1
|
Romijnders R, Atrsaei A, Rehman RZU, Strehlow L, Massoud J, Hinchliffe C, Macrae V, Emmert K, Reilmann R, Janneke van der Woude C, Van Gassen G, Baribaud F, Ahmaniemi T, Chatterjee M, Vitturi BK, Pinaud C, Kalifa J, Avey S, Ng WF, Hansen C, Manyakov NV, Maetzler W. Association of real life postural transitions kinematics with fatigue in neurodegenerative and immune diseases. NPJ Digit Med 2025; 8:12. [PMID: 39762451 PMCID: PMC11704267 DOI: 10.1038/s41746-024-01386-0] [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: 07/26/2024] [Accepted: 12/11/2024] [Indexed: 01/11/2025] Open
Abstract
Fatigue is prevalent in immune-mediated inflammatory and neurodegenerative diseases, yet its assessment relies largely on patient-reported outcomes, which capture perception but not fluctuations over time. Wearable sensors, like inertial measurement units (IMUs), offer a way to monitor daily activities and evaluate functional capacity. This study investigates the relationship between sit-to-stand and stand-to-sit transitions and self-reported physical and mental fatigue in participants with Parkinson's, Huntington's, rheumatoid arthritis, systemic lupus erythematosus, primary Sjögren's syndrome and inflammatory bowel disease. Over 4 weeks, participants wore an IMU and reported fatigue levels four times daily. Using mixed-effects models, associations were identified between fatigue and specific kinematic features, such as 5th and 95th percentiles of sit-to-stand performance, suggesting that fatigue alters the control and effort of movement. These kinematic features show promise as indicators for fatigue in these patient populations.
Collapse
Affiliation(s)
- Robbin Romijnders
- Department of Neurology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Germany.
| | - Arash Atrsaei
- Mindmaze SA, Digital Motion Analytics Team, Lausanne, Switzerland
| | | | - Lea Strehlow
- Department of Neurology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Germany
| | - Jèrôme Massoud
- Department of Neurology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Germany
| | - Chloe Hinchliffe
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Victoria Macrae
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Kirsten Emmert
- Department of Neurology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Germany
| | | | | | | | - Frédéric Baribaud
- Translational Development, Bristol Meyers Squibb, Spring House, PA, USA
| | - Teemu Ahmaniemi
- VTT Technical Research Centre of Finland Ltd, Tampere, Finland
| | | | - Bruno Kusznir Vitturi
- Department of Neurology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Germany
| | | | | | - Stefan Avey
- Janssen Research & Development, Spring House, PA, USA
| | - Wan-Fai Ng
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
- HRB Clinical Research Facility Cork, University College Cork, Cork, Ireland
| | - Clint Hansen
- Department of Neurology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Germany
| | | | - Walter Maetzler
- Department of Neurology, University Hospital Schleswig-Holstein Campus Kiel, Kiel University, Kiel, Germany
| |
Collapse
|
2
|
Zhang Y, Zhang Y, Yan Y, Kong X, Su S. Risk factors for falls in Parkinson's disease: a cross-sectional observational and Mendelian randomization study. Front Aging Neurosci 2024; 16:1420885. [PMID: 38915347 PMCID: PMC11194421 DOI: 10.3389/fnagi.2024.1420885] [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: 04/21/2024] [Accepted: 05/21/2024] [Indexed: 06/26/2024] Open
Abstract
Background Patients with Parkinson's disease (PD) exhibit a heightened risk of falls and related fractures compared to the general population. This study aims to assess the clinical characteristics associated with falls in the patient with PD and to gain further insight into these factors through Mendelian randomization analysis. Methods From January 2013 to December 2023, we included 591 patients diagnosed with Parkinson's disease at Shenzhen Baoan People's Hospital. Using univariate and multivariate logistic regression analyses, we identified clinical variables associated with falls. We constructed a nomogram based on these variables and evaluated the predictive efficacy of the model. Additionally, we employed summary statistics from genome-wide association studies to conduct two-sample Mendelian randomization (MR) analyses on key variables influencing falls. Results Compared to the control group, we identified osteoporosis, motor dysfunction, higher Hoehn and Yahr scale as significant risk factors for falls in PD patients. Conversely, treatment with levodopa and a higher level of education exhibited a protective effect against the risk of falling. MR analysis further confirmed a causal relationship between osteoporosis, education level and falls in PD patients. Conclusion Osteoporosis and educational attainment are correlated with falls in Parkinson's disease.
