Genetics of restless legs syndrome

Effectiveness and safety of massage in the treatment of restless legs syndrome: A protocol for systematic review and meta analysis

BACKGROUND

Restless legs syndrome (RLS), known as a kind of neurological disease, is prevalent but easy to be ignored. Studies have demonstrated that massage therapy can effectively reduce the symptoms of patients with RLS and improve their quality of life. However, the efficacy of massage therapy for RLS is still controversial. Therefore, this protocol aims to evaluate the reliability of massage therapy in treating RLS in a thorough way.

METHODS

We will search relevant randomized controlled trials from Chinese Biomedical Literature Database, Chongqing VIP, CNKI, Wanfang, Web of Science, Cochrane Library, PubMed, and EMBASE, when publication status and language are not considered and the time limit ends with September 6, 2020. Two experienced researchers will use RevMan V.5.3 software to perform the selection of literature, data collection, data analysis and synthesis separately. Besides, the quality of trials involved in this study will be measured with the Cochrane bias risk assessment tool.

RESULTS

This protocol will be applied to carry out a systematic evaluation of the massage therapy purposed to treat RLS for its effectiveness and safety.

CONCLUSION

The review will provide a credible evidence suggesting whether massage therapy is a reliable intervention for RLS.

INPLASY REGISTRATION NUMBER

INPLASY202090038.

Unraveling the Mysteries of Restless Leg Syndrome

Restless leg syndrome (RLS) or Willis-Ekbom disease (WED) is an under-diagnosed, chronic, and progressive primary sensory-motor disorder. It is characterized by an uncontrollable urge to move the legs due to uncomfortable and sometimes painful sensations, with a diurnal variation. RLS can lead to severe sleep disturbances, a usual cause of consultation. The pathophysiology is known partially, and it is believed that there is an association between the different variants of genetic mutations combined with dopaminergic and brain iron dysregulation, which plays an important role. The data used for this study were extracted from the articles found in the PubMed database that discuss different gene variants, pathophysiology, and various methods of treatment. They also highlight the role of iron in the pathogenesis of RLS as it is required for the synthesis of tyrosine hydroxylase, which is the rate-limiting step for dopamine synthesis. This review article provides a clinically useful overview of RLS in terms of pathophysiological findings, its genetic associations, and therapeutic options by using the currently available literature. Because RLS presents with vague symptoms and shares similarities with many other diseases, it might be overlooked by many physicians resulting in underdiagnosis and under-treatment. While these discoveries provide a breakthrough in understanding the details of RLS, further studies are recommended as these studies are limited to animal models and provide a limited representation of the general population.

Mineral absorption is an enriched pathway in a brain region of restless legs syndrome patients with reduced MEIS1 expression

Restless legs syndrome is a common complex disorder with different genetic and environmental risk factors. Here we used human cell lines to conduct an RNA-Seq study and observed how the gene showing the most significant association with RLS, MEIS1, acts as a regulator of the expression of many other genes. Some of the genes affected by its expression level are linked to pathways previously reported to be associated with RLS. We found that in cells where MEIS1 expression was either increased or prevented, mineral absorption is the principal dysregulated pathway. The mineral absorption pathway genes, HMOX1 and VDR are involved in iron metabolism and response to vitamin D, respectively. This shows a strong functional link to the known RLS pathways. We observed the same enrichment of the mineral absorption pathway in postmortem brain tissues of RLS patients showing a reduced expression of MEIS1. The expression of genes encoding metallothioneins (MTs) was observed to be dysregulated across the RNA-Seq datasets generated from both human cells and tissues. MTs are highly relevant to RLS as they bind intracellular metals, protect against oxidative stress and interact with ferritins which manage iron level in the central nervous system. Overall, our study suggests that in a subset of RLS patients, the contribution of MEIS1 appears to be associated to its downstream regulation of genes that are more directly involved in pathways that are relevant to RLS. While MTs have been implicated in the pathogenesis of neurodegenerative diseases such as Parkinson’s diseases, this is a first report to propose that they have a role in 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.).

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.

