Pathophysiology of restless legs syndrome: evidence for iron involvement

Adverse effects of antipsychotics on sleep in patients with schizophrenia. Systematic review and meta-analysis

Introduction

Our objective was to conduct a systematic review and meta-analysis of adverse effects on sleep in patients with schizophrenia receiving antipsychotic treatment.

Methods

A systematic search was performed in PubMed, Cochrane Central, Embase, Toxline, Ebsco, Virtual Health Library, Web of Science, SpringerLink, and in Database of abstracts of Reviews of Effects of Randomized Clinical Trials to identify eligible studies published from January 1990 to October 2021. The methodological quality of the studies was evaluated using the CONSORT list, and the Cochrane bias tool. Network meta-analysis was performed using the Bayesian random-effects model, with multivariate meta-regression to assess the association of interest.

Results

87 randomized clinical trials were identified that met the inclusion criteria, and 70 articles were included in the network meta-analysis. Regarding the methodological quality of the studies, 47 had a low or moderate bias risk. The most common adverse effects on sleep reported in the studies were insomnia, somnolence, and sedation. The results of the network meta-analysis showed that ziprasidone was associated with an increased risk of insomnia (OR, 1.56; 95% credible interval CrI, 1.18-2.06). Several of the included antipsychotics were associated with a significantly increased risk of somnolence; haloperidol (OR, 1.90; 95% CrI, 1.12-3.22), lurasidone (OR, 2.25; 95% CrI, 1.28-3.97) and ziprasidone (OR, 1.79; 95% CrI, 1.06-3.02) had the narrowest confidence intervals. In addition, perphenazine (OR, 5.33; 95% CrI, 1.92-14.83), haloperidol (OR, 2.61; 95% CrI, 1.14-5.99), and risperidone (OR, 2.41; 95% CrI, 1.21-4.80) were associated with an increased risk of sedation compared with placebo, and other antipsychotics did not differ. According to the SUCRAs for insomnia, chlorpromazine was ranked as the lowest risk of insomnia (57%), followed by clozapine (20%), while flupentixol (26 %) and perospirone (22.5%) were associated with a lower risk of somnolence. On the other hand, amisulpride (89.9%) was the safest option to reduce the risk of sedation.

Discussion

Insomnia, sedation, and somnolence were the most frequent adverse effects on sleep among the different antipsychotics administered. The evidence shows that chlorpromazine, clozapine, flupentixol, perospirone, and amisulpride had favorable safety profiles. In contrast, ziprasidone, perphenazine, haloperidol, and risperidone were the least safe for sleep.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42017078052, identifier: PROSPERO 2017 CRD42017078052.

The relationship between iron deficiency anemia with restless leg syndrome and sleep quality in workers working in a textile factory in Iran: a cross-sectional study

Background

The aim of this study is to investigate the relationship between iron deficiency anemia with restless leg syndrome (RLS) and sleep quality in workers working in a textile factory in Iran. This cross-sectional study was conducted on 216 workers working in a textile factory in Iran. In addition to demographic and occupational variables, Pittsburgh Sleep Quality Index (PSQI) and RLS questionnaires were used for the data collection. To investigate iron deficiency anemia, 2 CC of blood was taken from the brachial artery with the help of a 10-CC syringe with a blue or pink tip. Then, relevant data were entered into SPSS26 and analyzed.

Results

The mean (S. D.) age of the workers was 32.23 (6.14) and 60.6% of them were women. The prevalence of iron deficiency anemia was 21.2 and 69.5% in men and women, respectively. Most of the workers were in moderate condition in terms of RLS severity, and 78.2% had sleep disorders. There was an inverse and significant correlation between age (β= −0.200), work experience (β= −0.160), hemoglobin (β= −0.149), and ferritin (β= −0.186) with global PSQI score (P value<0.05). Also, an inverse and significant correlation was observed between age (β= −0.164), hemoglobin (β= −0.548), and ferritin (β= −0.410) with RLS score (P value<0.05). However, there was a direct and significant correlation between TIBC level and RLS score (β= 0.227) and global PSQI score (β= 0.395) (P value<0.05).

Conclusions

Intervention programs to reduce iron deficiency anemia and periodic screening programs to identify sleep disorders and RLS in textile factory workers seem necessary.

Evaluation of quality of life and depression in family caregivers of patients with type 1 diabetes in Iran: A case-control study

Objective

Diabetes as a silent epidemic and one of the top four causes of death in the world. This study was designed to evaluate the quality of life and depression in family caregivers of patients with type 1 diabetes in Iran.

