Chronic inflammation markers and cytokine-specific autoantibodies in Danish blood donors with restless legs syndrome.

Restless Legs Syndrome (RLS) is a neurological sensorimotor disorder negatively impacting sufferers' quality of sleep and health-related quality of life. The pathophysiology of RLS is poorly understood and research focusing on the link between RLS and inflammation has been limited. Our study aimed to investigate whether chronic inflammation markers C-reactive protein (CRP) and soluble urokinase-type plasminogen activator receptor (suPAR), as well plasma levels of five different cytokine-specific autoantibodies (c-aAb), i.e. modulators of inflammation, associate with RLS in otherwise healthy individuals. CRP, suPAR and c-aAb were measured in plasma samples of participants from the Danish Blood Donor Study in 2010. Returning donors between 2015 and 2018 completed the validated Cambridge-Hopkins RLS-questionnaire for RLS assessment, resulting in datasets with RLS assessment and values for CRP (N = 3564), suPAR (N = 2546) and c-aAb (N = 1478). We performed logistic regression models using the CRP, suPAR or c-aAb as the independent variable and RLS status as the dependent variable, adjusted for appropriate covariates. Our study indicates that a high concentration of CRP is associated with RLS, while an increased probability of experiencing frequent RLS symptoms in those with an elevated plasma suPAR level appears to be mediated through lifestyle factors. We additionally report that a high titer of autoantibodies specific against the cytokine interferon-alpha was associated with RLS. Our results support the existence of links between systemic inflammation and RLS, though further RLS studies on CRP, suPAR and c-aAb in larger cohorts are warranted to confirm our findings and further reveal the hitherto underexplored links between RLS and inflammation.

Investigating the inflammation marker neutrophil-to-lymphocyte ratio in Danish blood donors with restless legs syndrome.

BACKGROUND: Restless Legs Syndrome (RLS) is a neurological sensorimotor disorder that occurs in the evening and night, thereby impacting quality of sleep in sufferers. The pathophysiology of RLS is poorly understood but inflammation has been proposed as possibly being involved. The neutrophil-to-lymphocyte ratio (NLR) can be used as an inflammation marker but results from small studies have been inconclusive in determining whether NLR is associated with RLS. We aimed to assess whether an association between NLR and RLS exists in a large cohort of healthy individuals. METHODS: Neutrophils and lymphocytes were measured in blood samples of 13,055 individuals from the Danish Blood Donor Study, all of whom completed the validated Cambridge-Hopkins RLS-questionnaire for RLS assessment. RESULTS: In the sample, 661 individuals were determined as current RLS cases (5.1%). A higher proportion of individuals with RLS were females (62.5% vs 47.5%; P<0.001) and RLS cases were older than controls (P<0.001), but no differences in body mass index (BMI), smoking or alcohol consumption were found between the two groups. An increased NLR was observed in RLS cases compared to controls (median NLR: 1.80 vs 1.72; P = 0.033). In an unadjusted logistic regression model, increased NLR was associated with RLS (OR = 1.10 per NLR unit increase [95%CI:1.01-1.20]; P = 0.032); however, the association was not significant in multivariate models adjusting for sex and age (P = 0.094) or sex, age, alcohol consumption, smoking status and BMI (P = 0.107). CONCLUSION: We found no association between RLS and NLR among Danish blood donors after adjusting for sex, age, alcohol consumption, smoking status and BMI. Further studies are needed to determine whether inflammation is a risk factor for RLS.

Idiopathic and secondary restless legs syndrome during pregnancy in Japan: Prevalence, clinical features and delivery-related outcomes.