Disorders of sleep and circadian rhythms

Sleep is fundamental to the survival of humans. However, knowledge regarding the role of sleep and its regulation is poorly understood. Genetics in flies, mice, and humans has led to a detailed understanding of some aspects of circadian regulation. Sleep homeostasis (the effect of increasing periods of wakefulness on our sleep propensity) is largely not understood. Sleep homeostasis is distinct from, but also linked to, the circadian clock. It is only in the last two decades that our understanding of some sleep disorders has been revealed. These breakthroughs were mostly fueled by intensive investigation using genetic tools. Although modern human genetics has revolutionized scientific research of neurologic disorders beginning ~35 years ago, studies of sleep and sleep disorders have lagged behind those of many neurologic diseases. This is due to the complexity in phenotyping behaviors like sleep and the fact that sleep is strongly influenced by environmental and other factors. We have long been aware that the amount of sleep required by individuals is normally distributed in the general population with small proportions of people being natural short or natural long sleepers. However, it has been less than a decade since Mendelian families of natural short sleepers have been recognized. Recent work has made significant advances and mechanistic insights of several sleep disorders as well as familial natural short sleepers by using ever-improving human genetic and cellular molecular tools. Given recent advances into genetic and biologic understanding of sleep, the hope of understanding this indispensable process is closer. Ultimately, our growing understanding will lead to more effective treatments of human sleep disorders.

Targeted disruption of supraspinal motor circuitry reveals a distributed network underlying Restless Legs Syndrome (RLS)-like movements in the rat

In this study we uncovered, through targeted ablation, a potential role for corticospinal, cerebello-rubro-spinal, and hypothalamic A11 dopaminergic systems in the development of restless legs syndrome (RLS)-like movements during sleep. Targeted lesions in select basal ganglia (BG) structures also revealed a major role for nigrostriatal dopamine, the striatum, and the external globus pallidus (GPe) in regulating RLS-like movements, in particular pallidocortical projections from the GPe to the motor cortex. We further showed that pramipexiole, a dopamine agonist used to treat human RLS, reduced RLS-like movements. Taken together, our data show that BG-cortico-spinal, cerebello-rubro-spinal and A11 descending projections all contribute to the suppression of motor activity during sleep and sleep-wake transitions, and that disruption of these circuit nodes produces RLS-like movements. Taken together with findings from recent genomic studies in humans, our findings provide additional support for the concept that the anatomic and genetic etiological bases of RLS are diverse.

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.

Restless Legs Syndrome: Current Concepts about Disease Pathophysiology

Background

In the past few decades, much has been learned about the pathophysiology of restless legs syndrome (RLS). Investigators have studied neuropathology, imaging, electrophysiology, and genetics of RLS, identifying brain regions and biological systems affected in RLS. This manuscript will review RLS pathophysiology literature, examining the RLS state through consideration of the neuroanatomy, then the biological, organ, and genetic systems.

Methods

Pubmed (1966 to April 2016) was searched for the term “restless legs syndrome” cross-referenced with “pathophysiology,” “pathogenesis,” “pathology,” or “imaging.” English language papers were reviewed. Studies that focused on RLS in relation to another disease were not reviewed.

Results

Although there are no gross structural brain abnormalities in RLS, widespread brain areas are activated, including the pre- and post-central gyri, cingulate cortex, thalamus, and cerebellum. Pathologically, the most consistent finding is striatal iron deficiency in RLS patients. A host of other biological systems are also altered in RLS, including the dopaminergic, oxygen-sensing, opioid, glutamatergic, and serotonergic systems. Polymorphisms in genes including BTBD9 and MEIS1 are associated with RLS.

Discussion

RLS is a neurologic sensorimotor disorder that involves pathology, most notably iron deficiency, in motor and sensory brain areas. Brain areas not subserving movement or sensation such as the cingulate cortex and cerebellum are also involved. Other biological systems including the dopaminergic, oxygen-sensing, opioid, glutamatergic, and serotonergic systems are involved. Further research is needed to determine which of these anatomic locations or biological systems are affected primarily, and which are affected in a secondary response.

