Clinical Efficacy and Safety of Intravenous Ferric Carboxymaltose for Treatment of Restless Legs Syndrome: A Multicenter, Randomized, Placebo-controlled Clinical Trial

STUDY OBJECTIVES

Iron therapy is associated with improvements in restless legs syndrome (RLS). This multicenter, randomized, double-blind study evaluated the effect of intravenous ferric carboxymaltose (FCM) on RLS.

METHODS

A total of 209 adult patients with a baseline International Restless Legs Syndrome (IRLS) score ≥15 were randomized (1:1) to FCM (750 mg/15 mL) or placebo on study Days 0 and 5. Ongoing RLS medication was tapered starting on Day 5, with the goal of discontinuing treatment or achieving the lowest effective dose. Co-primary efficacy endpoints were change from baseline in IRLS total score and the proportion of patients rated as much/very much improved on the Clinical Global Impression-investigator (CGI-I) scale at Day 42 in the "As-Treated" population.

RESULTS

The "As-Treated" population comprised 107 FCM and 101 placebo recipients; 88 (82.2%) and 68 (67.3%), respectively, completed the Day 42 assessment. The IRLS score reduction was significantly greater with FCM versus placebo: least-squares mean (95% confidence interval [CI]) -8.0 (-9.5, -6.4) versus -4.8 (-6.4, -3.1); P = 0.0036. No significant difference was observed in the proportion of FCM (35.5%) and placebo (28.7%) recipients with a CGI-I response (odds ratio 1.37 [95% CI: 0.76, 2.47]; P = 0.2987). Fewer patients treated with FCM (32.7%) than placebo (59.4%) received RLS interventions between Day 5 and study end (P = 0.0002). FCM was well tolerated.

CONCLUSION

The IRLS score improved with intravenous FCM versus placebo, although the combination of both co-primary endpoints was not met. Potential methodological problems in the study design are discussed.

Restless legs syndrome, neuroleptic-induced akathisia, and opioid-withdrawal restlessness: shared neuronal mechanisms?

Restlessness is a core symptom underlying restless legs syndrome (RLS), neuroleptic-induced akathisia, and opioid withdrawal. These three conditions also share other clinical components suggesting some overlap in their pathophysiology. Recent prospective studies demonstrate the frequent incidence of RLS-like symptoms during opioid withdrawal and supervised prescription opioid tapering. Based on the therapeutic role of µ-opioid receptor (MOR) agonists in the three clinical conditions and recent preclinical experimental data in rodents, we provide a coherent and unifying neurobiological basis for the restlessness observed in these three clinical syndromes and propose a heuristic hypothesis of a key role of the specific striatal neurons that express MORs in akathisia/restlessness.

The Role of Circadian Rhythms and Sleep in Anorexia Nervosa

Importance

Observational studies have associated anorexia nervosa with circadian rhythms and sleep traits. However, the direction of causality and the extent of confounding by psychosocial comorbidities in these associations are unknown.

Objectives

To investigate the association between anorexia nervosa and circadian and sleep traits through mendelian randomization and to test the associations between a polygenic risk score (PRS) for anorexia nervosa and sleep disorders in a clinical biobank.

Design, Setting, and Participants

This genetic association study used bidirectional 2-sample mendelian randomization with summary-level genetic associations between anorexia nervosa (from the Psychiatric Genomics Consortium) and chronotype and sleep traits (primarily from the UK Biobank). The inverse-variance weighted method, in addition to other sensitivity approaches, was used. From the clinical Mass General Brigham (MGB) Biobank (n = 47 082), a PRS for anorexia nervosa was calculated for each patient and associations were tested with prevalent sleep disorders derived from electronic health records. Patients were of European ancestry. All analyses were performed between February and August 2023.

Exposures

Genetic instruments for anorexia nervosa, chronotype, daytime napping, daytime sleepiness, insomnia, and sleep duration.

Main Outcomes and Measures

Chronotype, sleep traits, risk of anorexia nervosa, and sleep disorders derived from a clinical biobank.

Results

The anorexia nervosa genome-wide association study included 16 992 cases (87.7%-97.4% female) and 55 525 controls (49.6%-63.4% female). Genetic liability for anorexia nervosa was associated with a more morning chronotype (β = 0.039; 95% CI, 0.006-0.072), and conversely, genetic liability for morning chronotype was associated with increased risk of anorexia nervosa (β = 0.178; 95% CI, 0.042-0.315). Associations were robust in sensitivity and secondary analyses. Genetic liability for insomnia was associated with increased risk of anorexia nervosa (β = 0.369; 95% CI, 0.073-0.666); however, sensitivity analyses indicated bias due to horizontal pleiotropy. The MGB Biobank analysis included 47 082 participants with a mean (SD) age of 60.4 (17.0) years and 25 318 (53.8%) were female. A PRS for anorexia nervosa was associated with organic or persistent insomnia in the MGB Biobank (odds ratio, 1.10; 95% CI, 1.03-1.17). No associations were evident for anorexia nervosa with other sleep traits.

Conclusions and Relevance

The results of this study suggest that in contrast to other metabo-psychiatric diseases, anorexia nervosa is a morningness eating disorder and further corroborate findings implicating insomnia in anorexia nervosa. Future studies in diverse populations and with subtypes of anorexia nervosa are warranted.

Lack of Efficacy of Suvorexant in People with Insomnia and Poorly Controlled Type 2 Diabetes

Objective/Background

Sleep disturbance is a common and underappreciated feature of diabetes and sleep may contribute to glycemic control in people with type 2 diabetes (T2D). We conducted a 3-month trial to examine the efficacy of suvorexant in improving sleep and health outcomes in people with suboptimally controlled T2D and insomnia.

Participants/Methods

This parallel, double-blind, randomized placebo-controlled trial was conducted using the sequential parallel comparison design (SPCD). Sixty-nine people with poorly controlled T2D (HbA1c ≥ 6.5) were randomized to placebo and/or suvorexant (10-20 mg). The primary outcome was subjective total sleep time (sTST), and secondary outcomes were Insomnia Severity Index (ISI) score and wake time after sleep onset (WASO). Exploratory outcomes included sleep efficiency, hemoglobin A1c (HbA1c), and C-reactive protein (CRP). Exploratory analyses were conducted on relationships between sleep and diabetes outcomes.

Results

There were no significant improvements in sTST (p = 0.27), ISI (p = 0.86), or WASO (p = 0.94) among participants taking suvorexant compared to placebo. There were also no significant changes in any of the exploratory endpoints. Improvements in sleep were associated with improvements in both objective (ie, HbA1c) and subjective (ie, Diabetes Distress Scale) measures of diabetes, as well as reductions in depressive symptoms, independent of treatment assignment.

Conclusion

The study did not find evidence that suvorexant is efficacious for insomnia in people with poorly controlled T2D. The associations of improved sleep with improvements in both diabetes-related metrics and depressive symptoms across groups highlight the importance of identifying and treating sleeping difficulties in this population.

CT Registration #

Nct03818581.

Prevalence of Current Restless Legs Syndrome Symptoms Among Patients Treated with Buprenorphine/Naloxone for Opioid Use Disorder

Objective

The purpose of this study was to determine the prevalence of Restless Legs Syndrome (RLS) in patients with Opioid Use Disorder (OUD) taking buprenorphine/naloxone maintenance therapy, and to assess symptom frequency, severity, and sleep disruption due to RLS.

