographic and clinical characteristics, but also on the identification of genetic factors. Methods: Here, we performed a systematic literature review on the topic of genetic variations in sleep-disordered schizophrenic patients in an attempt to identify high quality investigations reporting scientifically sound and clinically useful data. For this purpose, we conducted a thorough search of PubMed, ScienceDirect and GoogleScholar databases, according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) protocol. Results: Our search yielded 11 eligible studies. Certain genetic variations were reported to be associated with schizophrenia-related sleep disorders. Antipsychotic-induced restless legs syndrome was linked to polymorphisms located on CLOCK, BTBD9, GNB3, and TH genes, clozapine-induced somnolence was correlated with polymorphisms of HNMT gene, while insomnia was associated with variants of the MTNR1 gene. Conclusions: There are significant genetic associations between schizophrenia and co-morbid sleep disorders, implicating the circadian system, dopamine and histamine metabolism and signal transduction pathways.

Plasma copeptin levels in patients with restless legs syndrome

OBJECTIVES

Copeptin, the C-terminal fragment of antidiuretic hormone, is a new biomarker that has been found to be elevated in several disorders and could be related with prognosis. This study aimed to compare plasma copeptin levels in patients with restless legs syndrome (RLS) with healthy individuals and to investigate whether plasma copeptin levels were associated with the severity of disease.

MATERIAL AND METHODS

41 patients with primary RLS, who were followed in Bakirkoy Psychiatry and Neurology Research and Training Hospital and 41 age- and sex-matched healthy individuals were included into the study. RLS patients were divided into subgroups as mild-moderate, severe, and very severe according to the severity of symptoms. Sleep quality and excessive daytime sleepiness were determined according to Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale, respectively, and sleep quality scores were analyzed statistically among the groups divided according to disease severity. Copeptin levels in all the patients were compared to the controls. RLS subgroups were compared with each other to evaluate association between copeptin levels and disease severity.

RESULTS

Plasma copeptin levels in RLS patients were significantly higher than controls (P < .001). However, there was no association between copeptin levels and disease severity. Excessive daytime sleepiness was found as 14.63% and low sleep quality as 68.29% in patients.

CONCLUSIONS

Hypothalamic-pituitary-adrenal axis activation and sympathetic hyperactivity in RLS might be responsible for increased Antidiuretic hormone (ADH) and copeptin release. We think that copeptin might have a potential role in the pathogenesis of RLS and be a biomarker for this disease.

Association between serum hepcidin level and restless legs syndrome

BACKGROUND

To better understand the role of iron homeostasis dysregulation in restless legs syndrome, we compared serum hepcidin and ferritin levels in drug-free patients with primary restless legs syndrome and healthy controls and studied the relationship between hepcidin level and restless legs syndrome severity.

METHODS

One hundred and eight drug-free patients with primary restless legs syndrome (65 women; median age, 61.5 years) and 45 controls (28 women; median age, 53.9 years) were enrolled. Inclusion criteria were: normal ferritin level (>50 ng/mL) and absence of iron disorders, chronic renal or liver failure, and inflammatory or neurological diseases. Each subject underwent a thorough clinical examination and a polysomnography assessment. Serum hepcidin-25 was quantified using a validated mass spectrometry method. Restless legs syndrome severity was evaluated according to the International Restless Legs Syndrome Study Group.

RESULTS

Despite no group difference between normal ferritin levels and demographic features, serum hepcidin level and hepcidin/ferritin ratio were higher in patients than in controls. Hepcidin level and hepcidin/ferritin ratio, but not ferritin level, were positively correlated with periodic leg movements during sleep and wakefulness in the whole sample. Hepcidin level seem to be associated with restless legs syndrome severity in a complex U-shaped relationship, without relationship with age at restless legs syndrome onset, positive family history, sleep and depressive symptoms, genetic background, and polysomnographic measurements. No relationship was found between ferritin level and restless legs syndrome severity.

CONCLUSION

In drug-free patients with primary restless legs syndrome, hepcidin level is higher than in controls and may be associated with restless legs syndrome clinical severity. This result emphasizes the complex peripheral iron metabolism deregulation in restless legs syndrome, opening potential perspectives for a personalized approach with a hepcidin antagonist. © 2018 International Parkinson and Movement Disorder Society.