Susceptible genes of restless legs syndrome in migraine

Objective Several genetic variants have been found to increase the risk of restless legs syndrome (RLS). The aim of the present study was to determine if these genetic variants were also associated with the comorbidity of RLS and migraine in patients. Methods Thirteen single-nucleotide polymorphisms (SNPs) at six RLS risk loci ( MEIS1, BTBD9, MAP2K5, PTPRD, TOX3, and an intergenic region on chromosome 2p14) were genotyped in 211 migraine patients with RLS and 781 migraine patients without RLS. Association analyses were performed for the overall cohort, as well as for the subgroups of patients who experienced migraines with and without aura and episodic migraines (EMs) vs. chronic migraines (CMs). In order to verify which genetic markers were potentially related to the incidence of RLS in migraine patients, multivariate regression analyses were also performed. Results Among the six tested loci, only MEIS1 was significantly associated with RLS. The most significant SNP of MEIS1, rs2300478, increased the risk of RLS by 1.42-fold in the overall cohort ( p = 0.0047). In the subgroup analyses, MEIS1 augmented the risk of RLS only in the patients who experienced EMs (odds ratio (OR) = 1.99, p = 0.0004) and not those experiencing CMs. Multivariate regression analyses further showed that rs2300478 in MEIS1 (OR = 1.39, p = 0.018), a CM diagnosis (OR = 1.52, p = 0.022), and depression (OR = 1.86, p = 0.005) were independent predictors of RLS in migraine. Conclusions MEIS1 variants were associated with an increased risk of RLS in migraine patients. It is possible that an imbalance in iron homeostasis and the dopaminergic system may represent a link between RLS incidence and migraines.

Symptom Severity of Restless Legs Syndrome Predicts Its Clinical Course

OBJECTIVE

This study examines the clinical course of restless legs syndrome according to its severity and factors associated with the remission of restless legs syndrome symptoms.

METHODS

The remission or persistence of restless legs syndrome symptoms was investigated by considering patients with restless legs syndrome at the sleep clinic of Seoul National University Bundang Hospital. All subjects were observed for at least 18 months, and an incidence of remission was defined as having no restless legs syndrome symptoms for at least 1 year. Restless legs syndrome severity was evaluated by the International Restless Legs Syndrome Study Group Rating Scale.

RESULTS

A total of 306 patients participated in this study. Over the observation periods of 4.1 ± 1.6 years, the cumulative incidence of remission is 32.5% (95% confidence interval [CI], 27.0-38.0) and decreased with baseline restless legs syndrome severity (P < .001): 60% (95% CI, 44.9-75.1), 44% (95% CI, 34.4-53.6), and 16.7% (95% CI, 10.6-22.8) in mild, moderate, and severe to very severe restless legs syndrome cases, respectively. Most cases of remission (82/96) were observed within 1 year, and the remission occurred sooner for mild restless legs syndrome. The hazard ratios of remission by Cox proportional hazards model were lower for moderate (0.556; 95% CI, 0.340-0.909) and severe to very severe (0.193; 95% CI, 0.108-0.343) restless legs syndrome than for mild restless legs syndrome. The remission incidence was lower for those patients who had a family history of restless legs syndrome and were older at restless legs syndrome diagnosis.

CONCLUSIONS

Mild restless legs syndrome severity, no family history, and young age at restless legs syndrome diagnosis were significant predictors of restless legs syndrome remission. More than 80% of patients with severe restless legs syndrome showed a chronic clinical course.

The Effect of Massage With Lavender Oil on Restless Leg Syndrome in Hemodialysis Patients: A Randomized Controlled Trial

BACKGROUND

Restless leg syndrome (RLS) is a common problem in patients with chronic renal failure. It can reduce the quality of life and sleep disturbances. This disorder is usually treated pharmacologically. Recently, complementary medicine methods have been suggested because of chemical drugs adverse effects. There is not enough evidence about the effect of aromatherapy on RLS.

OBJECTIVES

The aim of this study was to determine the effects of massage with lavender oil on RLS symptoms in hemodialysis patients.

PATIENTS AND METHODS

This randomized clinical trial study included 70 hemodialysis patients with RLS that were randomly assigned into two groups in 2014. The experimental group received effleurage massage using lavender oil and control group received routine care for three weeks. Data was collected with RLS questionnaire and analyzed using independent and paired t-test and Chi-square test.