Methods

Surveys inquired about demographic information, amount of time on maintenance treatment, previous drug use, current prescribed medications and alcohol use, and RLS symptoms. Participants were determined to have definite, probable, possible, or no RLS symptoms based on pre-established criteria from the Cambridge-Hopkins Questionnaire.

Results

The sample (n=129) was 33.3% female, 81.5% white, and the mean age was 40.6 years (SD=11.9). The median duration of buprenorphine/naloxone use was 3 years. 13.2% of participants had definite/probable RLS symptoms; these symptoms tended to be of moderate severity, occur at least 5-15 times a month, and disrupt sleep to a moderate degree. Of the 17 participants with definite/probable RLS symptoms, just four were taking a medication commonly used to alleviate RLS. An additional 7.0% had possible RLS symptoms.

Conclusion

Relatively high rates of current RLS symptoms were observed; the prevalence of clinically significant RLS was notably higher than that seen in the general population or in previously assessed clinical populations. RLS is common in those acutely withdrawing from opioids, and our data demonstrate that these symptoms are present in a sizable portion of patients on OUD maintenance therapy. Most patients with definite/probable current RLS symptoms did not report taking prescribed medications that have established efficacy for RLS.

Efficacy and safety of tonic motor activation (TOMAC) for medication-refractory restless legs syndrome: a randomized clinical trial

STUDY OBJECTIVES

The purpose of this study was to evaluate the efficacy and safety/tolerability of bilateral high-frequency tonic motor activation (TOMAC) in patients with medication-refractory restless legs syndrome (RLS).

METHODS

RESTFUL was a multicenter, randomized, double-blind, sham-controlled trial in adults with medication-refractory moderate-to-severe primary RLS. Participants were randomized 1:1 to active or sham TOMAC for a double-blind, 4-week stage 1 and all received active TOMAC during open-label, 4-week stage 2. The primary endpoint was the Clinical Global Impressions-Improvement (CGI-I) responder rate at the end of stage 1. Key secondary endpoints included change to International RLS Study Group (IRLS) total score from study entry to the end of stage 1.

RESULTS

A total of 133 participants were enrolled. CGI-I responder rate at the end of stage 1 was significantly greater for the active versus sham group (45% vs. 16%; Difference = 28%; 95% CI 14% to 43%; p = .00011). At the end of stage 2, CGI-I responder rate further increased to 61% for the active group. IRLS change at the end of stage 1 improved for the active versus sham group (-7.2 vs. -3.8; difference = -3.4; 95% CI -1.4 to -5.4; p = .00093). There were no severe or serious device-related adverse events (AEs). The most common AEs were mild discomfort and mild administration site irritation which resolved rapidly and reduced in prevalence over time.

CONCLUSIONS

TOMAC was safe, well tolerated, and reduced symptoms of RLS in medication-refractory patients. TOMAC is a promising new treatment for this population.

CLINICAL TRIAL

Noninvasive Peripheral Nerve Stimulation for Medication-Refractory Primary RLS (The RESTFUL Study); clinicaltrials.gov/ct2/show/NCT04874155; Registered at ClinicalTrials.gov with the identifier number NCT04874155.

Disrupted white matter integrity in primary insomnia and major depressive disorder: relationships to sleep quality and depression severity

This study examined the integrity of white matter tracts in 25 participants with primary insomnia (PI), 50 participants with major depressive disorder (MDD), and 25 healthy controls. Seven white matter tracts, selected based on prior research, were quantified by fractional anisotropy (FA) as well as by related measures of diffusivity using diffusion tensor imaging (DTI) on a 3-T scanner. All 100 participants were free of significant medical, psychiatric (excluding the MDD group) and sleep disorders (excluding the PI group), were free of central nervous system medications, and completed an extensive clinical assessment. Subjective and objective sleep measures revealed significant sleep disruption in both the PI and MDD groups. Relative to the controls, both the PI and MDD groups demonstrated impaired integrity in three of the seven white matter tracts: the genu of the corpus callosum (GenuCC), the superior longitudinal fasciculus (SLF), and the inferior longitudinal fasciculus (ILF). We demonstrated reduced FA in the GenuCC, reduced FA and reduced axial diffusivity (AD) in the SLF, as well as reduced AD and radial diffusivity in the ILF. Finally, in an exploratory analysis of the combined cohorts, FA in the GenuCC and FA in the SLF were negatively correlated with depression severity and positively correlated with total sleep time. Abnormalities documented in the GenuCC, SLF and ILF, and present in both the PI and MDD groups may suggest some shared neurobiology.

A Novel Home-Based Study of Circadian Rhythms: Design, Rationale, and Methods for the Circadia Study

The Circadia Study (Circadia) is a novel "direct-to-participant" research study investigating the genetics of circadian rhythm disorders of advanced and delayed sleep phase and non-24 hour rhythms. The goals of the Circadia Study are twofold: (i) to create an easy-to-use toolkit for at-home circadian phase assessment for patients with circadian rhythm disorders through the use of novel in-home based surveys, tests, and collection kits; and (ii) create a richly phenotyped patient resource for genetic studies that will lead to new genetic loci associated with circadian rhythm disorders revealing possible loci of interest to target in the development of therapeutics for circadian rhythm disorders. Through these goals, we aim to broaden our understanding and elucidate the genetics of circadian rhythm disorders across a diverse patient population while increasing accessibility to circadian rhythm disorder diagnostics reducing health disparities through self-directed at-home dim light melatonin onset (DLMO) collections.

Do Insomnia Treatments Improve Daytime Function?

A scientific advisory panel of seven U.S. and Canadian sleep experts performed a clinical appraisal by comparing general medical opinion, assessed via a survey of practicing clinicians, regarding insomnia treatment, with the available scientific evidence. This clinical appraisal focuses on the specific statement, "Treatments for insomnia have uniformly been shown to significantly improve the associated daytime impairment seen with insomnia." The advisory panel reviewed and discussed the available body of evidence within the published medical literature to determine what discrepancies may exist between the currently published evidence base and general medical opinion. The advisory panels' evaluation of this statement was also compared with the results of a national survey of primary care physicians, psychiatrists, nurse practitioners, physician assistants, and sleep specialists in the United States. Contrary to general medical opinion, the expert advisory panel concluded that the medical literature did not support the statement. This gap highlights the need to educate the general medical community regarding insomnia treatment efficacy in pursuit of improved treatment outcomes.

Should Trazodone Be First-Line Therapy for Insomnia? A Clinical Suitability Appraisal

Trazodone is one of the most commonly used prescription medications for insomnia; however, some recent clinical guidelines do not recommend its use for treating insomnia. This clinical appraisal critically reviews the scientific literature on trazodone as a first-line treatment for insomnia, with the focus statement "Trazodone should never be used as a first-line medication for insomnia." In addition, field surveys were sent to practicing physicians, psychiatrists, and sleep specialists to assess general support for this statement. Subsequently, a meeting with a seven-member panel of key opinion leaders was held to discuss published evidence in support and against the statement. This paper reports on the evidence review, the panel discussion, and the panel's and healthcare professionals' ratings of the statement's acceptability. While the majority of field survey responders disagreed with the statement, the majority of panel members agreed with the statement based on the limited published evidence supporting trazodone as a first-line agent as they understood the term "first-line agent".

