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Calderón-Juárez M, Cruz-Vega IB, González-Gómez GH, Lerma C. Nonlinear Dynamics of Heart Rate Variability after Acutely Induced Myocardial Ischemia by Percutaneous Transluminal Coronary Angioplasty. ENTROPY (BASEL, SWITZERLAND) 2023; 25:469. [PMID: 36981358 PMCID: PMC10047678 DOI: 10.3390/e25030469] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/02/2023] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
Several heart rate variability (HRV) characteristics of patients with myocardial ischemia are associated with a higher mortality risk. However, the immediate effect of acute ischemia on the HRV nonlinear dynamical behavior is unknown. The objective of this work is to explore the presence of nonlinearity through surrogate data testing and describe the dynamical behavior of HRV in acutely induced ischemia by percutaneous transluminal coronary angioplasty (PTCA) with linear and recurrence quantification analysis (RQA). Short-term electrocardiographic recordings from 68 patients before and after being treated with elective PTCA were selected from a publicly available database. The presence of nonlinear behavior was confirmed by determinism and laminarity in a relevant proportion of HRV time series, in up to 29.4% during baseline conditions and 30.9% after PTCA without statistical difference between these scenarios. After PTCA, the mean value and standard deviation of HRV time series decreased, while determinism and laminarity values increased. Here, the diminishment in overall variability caused by PTCA is not accompanied by a change in nonlinearity detection. Therefore, the presence of nonlinear behavior in HRV time series is not necessarily in agreement with the change of traditional and RQA measures.
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Affiliation(s)
- Martín Calderón-Juárez
- Plan de Estudios Combinados en Medicina, Faculty of Medicine, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; (M.C.-J.); (I.B.C.-V.)
- Department of Electromechanical Instrumentation, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City 04480, Mexico
| | - Itayetzin Beurini Cruz-Vega
- Plan de Estudios Combinados en Medicina, Faculty of Medicine, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; (M.C.-J.); (I.B.C.-V.)
| | | | - Claudia Lerma
- Department of Electromechanical Instrumentation, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City 04480, Mexico
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Temporal clusters of age-related behavioral alterations captured in smartphone touchscreen interactions. iScience 2022; 25:104791. [PMID: 36039357 PMCID: PMC9418599 DOI: 10.1016/j.isci.2022.104791] [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: 12/30/2021] [Revised: 05/02/2022] [Accepted: 07/14/2022] [Indexed: 11/24/2022] Open
Abstract
Smartphones touchscreen interactions may help resolve if and how real-world behavioral dynamics are shaped by aging. Here, in a sample spanning the adult life span (16 to 86 years, N = 598, accumulating 355 million interactions), we clustered the smartphone interactions according to their next inter-touch interval dynamics. There were age-related behavioral losses at the clusters occupying short intervals (∼100 ms, R2 ∼ 0.8) but gains at the long intervals (∼4 s, R2 ∼ 0.4). Our approach revealed a sophisticated form of behavioral aging where individuals simultaneously demonstrated accelerated aging in one behavioral cluster versus a deceleration in another. Contrary to the common notion of a simple behavioral decline with age based on conventional cognitive tests, we show that the nature of aging systematically varies according to the underlying dynamics. Of all the imaginable factors determining smartphone interactions, age-sensitive cognitive and behavioral processes may dominatingly shape smartphone dynamics. The timing of smartphone touchscreen interactions varies from one person to the next A diverse range of interactions was studied by quantifying the next interval dynamics The smartphone dynamics reflected the performance in cognitive tests and age The way aging shapes behavior may depend on its underlying temporal dynamics
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Dressing A, Bormann T, Blazhenets G, Schroeter N, Walter LI, Thurow J, August D, Hilger H, Stete K, Gerstacker K, Arndt S, Rau A, Urbach H, Rieg S, Wagner D, Weiller C, Meyer PT, Hosp JA. Neuropsychological profiles and cerebral glucose metabolism in neurocognitive Long COVID-syndrome. J Nucl Med 2021; 63:1058-1063. [PMID: 34649946 PMCID: PMC9258569 DOI: 10.2967/jnumed.121.262677] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 10/04/2021] [Indexed: 11/16/2022] Open
Abstract