Collapse
Affiliation(s)
- Yifan Zhang
- Department of Intensive Care Medicine, ShenzhenBaoan People's Hospital, Shenzhen, China
- Department of Neurological Center, ShenzhenBaoan People's Hospital, Shenzhen, China
| | - Yuehui Zhang
- Department of Intensive Care Medicine, ShenzhenBaoan People's Hospital, Shenzhen, China
| | - Yuexin Yan
- Department of Intensive Care Medicine, ShenzhenBaoan People's Hospital, Shenzhen, China
| | - Xiangxu Kong
- Department of Intensive Care Medicine, ShenzhenBaoan People's Hospital, Shenzhen, China
| | - Shengyuan Su
- Department of Intensive Care Medicine, ShenzhenBaoan People's Hospital, Shenzhen, China
| |
Collapse
|
3
|
Hwang YS, Jo S, Park KW, Lee SH, Lee S, Chung SJ. Association of Depression With Early Occurrence of Postural Instability in Parkinson's Disease. J Mov Disord 2023; 16:68-78. [PMID: 36537065 PMCID: PMC9978256 DOI: 10.14802/jmd.22091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 09/30/2022] [Indexed: 12/24/2022] Open
Abstract
OBJECTIVE Depression in Parkinson's disease (PD) affects the quality of life of patients. Postural instability and gait disturbance are associated with the severity and prognosis of PD. We investigated the association of depression with axial involvement in early-stage PD patients. METHODS This study involved 95 PD patients unexposed to antiparkinsonian drugs. After a baseline assessment for depression, the subjects were divided into a depressed PD group and a nondepressed PD group. Analyses were conducted to identify an association of depression at baseline with the following outcome variables: the progression to Hoehn and Yahr scale (H-Y) stage 3, the occurrence of freezing of gait (FOG), levodopa-induced dyskinesia, and wearing-off. The follow-up period was 53.40 ± 16.79 months from baseline. RESULTS Kaplan-Meier survival curves for H-Y stage 3 and FOG showed more prominent progression to H-Y stage 3 and occurrences of FOG in the depressed PD group than in the nondepressed PD group (log-rank p = 0.025 and 0.003, respectively). Depression in drug-naïve, early-stage PD patients showed a significant association with the progression to H-Y stage 3 (hazard ratio = 2.55; 95% confidence interval = 1.32-4.93; p = 0.005), as analyzed by Cox regression analyses. In contrast, the occurrence of levodopa-induced dyskinesia and wearing-off did not differ between the two groups (log-rank p = 0.903 and 0.351, respectively). CONCLUSION Depression in drug-naïve, early-stage PD patients is associated with an earlier occurrence of postural instability. This suggests shared nondopaminergic pathogenic mechanisms and potentially enables the prediction of early development of postural instability.
Collapse
Affiliation(s)
- Yun Su Hwang
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea,Department of Neurology, Jeonbuk National University Medical School and Hospital, Jeonju, Korea
| | - Sungyang Jo
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Kye Won Park
- Department of Neurology, Uijeongbu Eulji Medical Center, Eulji University School of Medicine, Uijeongbu, Korea
| | - Seung Hyun Lee
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Sangjin Lee
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Sun Ju Chung
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea,Corresponding author: Sun Ju Chung, MD, PhD Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea / Tel: +82-2-3010-3440 / Fax: +82-2-474-4691 / E-mail:
| |
Collapse
|
4
|
Mantri S, Chahine LM, Nabieva K, Feldman R, Althouse A, Torsney B, Albert SM, Kopil C, Marras C. Demographic Influences on the Relationship Between Fatigue and Quality of Life in Parkinson's Disease. Mov Disord Clin Pract 2022; 9:76-81. [PMID: 35005068 DOI: 10.1002/mdc3.13360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/17/2021] [Accepted: 09/11/2021] [Indexed: 11/09/2022] Open
Abstract
Background Fatigue has a major impact on health-related quality of life (HR-QOL) in Parkinson's disease (PD). Objectives To determine whether demographic characteristics modify the relationship between fatigue and HR-QOL. Methods Patients with PD in the Fox Insight study completed the Parkinson Fatigue Scale (PFS-16) and Geriatric Depression Scale (GDS-15). Linear regression examined the relationship between the PFS-16 and Parkinson Disease Quality of Life, as modified by age, sex, and GDS-15. Results A total of 1029 participants (44% female, mean age 67.4 years, and mean disease duration 4.6 years) were included in this analysis. Multivariable regression modeling demonstrated a negative effect modification for age (β = -0.07, P < 0.001) and a positive effect modification for the GDS-15 (β = 0.057, P = 0.002), but not for sex (β = -0.021, P = 0.231). Conclusion The association between fatigue and worse HR-QOL is greater at younger ages and in individuals with more depressive symptoms. Targeted therapeutics for these individuals may provide the greatest impact on fatigue in PD.