RESULTS

The mean RLS scores were not significantly different in the two groups at the start of study (22.41 ± 7.67 vs. 22.90 ± 4.38, P = 0.76). At the end of study, the mean RLS score significantly decreased in the intervention group, while this score remained relatively un-changed in the control group (12.41 ± 5.49 vs. 23.23 ± 4.52, P < 0.0001).

CONCLUSIONS

Lavender oil massage was effective to improve RLS in hemodialysis patients. It has no adverse effects, is practical and cost-effective. It is suggested to be used along with routine treatment of RLS in hemodialysis patients.

The Molecular Genetics of Restless Legs Syndrome

Restless legs syndrome (RLS) is a common sensorimotor trait defined by symptoms that interfere with sleep onset and maintenance in a clinically meaningful way. Nonvolitional myoclonus while awake and asleep is a sign of the disorder and an informative endophenotype. The genetic contributions to RLS/periodic leg movements are substantial, are among the most robust defined to date for a common disease, and account for much of the variance in disease expressivity. The disorder is polygenic, as revealed by recent genome-wide association studies. Experimental studies are revealing mechanistic details of how these common variants might influence RLS expressivity.

Parkinson's disease and restless legs syndrome

AIMS

Various sleep-related complications are common in Parkinson's disease (PD). The prevalence of restless legs syndrome (RLS) and its association with other symptoms were studied.

METHODS

Altogether, 1,447 Parkinson patients, aged 43-89, participated in a questionnaire study.

RESULTS

The response rate was 59.0% and of these, 68% returned fully answered questionnaires (n = 577). RLS occurred in 20.3% of the PD subjects. In patients with RLS, the symptoms occurred in 81.9% at least once weekly. The degree of severity was moderate in 42.7%, severe in 23.9% and very severe in 15.4%. Daytime sleepiness, fatigue, chronic insomnia, sleep maintenance insomnia, intense dreaming, and low quality of life were more common in patients with RLS than in patients without RLS. The occurrence of early onset RLS (onset ≤ age of 45 years) was 4.2%. The occurrences of late onset (>45 years) drug naïve RLS and late onset RLS (with dopaminergic medication) were 5.4 and 10.4%, respectively.

CONCLUSION

In patients with PD, the early onset of RLS resembles idiopathic RLS with typical gender distribution and familial trait. Late onset of RLS is more common than idiopathic RLS.

Patients suffering from restless legs syndrome have low internal locus of control and poor psychological functioning compared to healthy controls

BACKGROUND

Restless legs syndrome (RLS) is a disturbing sensorimotor disorder negatively influencing both sleep and psychological functioning. The aim of the present study was to assess RLS patients with respect to locus of control, sleep-related personality traits, quality of life, and sleep as compared to healthy controls.

METHOD

Thirty-eight patients (18 females and 20 males; mean age: 56.06 years) diagnosed with RLS and an age- and gender-matched control group (n = 42) were recruited. Participants completed a series of questionnaires related to locus of control, personality traits, quality of life, and sleep.

RESULTS

Compared to healthy controls, RLS patients had a lower internal locus of control, unfavourable sleep-related personality traits such as low self-confidence and higher mental arousal, poorer quality of life, and more depressive symptoms. Sleep was also affected. Multiple regression analyses showed that a low internal and a high external locus of control were predicted by RLS.

CONCLUSIONS

The pattern of results suggests that RLS is associated with a low locus of control, negative personality traits, and poor quality of life as compared to healthy controls.

Review of the treatment of restless legs syndrome: focus on gabapentin enacarbil

The FDA approved gabapentin enacarbil in 2011 as the first non-dopaminergic agent for the treatment of restless legs syndrome (RLS) symptoms. Although gabapentin enacarbil is a pro-drug of gabapentin, its pharmacokinetics differ. Absorption of gabapentin enacarbil is more predictable, and inter-patient variability in bioavailability is lower than that of gabapentin. Studies have demonstrated superiority of gabapentin enacarbil compared to placebo. Comparisons to currently available RLS treatments are lacking, but clinical trials demonstrate comparable improvement in RLS symptoms to the dopamine agonists ropinirole and pramipexole, which are usually considered first-line therapy for daily RLS symptoms. Gabapentin enacarbil was well tolerated in clinical trials. The role of the drug in RLS treatment remains undefined, although it will likely be used as an alternative for refractory RLS when other treatments have failed. Additionally, gabapentin enacarbil may be recommended for patients with daily RLS symptoms that are less intense or are associated with pain as an alternative to dopamine agonists.