Long-Term Use of Insomnia Medications: An Appraisal of the Current Clinical and Scientific Evidence

While evidence supports the benefits of medications for the treatment of chronic insomnia, there is ongoing debate regarding their appropriate duration of use. A panel of sleep experts conducted a clinical appraisal regarding the use of insomnia medications, as it relates to the evidence supporting the focus statement, "No insomnia medication should be used on a daily basis for durations longer than 3 weeks at a time". The panelists' assessment was also compared to findings from a national survey of practicing physicians, psychiatrists, and sleep specialists. Survey respondents revealed a wide range of opinions regarding the appropriateness of using the US Food and Drug Administration (FDA)-approved medications for the treatment of insomnia lasting more than 3 weeks. After discussion of the literature, the panel unanimously agreed that some classes of insomnia medications, such as non-benzodiazepines hypnotics, have been shown to be effective and safe for long-term use in the appropriate clinical setting. For eszopiclone, doxepin, ramelteon and the newer class of dual orexin receptor antagonists, the FDA label does not specify that their use should be of a limited duration. Thus, an evaluation of evidence supporting the long-term safety and efficacy of newer non-benzodiazepine hypnotics is timely and should be considered in practice recommendations for the duration of pharmacologic treatment of chronic insomnia.

Randomized, crossover, open-label study of the relative bioavailability and safety of FT218, a once-nightly sodium oxybate formulation: Phase 1 study in healthy volunteers

OBJECTIVES

Treatment for narcolepsy with sodium oxybate (SXB) has required twice-nightly dosing, at bedtime and 2.5-4 h later. This study evaluated the pharmacokinetics of FT218, an investigational, extended-release, once-nightly formulation of SXB (ON-SXB), vs twice-nightly SXB.

METHODS

In this phase 1, open-label study, healthy volunteers were randomized (1:1) to ON-SXB 6 g or twice-nightly SXB (two 3-g doses administered 4 h apart); minimum 3-day washout before crossover. Doses were administered 2 h post-evening meal. Blood samples for pharmacokinetic assessments were collected predose and up to 14 h after the first dose during each treatment period.

RESULTS

Twenty-eight participants were enrolled (mean age, 39.6 years; 54% women; 93% white). Mean ± SEM area under the concentration-time curve for ON-SXB was 282.7 ± 30.2  μg·h/mL vs 273.3 ± 27.8 μg·h/mL for twice-nightly SXB. Geometric mean ratio (GMR; 90% CI) was 102.9 (98.0-108.0). Maximum γ-hydroxybutyrate (GHB) plasma concentration (C_max) was 65.8 ± 4.0 μg/mL for ON-SXB vs 77.1 ± 4.9 μg/mL for twice-nightly SXB (GMR [90% CI], 88.3 [80.5-97.0]). The GMR (90% CI) for GHB plasma concentrations 8 h post dose (C_8h) for ON-SXB vs twice-nightly SXB was 61.7 (45.8-83.0). The most frequently reported adverse events were the same for ON-SXB and twice-nightly SXB (nausea, dizziness, somnolence, vomiting).

CONCLUSIONS

GHB exposure and C_max with one 6-g dose of ON-SXB were bioequivalent to those with two 3-g doses of twice-nightly SXB, whereas C_8h was lower with ON-SXB. If approved, ON-SXB will provide a single bedtime oxybate option, with clinically relevant pharmacologic exposure during the entire sleep period.

Consensus guidelines on the construct validity of rodent models of restless legs syndrome

Our understanding of the causes and natural course of restless legs syndrome (RLS) is incomplete. The lack of objective diagnostic biomarkers remains a challenge for clinical research and for the development of valid animal models. As a task force of preclinical and clinical scientists, we have previously defined face validity parameters for rodent models of RLS. In this article, we establish new guidelines for the construct validity of RLS rodent models. To do so, we first determined and agreed on the risk, and triggering factors and pathophysiological mechanisms that influence RLS expressivity. We then selected 20 items considered to have sufficient support in the literature, which we grouped by sex and genetic factors, iron-related mechanisms, electrophysiological mechanisms, dopaminergic mechanisms, exposure to medications active in the central nervous system, and others. These factors and biological mechanisms were then translated into rodent bioequivalents deemed to be most appropriate for a rodent model of RLS. We also identified parameters by which to assess and quantify these bioequivalents. Investigating these factors, both individually and in combination, will help to identify their specific roles in the expression of rodent RLS-like phenotypes, which should provide significant translational implications for the diagnosis and treatment of RLS.

How effective are treatment guidelines for augmented RLS?

Study Objectives

The objective of this study was to assess the effectiveness of current treatment guidelines for restless legs syndrome (RLS) augmentation in patients on dopamine agonists (DAs) which recommend a cross-titration strategy to an alpha-2-delta ligand (A2D) and/or opioid.

Methods

Consecutive new consultations for RLS with both augmentation and active treatment with DAs at the time of initial assessment were included if followed >5 months. Clinical information from the semi-structured initial consultation, and subsequent visits until their most recent/final visit was extracted. Clinical Global Impression-Severity (CGI-S) and Clinical Global Impression-Improvement (CGI-I) scores were retrospectively determined by two independent evaluators.

Results

In the 63 patients with augmented RLS on DAs, followed for 5–59 months (mean = 28, SD = 14), the average age was 67.6 (SD = 9.8) and 63% were female. Mean duration of prior dopaminergic therapy was 11.6 years (SD = 6.7) and average pramipexole equivalent dose was 1.23 mg (SD = 1.22 mg). At baseline, RLS was “moderate-markedly” severe (CGI-S = 4.9). At the final/most recent visit, 78% (49/63) were classified as Responders (CGI-I ≤ 2, “Much” or “Very Much Improved”) with an average CGI-S of 2.4 (“borderline-mildly ill”). Responders (59%) were more likely to have discontinued DAs than Non-Responders (40%), and mean opioid doses were higher in Responders (39 vs 20 MME). No differences in baseline DA dose, final A2D dose, or iron therapy were observed between groups. Responders did have significantly more severe RLS, more sleep maintenance insomnia, and greater subjective daytime sleepiness at baseline (p < 0.05).

Conclusions

Guideline-based management is effective in most patients with augmented RLS on DAs.

Association Between Subjective-Objective Discrepancy of Sleeping Time and Health-Related Quality of Life: A Community-Based Polysomnographic Study

OBJECTIVE

This study aimed to investigate the existence of a difference in quality of life (QOL) between individuals with and without significant subjective-objective discrepancy (SOD) in total sleep time (TST).

METHODS

From the Sleep Heart Health Study 2, 2540 individuals who had completed polysomnography, a morning sleep survey, and the 36-item Short-Form Health Survey (SF-36) were included in the analyses. The participants were classified as normoestimators (estimation of TST <±60 minutes), underestimators (underestimation of TST ≥60 minutes), or overestimators (overestimation of TST ≥60 minutes). The standardized SF-36 QOL scores were compared among the three groups. An adjusted partial correlation analysis was conducted between SOD and QOL.

RESULTS

Of the 2540 participants, 1617 (63.7%), 433 (17.0%), and 490 (19.3%) were assigned to the normoestimator, underestimator, and overestimator groups, respectively. The bodily pain and social functioning components of the SF-36 score were significantly lower in the underestimators than in the normoestimators, whereas the physical functioning component was significantly lower in the overestimators than in the normoestimators. The absolute value of SOD in the TST showed a significant negative correlation with the physical and mental components of the SF-36.