Sleep disorders and Parkinson disease; lessons from genetics

Parkinson disease is a common, age-related neurodegenerative disorder, projected to afflict millions of individuals in the near future. Understanding its etiology and identifying clinical, genetic or biological markers for Parkinson disease onset and progression is therefore of major importance. Various sleep-related disorders are the most common group of non-motor symptoms in advanced Parkinson disease, but they can also occur during its prodromal phase. However, with the exception of REM sleep behavior disorder, it is unclear whether they are part of the early pathological process of Parkinson disease, or if they develop as Parkinson disease advances because of treatments and neurodegeneration progression. The advancements in genetic studies in the past two decades have generated a wealth of information, and recent genetic studies offer new insight on the association of sleep-related disorders with Parkinson disease. More specifically, comparing genetic data between Parkinson disease and sleep-related disorders can clarify their association, which may assist in determining whether they can serve as clinical markers for Parkinson disease risk or progression. In this review, we discuss the current knowledge on the genetics of sleep-related disorders in Parkinson disease context, and the potential implications on research, diagnosis, counseling and treatment.

Association of BTBD9 and MAP2K5/SKOR1 With Restless Legs Syndrome in Chinese Population

Study Objectives

The aim of the study was to investigate the relationship between genetic factors and primary restless legs syndrome (RLS) in Chinese population.

Methods

A total of 116 RLS patients and 200 controls were recruited and the diagnosis of RLS was based on the criteria of International RLS Study Group. Polymer chain reaction (PCR) and sequencing were used to detect 19 single nucleotide polymorphisms (SNPs) in six genetic loci (MEIS1, BTBD9, PTPRD, MAP2K5/SKOR1, TOX3, and Intergenic region of 2p14).

Results

Our study found that one SNP increased the risk of RLS in Chinese population: rs6494696 of MAP2K5/SKOR1 (odds ratio [OR] = 0.09, p < .0001, recessive model). A further meta-analysis of RLS in Asian population found that two SNPs of BTBD9 increased the risk of RLS: rs9296249 of BTBD9 (OR = 1.44, p = .000, T allele), rs9357271 of BTBD9 (OR = 1.38, p = .021, dominant model).

Conclusion

Our results confirmed the association of BTBD9 and MAP2K5/SKOR1 with primary RLS in Chinese population.

[Genetic risk variants in Parkinson's disease and other movement disorders]

Movement disorders are often genetically complex with genetic risk factors playing a major role. For example, monogenic causes of Parkinson's disease (PD) can be found in only 2-5% of patients who often have an early onset (<40 years). In the majority of patients, common genetic variants seem to contribute to the disease risk. To date, 24 genetic risk factors have been identified. For restless legs syndrome (RLS), six different risk variants have been reported but no monogenic cause is known yet. For the genetic risk factors of essential tremor and dystonia, which are less well studied, only five and two candidate variants, respectively, have been described but their roles still require independent confirmation. In this review, we provide an overview on the involved genes, their function, and discuss possible, disease mechanism-driven therapies.

Restless Legs Syndrome: From Pathophysiology to Clinical Diagnosis and Management

Restless legs syndrome (RLS), a common neurological sensorimotor disorder in western countries, has gained more and more attention in Asian countries. The prevalence of RLS is higher in older people and females. RLS is most commonly related to iron deficiency, pregnancy and uremia. The RLS symptoms show a significant circadian rhythm and a close relationship to periodic limb movements (PLMs) in clinical observations, while the pathophysiological pathways are still unknown. The diagnostic criteria have been revised in 2012 to improve the validity of RLS diagnosis. Recent studies have suggested an important role of iron decrease of brain in RLS pathophysiology. Dopaminergic (DA) system dysfunction in A11 cell groups has been recognized long ago from clinical treatment and autopsy. Nowadays, it is believed that iron dysfunction can affect DA system from different pathways and opioids have a protective effect on DA system. Several susceptible single nucleotide polymorphisms such as BTBD9 and MEIS1, which are thought to be involved in embryonic neuronal development, have been reported to be associated with RLS. Several pharmacological and non-pharmacological treatment are discussed in this review. First-line treatments of RLS include DA agents and α2δ agonists. Augmentation is very common in long-term treatment of RLS which makes prevention and management of augmentation very important for RLS patients. A combination of different types of medication is effective in preventing and treating augmentation. The knowledge on RLS is still limited, the pathophysiology and better management of RLS remain to be discovered.