Methods

The study was case-control study (cases, n = 50; controls, n = 50). The cases consisted of family caregivers of patients with type 1 diabetes who referred to the endocrinology clinic of Kosar Hospital in Semnan in 2020. The controls were a random sample from among family caregivers of non-diabetic patients who had referred to the same center in the same year. Demographic and family variables, the 36-Item Short Form Survey questionnaire, and Beck's Depression Inventory were used to collect data. Univariate and multivariable logistic regression models with receiver operator characteristic (ROC) curve were used to data analysis in STATA 14.

Results

The multivariable logistic regression model showed a significant association between existence of a patient with type 1 diabetes with number of caregivers' children (odds ratio (OR) = 1.77; 95% confidence interval (CI): 1.06-2.94), quality of life (OR = 0.82; 95% CI: 0.74-0.90), sex (OR = 10.04; 95% CI: 2.29-43.99), and income level of caregivers (OR = 6.49; 95% CI: 1.35-31.08); however, it did not show a significant relationship with depression (OR = 1.02; 95% CI: 0.94-1.10).

Conclusion

The quality of life in family caregivers of type 1 diabetics is low and gender, income level, and number of caregivers' children were the most important factors predicting it. Therefore, psychological interventions to manage stress and improve the quality of life of family caregivers are recommended.

BTBD9 attenuates manganese-induced oxidative stress and neurotoxicity by regulating insulin growth factor signaling pathway

Manganese (Mn) is an essential mineral, but excess exposure can cause dopaminergic neurotoxicity. Restless legs syndrome (RLS) is a common neurological disorder, but the etiology and pathology remain largely unknown. The purpose of this study was to identify the role of Mn in the regulation of an RLS genetic risk factor BTBD9, characterize the function of BTBD9 in Mn-induced oxidative stress and dopaminergic neuronal dysfunction. We found that human subjects with high blood Mn levels were associated with decreased BTBD9 mRNA levels, when compared with subjects with low blood Mn levels. In A549 cells, Mn exposure decreased BTBD9 protein levels. In Caenorhabditis elegans, loss of hpo-9 (BTBD9 homolog) resulted in more susceptibility to Mn-induced oxidative stress and mitochondrial dysfunction, as well as decreased dopamine levels and alternations of dopaminergic neuronal morphology and behavior. Overexpression of hpo-9 in mutant animals restored these defects and the protection was eliminated by mutation of the forkhead box O (FOXO). In addition, expression of hpo-9 upregulated FOXO protein levels and decreased protein kinase B levels. These results suggest that elevated Mn exposure might be an environmental risk factor for RLS. Furthermore, BTBD9 functions to alleviate Mn-induced oxidative stress and neurotoxicity via regulation of insulin/insulin-like growth factor signaling pathway.

Local iron deficiency in the substantia nigra directly contributes to hyperlocomotion phenotypes

Brain iron is precisely regulated, and disrupted brain iron homeostasis is implicated in neuropsychological disease. Mounting evidence connects the iron status of the substantia nigra (SN) with locomotion-related neural symptomatology. Researchers in this field have long speculated that iron deficiency in the SN directly causes the high-locomotion symptoms observed in neuropsychiatric disorders. However, no direct experimental evidence of a causal relationship has been presented. To explore the relationship between iron deficiency in the SN and locomotion-related phenotypes, we stereotaxically injected the well-documented iron chelator, deferiprone (DFP) into the SN of mice to induce regional brain iron deprivation and subsequently performed behavioral tests. Altered expression of iron metabolism-related molecules was detected in the brain regions with interventions, and behavioral changes were observed. Targeted iron chelation effectively decreased the local iron content of the SN. Among the brain regions examined, only DFP injected into the SN resulted in the hyperlocomotion phenotype. Upon SN iron chelation, transferrin receptor (Tfr) expression was found to be upregulated. Conversely, viral vector-mediated SN-Tfr knockdown was sufficient to induce SN iron deficiency and mimic the hyperlocomotion phenotype. All locomotion changes had a significant negative correlation with iron alteration in the SN. Furthermore, SN iron disturbance also contributed to poor sleep efficiency. Thus, SN iron deficiency directly contributed to triggering both hyperlocomotion and sleep disturbances. This study offers a promising research and therapeutic direction for iron-linked neuropsychiatric diseases.