CONCLUSIONS

QOL was significantly better in the normoestimator than in the other groups and linearly correlated with the absolute value of SOD. This study suggests that a high prevalence of positive and negative sleep misperception in a community population can be a potential factor associated with poor QOL and potential comorbidities.

A double-blind, randomized, placebo-controlled trial of suvorexant for the treatment of vasomotor symptom-associated insomnia disorder in midlife women

Study Objectives

The neuropeptide orexin promotes wakefulness, modulates thermoregulation, increases after menopause, and is normalized in women receiving estrogen therapy, suggesting a role for orexin antagonism as a treatment for the vasomotor symptom (VMS)-associated insomnia disorder. We tested the efficacy of the dual orexin receptor antagonist suvorexant for chronic insomnia related to nighttime VMS.

Methods

In a double-blind, placebo-controlled trial, 56 women with chronic insomnia associated with nighttime VMS, Insomnia Severity Index (ISI) scores ≥15, and &gt;30 min of diary-rated wake after sleep-onset (WASO) were randomized to receive oral suvorexant 10–20 mg (n = 27) or placebo (n = 29) nightly for 4 weeks. Analysis of within-person change in ISI was adjusted for baseline ISI and race.

Results

Mean baseline ISI scores were 18.1 (95% CI, 16.8 to 19.4) and 18.3 (95% CI, 17.2 to 19.5) in the suvorexant and placebo groups, respectively (p = .81). The average 4-week ISI within-person decrease from baseline was greater on suvorexant (−8.1 [95% CI, −10.2 to −6.0]) compared to placebo (−5.6 [95% CI, −7.4 to −3.9], p = .04). Compared to placebo, nighttime diary-rated VMS frequency was significantly reduced with suvorexant (p &lt; .01). While diary-rated WASO and total sleep time trended toward improvement on suvorexant, findings were not significant after adjustment for multiple comparisons. Daytime VMS and other sleep-related outcomes did not differ between groups. Suvorexant was well tolerated.

Conclusion

These results suggest that suvorexant is likely a well-tolerated and efficacious treatment for VMS-associated insomnia disorder and reduces nighttime VMS. Antagonism of orexin receptors could provide a novel therapeutic option for midlife women with VMS-associated chronic insomnia.

Clinical Trial Information

Efficacy of Suvorexant in the Treatment of Hot Flash-associated Insomnia, https://clinicaltrials.gov/ct2/show/NCT03034018, ClinicalTrials.gov Identifier: NCT03034018.

Restless Legs Syndrome Severity in the National RLS Opioid Registry During the COVID-19 Pandemic

Objective/background

No research has yet assessed the impact of the coronavirus disease 2019 (COVID-19) pandemic on restless legs syndrome (RLS). We hypothesized that RLS symptom severity would be increased during the COVID-19 pandemic in a sample of patients with diagnosed RLS.

Patients/methods

The National RLS Opioid Registry is a longitudinal observational study of patients using opioid medications for treatment of RLS. Questionnaires assessing RLS symptom severity, medication dosages, sleep disturbance, depression, and anxiety are administered at baseline and at recurring 6-month surveys. Survey responses from the outset of the pandemic in April/May 2020 were compared to responses completed by other participants in January/February 2020 (between-subjects analysis), as well as responses by the same participants at baseline, approximately six months later in September 2020 through February 2021, and approximately one year later in March through June 2021 (within-subjects analyses).

Results

These analyses provide evidence for higher RLS symptom severity scores at the outset of the COVID-19 pandemic in the US. Symptom severity scores were still elevated on subsequent questionnaires completed over six months into the pandemic but had returned towards baseline by the spring of 2021. Participants with increases in RLS severity were significantly more likely than others to see increases in sleep disturbance, depression, and anxiety.

Conclusions

This is the first study demonstrating increased RLS symptom severity during the earliest stage of the COVID-19 pandemic. These findings warrant similar investigations in other patient populations and suggest that clinicians should attend to RLS symptoms during times of socioeconomic and/or political uncertainty.

High National Rates of High-Dose Dopamine Agonist Prescribing for RLS

Study Objectives

Long-term dopamine agonist (DA) use in restless legs syndrome (RLS) is associated with augmentation, a dose-related symptom worsening leading to further dose escalation to manage RLS. This study investigated rates and factors of high-dose DA prescribing in US RLS patients.

Methods

This retrospective analysis examined data from a US longitudinal prescriptions database (October 2017–September 2018). Patients diagnosed with RLS (ICD-10 G255.81) without Parkinson’s disease who were prescribed ropinirole, pramipexole, and/or rotigotine were included. Daily DA dosage was categorized: LOW/MID (US Food and Drug Administration [FDA]-approved/guideline or slightly above FDA-approved [pramipexole]); HIGH (101%–149%); VERY HIGH (>150%). Patient counts were converted to US national estimates. Logistic regression of patient counts evaluated factors associated with HIGH/VERY HIGH DA dosing.

Results

Of 670,404 RLS patients (131,289,331 therapy days), 58.8% were prescribed DA therapy. Overall, 19.1% of RLS patients were prescribed DAs above maximum FDA-approved/guideline daily doses—over half of these were >150% maximum recommended doses; 67.6% of HIGH/VERY HIGH-dose prescriptions were pramipexole (OR [95% CI] pramipexole vs ropinirole, 5.8 [5.7 to 6.0]). The highest 1% of DA prescriptions were ≥10× the FDA-recommended maximum daily dose. Rates of HIGH/VERY HIGH DA dosing increased with patient age. Twice as many neurologists (31.1%) prescribed HIGH/VERY HIGH doses vs other specialties (OR [95% CI], 2.1 [1.2 to 2.0]).

Conclusions

Approximately 20% of DA-treated RLS patients were prescribed doses above the approved and guideline daily maximum. Pramipexole, Neurology as specialty, and patient age were independently associated with HIGH/VERY HIGH DA dosing. Increased education is warranted regarding risks of high-dose DA exposure in RLS.

The Management of Restless Legs Syndrome: An Updated Algorithm

Restless legs syndrome (RLS) is a common disorder. The population prevalence is 1.5% to 2.7% in a subgroup of patients having more severe RLS with symptoms occurring 2 or more times a week and causing at least moderate distress. It is important for primary care physicians to be familiar with the disorder and its management. Much has changed in the management of RLS since our previous revised algorithm was published in 2013. This updated algorithm was written by members of the Scientific and Medical Advisory Board of the RLS Foundation based on scientific evidence and expert opinion. A literature search was performed using PubMed identifying all articles on RLS from 2012 to 2020. The management of RLS is considered under the following headings: General Considerations; Intermittent RLS; Chronic Persistent RLS; Refractory RLS; Special Circumstances; and Alternative, Investigative, and Potential Future Therapies. Nonpharmacologic approaches, including mental alerting activities, avoidance of substances or medications that may exacerbate RLS, and oral and intravenous iron supplementation, are outlined. The choice of an alpha₂-delta ligand as first-line therapy for chronic persistent RLS with dopamine agonists as a second-line option is explained. We discuss the available drugs, the factors determining which to use, and their adverse effects. We define refractory RLS and describe management approaches, including combination therapy and the use of high-potency opioids. Treatment of RLS in pregnancy and childhood is discussed.