OBJECTIVE: The aim of this study was to investigate prevalence of idiopathic and secondary restless legs syndrome (RLS) according to pregnancy trimester, and its effects on delivery-related outcomes among pregnant women in Japan. METHODS: This was a single-center, prospective observational study. One hundred eighty-two consecutive pregnant women participated in the study from June 2014 to March 2016. Participants were interviewed and examined in the second and third trimesters of pregnancy and 1 month after delivery. At each term, RLS was identified by a research assistant and then specialist in sleep medicine based on the diagnostic criteria of the International Restless Legs Syndrome Study Group. Delivery-related data was collected from medical charts. RLS was classified as idiopathic RLS, which originally existed before the index pregnancy, or secondary RLS, which newly appeared during the index pregnancy. RESULTS: The prevalence of RLS was 4.9% (idiopathic 3.3%, secondary 1.6%) in the second trimester, 5.0% (idiopathic 0.0%, secondary 5.0%) in the third trimester, and 0.6% (idiopathic 0.0%, secondary 0.6%) after delivery. Prolonged labor, emergency Cesarean section, and arrest of labor tended to be more frequent in idiopathic and/or second RLS (all p<0.05). CONCLUSIONS: The prevalence of RLS during pregnancy was 4-5% and decreases after delivery in current Japan. The presence of RLS was associated with an increase in some delivery-related outcomes. Early detection and treatment of RLS during pregnancy may be beneficial to safe delivery for pregnant women.

Prevalence and determinants of restless leg syndrome in type 2 diabetes mellitus (T2DM) in Pakistan.

BACKGROUND AND AIMS: Restless legs syndromes (RLS) are intrinsic sleeping disorder and its prevalence rate is 10-15% in general population but it is observed that prevalence rate is different in diabetes patients. Current study aims to find prevalence and determinants of RLS in people living with type 2 diabetes mellitus in Pakistan. METHOD: A multicenter cross-sectional observational study was conducted in 388 diabetes patients attending daily diabetes clinics and teaching hospitals in Pakistan's twin city between August 2019 and February 2020. The chi-square test and linear regression were used to detect RLS-related factors in type 2 diabetes mellitus. RESULTS: The prevalence of RLS found was; 3.1% patients with diabetes were suffering from very severe RLS, 23.5% from severe RLS, 34% from moderate RLS, 21.1% from mild RLS and 18.3% from non-RLS. Gender, age, education, blood glucose fasting (BSF), blood glucose random (BSR) and HBA1c were found to be significant predictors of RLS in patients with diabetes. CONCLUSION: Policy makers can develop local interventions to curb the growing RLS prevalence by keeping in control the risk factors of RLS in people living with type 2 diabetes.

Which Factors in Spinocerebellar Ataxia Type 3 Patients Are Associated with Restless Legs Syndrome/Willis-Ekbom Disease?

There is evidence of a higher prevalence of restless legs syndrome/Willis-Ekbom disease (RLS/WED) in individuals with spinocerebellar ataxia type 3 (SCA3), although the factors underlying this association remain unknown. The present study aimed to determine the prevalence of RLS/WED in SCA3 patients and to investigate which factors of SCA3 patients are associated with presence of RLS/WED. From February to August of 2006, we carried out clinical interviews in 40 controls and 40 SCA3 patients, diagnosed and followed up at Faculty of Medicine of Ribeirão Preto, University of São Paulo. Twenty-seven SCA3 patients were submitted to a detailed clinical protocol, electroneuromyography, blood work up, polysomnography (PSG), suggested immobilization test (SIT), and magnetic resonance image (MRI). RLS/WED was found in 27.5% of SCA3 patients and 2.5% of normal controls (p = 0.003). The factors related to RLS/WED in SCA3 patients were female gender, age at start of the symptoms of ataxia after 30 years, presence of peripheral neuropathy, and documented iron deficiency. Among SCA3 patients, those with RLS showed higher values of maximal discomfort level and discomfort level sum compared to non-RLS individuals on SIT. There is a relation between RLS/WED and SCA3, which seems to be resultant of different factors whose identification could improve the quality of assistance to those patients as well as to promote a better comprehension of the pathophysiology of both RLS/WED and SCA3.

Circulating levels of cytokines are increased in restless legs syndrome.