Collapse
Affiliation(s)
- Sneha Mantri
- Department of Neurology Duke University School of Medicine Durham North Carolina USA
| | - Lana M Chahine
- Department of Neurology University of Pittsburgh School of Medicine Pittsburgh Pennsylvania USA
| | - Karina Nabieva
- The Edmond J Safra Program in Parkinson's disease Toronto Western Hospital, University of Toronto Toronto Ontario Canada
| | - Robert Feldman
- Center for Clinical Trials and Data Coordination, Division of General Internal Medicine University of Pittsburgh School of Medicine Pittsburgh Pennsylvania USA
| | - Andrew Althouse
- Center for Clinical Trials and Data Coordination, Division of General Internal Medicine University of Pittsburgh School of Medicine Pittsburgh Pennsylvania USA
| | - Benjamin Torsney
- Temple University College of Education and Human Development Philadelphia Pennsylvania USA
| | - Steven M Albert
- Behavioral and Community Health Sciences, Graduate School of Public Health University of Pittsburgh Pittsburgh Pennsylvania USA
| | | | - Connie Marras
- The Edmond J Safra Program in Parkinson's disease Toronto Western Hospital, University of Toronto Toronto Ontario Canada
| |
Collapse
|
5
|
Terra MB, Caramaschi IKF, Araújo HAGDO, Souza RJD, Silva TCOD, Nascimento TS, Probst VS, Smaili SM. Is fatigue associated with balance in Parkinson's disease? MOTRIZ: REVISTA DE EDUCACAO FISICA 2022. [DOI: 10.1590/s1980-657420220013921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
6
|
Khalil H, Alissa N, Al-Sharman A, E'leimat I, Majdi Al Qawasmeh, El-Salem K. Understanding the influence of pain and fatigue on physical performance, fear of falling and falls in people with Parkinson's disease: a pilot study. Neurodegener Dis Manag 2021; 11:113-124. [PMID: 33730860 DOI: 10.2217/nmt-2020-0053] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Objective: Pain and fatigue are highly prevalent debilitating symptoms in Parkinson's disease (PD), however, their relationship with physical performance, fear of falling (FOF) and falls is not clear. We aim in this pilot study to investigate the relationship of pain and fatigue with physical performance, FOF and falls in people with Parkinson's disease (PwPD). Materials & methods: 53 PD patients were assessed for fall history, physical performance, FOF, pain and fatigue. Results: Pain and fatigue are significantly associated with physical performance and FOF (p ≤ 0.002). Pain and fatigue were different between fallers and non-fallers (p < 0.5), but only fatigue could distinguish fallers from non-fallers (area under the receiver operating characteristics curve = 0.81; p < 0.0001). Conclusion: This pilot study indicated that FOF in PwPD is significantly associated with pain and fatigue. Furthermore, fatigue level is related to fall history. By addressing pain and fatigue, we may ameliorate the deterioration of FOF and falls in PwPD.
Collapse
Affiliation(s)
- Hanan Khalil
- Department of Rehabilitation Sciences, Jordan University of Science & Technology, Faculty of Applied Medical Sciences, Irbid, Jordan
| | - Nesreen Alissa
- School of Medicine, Department of Physical Therapy & Rehabilitation Science, University of Maryland, Baltimore, Baltimore, Maryland
| | - Alham Al-Sharman
- Department of Rehabilitation Sciences, Jordan University of Science & Technology, Faculty of Applied Medical Sciences, Irbid, Jordan
| | - Islam E'leimat
- Faculty of Medicine, Department of Neurosciences, Jordan University of Science & Technology, Irbid, Jordan
| | - Majdi Al Qawasmeh
- Faculty of Medicine, Department of Neurosciences, Jordan University of Science & Technology, Irbid, Jordan
| | - Khalid El-Salem
- Faculty of Medicine, Department of Neurosciences, Jordan University of Science & Technology, Irbid, Jordan
| |
Collapse
|
7
|
Lin I, Edison B, Mantri S, Albert S, Daeschler M, Kopil C, Marras C, Chahine LM. Triggers and alleviating factors for fatigue in Parkinson's disease. PLoS One 2021; 16:e0245285. [PMID: 33540422 PMCID: PMC7861907 DOI: 10.1371/journal.pone.0245285] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 12/24/2020] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Fatigue is common in Parkinson's Disease, but few effective treatments are available for it. Exploring triggers and alleviating factors, including effects of exercise, could inform development of management strategies for Parkinson's Disease fatigue. OBJECTIVES To examine triggers and alleviating factors for fatigue reported by individuals with Parkinson's Disease, including perceived effect of exercise. METHODS A sample of individuals with self-reported Parkinson's Disease participating in the study Fox Insight were administered an online survey. The survey included the Parkinson's Fatigue Scale, the Physical Activity Scale for the Elderly, and multiple-choice questions about triggers and alleviating factors for fatigue. RESULTS Among the sample of 1,029 individuals with Parkinson's disease, mean (standard deviation (SD)) age was 67.4 (9.3) years, 44.0% were female. Parkinson's Fatigue Scale score ranged from 16-80, mean (SD) 48.8 (16.2). Poor sleep (62.1%) and physical exertion (45.1%) were frequently reported triggers for fatigue. Coping strategies including sitting quietly (58.1%), laying down with or without napping, and exercise (20%). Physical Activity Scale for the Elderly scores were higher in those who reported that exercise alleviated their fatigue (49.7%) compared to those who reported it worsened their fatigue (18.9%) (mean (SD) score 158.5 (88.8) vs 119.8 (66.6) respectively; p<0.001). CONCLUSIONS Several behavioral and environmental triggers and alleviating strategies for fatigue are reported by individuals with Parkinson's disease. Many feel that exercise alleviates fatigue, though the relationship between exercise and fatigue in Parkinson's Disease appears complex. This exploratory study may inform future development of treatments or coping strategies for Parkinson's disease fatigue.