Restless legs syndrome and perceived olfactory and taste dysfunction: A community-based study

BACKGROUND AND PURPOSE

Restless legs syndrome (RLS) has been suggested as a prodromal symptom of Parkinson disease (PD). Olfactory or taste dysfunction can also occur preceding PD diagnosis. However, whether RLS is associated with chemosensory dysfunction remains unknown. We thus aim to investigate the association between RLS and perceived olfactory and taste dysfunction.

METHODS

We performed a cross-sectional analysis including 90,337 Chinese adults free of neurodegenerative diseases in the Kailuan study in 2016. Presence of RLS was defined using revised RLS diagnostic criteria or the Cambridge-Hopkins questionnaire for RLS. Perceived olfactory and taste dysfunction was collected via a questionnaire. The association between RLS and perceived olfactory and taste dysfunction was assessed using logistic regression model, adjusting for potential cofounders such as age, sex, and medical history.

RESULTS

RLS was associated with high odds of having perceived olfactory and/or taste dysfunction (adjusted odds ratio = 5.92, 95% confidence interval = 3.11-11.3). The significant association persisted when using the Cambridge-Hopkins questionnaire (adjusted odds ratio = 5.55, 95% confidence interval = 2.37-13.0) or when excluding participants with major chronic diseases.

CONCLUSIONS

RLS was associated with increased odds of perceived olfactory and taste dysfunction.

Baseline and 1-year longitudinal data from the National Restless Legs Syndrome Opioid Registry

STUDY OBJECTIVES

Restless legs syndrome (RLS) is a sensory-motor neurological disorder. Low dose opioid medications are prescribed for treatment-refractory RLS. We describe baseline and 1-year longitudinal dosing and symptom outcomes for the National RLS Opioid Registry.

METHODS

Individuals currently taking a prescribed opioid for diagnosed RLS are included in the registry. Information on initial and current opioid dosages, side effects, past and current concomitant RLS treatments, RLS severity, psychiatric history, and opioid abuse risk factors were collected at baseline. Follow-up online surveys were performed at 6 months and 1-year.

RESULTS

Participants (n = 500) are primarily white, elderly, educated, and retired. Half of all subjects are on opioid monotherapy. Nearly 50% of all subjects are taking methadone, and one-quarter are taking oxycodone formulations. The median total daily opioid dose is 30.0 morphine milligram equivalents (MME). At baseline, three-quarters of registry participants had been taking a prescribed opioid for RLS for more than 1 year and one-third for more than 5 years, and had mild-moderate RLS symptoms. At 1-year follow-up, 31.2% increased dose (median = 10 MME) and 16.0% decreased dose of their opioid. An MME increase ≥25 was associated with: opioid use for non-RLS pain, <1 year of opioid use, opioid switch to methadone, and discontinuation of non-opioid RLS medications which, combined, accounted for 91.7% of those with 1-year follow-up increases ≥25 MME.

CONCLUSIONS

In refractory RLS, prescribed opioids are generally used at low doses with good efficacy. Longitudinally over 1 year, roughly one-third of participants increased their prescribed opioid dose, though generally by small amounts, with larger dose increases accounted for by predictable features.

The Long-Term Psychiatric and Cardiovascular Morbidity and Mortality of Restless Legs Syndrome and Periodic Limb Movements of Sleep

Restless legs syndrome (RLS) is a sensory-motor neurological disorder that is associated with high levels of distress and sleep disturbance. Cross-sectional and longitudinal evidence suggests that individuals suffering from RLS may be at an increased risk of certain psychiatric illnesses and cardiovascular diseases. There also is evidence for increased mortality rates in RLS patients, although contrasting results do exist. Periodic limb movements of sleep (PLMS), repetitive leg movement observed in most RLS patients, and sleep disturbance may mediate the relationship between RLS and long-term morbidity. This article summarizes the literature investigating the potential consequences of both RLS and PLMS.

We need to do better: A systematic review and meta-analysis of diagnostic test accuracy of restless legs syndrome screening instruments

This systematic review and meta-analysis evaluated the diagnostic accuracy of screening instruments for restless legs syndrome (RLS) and reports sensitivity, specificity, positive (PPV) and negative predictive values (NPV). Searches for primary studies were conducted in electronic databases. Of the 1541 citations identified, 52 were included in the meta-analysis. The methodological quality of each study was evaluated using QUADAS-2. Only 14 studies assessed the reference standard in all participants or in all screen-positives and a selection of screen-negatives. Bivariate meta-analysis of these 14 studies estimated median sensitivity to be 0.88 (0.72-0.96) and specificity 0.90 (0.84-0.93); based on a population prevalence of 5%, the calculated PPV was 0.31 (0.27-0.34). For all 52 studies, with either full or partial verification of RLS status, we constructed best-case scenario sensitivities and specificities at pre-defined levels of prevalence: across all samples, when prevalence is 5%, the median best-case scenario PPV is 0.48 with significant between-study heterogeneity. No RLS screening instruments can currently be recommended for use without an expert clinical interview in epidemiological studies. For conditions with statistically low prevalence such as RLS, the specificity, not the sensitivity, of a screening instrument determines true prevalence. Therefore, future instruments should maximize specificity. We provide guidelines on RLS ascertainment in epidemiological studies that requires a two-step process with clinical interview following a screening test, and given the poor reporting quality of many RLS epidemiological studies, we include an RLS reporting checklist.

Consensus Guidelines on Rodent Models of Restless Legs Syndrome

Restless legs syndrome (RLS) is a chronic sensorimotor disorder diagnosed by clinical symptoms. It is challenging to translate the diagnostic self-reported features of RLS to animals. To help researchers design their experiments, a task force was convened to develop consensus guidelines for experimental readouts in RLS animal models. The RLS clinical diagnostic criteria were used as a starting point. After soliciting additional important clinical features of RLS, a consensus set of methods and outcome measures intent on capturing these features-in the absence of a face-to-face interview-was generated and subsequently prioritized by the task force. These were, in turn, translated into corresponding methods and outcome measures for research on laboratory rats and mice and used to generate the final recommendations. The task force recommended activity monitoring and polysomnography as principal tools in assessing RLS-like behavior in rodents. Data derived from these methods were determined to be the preferred surrogate measures for the urge to move, the principal defining feature of RLS. The same tools may be used to objectively demonstrate sleep-state features highly associated with RLS, such as sleep disturbance and number and periodicity of limb movements. Pharmacological challenges and dietary or other manipulations that affect iron availability are desirable to aggravate or improve RLS-like behavior and lend greater confidence that the animal model being proffered replicates key clinical features of RLS. These guidelines provide the first consensus experimental framework for researchers to use when developing new rodent models of RLS. © 2020 International Parkinson and Movement Disorder Society.

Recognizing and Treating Excessive Daytime Sleepiness in Patients With Narcolepsy

Sleep disorders such as narcolepsy can cause excessive daytime sleepiness (EDS). The diagnosis of narcolepsy is often delayed by years. Clinicians can improve the recognition of EDS and diagnosis of sleep disorders using screening tools such as the Epworth Sleepiness Scale and other tests. By following up with patients who present with EDS and continuing to assess until a cause is found, clinicians can lessen the time to diagnosis and initiate appropriate treatment. Fortunately, existing pharmacologic interventions are effective in reducing EDS for many patients, but elimination of EDS for most patients has not been achieved. Some interventions also show efficacy in cataplexy. Nonpharmacologic strategies should also be discussed with patients. Clinicians must monitor EDS during ongoing treatment so that residual symptoms can be addressed. Research suggests a causative role for hypocretin deficiency in narcolepsy, and treatments ameliorating this deficiency are needed. ​.