BACKGROUND: Restless legs syndrome [RLS] is known as a disease of iron and dopaminergic dysregulation but inflammatory processes might also have a role in the pathogenesis. In this study, we compared the circulating levels of hsCRP, IL-1ß, IL-6, and TNF-α in patients with primary restless legs syndrome [RLS] and healthy control subjects. METHODS: We prospectively included 29 patients with primary RLS and 65 healthy controls [HC], all age-sex matched. The diagnosis of RLS was established using international guidelines. IRLSSG Severity Scale was used to evaluate the severity of RLS. Plasma levels of hsCRP, IL-1ß, IL-6, and TNF-α were measured in all participants. RESULTS: The mean age of patients was 37.8 ± 11.3 and 52% of RLS group were women. Serum IL-1ß, IL-6, and TNF-α levels of the patient group were statistically significantly higher compared to HC [p < 0.001 for all variables]. Plasma levels of hsCRP did not differ between groups. There were 8 patients with mild RLS [28%], 13 patients with moderate RLS [45%], and 8 patients with severe RLS [28%]. Only IL-6 values were significantly different between the groups. In the severe group, the value of IL-6 was significantly higher than in the other groups [p: 0.03]. CONCLUSION: These results showing higher circulating levels of inflammatory cytokines in patients with RLS support the notion that inflammation may be involved in the pathogenesis of primary RLS. However, it is necessary to perform further studies to determine if this finding is a cause or an effect.

Relation of serum hepcidin levels and restless legs syndrome in chronic hemodialysis patients.

BACKGROUND: Iron deficiency anemia, pregnancy, and end-stage renal disease (ESRD) are common causes of secondary restless legs syndrome (RLS). Serum ferritin is considered the most specific test associated with the total amount of body iron stores. However, due to the increase of serum ferritin secondary to inflammation in chronic hemodialysis (HD) patients, serum ferritin test results do not fully reflect decreased iron stores in these patients. The present study evaluates the serum hepcidin levels, as the main regulator of iron metabolism, and its relationship with RLS in chronic HD patients. METHODS: The present cross-sectional study involved 72 patients (36 with and 36 without RLS) who received chronic HD treatment between April 2014 and April 2015. Demographic and biochemical data were evaluated in all patients, and statistical analyses were performed. RESULTS: The mean age and mean dialysis vintage of all patients (56% women) included in the study were 65.3 ± 11.6 years and 41.5 ± 36.5 months, respectively. Serum hepcidin, hemoglobin A1C (HbA1C), and ferritin levels were significantly higher in patients with RLS (p = 0.001, p = 0.032, p = 0.042, respectively). In addition, a positive correlation was found between International Restless Legs Syndrome Study Group severity scale score and serum hepcidin levels, HbA1C, and ferritin (r = 0.387, p = 0.001; r = 0.426, p = 0.034; r = 0.240, p = 0.046, respectively). A multivariate linear regression analysis revealed hepcidin and HbA1C to be independently associated with the presence of RLS. CONCLUSION: A significant relationship was detected between RLS and increased serum hepcidin levels in chronic HD patients, and uncontrolled diabetes was noted to contribute to this association.

Prospective associations of sleep apnea, periodic limb movements, and plasma fibrinogen level.