Prevalence of restless legs syndrome in a Georgian primary healthcare setting: a pilot study

BACKGROUND

The prevalence of restless legs syndrome (RLS) is approximately 10% in Western Europe, but unknown in Georgia. This pilot study aimed to assess RLS prevalence in a focused Georgian population.

METHODS

An RLS epidemiological questionnaire [Allen et al.: Sleep Med 2003;4:101-119] was filled out by patients in five primary healthcare centers in two Georgian cities between March and September 2006. Additionally, questions related to RLS symptom onset, family history, treatment, sleep disturbance and history of iron deficiency were included. RLS diagnosis was based on an expert interview and an epidemiological questionnaire for RLS.

RESULTS

The total number of respondents was 115 (75% women/25% men); mean age was 47 years (range 18-85). Thirteen subjects (11.3%) reported RLS symptoms (9 women/4 men); mean age was 52 years (range 32-83). Eleven (85%) had a positive family history of RLS. All subjects had sleep disturbance and none had a history of known iron deficiency.

CONCLUSION

The prevalence of RLS in a focused Georgian population is in line with other RLS epidemiologic studies performed in clinical settings. However, the prevalence rate of RLS in a studied group might not be representative for the general Georgian population. Further population-based epidemiological studies are required.

Genome-wide association study of motor coordination problems in ADHD identifies genes for brain and muscle function

OBJECTIVES

Motor coordination problems are frequent in children with attention deficit/hyperactivity disorder (ADHD). We performed a genome-wide association study to identify genes contributing to motor coordination problems, hypothesizing that the presence of such problems in children with ADHD may identify a sample of reduced genetic heterogeneity.

METHODS

Children with ADHD from the International Multicentre ADHD Genetic (IMAGE) study were evaluated with the Parental Account of Children's Symptoms. Genetic association testing was performed in PLINK on 890 probands with genome-wide genotyping data. Bioinformatics enrichment-analysis was performed on highly ranked findings. Further characterization of the findings was conducted in 313 Dutch IMAGE children using the Developmental Coordination Disorder Questionnaire (DCD-Q).

RESULTS

Although none of the findings reached genome-wide significance, bioinformatics analysis of the top-ranked findings revealed enrichment of genes for motor neuropathy and amyotrophic lateral sclerosis. Genes involved in neurite outgrowth and muscle function were also enriched. Among the highest ranked genes were MAP2K5, involved in restless legs syndrome, and CHD6, causing motor coordination problems in mice. Further characterization of these findings using DCD-Q subscales found nominal association for 15 SNPs.

CONCLUSIONS

Our findings provide clues about the aetiology of motor coordination problems, but replication studies in independent samples are necessary.

The use of rotigotine in the treatment of restless legs syndrome

Restless legs syndrome (RLS) is a neurological disorder characterized by an urge to move the legs often accompanied by unpleasant sensations. Symptoms appear during periods of rest or inactivity, particularly in the evening and at night, and are usually relieved by movement. The prevalence of RLS among Whites is approximately 5-15%. RLS can be distinguished into primary and secondary forms. Most patients (70-80%) are affected by the primary form of RLS. The uncomfortable sensations related to RLS often cause a minimal discomfort, thus a therapeutic approach is not necessary. However, almost 3% of the general population reports to be affected by severe symptoms of RLS, requiring pharmacological treatment. Secondary forms of RLS are relieved by the remission of the underlying clinical condition. Dopamine agonists are considered to be first-line treatments for primary RLS. Rotigotine is a nonergoline dopamine agonist with selectivity for D1, D2 and D3 receptors. It is administered once a day in the form of an adhesive matrix patch. The efficacy and safety of the drug in patients with primary RLS has been demonstrated by four clinical trials using dosages of 0.5, 1, 2, 3 and 4 mg/24 h. A dose-response relationship was observed between the dosages of 0.5 and 3 mg/24 h. Side effects were usually mild, the most frequent being skin reaction at the site of patch application. More trials are ongoing and results will soon be published for the long-term (5 years) treatment of RLS with rotigotine transdermal patches. Rotigotine is a promising drug for the treatment of RLS. Its continuous delivery throughout 24 h makes it especially indicated for those cases also presenting daytime symptoms, and for those presenting the so-called augmentation syndrome after prolonged treatment with L-dopa or dopamine agonists.