Collapse
Affiliation(s)
- Iris Lin
- Department of Neurology, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Briana Edison
- Department of Neurology, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Sneha Mantri
- Department of Neurology, Duke University, Durham, NC, United States of America
| | - Steven Albert
- Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Margaret Daeschler
- Columbia University School of Social Work, New York, NY, United States of America
| | - Catherine Kopil
- The Michael J. Fox Foundation for Parkinson’s Research, New York, NY, United States of America
| | - Connie Marras
- Department of Neurology, University of Toronto, Toronto, Ontario, Canada
| | - Lana M. Chahine
- Department of Neurology, University of Pittsburgh, Pittsburgh, PA, United States of America
| |
Collapse
|
8
|
Cohen JN, Seng E, Foley FW. Cognitive and motor slowing mediate the relationship between depression and falls in multiple sclerosis patients. Mult Scler Relat Disord 2021; 50:102808. [PMID: 33596493 DOI: 10.1016/j.msard.2021.102808] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 01/08/2021] [Accepted: 01/31/2021] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Given the limited research concerning the relationship between depression and falls in multiple sclerosis (MS), this study aimed to examine the direct and indirect association between fall history and depressive symptoms. METHODS One hundred and forty seven MS patients had completed at least one neuropsychological assessment that included detailed information regarding fall history, as well as measures of depression, motor function, and cognitive processing speed. RESULTS Fall history was associated with higher depressive symptoms and poorer overall motor function. Higher self-reported depressive symptoms were associated with higher odds of falls in the last year (OR = 1.64, 95% CI 1.16, 2.31) in an age adjusted model. Cognitive and motor slowing serially mediated the relationship between depressive symptoms and fall history (estimate = 0.060, 95% CI = 0.01, 0.15). CONCLUSIONS With the extensive research on the cognitive and motor correlates of falls in MS, our findings suggest that depressive symptoms are also associated with falls in people with MS. Moreover, this study provides preliminary support for a pathway by which depressive symptoms are related to falls in part through their relationships with cognitive and motor slowing.
Collapse
Affiliation(s)
- Jenna N Cohen
- Ferkauf Graduate School of Psychology, Yeshiva University, 1300 Morris Park Avenue, Bronx, NY 10461, United States
| | - Elizabeth Seng
- Ferkauf Graduate School of Psychology, Yeshiva University, 1300 Morris Park Avenue, Bronx, NY 10461, United States; The Saul R Korey Department of Neurology, Albert Einstein College of Medicine, 1225 Morris Park Avenue, Van Etten Building, Bronx, NY 10461, United States
| | - Frederick W Foley
- Ferkauf Graduate School of Psychology, Yeshiva University, 1300 Morris Park Avenue, Bronx, NY 10461, United States; Holy Name Medical Center Multiple Sclerosis Center, 718 Teaneck Road, Teaneck, NJ 07666, United States.
| |
Collapse
|
9
|
The effect of fatigue on balance performance in Parkinson's disease. Clin Park Relat Disord 2020; 3:100047. [PMID: 34316632 PMCID: PMC8298774 DOI: 10.1016/j.prdoa.2020.100047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 01/06/2020] [Accepted: 02/19/2020] [Indexed: 01/07/2023] Open
Abstract
Introduction Balance loss and falls are a common and multifactorial finding in persons with Parkinson's Disease (pwPD). Objective fatigability is thought to contribute to falls in other neurologic conditions, but its impact on balance in pwPD is not known. The two-fold purpose of this study was to: 1) establish that a 6-minute walk (6MWFast) is a stimulus to subjective fatigue for pwPD; and, 2) determine if the Mini Balance Evaluation Systems Test (MBT) is sensitive to change that was induced by a fatiguing condition. Methods Using a randomized crossover design, 19 research participants performed a Mini Balance Evaluation Systems Test (MBT) before and after either a ‘fast’ 6-minute walk (6MWFast) to induce fatigue or a 6-minute rest. Results VASF scores increased after the 6MWFast. Total MBT scores in research participants with Modified Hoehn and Yahr (H&Y) scores of 3.0 and above differed significantly before and after the ‘fast’ 6-minute walk (p = .007, n = 9) while participants with H&Y scores of 1.5 to 2.5 (p = .084, n = 10) did not, suggesting that more disabled pwPD were more likely to experience fatigability that interfered with balance. Conclusions A 6MWFast is a sufficient stimulus to induce subjective fatigue in pwPD and to decrease total MBT scores for more disabled pwPD. Balance evaluations should occur when pwPD are in fatigued and unfatigued states to determine whether fatigue has an impact on balance performance. Both subjective fatigue and objective fatigability can occur in Parkinsons Disease (PD). Objective fatigability may be a factor in balance impairment in persons with PD. Balance assessments in PD should be made with the patient in both a fatigued and non fatigued state.
Collapse
|
10
|
Alvarado-Bolaños A, Cervantes-Arriaga A, Arredondo-Blanco K, Salinas-Barboza K, Isais-Millán S, Rodríguez-Violante M. Falls in persons with Parkinson's disease: Do non-motor symptoms matter as much as motor symptoms? ARQUIVOS DE NEURO-PSIQUIATRIA 2019; 77:761-767. [DOI: 10.1590/0004-282x20190148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 07/28/2019] [Indexed: 11/22/2022]
Abstract
ABSTRACT Falls are common among persons with Parkinson's disease (PD). On the other hand, predicting falls is complex as there are both generic and PD-specific contributors. In particular, the role of non-motor symptoms has been less studied. Objective: The objective of this study was to identify the role of non-motor predictors of falling in persons with PD (PwP). Methods: A cross-sectional study was carried out in PwP recruited from a movement disorders clinic. Clinical and demographical data were collected. All PwP were assessed using the Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) and the Non-Motor Symptoms Scale (NMSS). Variables were assessed at the bivariate level. Significant variables were put into a logistic regression model. Results: A total of 179 PwP were included. Overall, 16.8% of PwP had fallen in the past 12 months, with 53.3% of them being recurrent fallers. The mean number of monthly falls was 2.5 ± 3.3. Factors associated with falling in the bivariate analysis included the disease duration, Hoehn and Yahr stage, MDS-UPDRS part I and II, postural instability/gait disturbance (PIGD) subtype, NMSS urinary domain, NMSS miscellaneous domain, and non-motor severity burden (all p-values < 0.05). After multivariate analysis, only the disease duration (p = 0.03) and PIGD (p = 0.03) remained as independent risk factors. Conclusion: Disease duration and the PIGD subtype were identified as relevant risk factors for falls in PwP Non-motor symptoms appear to have a less important role as risk factors for falls.
