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Li YS, Yeh WC, Hsu CY. Association of low serum ferritin levels with augmentation in patients with restless legs syndrome: A systematic review and meta-analysis. Sleep Med 2023; 112:173-180. [PMID: 37879259 DOI: 10.1016/j.sleep.2023.10.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 10/09/2023] [Accepted: 10/19/2023] [Indexed: 10/27/2023]
Abstract
BACKGROUND Augmentation of restless legs syndrome (RLS) is an iatrogenic side effect induced by dopaminergic agents, and it is a major cause of therapeutic failure. Iron deficiency is a risk factor for RLS, but its effects on the development of RLS augmentation are unclear. This meta-analysis aimed to elucidate the association between serum ferritin and RLS augmentation. METHODS We searched the PubMed, Cochrane Library, Embase, ClinicalKey, ScienceDirect, and ProQuest databases for studies comparing the serum ferritin levels of patients with augmented RLS and nonaugmented RLS. A meta-analysis based on a random-effects model was conducted. Levodopa equivalent dose (LED), International Restless Legs Study Group Severity Rating Scale (IRLS), and serum hemoglobin levels were also analyzed. RESULTS Six observational studies fulfilled the eligibility criteria of this meta-analysis. A total of 220 RLS patients with augmentation and 687 RLS patients without augmentation were included. The results revealed that augmented RLS was significantly associated with low serum ferritin levels (p = 0.002), high LEDs (p = 0.026), and nonsignificantly associated with high IRLS scores (p = 0.227). CONCLUSIONS A low serum ferritin level is associated with RLS augmentation. For patients with RLS who are iron deficient, iron supplements can not only relieve their fundamental RLS symptoms but also lower the risk of RLS augmentation. Moreover, non-dopminergic agents should be considered as the first-line treatment for patients with persistent low serum ferritin levels or those with moderate to severe RLS to prevent augmentation.
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Affiliation(s)
- Ying-Sheng Li
- Sleep Disorders Center, Department of Neurology, Kaohsiung Medical University Hospital, Kaohsiung City, Taiwan; Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung City, Taiwan
| | - Wei-Chih Yeh
- Department of Neurology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University Hospital, Kaohsiung City, Taiwan; Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung City, Taiwan
| | - Chung-Yao Hsu
- Sleep Disorders Center, Department of Neurology, Kaohsiung Medical University Hospital, Kaohsiung City, Taiwan; Department of Neurology, College of Medicine, Kaohsiung Medical University, Kaohsiung City, Taiwan.
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Zeng P, Wang T, Zhang L, Guo F. Exploring the causes of augmentation in restless legs syndrome. Front Neurol 2023; 14:1160112. [PMID: 37840917 PMCID: PMC10571710 DOI: 10.3389/fneur.2023.1160112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 09/13/2023] [Indexed: 10/17/2023] Open
Abstract
Long-term drug treatment for Restless Legs Syndrome (RLS) patients can frequently result in augmentation, which is the deterioration of symptoms with an increased drug dose. The cause of augmentation, especially derived from dopamine therapy, remains elusive. Here, we review recent research and clinical progress on the possible mechanism underlying RLS augmentation. Dysfunction of the dopamine system highly possibly plays a role in the development of RLS augmentation, as dopamine agonists improve desensitization of dopamine receptors, disturb receptor interactions within or outside the dopamine receptor family, and interfere with the natural regulation of dopamine synthesis and release in the neural system. Iron deficiency is also indicated to contribute to RLS augmentation, as low iron levels can affect the function of the dopamine system. Furthermore, genetic risk factors, such as variations in the BTBD9 and MEIS1 genes, have been linked to an increased risk of RLS initiation and augmentation. Additionally, circadian rhythm, which controls the sleep-wake cycle, may also contribute to the worsening of RLS symptoms and the development of augmentation. Recently, Vitamin D deficiency has been suggested to be involved in RLS augmentation. Based on these findings, we propose that the progressive reduction of selective receptors, influenced by various pathological factors, reverses the overcompensation of the dopamine intensity promoted by short-term, low-dose dopaminergic therapy in the development of augmentation. More research is needed to uncover a deeper understanding of the mechanisms underlying the RLS symptom and to develop effective RLS augmentation treatments.
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Affiliation(s)
- Pengyu Zeng
- Department of Neurobiology, Department of Neurology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
| | - Tiantian Wang
- Department of Pharmacy, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Center for Sleep Medicine, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Lisan Zhang
- Department of Neurobiology, Department of Neurology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Center for Sleep Medicine, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Fang Guo
- Department of Neurobiology, Department of Neurology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
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Parrino L, Halasz P, Szucs A, Thomas RJ, Azzi N, Rausa F, Pizzarotti S, Zilioli A, Misirocchi F, Mutti C. Sleep medicine: Practice, challenges and new frontiers. Front Neurol 2022; 13:966659. [PMID: 36313516 PMCID: PMC9616008 DOI: 10.3389/fneur.2022.966659] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
Sleep medicine is an ambitious cross-disciplinary challenge, requiring the mutual integration between complementary specialists in order to build a solid framework. Although knowledge in the sleep field is growing impressively thanks to technical and brain imaging support and through detailed clinic-epidemiologic observations, several topics are still dominated by outdated paradigms. In this review we explore the main novelties and gaps in the field of sleep medicine, assess the commonest sleep disturbances, provide advices for routine clinical practice and offer alternative insights and perspectives on the future of sleep research.