Prevalence of restless legs syndrome in North American and Western European populations: a systematic review

BACKGROUND

Restless legs syndrome (RLS) is a potentially debilitating sleep disorder that affects a significant percentage of North American and European adults. Although standardized RLS diagnostic criteria are now established and widely accepted, reported prevalence estimates have varied widely. In this paper, we review the literature regarding RLS prevalence in North American and Western European adult populations, examine potential sources of variation, briefly discuss the impact of RLS, and offer recommendations for future research.

METHODS

To identify qualifying studies, we searched 6 scientific databases and scanned bibliographies of relevant review papers and all identified articles. Studies including fewer than 300 participants, that did not use any of the 4 standard diagnostic criteria, were published prior to 1995 or targeted clinical populations were excluded.

RESULTS

Thirty-four papers detailing results of large, population-based studies in 16 North American and Western European countries met our inclusion criteria, including 5 multi-country studies (N=69,992 participants) and 29 single country studies (N=163,188 participants); all but one were cross-sectional. Reported general prevalence rates ranged from 4% to 29% of adults, averaging 14.5±8.0% across studies. Reported prevalence averaged higher in primary care populations than in populations derived from random sampling or geographically defined cohorts (19.5±7.9% vs. 12.3±7.2%). Diagnostic and severity criteria differed considerably among studies, as did inclusion criteria, with corresponding variation in prevalence estimates. Prevalence averaged higher in women and older adults; more limited data suggest race/ethnicity, parity, health status, and other factors may also contribute to the observed variation in prevalence. RLS has profound, negative effects on health, well-being, and quality of life, yet detection rates remain low.

CONCLUSIONS

Collectively, these studies indicate that RLS is a common disorder of major clinical and public health significance in the Western industrialized world, affecting between 4% and 29% of adults. The wide variation in reported prevalence likely reflects differences in demographic factors, health status, and other population characteristics; study population source and sampling frame; and inconsistencies in RLS diagnostic criteria and procedures. Prospective studies and corresponding incidence data on RLS are lacking, hindering the evaluation of both causal factors and sequelae.

Restless legs syndrome and conditions associated with metabolic dysregulation, sympathoadrenal dysfunction, and cardiovascular disease risk: a systematic review

Restless legs syndrome (RLS) is a distressing sleep and sensorimotor disorder that affects a large percentage of adults in the western industrialized world and is associated with profound reductions in quality of life. However, the etiology of RLS remains incompletely understood. Enhanced understanding regarding both the antecedents and sequelae of RLS could shed new light on the pathogenesis of RLS. Evidence from an emerging body of literature suggests associations between RLS and diabetes, hypertension, obesity, and related conditions linked to sympathetic activation and metabolic dysregulation, raising the possibility that these factors may likewise play a significant role in the development and progression of RLS, and could help explain the recently documented associations between RLS and subsequent cardiovascular disease. However, the relation between RLS and these chronic conditions has received relatively little attention to date, although potential implications for the pathogenesis and treatment of RLS could be considerable. In this paper, we systematically review the recently published literature regarding the association of RLS to cardiovascular disease and related risk factors characterized by sympathoadrenal and metabolic dysregulation, discuss potential underlying mechanisms, and outline some possible directions for future research.