Collapse
Affiliation(s)
| | | | | | | | | | - Mayela Rodríguez-Violante
- Instituto Nacional de Neurología y Neurocirugía, Mexico; Instituto Nacional de Neurología y Neurocirugía, Mexico
| |
Collapse
|
11
|
Chahine LM, Amara AW, Videnovic A. A systematic review of the literature on disorders of sleep and wakefulness in Parkinson's disease from 2005 to 2015. Sleep Med Rev 2017; 35:33-50. [PMID: 27863901 PMCID: PMC5332351 DOI: 10.1016/j.smrv.2016.08.001] [Citation(s) in RCA: 222] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 08/10/2016] [Accepted: 08/12/2016] [Indexed: 01/06/2023]
Abstract
Sleep disorders are among the most common non-motor manifestations in Parkinson's disease (PD) and have a significant negative impact on quality of life. While sleep disorders in PD share most characteristics with those that occur in the general population, there are several considerations specific to this patient population regarding diagnosis, management, and implications. The available research on these disorders is expanding rapidly, but many questions remain unanswered. We thus conducted a systematic review of the literature published from 2005 to 2015 on the following disorders of sleep and wakefulness in PD: REM sleep behavior disorder, insomnia, nocturia, restless legs syndrome and periodic limb movements, sleep disordered breathing, excessive daytime sleepiness, and circadian rhythm disorders. We discuss the epidemiology, etiology, clinical implications, associated features, evaluation measures, and management of these disorders. The influence on sleep of medications used in the treatment of motor and non-motor symptoms of PD is detailed. Additionally, we suggest areas in need of further research.
Collapse
Affiliation(s)
- Lama M Chahine
- Parkinson's Disease and Movement Disorders Center, Department of Neurology, Perelman School of Medicine, University of Pennsylvania, 330 S. 9th st, Philadelphia, PA 19107, USA.
| | - Amy W Amara
- Division of Movement Disorders, Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Aleksandar Videnovic
- Neurobiological Clinical Research Institute, Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| |
Collapse
|
12
|
Longitudinal Association Between Subjective Fatigue and Future Falls in Community-Dwelling Older Adults: The Locomotive Syndrome and Health Outcomes in the Aizu Cohort Study (LOHAS). J Aging Health 2017; 31:67-84. [DOI: 10.1177/0898264317721825] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Objective:We examined the longitudinal association between the severity of fatigue and falls in community-dwelling older adults. Method: Subjective fatigue was assessed using the Short Form 36 Health Survey (SF-36) Vitality subscale and classified into four categories by quartile (mildest, mild, moderate, severe). The main outcome was the incidence of any falls during the 2-year follow-up period. Results: Of the 751 participants, 236 (31.4%) experienced falls during the 2-year period. In multivariable logistic regression analysis with adjustment for possible confounding factors, the adjusted odds ratios (and 95% confidence intervals) for mild, moderate, and severe categories (vs. mildest category) of 1.60 (0.94-2.75), 1.87 (1.12-3.11), and 2.15 (1.23-3.76), respectively ( p for trend = .007). Discussion: Our results suggest that the severity of fatigue is associated with the risk of subsequent falls for community-dwelling older adults even after adjustment for possible confounding factors.
Collapse
|
13
|
Youn J, Okuma Y, Hwang M, Kim D, Cho JW. Falling Direction can Predict the Mechanism of Recurrent Falls in Advanced Parkinson's Disease. Sci Rep 2017. [PMID: 28634343 PMCID: PMC5478627 DOI: 10.1038/s41598-017-04302-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Falls are a common and disabling symptom in patients with Parkinson’s disease (PD). For prevention, it is important to understand the pathophysiology of falls in PD patients, but the predictors for the possible mechanisms underlying such falls have not been clearly elucidated. In this prospective observational study, we investigated the implications of falling direction to predict the mechanisms of recurrent falls in PD patients. We enrolled 62 recurrent fallers with PD and divided them into two groups according to the main falling directions: 45 PD fallers who fell forward (forward fallers), and 17 PD fallers who fell in the other directions (non-forward fallers). Although there was no difference in demographic data, parkinsonism, or frontal lobe function, forward fallers showed more severe falls and tended to fall during walking or turning, while non-forward fallers usually fell during sitting/standing or turning. Additionally, forward fallers revealed higher score on a freezing of gait (FOG) questionnaire. Logistic regression analysis demonstrated that FOG was associated with falling forward, while balance impairment, akinetic-rigid subtype, and neuropsychiatric symptoms were associated with falling into the other directions. Our results indicate that FOG and balance impairment are two major mechanisms for recurrent falling in PD patients, and falling direction is an important predictor for these mechanisms.