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Affiliation(s)
- Liborio Parrino
- Department of General and Specialized Medicine, Sleep Disorders Center, University Hospital of Parma, Parma, Italy
- *Correspondence: Liborio Parrino
| | - Peter Halasz
- Szentagothai János School of Ph.D Studies, Clinical Neurosciences, Semmelweis University, Budapest, Hungary
| | - Anna Szucs
- Department of Behavioral Sciences, National Institute of Clinical Neurosciences, Semmelweis University, Budapest, Hungary
| | - Robert J. Thomas
- Division of Pulmonary, Critical Care and Sleep, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States
| | - Nicoletta Azzi
- Department of General and Specialized Medicine, Sleep Disorders Center, University Hospital of Parma, Parma, Italy
| | - Francesco Rausa
- Department of General and Specialized Medicine, Sleep Disorders Center, University Hospital of Parma, Parma, Italy
- Department of Medicine and Surgery, Unit of Neurology, University of Parma, Parma, Italy
| | - Silvia Pizzarotti
- Department of General and Specialized Medicine, Sleep Disorders Center, University Hospital of Parma, Parma, Italy
| | - Alessandro Zilioli
- Department of Medicine and Surgery, Unit of Neurology, University of Parma, Parma, Italy
| | - Francesco Misirocchi
- Department of Medicine and Surgery, Unit of Neurology, University of Parma, Parma, Italy
| | - Carlotta Mutti
- Department of General and Specialized Medicine, Sleep Disorders Center, University Hospital of Parma, Parma, Italy
- Department of Medicine and Surgery, Unit of Neurology, University of Parma, Parma, Italy
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Colzato LS, Zhang W, Brandt MD, Stock AK, Beste C. Cognitive profile in Restless Legs Syndrome: A signal-to-noise ratio account. CURRENT RESEARCH IN NEUROBIOLOGY 2021; 2:100021. [PMID: 36246509 PMCID: PMC9559071 DOI: 10.1016/j.crneur.2021.100021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 07/05/2021] [Accepted: 07/29/2021] [Indexed: 11/19/2022] Open
Abstract
Restless legs syndrome (RLS) is a common neurological disorder characterized by a sensorimotor condition, where patients feel an uncontrollable urge to move the lower limbs in the evening and/or during the night. RLS does not only have a profound impact on quality of life due to the disturbed night-time sleep, but there is growing evidence that untreated or insufficiently managed RLS might also cause cognitive changes in patients affected by this syndrome. It has been proposed that RLS is caused by alterations in the signal-to-noise ratio (SNR) and in dopamine (DA) neurotransmission in the nervous system. Based on this evidence, we propose the “SNR-DA hypothesis” as an explanation of how RLS could affect cognitive performance. According to this hypothesis, variations/reductions in the SNR underlie RLS-associated cognitive deficits, which follow an inverted U-shaped function: In unmedicated patients, low dopamine levels worsen the SNR, which eventually impairs cognition. Pharmacological treatment enhances DA levels in medicated patients, which likely improves/normalizes the SNR in case of optimal doses, thus restoring cognition to a normal level. However, overmedication might push patients past the optimal point on the inverted U-shaped curve, where an exaggerated SNR potentially impairs cognitive performance relying on cortical noise such as cognitive flexibility. Based on these assumptions of SNR alterations, we propose to directly measure neural noise via “1/f noise” and related metrics to use transcranial random noise stimulation (tRNS), a noninvasive brain stimulation method which manipulates the SNR, as a research tool and potential treatment option for RLS. Restless legs syndrome (RLS) is a common neurological disorder. RLS is caused by alterations in the SNR ratio and in DA neurotransmission. The SNR- DA hypothesis how RLS affects cognitive performance is presented.
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Affiliation(s)
- Lorenza S. Colzato
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Germany
- Cognitive Psychology, Faculty of Psychology, Shandong Normal University, Jinan, China
- University Neuropsychology Center, Faculty of Medicine, TU Dresden, Germany
| | - Wenxin Zhang
- Cognitive Psychology, Faculty of Psychology, Shandong Normal University, Jinan, China
| | - Moritz D. Brandt
- Department of Neurology, University Hospital, Technische Universität Dresden, Dresden, Germany
- German Center for Neurodegenerative Diseases (DZNE) Dresden, Dresden, Germany
| | - Ann-Kathrin Stock
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Germany
- University Neuropsychology Center, Faculty of Medicine, TU Dresden, Germany
- Biopsychology, Faculty of Psychology, TU Dresden, Dresden, Germany
| | - Christian Beste
- Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine, TU Dresden, Germany
- Cognitive Psychology, Faculty of Psychology, Shandong Normal University, Jinan, China
- University Neuropsychology Center, Faculty of Medicine, TU Dresden, Germany
- Corresponding author. Cognitive Neurophysiology, Department of Child and Adolescent Psychiatry, Faculty of Medicine of the TU Dresden, Germany Schubertstrasse 42, D-01309, Dresden, Germany.
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