PURPOSE: Our previous cross-sectional study showed that periodic limb movements during sleep (PLMS) were frequently found in patients with obstructive sleep apnea (OSA) and that both OSA and PLMS were associated with higher plasma fibrinogen levels. We explored the longitudinal relationships among these factors. METHODS: Plasma fibrinogen levels were measured in 333 consecutive patients who underwent polysomnography to diagnose OSA. Patients who initiated continuous positive airway pressure (CPAP) underwent follow-up polysomnography after 3 months of CPAP use. They were categorized into groups with good or poor adherence (% days with ≥ 4 h/night of CPAP use ≥ 70% or < 70%, respectively). Changes in sleep parameters and plasma fibrinogen levels during the treatment period were compared between these groups. RESULTS: The cross-sectional analysis of all reviewed 333 patients indicated that fibrinogen levels were associated with the severities of OSA and PLMS. The 60 patients (27 good and 33 poor adherence) who underwent follow-up polysomnography were included in the longitudinal analysis. The median (interquartile range) periodic limb movement index did not change significantly from CPAP titration to the 3-month follow-up (good adherence: 10.5 (0-23.8) to 10.8 (0-70.2) events/h, p = 0.21; poor adherence: 1.2 (0-14.3) to 0.8 (0-15.7) events/h, p = 0.67). However, the plasma fibrinogen level significantly decreased only in the good adherence group (good adherence: baseline 275 ± 46 to follow-up 255 ± 47 mg/dl, p < 0.01; poor adherence: 277 ± 52 to 284 ± 70 mg/dl, p = 0.48). CONCLUSIONS: These results did not support a longitudinal association between PLMS and OSA. However, good adherence to CPAP could reduce plasma fibrinogen levels, thus ameliorating elevations in plasma fibrinogen as a risk factor for future cardiovascular events.

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.

Mu opioid receptor knockout mouse: Phenotypes with implications on restless legs syndrome.

Restless legs syndrome (RLS) is characterized by an irresistible need to move the legs while sitting or lying at night with insomnia as a frequent consequence. Human RLS has been associated with abnormalities in the endogenous opioid system, the dopaminergic system, the iron regulatory system, anemia, and inflammatory and auto-immune disorders. Our previous work indicates that mice lacking all three subtypes of opioid receptors have a phenotype similar to that of human RLS. To study the roles of each opioid receptor subtype in RLS, we first used mu opioid receptor knockout (MOR KO) mice based on our earlier studies using postmortem brain and cell culture. The KO mice showed decreased hemoglobin, hematocrit, and red blood cells (RBCs), with an appearance of microcytic RBCs indicating anemia. Together with decreased serum iron and transferrin, but increased ferritin levels, the anemia is similar to that seen with chronic inflammation in humans. A decreased serum iron level was also observed in the wildtype mice treated with an MOR antagonist. Iron was increased in the liver and spleen of the KO mice. Normal circadian variations in the dopaminergic and serotoninergic systems were absent in the KO mice. The KO mice showed hyperactivity and increased thermal sensitivity in wakefulness primarily during what would normally be the sleep phase similar to that seen in human RLS. Deficits in endogenous opioid system transmission could predispose to anemia of inflammation and loss of circadian variations in dopaminergic or serotonergic systems, thereby contributing to an RLS-like phenotype.

The effect of vitamin D on restless legs syndrome: prospective self-controlled case study.

PURPOSE: To evaluate the effect of vitamin D on severity of restless legs syndrome in patients with idiopathic restless legs syndrome (RLS). METHODS: Patients with idiopathic RLS completed questionnaires including the International Restless Legs Severity Scale (IRLSS) and were evaluated for vitamin D deficiency. Patients with deficiency of vitamin D were treated with 50,000 units per week for 2 months. At the end of the 2 months, vitamin D levels were re-measured and disease severity was re-evaluated in patients who reached adequate vitamin D level. Subgroups of IRLSS questionnaire were also analyzed. RESULTS: Of 35 patients enrolled, 21 (60%) had vitamin D deficiency and received vitamin D therapy. In 2 patients, vitamin D levels did not rise to sufficient levels with supplementation and these 2 patients were excluded from analysis. The remaining 19 patients showed vitamin D levels increased from 13.2 ± 4.0 to 42.8 ± 9.6 ng/mL while IRLSS improved from 24.9 ± 5.1 to 21.1 ± 2.9 points (p <0.001). Selected subscores of the IRLSS were also improved including symptom severity (p <0.001), impact on sleep (p <0.001), symptom measures (p =0.002), and disease impact measures (p <0.001). There were trends toward improvement in subscores of frequency (p =0.11) and mood (p =0.051). CONCLUSIONS: The findings suggest that vitamin D levels should be evaluated in patients with RLS and if vitamin D deficiency is revealed, consideration should be given to replacement therapy.u.