Collapse
Affiliation(s)
- Jinyoung Youn
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.,Neuroscience Center, Samsung Medical Center, Seoul, Korea
| | - Yasuyuki Okuma
- Department of Neurology, Juntendo University Shizuoka Hospital, Shizuoka, Japan
| | - Minho Hwang
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.,Neuroscience Center, Samsung Medical Center, Seoul, Korea
| | - Dongyeop Kim
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.,Neuroscience Center, Samsung Medical Center, Seoul, Korea
| | - Jin Whan Cho
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. .,Neuroscience Center, Samsung Medical Center, Seoul, Korea.
| |
Collapse
|
14
|
Wu L, Sun D. Sleep duration and falls: a systemic review and meta-analysis of observational studies. J Sleep Res 2017; 26:293-301. [PMID: 28220576 DOI: 10.1111/jsr.12505] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 12/19/2016] [Indexed: 11/27/2022]
Abstract
Several epidemiological studies have linked sleep duration with falls; however, the findings yielded inconsistent results. No quantitative analysis has specifically assessed the influence of sleep duration on falls. PubMed and Embase were screened for observational studies from inception to 13 September 2016. A generic inverse-variance method was used to pool the outcome data for sleep duration categories of the lowest category versus reference, and the highest category versus reference with a random-effects model. Dose-response analysis was performed to evaluate the potential relationship of sleep duration with falls. Finally, seven eligible observational studies involving a total of 212 829 participants were included in the present meta-analysis. Compared with the reference category, both short and long sleep duration were significantly associated with falls, and the pooled odds ratios (95% confidence intervals) were 1.32 (1.21, 1.46) and 1.35 (1.17, 1.56), respectively, both with evidence of significant heterogeneity. An approximately 'U-shaped' curve was observed, and the lowest risk of falls was shown at 7-8 h day-1 of sleep duration. Further subgroup analysis found that the association of long sleep duration and falls was more pronounced among Caucasians. The present study is limited to its small number of included studies, considerable heterogeneity, observational study design and the large contribution of a single article. Further researches are still needed to confirm the causal association between sleep duration and falls in populations with different gender, age and ethnicity.
Collapse
Affiliation(s)
- Lei Wu
- Department of Epidemiology, Institute of Geriatrics, Chinese People's Liberation Army General Hospital, Beijing, China
| | - Dali Sun
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, USA
| |
Collapse
|
15
|
Kader M, Iwarsson S, Odin P, Nilsson MH. Fall-related activity avoidance in relation to a history of falls or near falls, fear of falling and disease severity in people with Parkinson's disease. BMC Neurol 2016; 16:84. [PMID: 27250988 PMCID: PMC4890527 DOI: 10.1186/s12883-016-0612-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 05/27/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND There is limited knowledge concerning fall-related activity avoidance in people with Parkinson's disease (PD); such knowledge would be of importance for the development of more efficient PD-care and rehabilitation. This study aimed to examine how fall-related activity avoidance relates to a history of self-reported falls/near falls and fear of falling (FOF) as well as to disease severity in people with PD. METHODS Data were collected from 251 (61 % men) participants with PD; their median (min-max) age and PD duration were 70 (45-93) and 8 (1-43) years, respectively. A self-administered postal survey preceded a home visit which included observations, clinical tests and interview-administered questionnaires. Fall-related activity avoidance was assessed using the modified Survey of Activities and Fear of Falling in the Elderly (mSAFFE) as well as by using a dichotomous (Yes/No) question. Further dichotomous questions concerned: the presence of FOF and the history (past 6 months) of falls or near falls, followed by stating the number of incidents. Disease severity was assessed according to the Hoehn and Yahr (HY) stages. RESULTS In the total sample (n = 251), 41 % of the participants reported fall-related activity avoidance; the median mSAFFE score was 22. In relation to a history of fall, the proportions of participants (p < 0.001) that reported fall-related activity avoidance were: non-fallers (30 %), single fallers (50 %) and recurrent fallers, i.e. ≥ 2 falls (57 %). Among those that reported near falls (but no falls), 51 % (26 out of 51) reported fall-related activity avoidance. Of those that reported FOF, 70 % reported fall-related activity avoidance. Fall-related activity avoidance ranged from 24 % in the early PD-stage (HY I) to 74 % in the most severe stages (HY IV-V). CONCLUSIONS Results indicate that fall-related activity avoidance may be related to a history of self-reported falls/near falls, FOF and disease severity in people with PD. Importantly, fall-related activity avoidance is reported among those that do not fall and already in mild PD-stages (HY I-II). Although further studies are needed, our findings indicate that fall-related activity avoidance needs to be addressed early in order to prevent sedentary behavior and participation restrictions.