Restless legs syndrome and cardiovascular diseases: A case-control study

Objective

The association between restless legs syndrome (RLS), cardiovascular diseases (CVD) and hypertension is inconsistent. This case-control study examined i) the association between primary RLS, CVD and hypertension by taking into account many potential confounders and ii) the influence of RLS duration, severity and treatment, sleep and depressive symptoms on CVD and hypertension in primary RLS.

Methods

A standardized questionnaire to assess the RLS phenotype, history of CVD and hypertension, sleep and depressive symptoms, drug intake and demographic/clinical features was sent to the France-Ekbom Patients Association members. A CVD event was defined as a self-reported history of coronary heart disease, heart failure, arrhythmia or stroke. Hypertension was also self-assessed. Current treatment for hypertension and arrhythmia also defined underlying hypertension and arrhythmia. Controls without RLS and without consanguinity were chosen by the patients.

Results

487 patients with primary RLS (median age 71 years; 67.4% women) and 354 controls (68 years, 47.7% women) were included. Most of the patients (91.7%) were treated for RLS, especially with dopaminergic agonists. The median age of RLS onset was 45 years. CVD and hypertension were associated with RLS in unadjusted association, but not after adjustment for age, sex and body mass index. Patients with RLS and with CVD and/or hypertension were significantly older, with hypercholesterolemia, sleep apnea and older age at RLS and at daily RLS onset compared with patients without CVD and/or hypertension. No significant difference was found for other RLS features, ferritin levels, daytime sleepiness, insomnia and depressive symptoms.

Conclusion

Despite some limitations in the design of this study, we found that most of the treated patients for primary RLS had no association with CVD and hypertension after controlling for key potential confounders. Comorbid CVD or hypertension was associated with cardiovascular risk factors, but not with RLS features except for older age at onset.

MEIS1 variant as a determinant of autonomic imbalance in Restless Legs Syndrome

Restless Legs Syndrome (RLS) is a genetically complex neurological disorder in which overlapping genetic risk factors may contribute to the diversity and heterogeneity of the symptoms. The main goal of the study was to investigate, through analysis of heart rate variability (HRV), whether in RLS patients the MEIS1 polymorphism at risk influences the sympathovagal regulation in different sleep stages. Sixty-four RLS patients with periodic leg movement index above 15 per hour, and 38 controls underwent one night of video-polysomnographic recording. HRV in the frequency- and time- domains was analyzed during nighttime sleep. All RLS patients were genotyped, and homozygotes for rs2300478 in the MEIS1 locus were used for further analysis. Comparison of the sympathovagal pattern of RLS patients to control subjects did not show significant differences after adjustments for confounding factors in frequency-domain analyses, but showed an increased variability during N2 and N3 stages in time-domain analyses in RLS patients. Sorting of RLS patients according to MEIS1 polymorphism reconfirmed the association between MEIS1 and PLMS, and showed a significant increased sympathovagal balance during N3 stage in those homozygotes for the risk allele. RLS patients should be considered differently depending on MEIS1 genotype, some being potentially at risk for cardiovascular disorders.

Iron, dopamine, genetics, and hormones in the pathophysiology of restless legs syndrome

Restless legs syndrome (RLS) is a common, chronic neurologic condition, which causes a persistent urge to move the legs in the evening that interferes with sleep. Human and animal studies have been used to study the pathophysiologic state of RLS and much has been learned about the iron and dopamine systems in relation to RLS. Human neuropathologic and imaging studies have consistently shown decreased iron in different brain regions including substantia nigra and thalamus. These same areas also demonstrate a state of relative dopamine excess. While it is not known how these changes in dopamine or iron produce the symptoms of RLS, genetic and hormone studies of RLS have identified other biologic systems or genes, such as the endogenous opioid and melanocortin systems and BTBD9 and MEIS1, that may explain some of the iron or dopamine changes in relation to RLS. This manuscript will review what is known about the pathophysiology of RLS, especially as it relates to changes in iron, dopamine, genetics, and hormonal systems.