Evaluation of contributing factors to restless legs syndrome in migraine patients

Recent studies have provided evidence for a positive association between migraine and restless legs syndrome (RLS), although the exact mechanisms and contributing factors remain unclear. A cross-sectional, case-control study was conducted, including patients with migraine (n = 262) and headache-free control subjects (n = 163). Migraine was diagnosed according to International Classification of Headache Disorders II criteria. RLS diagnosis was made based on four essential criteria as described by the International Restless Legs Syndrome Study Group. All patients completed the Migraine Disability Assessment (MIDAS) questionnaire, Beck Depression Inventory (BDI)-II scores, Pittsburgh Sleep Quality Index (PSQI), and Epworth Sleepiness Scale (ESS). A total of 210 blood samples were collected to correlate various parameters with RLS. RLS frequency was significantly greater in patients with migraine than in controls (13.7 vs. 1.8%). Migraine patients with RLS had high scores for MIDAS, BDI-II, PSQI, and ESS compared with those without RLS. In addition, migraine patients with RLS had a high rate of smoking and RLS family history, as well as increased levels of serum phosphorus and urea nitrogen compared with those without RLS. However, there was no difference in serum iron and ferritin levels between the groups. In migraine patients, logistic regression analysis revealed that positive RLS family history, BDI-II, ESS, and serum phosphorus levels were significant RLS predictors. Our study confirmed a positive association between RLS and migraine. RLS comorbidity in migraine patients was associated with insomnia, daytime sleepiness, depressive symptoms, headache-related disability, and increased serum phosphorus levels. These findings may provide a better understanding of RLS pathogenesis in migraine.

Algorithms for the diagnosis and treatment of restless legs syndrome in primary care

BACKGROUND

Restless legs syndrome (RLS) is a neurological disorder with a lifetime prevalence of 3-10%. in European studies. However, the diagnosis of RLS in primary care remains low and mistreatment is common.

METHODS

The current article reports on the considerations of RLS diagnosis and management that were made during a European Restless Legs Syndrome Study Group (EURLSSG)-sponsored task force consisting of experts and primary care practitioners. The task force sought to develop a better understanding of barriers to diagnosis in primary care practice and overcome these barriers with diagnostic and treatment algorithms.

RESULTS

The barriers to diagnosis identified by the task force include the presentation of symptoms, the language used to describe them, the actual term "restless legs syndrome" and difficulties in the differential diagnosis of RLS.

CONCLUSION

The EURLSSG task force reached a consensus and agreed on the diagnostic and treatment algorithms published here.

Advances in the science of genomics in restless legs syndrome

Restless legs syndrome (RLS) is a sleep and movement disorder that affects up to 15% of the population across the lifespan. Many health care providers have doubted its validity as an illness and are uncertain as to the implications of health care outcomes. The cause of RLS is unknown. Common treatment options include dopaminergics, benzodiazepines, and opioids; however, the pharmacogenetic mechanisms of treatment are unknown. One of the greatest genetic discoveries in 2007 was the identification of genetic variance associated with RLS. There is, however, a lack of knowledge related to RLS and its genetic basis. Therefore, the purposes of this article are to (a) provide information about the science of clinical care related to RLS; (b) present a systematic review of the literature on the status of genetics/genomics of RLS, including the discovery of associated genetic variance; and (c) identify implications of the current state of the science for health care providers and biobehavioral researchers. With the continuing genetic discoveries in RLS, health care providers, specifically nurses who play a major role in research, genetic counseling, and education, need to understand the implications of this sleep and movement disorder for patients across the lifespan.

[Restless legs syndrome, periodic limb movements, and psychopharmacology]

Restless legs syndrome (RLS) and the often associated periodic limb movement disorder in sleep (PLMD) frequently occur in the general population as a primary disorder. In addition to organic disease, secondary forms are caused by psychotropic medication. Several antidepressants, antipsychotics, lithium, and opioid withdrawal have been shown to induce or exacerbate RLS and PLMD, while several antiepileptics used as mood stabilizers and some benzodiazepines demonstrate therapeutic potential for treating RLS/PLMD. Systematic or controlled studies for evaluating these side effects still do not exist. Among the antidepressants at higher risk of inducing this disorder are selective serotonin reuptake inhibitors, venlafaxine, and some tetracyclic antidepressants. Under medication with some tricyclic substances, periodic limb movements were observed more often. For some antidepressants with differing transmitter profiles such as bupropion RLS/PLMD ameliorating effects or at least neutral effects (Trazodon, Nortriptylin) have been described in small studies. In case of continued of or newly occurring insomnia a thorough history should be taken to identify a possible RLS/PLMD as an intolerable side effect of treatment. A change in medications should be considered if clinically feasible. In case of RLS/PLMD occurring in psychotic patients switching the antipsychotic and additionally using a second line medication such as antiepileptics or a benzodiazepine should be considered.