Frequency of iron deficiency anemia in pregnant and non-pregnant women suffering from restless legs syndrome.

Objectives. Restless Legs Syndrome is a movement disorder characterized by unpleasant sensations in the legs described as a burning, tingling, etc. Symptoms become worse in the evening and are relieved by moving the limbs. The idiopathic form of the disease is associated with a lack of dopamine, and the secondary form is associated with iron deficiency anemia, pregnancy, and kidney disease. The aim of this study was to investigate the incidence of iron deficiency anemia in pregnant women and non-pregnant women suffering from RLS.Methods. The study was conducted on a sample of 231 pregnant women aged 18-50. The pregnant women were interviewed at the outpatient clinic of the Department of Gynaecology and Obstetrics. This study also included a control group of 231 age-compatible non-pregnant women. Women who met the international criteria for diagnosing the syndrome filled in a sociodemographic questionnaire.Results. A statistically significant association between the existence of iron deficiency anemia and RLS in the sample of the examined women was proven (p < 0.001). It was also shown that RLS is more frequent in a sample of anemic pregnant women than non-anemic pregnant women (p = 0.008).Conclusion. Iron deficiency anemia is related with RLS. Pregnant women with RLS are more likely to be anemic than pregnant women without RLS.

Rotigotine suppresses sleep-related muscle activity augmented by injection of dialysis patients' sera in a mouse model of restless legs syndrome.

Idiopathic restless legs syndrome (RLS) has a genetic basis wherein BTBD9 is associated with a higher risk of RLS. Hemodialysis patients also exhibit higher rates of RLS compared with the healthy population. However, little is known about the relationship of BTBD9 and end-stage renal disease to RLS pathophysiology. Here we evaluated sleep and leg muscle activity of Btbd9 mutant (MT) mice after administration of serum from patients with either idiopathic or RLS due to end-stage renal disease (renal RLS) and investigated the efficacy of treatment with the dopamine agonist rotigotine. At baseline, the amount of rapid eye movement (REM) sleep was decreased and leg muscle activity during non-REM (NREM) sleep was increased in MT mice compared to wild-type (WT) mice. Wake-promoting effects of rotigotine were attenuated by injection of serum from RLS patients in both WT and MT mice. Leg muscle activity during NREM sleep was increased only in MT mice injected with serum from RLS patients of ideiopatic and renal RLS. Subsequent treatment with rotigotine ameliorated this altered leg muscle activity. Together these results support previous reports showing a relationship between the Btbd9/dopamine system and RLS, and elucidate in part the pathophysiology of RLS.

Evaluation of potential cardiovascular risk protein biomarkers in high severity restless legs syndrome.

Restless legs syndrome (RLS) is a common sensorimotor disorder that, in case of severe symptoms, can be very distressing and negatively interfere with quality of life. Moreover, increasing evidences associate RLS with higher risk of cerebrovascular and cardiovascular disease (CVD). The purpose of this study was to quantify two proteins, previously identified by proteomics and potentially linked with CVD risk, namely kininogen-1 (KNG1) and alpha-1-antitrypsin (A1AT), in primary RLS patients at high severity grade (HS-RLS) in comparison to healthy control subjects. Proteins were quantified through enzyme-linked immunosorbent assay (ELISA) in plasma samples from 14 HS-RLS patients and 15 control individuals. The two groups were closely matched for age and gender. The expression level of KNG1 resulted significantly higher (p < 0.001), while A1AT was significantly decreased (p < 0.05) in HS-RLS patients compared to controls, confirming the relationship between these proteins and the disease severity. Furthermore, in patients group the association between the protein concentrations and the following parameters was further evaluated: age, disease onset and diagnosis, scores obtained from the RLS rating scales (Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, Beck Depression Inventory) and smoking habit. All the considered variables resulted independent of protein levels, so the disease can be reasonably considered the main cause of protein changes. As emerged from the literature, high levels of KNG1 and low amounts of A1AT seem to be related with a highest probability to develop CVD. Consequently, these proteins may be reliable candidate biomarkers of CVD risk in patients with RLS at high severity grade.