Iron, neuro‐bioavailability and depression

Medical management of iron deficiency (ID) requires to consider its consequences in biochemical and physiological plural functions, beyond heme/hemoglobin disrupted synthesis. Fatigue, muscle weakness, reduced exercise capacity, changes in thymia and modified emotional behaviors are the commonest symptoms integrated in the history of ID, dependent or not of the hemoglobin concentration. The relationship between depression and absolute ID (AID) is a condition which is often unrecognized. Neuro‐bioavailability and brain capture of blood iron are necessary for an appropriate synthesis of neurotransmitters (serotonin, dopamine, noradrenaline). These neurotransmitters, involved in emotional behaviors, depend on neuron aromatic hydoxylases functioning with iron as essential cofactor. Noradrenaline also has impact on neuroplasticity via brain‐derived neurotrophic factor (BDNF), which is key for prefrontal and hippocampus neurons playing a role in depression. Establishing the formal relationship between depression and AID remains difficult. Intracerebral reduced iron is still hard to quantify by neuroimaging and single‐photon emission computed tomography (SPECT) now tends to explore the neurotransmission pathways. AID has to be looked for and identified in the context of depression, major episode or resistant to conventional treatment such as serotonin reuptake inhibitor, and even in the absence of anemia, microcytosis or hypochromia (non‐anemic ID). Confronted to brain imaging, blood iron status evaluation is indicated, especially in depressed, treatment‐resistant, iron‐deficient young women. In patients suffering from depression, increase in the prevalence of AID should be considered, in order to deliver a suitable treatment, considering both anti‐depressive program and iron supplementation if AID.

Changes in Hepcidin Serum Levels Correlate with Clinical Improvement in Idiopathic Restless Legs Syndrome Patients

BACKGROUND

Restless legs syndrome (RLS) is a common sensory motor neurological disorder that is related to iron-dopamine dysregulation and immune system alteration. We aimed to assess the effects of serum hepcidin, an iron-regulating hormone, in drug-naive RLS patients compared to healthy controls and to evaluate its role in helping to predict clinical improvement after treatment with dopamine agonist.

METHODS

Nonanemic and drug-naive RLS patients (n = 18) and healthy controls (n = 15) were enrolled. The serum hepcidin and iron-related values in the serum were measured upon the first visit in both groups and 12 weeks later after dopaminergic treatment in 12 patients. Information about sociodemographic characteristics, sleep-related profiles, mood and anxiety was obtained upon the first visit in all participants as well as after treatment in RLS patients.

RESULTS

Serum hepcidin levels exhibited no significant differences between patients with drug-naïve RLS and healthy controls at diagnosis (7.1 ± 2.4 vs. 7.0 ± 3.2 ng/mL, p = 0.357). Decreased hepcidin levels were significantly associated with decreased RLS severity (β = 0.002, 95% CI = 0.00-0.00, p = 0.005) and improved quality of life (β = 0.002, 95% CI = 0.00-7.01, p = 0.044) in a dose-dependent manner after 12 weeks of treatment with a dopamine agonist. This association was independent of age, sex, inflammatory markers, sleep quality, insomnia, daytime sleepiness, depression and anxiety.

CONCLUSIONS

This study demonstrates the role of hepcidin in evaluating the positive therapeutic response in RLS.

Iron and manganese-related CNS toxicity: mechanisms, diagnosis and treatment

INTRODUCTION

Iron (Fe) and manganese (Mn) are essential nutrients for humans. They act as cofactors for a variety of enzymes. In the central nervous system (CNS), these two metals are involved in diverse neurological activities. Dyshomeostasis may interfere with the critical enzymatic activities, hence altering the neurophysiological status and resulting in neurological diseases. Areas covered: In this review, the authors cover the molecular mechanisms of Fe/Mn-induced toxicity and neurological diseases, as well as the diagnosis and potential treatment. Given that both Fe and Mn are abundant in the earth crust, nutritional deficiency is rare. In this review the authors focus on the neurological disorders associated with Mn and Fe overload. Expert commentary: Oxidative stress and mitochondrial dysfunction are the primary molecular mechanism that mediates Fe/Mn-induced neurotoxicity. Although increased Fe or Mn concentrations have been found in brain of patients, it remains controversial whether the elevated metal amounts are the primary cause or secondary consequence of neurological diseases. Currently, treatments are far from satisfactory, although chelation therapy can significantly decrease brain Fe and Mn levels. Studies to determine the primary cause and establish the molecular mechanism of toxicity may help to adapt more comprehensive and satisfactory treatments in the future.

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.