Real-world evidence on the use of benzodiazepine receptor agonists and the risk of venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE) is a life-threatening disease, and some studies reported that benzodiazepine receptor agonist (BZRA) use could increase the risk of VTE, but this association lacks population-based evidence.

OBJECTIVES

To investigate the association between BZRA use and the risk of VTE.

PATIENTS/METHODS

A nested case-control study analyzing Taiwan's claims database was conducted of patients with at least one new BZRA prescription on record from January 1, 2002, to December 31, 2012. We included new users who did not have any BZRA prescriptions in the preceding 2 years and identified cases with VTE and disease risk score matched control subjects. We used a logistic regression model to investigate the association between BZRA exposure and the risk of VTE. The exposure duration, dose, and classes of BZRAs were comprehensively evaluated.

RESULTS

We identified 2800 VTE cases and 2800 matched controls. Current BZRA prescription (≤90 days) was associated with VTE occurrence (adjusted odds ratio [aOR]: 1.83; 95% confidence interval [CI], 1.62-2.06). The point estimates of benzodiazepine hypnotics (aOR: 2.00; 95% CI, 1.45-2.76) had a marginally higher risk of VTE than nonbenzodiazepine hypnotics (aOR: 1.39; 95% CI, 1.07-1.81). The VTE risk was increased with combination BZRA use, number of BZRA used, and a higher dose of BZRA. On examination of individual BZRA, the risk of VTE was higher with flunitrazepam use (aOR: 2.99; 95% CI, 1.43-6.28) than other BZRAs.

CONCLUSIONS

This study presents that current BZRA use may increase the risk of VTE. Also, benzodiazepine hypnotics, especially flunitrazepam, have a higher risk of VTE.

1H MRS Measurement of Cortical GABA and Glutamate in Primary Insomnia and Major Depressive Disorder: Relationship to Sleep Quality and Depression Severity

BACKGROUND

Both Major Depressive Disorder (MDD) and Primary Insomnia (PI) have been linked to deficiencies in cortical γ-aminobutyric acid (GABA) and glutamate (Glu) thus suggesting a shared neurobiological link between these two conditions. The extent to which comorbid insomnia contributes to GABAergic or glutamatergic deficiencies in MDD remains unclear.

METHODS

We used single-voxel proton magnetic resonance spectroscopy (1H MRS) at 4 Tesla to examine GABA+ and Glu relative to creatine (Cr) in the dorsal anterior cingulate cortex (dACC) and in the parieto-occipital cortex (POC) of 51 non-medicated adults with MDD, 24 adults with Primary Insomnia (PI), and 25 age- and sex-matched good sleeper controls (HC). Measures of depression severity and subjective and objective sleep quality were compared with 1H MRS metabolite measures.

RESULTS

MDD subjects exhibited a 15% decrease in Glu/Cr in the dACC compared to HC. Within the MDD group, there was a trend inverse correlation between dACC Glu/Cr and anhedonia ratings. We observed no significant association between measures of sleep quality with dACC Glu/Cr in those with MDD.

LIMITATIONS

The protocol and data interpretation would have been enhanced by the recruitment of MDD subjects with a broader range of affect severity and a more comprehensive assessment of clinical features.

CONCLUSIONS

These findings support the role of cortical glutamatergic mechanisms in the pathophysiology of MDD. Insomnia severity did not further contribute to the relative deficiency of glutamatergic measures in MDD.

Screening for Excessive Daytime Sleepiness and Diagnosing Narcolepsy

Sleep disorders such as narcolepsy can cause excessive daytime sleepiness (EDS). However, the diagnosis of narcolepsy is often delayed by years in both children and adults, reducing their quality of life. Clinicians can improve the recognition of EDS and diagnosis of sleep disorders using screening tools such as the Epworth Sleepiness Scale, collecting sleep histories, and using sleep laboratory tests. By following up with patients who present with EDS and continuing to assess until a cause is found, clinicians can lessen the time to diagnosis and the negative impact of narcolepsy by initiating appropriate treatment.

0797 Restless Legs Syndrome and Perceived Olfactory and Taste Dysfunction: A Community-Based Study

Introduction

Restless legs syndrome (RLS), an under-recognized sensorimotor condition worldwide, is thought to be a prodromal symptom of Parkinson’s disease as suggested by previous evidences. However, its association with prodromal chemosensory impairments, including olfactory or taste dysfunction, has remained largely unknown. Few studies of small sample sizes were conducted in predominantly Caucasian populations and results were inconsistent.

Methods

We performed a cross-sectional analysis including 90,337 Chinese adults free of neurodegenerative diseases in the Kailuan study in 2016. Presence of RLS was defined using revised RLS diagnostic criteria and further verified by Cambridge-Hopkins questionnaire for RLS. Perceived olfactory and taste dysfunction was collected via a questionnaire. The association between RLS and perceived olfactory and taste dysfunction was assessed using logistic regression model, adjusting for potential cofounders such as age, sex, smoking, alcohol consumption sleep conditions and medical history.

Results

RLS was associated with high odds of having perceived olfactory and/or taste dysfunction (adjusted odds ratio =5.92; 95% confidence interval, 3.11, 11.3). The significant association persisted when using Cambridge-Hopkins questionnaire for RLS (adjusted odds ratio =5.55; 95% confidence interval, 2.37-13.0) or when excluding participants with major chronic diseases.

Conclusion

RLS was associated with increased odds of perceived olfactory and taste dysfunction.

Support

This research was supported by start-up grant from the College of Health and Human Development and the Department of Nutritional Sciences, Pennsylvania State University, the Institute for CyberScience Seed Grant Program, Pennsylvania State University, and Natural Science Foundation of Hebei Province (H2018209318).

0793 Nearly 25% of Restless Legs Syndrome (RLS) Patients Nationally Treated with Dopamine Agonists are Taking Higher Doses than the Maximum Recommended by FDA and Expert Guidelines

Introduction

Dopamine agonists (DAs) have been first-line therapy for restless legs syndrome (RLS) for 30 years. Long-term DA use is associated with augmentation, a dose-related iatrogenic worsening of RLS, which results in a vicious cycle of escalating DA dosing to manage worsening symptoms. The objective of this study was to investigate rates of high-dose DA prescribing in patients with RLS nationally.

Methods

Patients with a diagnosis of RLS (ICD-10 G255.81), and no diagnosis of Parkinson’s disease, treated with rotigotine, pramipexole, and ropinirole, alone or in combination for &gt;180 days, were identified from National Prescription Audit database from October 2017-September 2018. Daily total dosage was grouped into low (FDA-approved) and high (above FDA-approved) dose ranges, respectively (rotigotine: &gt;0-≤3mg/&gt;3mg; pramipexole: &gt;0-≤0.75mg/&gt;0.75mg; ropinirole: &gt;0-≤4mg/&gt;4mg). When DAs were used in combination with each other, dose-equivalent algorithms were used (rotigotine/ropinirole/pramipexole, 1:1:4).