Assessment of serum uric acid levels in patients with restless legs syndrome.

In our study, the aim was to collect data in relation to our hypothesis that oxidative stress is effective in the etiopathogenesis of restless legs syndrome (RLS) by assessing the serum uric acid levels, an important biomarker of oxidative stress, among RLS patients. The study included a total of 281 patients with restless legs syndrome diagnosis according to the "2012 Revised International Restless Legs Syndrome Study Group Diagnostic Criteria". Disease severity was assessed according to the "International Restless Legs Syndrome Study Group Severity Scale". The control group comprised 237 healthy individuals with the same age and gender features as the control group. The result showed no statistically significant difference in the mean age and gender between RLS and control group (p = 0.923; p = 0.433). The hemoglobin, ferritin, and uric acid levels of patients with RLS were found to be low (p < 0.001). Total iron-binding capacity level was higher in patients (p < 0.01; p < 0.05). In RLS patients, the serum uric acid level was not affected by disease severity (p > 0.05). Variables affecting uric acid level in RLS patients were determined to be age, disease duration, and hemoglobin level. The hypothesis that uric acid level, accepted as a biomarker of oxidative stress, is important in the pathogenesis of restless legs syndrome is supported by our study.

Decreased serum ferritin may be associated with increased restless legs syndrome in Parkinson's disease (PD): a meta-analysis for the diagnosis of RLS in PD patients.

Objective: Restless legs syndrome (RLS) is one of the most common non-motor symptoms of Parkinson's disease (PD), but its pathogenesis in a PD background is unclear. Abnormal iron metabolism may be involved, in which case it may be a marker of RLS risk. Here, the literature was systematically searched and meta-analyzed to compare iron metabolism markers between PD patients with or without RLS. Method: The databases PubMed, Embase, Chinese National Knowledge Infrastructure, Wanfang, Web of Science, and SinoMed were searched for case-control and observational studies examining RLS-related changes in iron metabolism in PD, in terms of serum iron, serum ferritin and hemoglobin. Eligible studies were meta-analyzed using Stata 12.0. Results: Meta-analysis of 11 case-control studies showed that serum ferritin concentration was lower in PD patients with RLS than in those without RLS. (95%CI -0.32 to -0.03, p = 0.018). In contrast, levels of serum iron or hemoglobin did not differ significantly between PD patients with or without RLS. Conclusion: This meta-analysis may provide the first reliable pooled estimate of the correlation between abnormal iron metabolism and RLS in PD. The available evidence indicates that levels of ferritin, but not of serum iron or hemoglobin, correlate significantly with RLS in PD, with lower ferritin levels correlating to greater prevalence of RLS.

Serum C-reactive protein/albumin ratio and restless legs syndrome.

OBJECTIVES: Our study aimed to assess the variation in serum C-reactive protein/albumin ratio (CAR), a biomarker of peripheral inflammation and oxidative stress, in patients with restless legs syndrome (RLS). METHODS: The study included a total of 380 individuals including 197 with RLS diagnosis. RLS diagnosis was determined according to the "International Restless Legs Syndrome Study Group" questionnaire. Disease severity was assessed according to the "International Restless Legs Syndrome Study Group Severity Scale''. RESULTS: The mean age of patients with restless legs syndrome was 52.5 ± 12.7 years, while the mean age in the control group was 50.8 ± 11.2, with no statistically significant difference found (p = 0.156). The hemoglobin, iron and ferritin levels in the patient group were lower than in the control group (p < 0.001; p < 0.01; p < 0.001), with total iron binding capacity levels higher than the control group (p < 0.001). The mean ferritin in the RLS group (49.8 ± 51.2) was lower than the control group (76.9 ± 44.7). In patients, the c-reactive protein, albumin and c-reactive protein/albumin ratio were found to be 0.21 ± 0.18, 4.43 ± 0.31 and 0.07 ± 0.05, respectively. When compared with the control group, the patient group had high c-reactive protein (CRP), CAR and low albumin levels (p < 0.001). Among patients with "very severe" disease severity, ferritin levels were found to be lower than those with "moderate" disease severity. Additionally, patients with "very severe" disease had albumin levels which were significantly low compared to those with "mild" disease severity (p < 0.05). CONCLUSION: Our study supports the hypothesis that serum albumin level, ferritin, CRP, and CAR may be associated with restless legs syndrome.