Contributions to magnetic susceptibility of brain tissue

This review discusses the major contributors to the subtle magnetic properties of brain tissue and how they affect MRI contrast. With the increased availability of high-field scanners, the use of magnetic susceptibility contrast for the study of human brain anatomy and function has increased dramatically. This has not only led to novel applications, but has also improved our understanding of the complex relationship between MRI contrast and magnetic susceptibility. Chief contributors to the magnetic susceptibility of brain tissue have been found to include myelin as well as iron. In the brain, iron exists in various forms with diverse biological roles, many of which are now only starting to be uncovered. An interesting aspect of magnetic susceptibility contrast is its sensitivity to the microscopic distribution of iron and myelin, which provides opportunities to extract information at spatial scales well below MRI resolution. For example, in white matter, the myelin sheath that surrounds the axons can provide tissue contrast that is dependent on the axonal orientation and reflects the relative size of intra- and extra-axonal water compartments. The extraction of such ultrastructural information, together with quantitative information about iron and myelin concentrations, is an active area of research geared towards the characterization of brain structure and function, and their alteration in disease. Copyright © 2016 John Wiley & Sons, Ltd.

Contributions to magnetic susceptibility of brain tissue

This review discusses the major contributors to the subtle magnetic properties of brain tissue and how they affect MRI contrast. With the increased availability of high-field scanners, the use of magnetic susceptibility contrast for the study of human brain anatomy and function has increased dramatically. This has not only led to novel applications, but has also improved our understanding of the complex relationship between MRI contrast and magnetic susceptibility. Chief contributors to the magnetic susceptibility of brain tissue have been found to include myelin as well as iron. In the brain, iron exists in various forms with diverse biological roles, many of which are now only starting to be uncovered. An interesting aspect of magnetic susceptibility contrast is its sensitivity to the microscopic distribution of iron and myelin, which provides opportunities to extract information at spatial scales well below MRI resolution. For example, in white matter, the myelin sheath that surrounds the axons can provide tissue contrast that is dependent on the axonal orientation and reflects the relative size of intra- and extra-axonal water compartments. The extraction of such ultrastructural information, together with quantitative information about iron and myelin concentrations, is an active area of research geared towards the characterization of brain structure and function, and their alteration in disease. Copyright © 2016 John Wiley & Sons, Ltd.

Pathology of behavior in PD: What is known and what is not?

Abnormal behavior in Parkinson's disease (PD) stems from a complex orchestration of impaired neural networks that result from PD-related neurodegeneration across multiple levels. Typically, cellular and tissue abnormalities generate neurochemical changes and disrupt specific regions of the brain, in turn creating impaired neural circuits and dysfunctional global networks. The objective of this chapter is to provide an overview of the array of pathological changes that have been linked to different behavioral symptoms of PD such as depression, anxiety, apathy, fatigue, impulse control disorders, psychosis, sleep disorders and dementia.

Mechanisms and regulation of iron trafficking across the capillary endothelial cells of the blood-brain barrier

The transcellular trafficking of iron from the blood into the brain interstitium depends on iron uptake proteins in the apical membrane of brain microvascular capillary endothelial cells and efflux proteins at the basolateral, abluminal membrane. In this review, we discuss the three mechanisms by which these cells take-up iron from the blood and the sole mechanism by which they efflux this iron into the abluminal space. We then focus on the regulation of this efflux pathway by exocrine factors that are released from neighboring astrocytes. Also discussed are the cytokines secreted by capillary cells that regulate the expression of these glial cell signals. Among the interstitial factors that regulate iron efflux into the brain is the Amyloid precursor protein (APP). The role of this amyliodogenic species in brain iron metabolism is discussed. Last, we speculate on the potential relationship between iron transport at the blood-brain barrier and neurological disorders associated with iron mismanagement.

Restless legs syndrome

Restless legs syndrome is a common sensorimotor disorder characterized by an urge to move, and associated with uncomfortable sensations in the legs (limbs). Restless legs syndrome can lead to sleep-onset or sleep-maintenance insomnia, and occasionally excessive daytime sleepiness, all leading to significant morbidity. Brain iron deficiency and dopaminergic neurotransmission abnormalities play a central role in the pathogenesis of this disorder, along with other nondopaminergic systems, although the exact mechanisms are still. Intensive care unit patients are especially vulnerable to have unmasking or exacerbation of restless legs syndrome because of sleep deprivation, circadian rhythm disturbance, immobilization, iron deficiency, and use of multiple medications that can antagonize dopamine.

T2 relaxometry using 3.0-tesla magnetic resonance imaging of the brain in early- and late-onset restless legs syndrome

Background and Purpose

Previous T2 relaxometry studies have provided evidence for regional brain iron deficiency in patients with restless legs syndrome (RLS). Measurement of the iron content in several brain regions, and in particular the substantia nigra (SN), in early- and late-onset RLS patients using T2 relaxometry have yielded inconsistent results. In this study the regional iron content was assessed in patients with early- and late-onset RLS using magnetic resonance imaging (MRI), and compared the results with those in controls.