Collapse
Affiliation(s)
- Manzur Kader
- Department of Health Sciences, Lund University, PO Box 157, SE-221 00, Lund, Sweden.
| | - Susanne Iwarsson
- Department of Health Sciences, Lund University, PO Box 157, SE-221 00, Lund, Sweden
| | - Per Odin
- Department of Clinical Sciences, Lund University, Lund, Sweden.,Department of Clinical Sciences, Section for Neurology, Skåne University Hospital, Lund, Sweden.,Department of Neurology, Central Hospital, Bremerhaven, Germany
| | - Maria H Nilsson
- Department of Health Sciences, Lund University, PO Box 157, SE-221 00, Lund, Sweden.,Memory Clinic, Skåne University Hospital, Malmö, Sweden
| |
Collapse
|
16
|
Reynolds GO, Otto MW, Ellis TD, Cronin-Golomb A. The Therapeutic Potential of Exercise to Improve Mood, Cognition, and Sleep in Parkinson's Disease. Mov Disord 2016; 31:23-38. [PMID: 26715466 PMCID: PMC4724300 DOI: 10.1002/mds.26484] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 10/11/2015] [Accepted: 10/15/2015] [Indexed: 01/15/2023] Open
Abstract
In addition to the classic motor symptoms, Parkinson's disease (PD) is associated with a variety of nonmotor symptoms that significantly reduce quality of life, even in the early stages of the disease. There is an urgent need to develop evidence-based treatments for these symptoms, which include mood disturbances, cognitive dysfunction, and sleep disruption. We focus here on exercise interventions, which have been used to improve mood, cognition, and sleep in healthy older adults and clinical populations, but to date have primarily targeted motor symptoms in PD. We synthesize the existing literature on the benefits of aerobic exercise and strength training on mood, sleep, and cognition as demonstrated in healthy older adults and adults with PD, and suggest that these types of exercise offer a feasible and promising adjunct treatment for mood, cognition, and sleep difficulties in PD. Across stages of the disease, exercise interventions represent a treatment strategy with the unique ability to improve a range of nonmotor symptoms while also alleviating the classic motor symptoms of the disease. Future research in PD should include nonmotor outcomes in exercise trials with the goal of developing evidence-based exercise interventions as a safe, broad-spectrum treatment approach to improve mood, cognition, and sleep for individuals with PD.
Collapse
Affiliation(s)
| | - Michael W. Otto
- Boston University, Department of Psychological and Brain Sciences
| | - Terry D. Ellis
- Boston University College of Health and Rehabilitation Sciences: Sargent College, Department of Physical Therapy & Athletic Training and Center for Neurorehabilitation
| | | |
Collapse
|
17
|
Chomiak T, Pereira FV, Clark TW, Cihal A, Hu B. Concurrent arm swing-stepping (CASS) can reveal gait start hesitation in Parkinson's patients with low self-efficacy and fear of falling. Aging Clin Exp Res 2015; 27:457-63. [PMID: 25577232 DOI: 10.1007/s40520-014-0313-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 12/30/2014] [Indexed: 11/29/2022]
Abstract
BACKGROUND Movement incoordination, freezing of gait, fear of falling, low self-efficacy, and multi-tasking can all contribute to falls in Parkinson's disease. How these multi-factorial risks interact in individual patients remain poorly understood. METHODS Concurrent arm swing-stepping is a simple motor test in which subjects are first asked to swing their arms before being instructed to initiate the secondary task of leg stepping-in-place. We postulated that in patients with multiple fall risks, sensorimotor impairments in upper- and lower-limb movement control can render concurrent arm swing-stepping a demanding dual task, thereby triggering gait hesitation. A total of 31 subjects with Parkinson's disease were enrolled in the study. RESULTS It was found that concurrent arm swing-stepping induced hesitation primarily in Parkinson's disease patients with low fall-related self-efficacy and a fear of falling. By contrast, concurrent arm swing-stepping led to limb incoordination in both patients and in healthy elderly controls. The calculated specificity and sensitivity of the concurrent arm swing-stepping test was 100 and 42 % for hesitation and 12 and 77 % for incoordination. CONCLUSION These results suggest that the concurrent arm swing-stepping test can be used in conjunction with conventional psychometric assessments to facilitate multi-factorial assessment of potential fall risk.
Collapse
Affiliation(s)
- Taylor Chomiak
- Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, 1AC60 HRIC, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada,
| | | | | | | | | |
Collapse
|
18
|
Why do patients with Parkinson's disease fall? A cross-sectional analysis of possible causes of falls. NPJ PARKINSONS DISEASE 2015; 1:15011. [PMID: 28409181 PMCID: PMC5388183 DOI: 10.1038/npjparkd.2015.11] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Background: Falls in Parkinson’s disease (PD) are associated with significant injury, disability, hospitalization, and reduced quality of life. Aims: To identify modifiable medical causes of falls in a cohort of PD patients. Methods: Eighty seven PD patients were interviewed and examined using validated scales assessing motor and nonmotor aspects of PD, comorbidities and medication use. The frequency of falls in the last month was the primary outcome measure. Falls were hypothesized to be associated with increasing age, advanced motor severity, particularly axial features (e.g., freezing and postural instability), and dyskinesia. Nonmotor features hypothesized to be associated with falls included; cognitive impairment, psychosis, sleep disorders, cardiovascular dysfunction, and ophthalmological and medical comorbidities. Results: Fallers had longer disease duration, higher Levodopa-equivalent doses, greater ‘On’ time with dyskinesia (all P<0.005), and higher scores on some Movement Disorder Society-Unified Parkinson’s Disease Rating Scale items, particularly axial scores. However, patients with falls did not differ from non-fallers in age or overall motor UPDRS scores. Severity of psychosis, executive cognitive impairment, autonomic (particularly cardiovascular) dysfunction and sleep disturbances (particularly REM sleep behavioral disorder) were significantly associated with falls (all P<0.005). Fallers more frequently reported use of antidepressants (both tricyclics and SSRIs) and neuroleptics (P<0.001), but not hypnotics. There was no difference in medical comorbidities, ophthalmological assessments, fatigue, and apathy scores between the groups. In logistic regression analysis, cardiovascular dysfunction, antidepressant use, and REM sleep behavioral disorder were significantly associated with falls. Conclusions: The causes of falls in PD are multifactorial and extend beyond motor impairment and dyskinesia; addressing these in patients already treated with dopaminergic medications has the potential to improve this important complication of PD.