Determination of restless legs syndrome prevalence in children aged 13-16years in the provincial center of Kayseri

OBJECTIVE

This study was conducted to determine the prevalence rate of restless legs syndrome (RLS) and associated factors in adolescents aged 13-16years in the provincial center of Kayseri.

MATERIALS AND METHODS

The study sample included 5720 adolescents who were selected from among 74,421 grade 7-10 students aged 13-16years in the provincial center of Kayseri. Overall, datas from 4792 subjects were included into analysis. Data were collected by using a self reported questionnaire and the Epworth Sleepiness Scale (ESS). The prevalence rate of RLS was determined by questionnaire datas and phone interviews. The effects of age, gender, economical status and body weight on RLS prevalence rate were analyzed. Mean ESS score was calculated. The effect of RLS on academic success, as measured by grade point average, was also assessed. The subjects were stratified as underweight, normal, overweight and obese according to the body mass index and the RLS prevalence rate was compared among groups.

RESULTS

The RLS prevalence rate was determined to be 2.9% among adolescents aged 13-16years in the study group. It was found that gender and economical status had no significant effect on RLS prevalence. Mean age at symptom onset was 11.4years of age. There was a positive family history in 11.3% of subjects. Mean body mass index (BMI) was found to be significantly higher in subjects with RLS (21.5±3.8 vs. 20.5±3.2). Academic success (72.0±11.2 vs. 77.0±12.0) was found to be poorer and daytime sleepiness level, as measured by ESS (11.4±3.9 vs. 6.3±4.0), was found to be higher in subjects with RLS.

CONCLUSION

The RLS prevalence rate was 2.9% in the study sample while gender and economical status had no significant effect on prevalence rate. The RLS, which results in decreased sleep quality and academic success, is an important disorder with a considerable prevalence in the population.

Electrophysiological findings of Turkish patients with restless legs syndrome

We aimed to investigate changes in electrophysiological findings in Turkish patients with restless legs syndrome (RLS), including F-wave latency (FWL), peripheral silent period (PSP), and Hoffmann reflex. The study took place in a university hospital in Turkey and involved 30 newly diagnosed RLS patients and 30 healthy controls who were matched for age and gender. Participant's demographics (age, gender, weight, and height), laboratory findings, and electrophysiological test outcomes were gathered and analyzed. There was no significant difference in the FWL of the median and ulnar nerves, whereas the H-wave maximum amplitude and H/M ratio were significantly higher in the RLS patients than in the controls at rest. All of the PSP parameters were similar between patients and controls for the abductor pollicis brevis and gastrocnemius muscles. However, for the tibialis anterior muscle, all the PSP duration parameters were shorter in the RLS patients, whereas the PSP latency parameters were similar. The data suggest that there may be a reduction in spinal segmental inhibition at the L4-L5-S1 level, but the mechanisms of inhibition at the L4-L5 and S1 levels may be different; furthermore, there may be no pathology in the peripheral nerves. Further prospective studies with larger cohorts are now needed to evaluate the pathophysiology of RLS with different neurophysiological assessment tools.

Prevalence of Restless Legs Syndrome in Adult ADHD and Its Subtypes

In this observational cross-sectional study, 49 subjects were assessed for sleep disorders and for ADHD symptoms. Thirty-six received an ADHD diagnosis (29: combined type (ADHD-C); 7: inattentive type). An RLS and RLS symptoms prevalence of 34.5% was found, with a higher prevalence rate in the ADHD-C subgroup, although not significantly (p = 0.066). RLS symptoms were correlated with particularly hyperactivity-impulsivity (ρ = 0.742; p: 0.000). ADHD patients with positive RLS scores reported higher scores on the ADHD-Rating scale compared with patients with negative RLS scores (Z: -2.968, p = 0.003), mainly due to higher hyperactivity-impulsivity scores (Z: -3.145; p = 0.002). Our findings show that clinicians need to be aware of RLS among adult ADHD patients, particularly those with severe hyperactivity-impulsivity symptoms.