Methods

Thirty-seven patients with idiopathic RLS (20 with early onset and 17 with late onset) and 40 control subjects were studied using a 3.0-tesla MRI with a gradient-echo sampling of free induction decay and echo pulse sequence. The regions of interest in the brain were measured independently by two trained analysts using software known as medical image processing, analysis, and visualization. The results were compared and a correlation analysis was conducted to investigate which brain areas were related to RLS clinical variables.

Results

The iron index in the SN was significantly lower in patients with late-onset RLS than in controls (p=0.034), while in patients with early-onset RLS there was no significant difference. There was no significant correlation between the SN iron index of the late-onset RLS group and clinical variables such as disease severity.

Conclusions

Late-onset RLS is associated with decreased iron content in the SN. This finding supports the hypothesis that regional brain iron deficiency plays a role in the pathophysiology of late-onset RLS.

Altered white matter integrity in primary restless legs syndrome patients: diffusion tensor imaging study

OBJECTIVES

A prior diffusion tensor imaging (DTI) of restless legs syndrome (RLS) subjects found alterations in brain white matter (WM). The aim of this study was to explore the possible mechanism of altered integrity of brain WM in RLS patients.

METHODS

The DTI measurement was performed in 22 subjects with RLS and 22 age-matched control subjects. Using a voxel-based analysis, fractional anisotropy (FA) and axial and radial diffusivities (AD and RD) were compared between RLS and control subjects with a two-sample t-test, and correlation analysis was performed in RLS subjects.

RESULTS

RLS subjects demonstrated decreased FA in the genu of the corpus callosum and frontal WM adjacent to the inferior frontal gyrus compared with the control subjects. For areas of decreased FA, both the AD and RD were higher than that in the control subjects.

DISCUSSION

Our findings suggest that loss of axonal density and myelin may account for WM changes seen in a prior study of RLS subjects.

Human L-ferritin deficiency is characterized by idiopathic generalized seizures and atypical restless leg syndrome

Human L-ferritin deficiency causes reduced cellular iron availability and increased ROS production with enhanced oxidized proteins, which results in idiopathic generalized seizures and atypical restless leg syndrome.

The ubiquitously expressed iron storage protein ferritin plays a central role in maintaining cellular iron homeostasis. Cytosolic ferritins are composed of heavy (H) and light (L) subunits that co-assemble into a hollow spherical shell with an internal cavity where iron is stored. The ferroxidase activity of the ferritin H chain is critical to store iron in its Fe3+ oxidation state, while the L chain shows iron nucleation properties. We describe a unique case of a 23-yr-old female patient affected by a homozygous loss of function mutation in the L-ferritin gene, idiopathic generalized seizures, and atypical restless leg syndrome (RLS). We show that L chain ferritin is undetectable in primary fibroblasts from the patient, and thus ferritin consists only of H chains. Increased iron incorporation into the FtH homopolymer leads to reduced cellular iron availability, diminished levels of cytosolic catalase, SOD1 protein levels, enhanced ROS production and higher levels of oxidized proteins. Importantly, key phenotypic features observed in fibroblasts are also mirrored in reprogrammed neurons from the patient’s fibroblasts. Our results demonstrate for the first time the pathophysiological consequences of L-ferritin deficiency in a human and help to define the concept for a new disease entity hallmarked by idiopathic generalized seizure and atypical RLS.

Restless legs syndrome, pica, and iron status in blood donors

BACKGROUND

The association of blood donation-related iron deficiency with pica or restless legs syndrome (RLS) remains poorly elucidated. This study evaluated the prevalence of RLS and pica in blood donors completing the REDS-II Iron Status Evaluation (RISE) study.

STUDY DESIGN AND METHODS

RISE enrolled 2425 blood donors in a prospective cohort study; 1334 donors provided blood samples to characterize iron status and answered a questionnaire inquiring into symptoms of RLS and pica at a final visit after 15 to 24 months of follow-up. Associations between both conditions and iron status were evaluated.

RESULTS

There were 9 and 20% of donors reporting symptoms of probable or probable/possible RLS, respectively. Iron depletion and donation intensity were not predictive of RLS. Pica was reported by 65 donors (5.5%), half of whom reported daily cravings. Prevalence of pica increased with degree of iron depletion in women (2% in iron-replete females, 13% in those with ferritin < 12 ng/mL), but not in men. Probable RLS and pica coexpressed in eight individuals, but no more frequently than expected by chance.

CONCLUSION

RLS and pica have been associated with iron deficiency in nondonor populations. This study indicates a potentially high prevalence of RLS in frequent blood donors but shows no association with iron status or donation intensity. Low iron stores were associated with higher prevalence of pica, but only in females. Furthermore, the results are incompatible with RLS and pica sharing a common pathophysiology.