Results

Prescriptions for 244,423 patients meeting inclusion criteria were sampled, constituting 71,181,466 therapy days. For all patients on DA therapy for RLS, 23.5% (57,552/244,423) were prescribed higher than FDA-recommended doses. For patients on DA monotherapy, high-dose prescriptions were provided to 42.7% (819/1919) on rotigotine, 40.7% (38,342/94,275) on pramipexole, and 11.5% (16,900/146,355) on ropinirole. Nearly one-quarter (23.2%) of all pramipexole monotherapy prescriptions were for very high dosages (&gt;1.25 mg). For patients on DA combination therapy, high-dose prescriptions were provided to 79.6% (1,491/1,874).

Conclusion

Roughly 25% of RLS patients treated with DAs were prescribed doses above FDA and expert guideline-recommended maximum doses. Patients on DA combination therapy had substantially higher rates of cumulative high-dose prescriptions. High-dosage DA use is likely due to dose escalation in response to augmentation, risking further augmentation and adverse events such as impulse control disorders. Prescriber education on risks of high-dose DA prescribing for RLS is important.

Support

Arbor Pharmaceuticals, LLC

Individual periodic limb movements with arousal are temporally associated with nonsustained ventricular tachycardia: a case-crossover analysis

STUDY OBJECTIVES

Both periodic limb movements during sleep (PLMS) and arousals are associated with sympathetic nervous system activation and may be arrhythmogenic. We hypothesize a temporal relationship exists between individual PLMS, particularly with arousal, and nonsustained ventricular tachycardia (NSVT) events.

METHODS

A bidirectional time-stratified case-crossover design was used to assess temporal associations between PLMS and NSVT during sleep in 49 Osteoporotic Fractures in Men Sleep Study participants with NSVT in a community-based cohort (n = 2,911). Sleep time was divided into approximate 30-min segments. For each NSVT (n = 141), we selected a preceding 30-s hazard period and three randomly chosen 30-s control periods from sleep within the same segment and evaluated for PLMS, respiratory events, minimum saturation, and arousals. Odds ratios and 95% confidence intervals-OR (95% CI)-were determined by conditional logistic regression; covariates included EEG arousals, minimum saturation, and respiratory events in the same hazard/control period.

RESULTS

Participants with NSVT were 79.5 ± 6.2 years with a PLMS index of 32.1 (IQR: 10.1, 61.4) and apnea-hypopnea index of 17.1 (IQR: 9.4, 26.1). PLMS without arousal were not significantly associated with NSVT (OR = 0.80, 95% CI: 0.41-1.59). PLMS with arousal were associated with NSVT in unadjusted analyses (OR = 2.50, 95% CI: 1.11-5.65) and after adjustment (OR = 2.31, 95% CI: 1.02-5.25). Arousals associated with PLMS were associated with NSVT in unadjusted (OR = 2.84, 95% CI: 1.23-6.56) and adjusted analyses (OR = 2.61, 95% CI: 1.13-6.05).

CONCLUSIONS

PLMS with (but not without) arousals are temporally associated with a greater than twofold higher odds of subsequent NSVT episodes. PLMS-related arousals may be physiologically important ventricular arrhythmia triggers.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT00070681.

Major depressive disorder and insomnia: Exploring a hypothesis of a common neurological basis using waking and sleep-derived heart rate variability

It remains unclear whether neurobiological dysfunction observed in major depressive disorder (MDD) and insomnia is an expression of common or independent bases. The present investigation sought to explore differences in heart rate variability (HRV)-a widely utilized biomarker of neurobiological functioning-among individuals with MDD, insomnia, and healthy controls, while awake and during distinct sleep stages (REM, N2), with the goal of improving our understanding of shared neurobiological factors in depression and insomnia. Participants were 73 adults who underwent home polysomnography. All N2 and REM sleep epochs with a duration greater than or equal to 5 min were identified for HRV analysis. Additionally, a single waking epoch was defined for each participant. From waking to N2 sleep, and waking to REM sleep, changes in HRV indices indicated participants experienced reductions in sympathetic arousal and increases in parasympathetic arousal. Contrary to hypotheses, however, no between group differences were observed in HRV. Though the present findings do not support the hypotheses of a shard neurobiological pathway between MDD and insomnia, more work is warranted to advance our understanding of the neurobiological bases of these common, debilitating, and frequently co-occurring psychiatric conditions, to improve early detection and identify novel intervention targets for these disorders.

Topiramate reduces nocturnal eating in sleep-related eating disorder

Study Objectives

Sleep-related eating disorder (SRED) is a parasomnia characterized by partial arousals from sleep with compulsive consumption of food with impaired level of awareness and memory for the event. Small case series’ have demonstrated efficacy of topiramate in SRED. We conducted a placebo-controlled randomized clinical trial of topiramate to assess efficacy in SRED.

Methods

Thirty-four participants with an ICSD-2/ICSD-3 diagnosis of SRED with &gt;6 months of symptoms and ≥3 sleep-related eating episodes per week were randomized to placebo or topiramate with flexible dosing to a maximum dosage of 300 mg for 13 weeks. Primary outcomes were percentage of nights with eating and Clinician Global Impression-Improvement (CGI-I). Intention-to-treat last observation carried forward (ITT LOCF) analysis was conducted.

Results

Mean age was 39.5 years, 74% were female, with mean duration of sleep-related eating of 13.7 years. SRED symptoms were significantly reduced with topiramate (74.7% to 33.2% nights/week; n = 15) compared to placebo (77.0% to 57.4%; n = 17) (p = 0.035). There were significantly more CGI-I responders on topiramate (71%) than placebo (27%) (p = 0.016). Level of wakefulness (r = −0.49) and memory for nighttime eating (r = −0.58) at baseline predicted topiramate response. The topiramate group lost significantly more weight than the placebo group (−8.5 lbs vs. +1.0 lbs, p = 0.001). The most common side effects were paresthesias and cognitive dysfunction.

Conclusions

This first randomized controlled trial demonstrating efficacy for treatment of SRED supports preliminary data on the use of topiramate for SRED. Side effects were prominent for topiramate. Limitations include a small sample size and a high drop-out rate in both study groups.

Clinical Trial Information

NCT00606411

Association of Restless Legs Syndrome With Risk of Suicide and Self-harm

IMPORTANCE

Restless legs syndrome (RLS) is a common neurologic disorder that has been previously found to be associated with higher odds of suicidal ideation. In the context of the increasing suicide rate in the United States, the evidence regarding the association between RLS and the risk of suicide and self-harm is limited.

OBJECTIVE

To investigate the association between RLS and risk of suicide and self-harm.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was performed using Truven Health MarketScan national claims data from 2006 to 2014; the baseline data were from 2006 to 2008, and the follow-up data covered 6 years (January 1, 2009, to December 31, 2014). Included were 24 179 nonpregnant participants with RLS and 145 194 age- and sex-matched participants without RLS at baseline (2006-2008), who were free of suicide, self-harm, cardiovascular disease, or cancer at study baseline. Data analysis was performed from February 1, 2018, to January 1, 2019.

EXPOSURE

Diagnosis of RLS, as identified by the International Classification of Diseases, Ninth Revision code.

MAIN OUTCOMES AND MEASURES

Incident suicide and self-harm event, identified by the International Classification of Diseases, Ninth Revision diagnosis code.