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.

Discovery of restless legs syndrome plasmatic biomarkers by proteomic analysis.

OBJECTIVES: Restless legs syndrome (RLS) can lead to severe clinical consequences, thus negatively impacts on patients' overall health and quality of life. Nevertheless, the pathophysiology of RLS is still unclear, resulting in underestimate, incorrect, or ignored diagnosis and in limited management and treatment. The aim of this study was to compare the plasma proteome of RLS patients and healthy controls, in the search of diagnostic biomarkers related to the disease severity. MATERIALS AND METHODS: Two-dimensional gel electrophoresis coupled with liquid chromatography-mass spectrometry was employed to analyze plasma samples of 34 patients with primary RLS, divided into two subgroups according to the disease severity: MMS group (mild-moderate symptoms) and HS group (severe and very severe symptoms), and 17 age- and sex-matched control subjects. Sleep quality, daytime sleepiness, and the level of depression were also evaluated. RESULTS: We identified eight upregulated spots, corresponding to five unique proteins, in both RLS group vs. controls (alpha-1B-glycoprotein, alpha-1-acid glycoprotein 1, haptoglobin, complement C4-A, and immunoglobulin kappa constant); five increased spots, consistent with three unique proteins, only in HS-RLS (kininogen-1, immunoglobulin heavy constant alpha 1, and immunoglobulin lambda constant 2); one downregulated spot in both patient's groups (complement C3) and another one only in HS-RLS (alpha-1-antitrypsin). CONCLUSIONS: The significantly different plasma proteins detected in RLS were mainly associated with inflammation, immune response, and cardiovascular disorders. Particularly, the gradual increasing in immunoglobulins could be indicative of the disease severity and evolution. Accordingly, these proteins may represent a valid set of useful biomarkers for RLS diagnosis, progression and treatment.

Rate of augmentation and risk factors with long-term follow-up in Japanese patients with restless legs syndrome.

OBJECTIVES: Preventing augmentation is the critical clinical issue for RLS treatment. As for augmentation in Asian RLS patients, there have been only four studies and the follow-up durations of these studies were not long. We investigated Japanese RLS patients with longer duration of treatment in a clinical setting. METHODS: This study is a retrospective assessment of 42 RLS patients with follow-up durations of longer than 18 months (78.4 ± 29.2, range 19-139) at two urban sleep centers in Osaka, Japan from May 2004 to April 2014. RESULTS: The mean age of first visit was 63.5 ± 14.1 years old and the estimated age of RLS onset was 47.9 ± 16.5 years old. Twenty-eight out of 42 patients were female. At initial evaluation, the mean International Restless Legs Scale score (IRLS score) was 22.0 ± 5.9. Thirty-one of 42 had already visited other clinics before coming to our sleep centers, and the number of clinics visited was 1.3 ± 0.6. Augmentation developed in two patients (4.8%), and the dosage of dopamine equivalent in patients with and without augmentation was 12.5 and 18.8 mg vs. 15.8 ± 17.7 mg. In the two RLS patients with augmentation, ferritin was 113.1 and 114.1 ng/mL, respectively, and the number of clinics before coming to our sleep centers was both three. CONCLUSIONS: The augmentation rate of Japanese RLS patients from our study is low compared with previous Western and Asian studies. It might be attributable to racial difference, lower dosage of dopaminergic treatment, and the level of ferritin.