Iron's role in paediatric restless legs syndrome - a review

Paediatric restless legs syndrome (RLS) treatment is important because RLS's associated sleep disturbance causes significant developmental-behavioural morbidity and impacts family well-being. RLS is associated with brain iron insufficiency and dopaminergic dysfunction. Diagnosis requires fulfillment of diagnostic criteria, which for children are currently in evolution, and have limitations, especially in preschoolers. The community physician needs to recognize the possibility of RLS to refer to a sleep specialist for diagnostic confirmation and management recommendations, which include oral iron therapy, even though there is currently no definitive research evidence for iron efficacy in most children with RLS. A 3 mg to 6 mg elemental iron/kg/day dose for three months could be tried if the ferritin level is <50 ug/L. Sleep hygiene and behavioural strategies are also recommended. Iron supplementation should be safe in the absence of iron metabolism disorders, provided that transferrin saturation and ferritin levels are monitored pre-and post-treatment.

Parkinson's disease and sleep/wake disturbances

Parkinson's disease (PD) has traditionally been characterized by its cardinal motor symptoms of bradykinesia, rigidity, resting tremor, and postural instability. However, PD is increasingly being recognized as a multidimensional disease associated with myriad nonmotor symptoms including autonomic dysfunction, mood disorders, cognitive impairment, pain, gastrointestinal disturbance, impaired olfaction, psychosis, and sleep disorders. Sleep disturbances, which include sleep fragmentation, daytime somnolence, sleep-disordered breathing, restless legs syndrome (RLS), nightmares, and rapid eye movement (REM) sleep behavior disorder (RBD), are estimated to occur in 60% to 98% of patients with PD. For years nonmotor symptoms received little attention from clinicians and researchers, but now these symptoms are known to be significant predictors of morbidity in determining quality of life, costs of disease, and rates of institutionalization. A discussion of the clinical aspects, pathophysiology, evaluation techniques, and treatment options for the sleep disorders that are encountered with PD is presented.

Dopamine agonists for restless legs syndrome

BACKGROUND

According to clinical guidelines, dopamine agonists are the first-line treatment of restless legs syndrome (RLS).

OBJECTIVES

To evaluate efficacy and safety of dopamine agonists for RLS.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library 2008, Issue 4), MEDLINE, EMBASE, PsycINFO and CINAHL, from January 1985 to December 2008, plus reference lists of articles. We contacted pharmaceutical companies.

SELECTION CRITERIA

We included double-blind randomised controlled trials (RCTs) of dopamine agonist treatment versus placebo or other treatment for a period of at least seven days in patients with RLS (≥ 18 years). Outcomes included the International RLS Severity Rating Scale (IRLS), Clinical Global Impressions (CGI-I), polysomnography and self rated sleep quality, quality of life, daytime functioning, and safety parameters.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data separately; assessed risk of bias; and contacted pharmaceutical companies and authors for additional information. We collected dropout rates due to adverse events and experience of adverse events.

MAIN RESULTS

We included 35 placebo controlled and three active controlled RCTs (N = 7365). The mean reduction on the IRLS was -5.7 points lower in dopamine agonist treatment compared to placebo (95% confidence interval (CI) -6.7 to -4.7). Periodic limb movements in sleep per hour of sleep (PLMS-Index; PLMSI) were -22.4/h lower than in placebo (95% CI -27.8 to -16.9). Self rated quality of sleep and disease specific quality of life were improved by a standardised mean difference (SMD) of 0.40 (95% CI 0.33 to 0.47) and 0.34 (95% CI 0.23 to 0.44), respectively. Patients were more likely to drop out (odds ratio (OR) 1.82, 95% CI 1.35 to 2.45) and experienced more adverse events under dopamine agonist treatment than with placebo (OR 1.82, 95% CI 1.59 to 2.08). Visual inspection of forest plots showed the highest efficacy in three studies investigating cabergoline and pergolide (N = 3). Active controlled trials investigated effects of cabergoline, pergolide, and pramipexole in a number of outcomes. The IRLS score was lower with cabergoline and pramipexole compared to levodopa (MD -5.3, 95% CI -8.4 to -2.1). Only four studies investigated treatment efficacy up to seven months. The most severe side effect, augmentation, was not assessed reliably.

AUTHORS' CONCLUSIONS

The meta-analyses show the superiority of dopamine agonists over placebo in RCTs up to seven months. Cabergoline and pramipexole showed larger efficacy compared to levodopa in some but not all outcomes.