RESULTS

Among 169 373 participants in the current analysis, the mean (SD) age was 49.4 (9.1) years; 53 426 (31.5%) participants were men. During a mean (SD) follow-up duration of 5.2 (2.2) years, 119 incident suicide and self-harm cases were identified. Individuals with RLS had a higher risk of suicide or self-harm compared with those without RLS (adjusted hazard ratio, 2.66; 95% CI, 1.70-4.15), after adjusting for lifestyle factors (eg, alcohol and obesity), presence of chronic diseases (eg, depression, insomnia, diabetes, chronic kidney disease, peripheral neuropathy, iron-deficiency anemia, and Parkinson disease), and use of medications. Excluding those with depression, insomnia, obstructive sleep apnea, and other common chronic conditions, the significant association between RLS and suicide or self-harm persisted (adjusted hazard ratio, 4.14; 95% CI, 2.17-7.92).

CONCLUSIONS AND RELEVANCE

Restless legs syndrome was associated with a high risk of suicide and self-harm, and the risk was independent of most identified diseases and conditions.

Opioid-galanin receptor heteromers mediate the dopaminergic effects of opioids

Identifying non-addictive opioid medications is a high priority in medical sciences, but μ-opioid receptors mediate both the analgesic and addictive effects of opioids. We found a significant pharmacodynamic difference between morphine and methadone that is determined entirely by heteromerization of μ-opioid receptors with galanin Gal1 receptors, rendering a profound decrease in the potency of methadone. This was explained by methadone's weaker proficiency to activate the dopaminergic system as compared to morphine and predicted a dissociation of therapeutic versus euphoric effects of methadone, which was corroborated by a significantly lower incidence of self-report of "high" in methadone-maintained patients. These results suggest that μ-opioid-Gal1 receptor heteromers mediate the dopaminergic effects of opioids that may lead to a lower addictive liability of opioids with selective low potency for the μ-opioid-Gal1 receptor heteromer, exemplified by methadone.

Biological and clinical insights from genetics of insomnia symptoms

Insomnia is a common disorder linked with adverse long-term medical and psychiatric outcomes. The underlying pathophysiological processes and causal relationships of insomnia with disease are poorly understood. Here we identified 57 loci for self-reported insomnia symptoms in the UK Biobank (n = 453,379) and confirmed their effects on self-reported insomnia symptoms in the HUNT Study (n = 14,923 cases and 47,610 controls), physician-diagnosed insomnia in the Partners Biobank (n = 2,217 cases and 14,240 controls), and accelerometer-derived measures of sleep efficiency and sleep duration in the UK Biobank (n = 83,726). Our results suggest enrichment of genes involved in ubiquitin-mediated proteolysis and of genes expressed in multiple brain regions, skeletal muscle, and adrenal glands. Evidence of shared genetic factors was found between frequent insomnia symptoms and restless legs syndrome, aging, and cardiometabolic, behavioral, psychiatric, and reproductive traits. Evidence was found for a possible causal link between insomnia symptoms and coronary artery disease, depressive symptoms, and subjective well-being.

Short Sleep Duration Is Associated With Increased Serum Homocysteine: Insights From a National Survey

STUDY OBJECTIVES

Both short sleep duration and increased serum homocysteine levels are associated with cardiovascular events. However, research on the relationship between sleep duration and serum homocysteine levels is sparse. The aim of this study is to examine the association between sleep duration and serum homocysteine levels from a national database.

METHODS

In total, 4,480 eligible participants older than 20 years who had serum homocysteine data and reported sleep duration were enrolled from the US National Health and Nutrition Examination Survey of 2005 to 2006. The association between sleep duration and serum homocysteine levels was analyzed using multivariate regression models for covariate adjustment.

RESULTS

Serum homocysteine level was lowest in individuals with a sleep duration of 7 hours and increased in those with both shorter and longer self-reported total sleep time (groups were categorized into ≤ 5 hours, 6 hours, 7 hours, 8 hours, and ≥ 9 hours). After adjustment for covariates, those in the group sleeping ≤ 5 hours had significantly higher serum homocysteine levels than the reference group (sleep duration of 7 hours). In subgroup analyses by sex, body mass index (BMI), and ethnicity, the association between short sleep duration (≤ 5 hours) and higher serum homocysteine levels persisted in women, individuals with obesity (BMI ≥ 30 kg/m²), and non-Hispanic whites.

CONCLUSIONS

This study highlighted that short sleep duration was associated with higher serum homocysteine levels in women, individuals with obesity (BMI ≥ 30 kg/m²), and non-Hispanic whites; this finding might suggest increased vulnerability to cardiovascular risk or other atherothrombotic events in these groups in the context of short sleep.

Respiratory-Related Leg Movements of Sleep Are Associated With Serotonergic Antidepressants But Not Bupropion

STUDY OBJECTIVES

Respiratory-related leg movements (RRLMs) may contribute to the cardiovascular risk associated with obstructive sleep apnea (OSA). Selective serotonin reuptake inhibitors (SSRIs), but not bupropion, increase periodic leg movements in sleep. This study examines whether patients with OSA using SSRIs have more RRLMs than those taking bupropion or no antidepressant.

METHODS

Patients with an apnea-hypopnea index (AHI) of at least 10 events/h during a full-night diagnostic study or split-night study, who were taking bupropion (n = 32), an SSRI (n = 31), or no antidepressant (n = 31), were selected from a database of prestudy questionnaires. RRLMs were scored according to World Association of Sleep Medicine 2016 standards.

RESULTS

Patients using SSRIs had significantly greater overall RRLM% (defined as the percentage of respiratory events associated with a leg movement, including apneas, hypopneas, and respiratory effort-related arousals), RRLM index, and periodic limb movement index relative to patients using bupropion and control patients. The difference between the RRLM% in the SSRI and bupropion groups was limited to patients undergoing split-night studies, and that of the SSRI and control groups was limited to patients undergoing full-night diagnostic studies.

CONCLUSIONS

The greater number of RRLMs and PLMs in the SSRI group may contribute to treatment-emergent insomnia often seen with SSRI use. Fragmented sleep and elevated autonomic nervous system activation associated with increased RRLMs in patients with OSA taking SSRIs might also limit the tolerability of antidepressant treatment, as well as increase the risk for cardiovascular disease.

Sleep EEG spectral power is correlated with subjective-objective discrepancy of sleep onset latency in major depressive disorder

We aimed to identify the sleep electroencephalography (EEG) spectral power correlates of the subjective-objective discrepancy (SOD) of sleep onset latency (SOL) in major depressive disorder (MDD), primary insomnia (PI), and normal sleeping control (NSC) groups. We examined relative power values in standard frequency bands of the EEG spectra during the first Non-Rapid Eye Movement (NREM) sleep period as correlates of SOD of SOL between sleep diary and polysomnography in MDD (n = 36), PI (n = 19), and NSC (n = 23) groups. We also compared the relative spectral power of sleep EEG among MDD (n = 40), PI (n = 19), and NSC (n = 23) groups. SOD of SOL in MDD patients was positively correlated with relative sigma (r = 0.622, p corrected < 0.001), beta power (r = 0.559, p corrected = 0.002), and alpha power (r = 0.469, p corrected = 0.024) in the first NREM sleep period. There was no significant difference of sleep EEG power spectra among the three groups. SOD was positively correlated with high frequency EEG in MDD. High frequency EEG power is thought to be associated with hyperarousal and memory consolidation, and future larger-scale studies may further elucidate the neurophysiological mechanisms underlying SOD of sleep onset duration.