Clinical and genetic description of a family with a high prevalence of autosomal dominant restless legs syndrome

OBJECTIVE

To conduct clinical and molecular genetic analyses of the members of an extended family in Central Indiana with a high prevalence of restless legs syndrome (RLS).

PARTICIPANTS AND METHODS

From February 1, 2006, through August 31, 2008, we collected data from members of this family, which is of English descent. Genealogical methods were used to expand the family tree, and family members were screened with an RLS questionnaire. Telephone interviews and personal examinations were performed at Mayo Clinic and during a field trip to Central Indiana. Blood samples were collected for molecular genetic analysis. A follow-up telephone interview was conducted 1 year later.

RESULTS

The family tree spans 7 generations with 88 living members, 30 of whom meet the criteria for diagnosis of RLS established by the International Restless Legs Syndrome Study Group. Three affected family members also have Parkinson disease or essential tremor. The mode of RLS inheritance is compatible with an autosomal dominant pattern. The affected family members do not exhibit linkage to the 5 known RLS loci or mutations in the RLS susceptibility genes MEIS1 and BTBD9.

CONCLUSION

Of 88 members of this single extended family in Central Indiana, 30 were diagnosed as having RLS. Because our analysis shows that the disease is not linked to any of the known RLS loci or risk-associated genes, we postulate that members of this family may carry a gene mutation in a novel genetic locus.

Clinical and genetic description of a family with a high prevalence of autosomal dominant restless legs syndrome

OBJECTIVE

To conduct clinical and molecular genetic analyses of the members of an extended family in Central Indiana with a high prevalence of restless legs syndrome (RLS).

PARTICIPANTS AND METHODS

From February 1, 2006, through August 31, 2008, we collected data from members of this family, which is of English descent. Genealogical methods were used to expand the family tree, and family members were screened with an RLS questionnaire. Telephone interviews and personal examinations were performed at Mayo Clinic and during a field trip to Central Indiana. Blood samples were collected for molecular genetic analysis. A follow-up telephone interview was conducted 1 year later.

RESULTS

The family tree spans 7 generations with 88 living members, 30 of whom meet the criteria for diagnosis of RLS established by the International Restless Legs Syndrome Study Group. Three affected family members also have Parkinson disease or essential tremor. The mode of RLS inheritance is compatible with an autosomal dominant pattern. The affected family members do not exhibit linkage to the 5 known RLS loci or mutations in the RLS susceptibility genes MEIS1 and BTBD9.

CONCLUSION

Of 88 members of this single extended family in Central Indiana, 30 were diagnosed as having RLS. Because our analysis shows that the disease is not linked to any of the known RLS loci or risk-associated genes, we postulate that members of this family may carry a gene mutation in a novel genetic locus.

Restless legs syndrome: differential diagnosis and management with rotigotine

RLS is a common sleep disorder with distinctive clinical features. The prevalence of RLS in Caucasians and North Americans ranges from 5% to 10%. However, only some of these subjects (almost the 3% of the general population) report being affected by a frequent and severe form of the sleep disorder. RLS is diagnosed clinically by means of four internationally recognized criteria that summarize the main characteristics of the sleep disorder. Besides the essential criteria, supportive and associated features of RLS have been established by experts in order to help physicians treat patients with doubtful symptoms. Several clinical conditions may mimic this sleep disorder. In order to increase the sensibility and specificity of RLS diagnosis, doctors should perform a meticulous patient history and then an accurate physical and neurological examination. Dopamine agonists are recognized as the preferred first-line treatment for RLS. Rotigotine is a non-ergoline dopamine agonist with selectivity for D1, D2 and D3 receptors. The drug is administered via transdermal patches which release rotigotine for 24 hours. Four clinical trials demonstrated that this compound is able to improve RLS symptomatology with few and moderate adverse events. Head to head trials are required to compare the efficacy and tolerability of rotigotine with other dopamine agonists administered via oral intake. Rotigotine has been approved by the FDA and EMEA for Parkinson's disease. For the treatment of moderate to severe idiopathic RLS, rotigotine has been recommended for approval by the EMEA and is under review by the FDA.