Decreased CSF transferrin in sCJD: a potential pre-mortem diagnostic test for prion disorders

Sporadic Creutzfeldt-Jakob-disease (sCJD) is a fatal neurodegenerative condition that escapes detection until autopsy. Recently, brain iron dyshomeostasis accompanied by increased transferrin (Tf) was reported in sCJD cases. The consequence of this abnormality on cerebrospinal-fluid (CSF) levels of Tf is uncertain. We evaluated the accuracy of CSF Tf, a ‘new’ biomarker, as a pre-mortem diagnostic test for sCJD when used alone or in combination with the ‘current’ biomarker total-tau (T-tau). Levels of total-Tf (T-Tf), isoforms of Tf (Tf-1 and Tf-β2), and iron saturation of Tf were quantified in CSF collected 0.3–36 months before death (duration) from 99 autopsy confirmed sCJD (CJD+) and 75 confirmed cases of dementia of non-CJD origin (CJD-). Diagnostic accuracy was estimated by non-parametric tests, logistic regression, and receiver operating characteristic (ROC) analysis. Area under the ROC curve (AUC), sensitivity, specificity, positive and negative predictive values (PV), and likelihood ratios (LR) of each biomarker and biomarker combination were calculated. We report that relative to CJD-, CJD+ cases had lower median CSF T-Tf (125,7093 vs. 217,7893) and higher T-tau (11530 vs. 1266) values. AUC was 0.90 (95% confidence interval (CI), 0.85–0.94) for T-Tf, and 0.93 (95% CI, 0.89–0.97) for T-Tf combined with T-tau. With cut-offs defined to achieve a sensitivity of ∼85%, T-Tf identified CJD+ cases with a specificity of 71.6% (95% CI, 59.1–81.7), positive LR of 3.0 (95% CI, 2.1–4.5), negative LR of 0.2 (95% CI, 0.1–0.3), and accuracy of 80.1%. The effect of patient age and duration was insignificant. T-Tf combined with T-tau identified CJD+ with improved specificity of 87.5% (95%CI, 76.3–94.1), positive LR of 6.8 (95% CI, 3.5–13.1), negative LR of 0.2 (95% CI, 0.1–0.3), positive-PV of 91.0%, negative-PV of 80.0%, and accuracy of 86.2%. Thus, CSF T-Tf, a new biomarker, when combined with the current biomarker T-tau, is a reliable pre-mortem diagnostic test for sCJD.

Levodopa for restless legs syndrome

BACKGROUND

Levodopa plus dopamine decarboxylase inhibitor is a common treatment for restless legs syndrome (RLS).

OBJECTIVES

To evaluate efficacy and safety of levodopa for RLS compared to placebo and other active agents.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library 2008, Issue 4), MEDLINE, EMBASE, PsycINFO and CINAHL, from January 1985 to December 2008, reference lists of articles, and contacted pharmaceutical companies.

SELECTION CRITERIA

We included double-blind randomised controlled trials (RCT) investigating levodopa treatment versus placebo or other treatment for at least seven days in patients with RLS (age ≥ 18 years). Outcomes included symptom severity, CGI-I, objective as well as self rated sleep parameters, quality of life, and safety parameters.

DATA COLLECTION AND ANALYSIS

Two authors extracted data, assessed risk of bias, and contacted pharmaceutical companies and authors for additional information. We collected dropouts due to adverse events and patients experiencing adverse events.

MAIN RESULTS

Six placebo controlled and three active controlled RCTs were included (521 participants). Symptom severity (11 point rating scale, 0 points indicating no symptoms, 10 points indicating maximally severe symptoms) was more reduced with levodopa than placebo in two studies (mean difference (MD) -1.34, 95% confidence interval (CI) -2.18 to -0.5, P = 0.002). Periodic limb movements in sleep per hour of sleep (PLMS-Index; PLMSI) improved by -26.28/h compared to placebo (95% CI -30.53 to -22.02, P < 0.00001).The CGI-I changed more with levodopa than placebo in two studies (MD -1.25, 95% CI -1.89 to -0.62, P = 0.0001). In two studies, sleep quality (sleep questionnaire, visual analogue scale) showed a large effect (standardised mean difference (SMD) 0.92, 95% CI 0.52 to 1.33, P < 0.00001) whereas quality of life (50 mm Visual Analogue Scales) improved by 3.23 compared to placebo (95% CI 1.64 to 4.82, P < 0.0001). Few patients dropped out of treatment (3 of 218 patients) but more levodopa treated patients experienced adverse events than with placebo (odds ratio 2.61, 95% CI 1.35 to 5.04, P = 0.004). Two dopamine agonist controlled studies showed smaller effects with levodopa than cabergoline and pramipexole on the IRLS (MD 5.25, 95% CI 2.10 to 8.40, P =0.001), CGI-I (MD 0.62, 95% CI 0.37 to 0.87, P < 0.00001), and quality of life (MD 5.54, 95% CI 2.65 to 8.43, P = 0.0002).