Collapse
|
19
|
Louis ED, Machado DG. Tremor-related quality of life: A comparison of essential tremor vs. Parkinson's disease patients. Parkinsonism Relat Disord 2015; 21:729-35. [PMID: 25952960 DOI: 10.1016/j.parkreldis.2015.04.019] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 04/15/2015] [Accepted: 04/18/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND Tremor-related quality of life is a multi-dimensional concept that reflects the physical, emotional and other health effects of tremor. Curiously, tremor-related quality of life has never been directly compared in patients with the two major tremor disorders, essential tremor (ET) and Parkinson's disease (PD). We performed a head-to-head comparison of ET with PD patients. METHODS The Quality of Life in Essential Tremor (QUEST) questionnaire was administered to 103 ET and 103 matched PD patients enrolled in a clinical-epidemiological study in New York. RESULTS The QUEST total score and QUEST physical subscore were higher in ET than PD patients (both p < 0.05). In relative terms, ET patients reported significantly more impairment than PD patients in multiple areas; PD patients reported more impairment than ET patients in one area (all p ≤ 0.02). In absolute terms, tremor impacted on many aspects of quality of life in both diseases, including physical and psychosocial, and in one-third or more of PD patients, tremor sometimes, frequently or always interfered with numerous physical activities, including writing, using a typewriter/computer, fixing small things, dressing, eating, and holding reading material. CONCLUSIONS Tremor is a clinical entity that can have numerous effects on patients. While there were relative differences between the two major tremor disorders, ET and PD, in absolute terms, tremor impacted on several domains of quality of life, from physical to psychosocial, in a large proportion of ET and PD patients. Attempts to judge the efficacy of treatments for tremor, whether pharmacological or surgical, should consider its broad impact.
Collapse
Affiliation(s)
- Elan D Louis
- Division of Movement Disorders, Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, USA; Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, CT, USA.
| | - Duarte G Machado
- Division of Movement Disorders, Department of Neurology, Yale School of Medicine, Yale University, New Haven, CT, USA
| |
Collapse
|
20
|
Spindler M, Gooneratne NS, Siderowf A, Duda JE, Cantor C, Dahodwala N. Daytime sleepiness is associated with falls in Parkinson's disease. JOURNAL OF PARKINSONS DISEASE 2014; 3:387-91. [PMID: 23948992 DOI: 10.3233/jpd-130184] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Falls are frequent in Parkinson's disease (PD), and may be influenced by daytime sleepiness. We reviewed the records of 120 men with PD. Mean Epworth Sleepiness Scale (ESS) values were significantly different between non-fallers and fallers (6.0 vs. 9.7, p < 0.01). In multivariate analysis, ESS remained significantly associated with falls (OR 1.2, 95% CI 1.1-1.4, p = 0.02), along with cognitive impairment (OR 4.4 95% CI 1.0-18.7, p = 0.04) and postural instability/gait dysfunction (OR 1.6 95% CI 1.0-2.4, p = 0.03) in non-depressed patients. In conclusion, non-depressed PD patients are 20% more likely to fall for every one unit increase in the ESS measure of sleepiness.
Collapse
Affiliation(s)
- Meredith Spindler
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA Parkinson's Disease Research, Education, and Clinical Center, Philadelphia Veterans Affairs Medical Center, Philadelphia, PA, USA
| | | | | | | | | | | |
Collapse
|
21
|
Santos PCRD, Barbieri FA, Orcioli-Silva D, Simieli L, Gobbi LTB. Effects of Physical Activity Levels on Fatigue Perception in Patients with Parkinson’s Disease and Neurologically Healthy Individuals. Health (London) 2014. [DOI: 10.4236/health.2014.621331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
22
|
Most Frequently Observed Risk Factors for Adult Inpatient Injurious Falls in Hospitals. CLIN NURSE SPEC 2013; 27:314-22. [DOI: 10.1097/nur.0b013e3182a87271] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
23
|
Body Weight-Supported High-Intensity Locomotor Training and Adapted Physical Activity Program in Patients With Parkinson's Disease: A Complementary Approach? Arch Phys Med Rehabil 2013; 94:2032-3. [DOI: 10.1016/j.apmr.2013.02.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 02/17/2013] [Indexed: 11/20/2022]
|
24
|
Falup-Pecurariu C. Fatigue assessment of Parkinson’s disease patient in clinic: specific versus holistic. J Neural Transm (Vienna) 2013; 120:577-81. [DOI: 10.1007/s00702-013-0969-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Accepted: 01/04/2013] [Indexed: 10/27/2022]
|