AUTHORS' CONCLUSIONS

Levodopa is efficacious for the short-term treatment of RLS. Augmentation, the clinically most relevant adverse event, was not investigated sufficiently.

Intravenous iron dextran for severe refractory restless legs syndrome

Reduced brain iron is strongly associated with restless legs syndrome (RLS). Oral iron supplements are commonly recommended for RLS but are largely ineffective due to poor absorption and poor tolerability at required doses. Intravenous iron dextran has been shown to increase brain iron content. Surprisingly only a few reports have ever presented data on the clinical effect of high dose intravenous iron for RLS. We retrospectively identified 25 subjects (age 53.2+/-11.9, 7 male) that received intravenous iron for RLS refractory to conventional treatments. We infused 1g of high molecular weight iron dextran over five hours. The age of RLS onset was 32.6+/-13.0 years and 15 subjects had a positive family history of RLS. Patients attempted 7.5+/-2.7 medications for RLS prior to iron therapy. Baseline ferritins ranged from 5 to 248 ng/ml (mean 43.5+/-58.0) and 20/25 had ferritins of less than 50. Two subjects did not complete their entire infusion due to anaphylactic type symptoms but are included. Overall, 2 subjects reported complete amelioration of all RLS symptoms, 11 reported marked improvement, 2 moderate improvement, 3 mild improvement, and 6 reported no improvement. For those with improvement, the duration of effect was highly variable (mean 15.8+/-17.7 weeks, range 1-60 weeks). Twelve subjects had multiple infusions. Iron dextran can dramatically improve refractory RLS but results are inconsistent and not predicted by patient demographics. Although burdened by a higher rate of anaphylactic reactions, iron dextran may be superior to other IV iron preparations.

Iron deficiency in Indian children with attention deficit hyperactivity disorder

A case control study was conducted at the Child Development and Early Intervention Clinic to determine the body iron status of children with ADHD, and study the correlation between the body iron status and ADHD symptoms. Serum ferritin was measured in newly diagnosed cases with ADHD and compared with that of controls. Correlation was studied between serum ferritin levels and the severity of ADHD symptoms as determined by Conners Rating Scale. Serum ferritin was found to be significantly lower in children with ADHD (6.04 ± 3.85 ng/mL) as compared to controls (48.96 ± 41.64 ng/mL, P value < 0.001). There was a significant negative correlation between serum ferritin levels and oppositional subscore on Conners Rating Scale.

A case of reversible restless legs syndrome (RLS) and sleep-related eating disorder relapse triggered by acute right leg herpes zoster infection: literature review of spinal cord and peripheral nervous system contributions to RLS

Restless legs syndrome (RLS) is thought to be due to abnormalities of iron metabolism in the central nervous system; however, occasional cases are associated with lesions of the spinal cord, spinal rootlets, and peripheral nervous system. This is a case report of RLS exacerbated by shingles with a review of the literature of extra-cerebral lesions or disorders causing or contributing to RLS.

Systems genetics analysis of iron regulation in the brain

Iron imbalances in the brain, including excess accumulation and deficiency, are associated with neurological disease and dysfunction; yet, their origins are poorly understood. Using systems genetics analysis, we have learned that large individual differences exist in brain iron concentrations, even in the absence of neurological disease. Much of the individual differences can be tied to the genetic makeup of the individual. This genetic-based differential regulation can be modeled in genetic reference populations of rodents. The work in our laboratory centers on iron regulation in the brain and our animal model consists of 25 BXD/Ty recombinant inbred mouse strains. By studying naturally occurring variation in iron phenotypes, such as tissue iron concentration, we can tie that variability to one or more genes by way of quantitative trait loci (QTL) analysis. Moreover, we can conduct genetic correlation analyses between our phenotypes and others previously measured in the BXD/Ty strains. We have observed several suggestive QTL related to ventral midbrain iron content, including one on chromosome 17 that contains btbd9, a gene that in humans has been associated with restless legs syndrome and serum ferritin. We have also observed gene expression correlations with ventral midbrain iron, including btbd9 expression and dopamine receptor expression. In addition, we have observed significant correlations between ventral midbrain iron content and dopamine-related phenotypes. The following is a discussion of iron regulation in the brain and the contributions a systems genetics approach can make toward understanding the genetic underpinnings and relation to neurological disease.