During the Corona Virus Disease 2019 (COVID-19) pandemic, Long COVID-syndrome, which impairs patients through cognitive deficits, fatigue, and exhaustion, has become increasingly relevant. Its underlying pathophysiology, however, is unknown. In this study, we assessed cognitive profiles and regional cerebral glucose metabolism as a biomarker of neuronal function in outpatients suffering from long-term neurocognitive symptoms after COVID-19. Methods: Outpatients seeking neurological counseling with neurocognitive symptoms persisting for more than three months after polymerase chain reaction (PCR)-confirmed COVID-19 were included prospectively between June 16, 2020, and January 29, 2021. Patients (n = 31, 54±2.0 years) in the long-term phase after COVID-19 (202±58 days after positive PCR) were assessed with a neuropsychological test battery. Cerebral 18F-FDG PET imaging was performed in 14/31 patients. Results: Patients self-reported impaired attention, memory, and multitasking abilities (31/31), word-finding difficulties (27/31), and fatigue (24/31). Twelve of 31 patients could not return to the previous level of independence/employment. For all cognitive domains, average group results of the neuropsychological test-battery showed no impairment, but deficits (z-score<-1.5) were present on single-patient level mainly in the domain of visual memory (in 7/31; other domains ≤2/31). Mean MoCA performance (27/30 points) was above the cutoff-value for detection of cognitive impairment (< 26 points), although 9/31 patients performed slightly below this level (23-25 points). In the subgroup of patients who underwent 18F-FDG PET, we found no significant changes of regional cerebral glucose metabolism. Conclusion: Long COVID patients self-report uniform symptoms hampering their ability to work in a relevant fraction. However, cognitive testing showed minor impairments only on single-patient level approximately six months after the infection, whereas functional imaging revealed no distinct pathological changes. This clearly deviates from previous findings in subacute COVID-19 patients, suggesting that underlying neuronal causes are different and possibly related to the high prevalence of fatigue.
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Affiliation(s)
- Andrea Dressing
- Dept. of Neurology and Clinical Neuroscience, Medical Center - University of Freiburg, Germany
| | - Tobias Bormann
- Dept. of Neurology and Clinical Neuroscience, Medical Center - University of Freiburg, Germany
| | - Ganna Blazhenets
- Dept. of Nuclear Medicine, Medical Center - University of Freiburg, Germany
| | - Nils Schroeter
- Dept. of Neurology and Clinical Neuroscience, Medical Center - University of Freiburg, Germany
| | - Lea I Walter
- Dept. of Neurology and Clinical Neuroscience, Medical Center - University of Freiburg, Germany
| | - Johannes Thurow
- Dept. of Nuclear Medicine, Medical Center - University of Freiburg, Germany
| | - Dietrich August
- Division of Infectious Diseases, Dept. of Medicine II, Medical Center - University of Freiburg, Germany
| | - Hanna Hilger
- Division of Infectious Diseases, Dept. of Medicine II, Medical Center - University of Freiburg, Germany
| | - Katarina Stete
- Division of Infectious Diseases, Dept. of Medicine II, Medical Center - University of Freiburg, Germany
| | - Kathrin Gerstacker
- Dept. of Otorhinolaryngology - Head and Neck Surgery, Medical Center - University of Freiburg, Germany
| | - Susan Arndt
- Dept. of Otorhinolaryngology - Head and Neck Surgery, Medical Center - University of Freiburg, Germany
| | - Alexander Rau
- Dept. of Neuroradiology, Medical Center - University of Freiburg, Germany
| | - Horst Urbach
- Dept. of Neuroradiology, Medical Center - University of Freiburg, Germany
| | - Siegbert Rieg
- Division of Infectious Diseases, Dept. of Medicine II, Medical Center - University of Freiburg, Germany
| | - Dirk Wagner
- Division of Infectious Diseases, Dept. of Medicine II, Medical Center - University of Freiburg, Germany
| | - Cornelius Weiller
- Dept. of Neurology and Clinical Neuroscience, Medical Center - University of Freiburg, Germany
| | - Philipp T Meyer
- Dept. of Nuclear Medicine, Medical Center - University of Freiburg, Germany
| | - Jonas A Hosp
- Dept. of Neurology and Clinical Neuroscience, Medical Center - University of Freiburg, Germany
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Hussenoeder FS, Conrad I, Roehr S, Glaesmer H, Hinz A, Enzenbach C, Engel C, Witte V, Schroeter ML, Loeffler M, Thiery J, Villringer A, Riedel-Heller SG, Rodriguez FS. The association between mental demands at the workplace and cognitive functioning: the role of the big five personality traits. Aging Ment Health 2020; 24:1064-1070. [PMID: 31129995 DOI: 10.1080/13607863.2019.1617244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Objectives: Mental demands at the workplace can be preventive against cognitive decline. However, personality shapes the way information is processed and we therefore assume that Neuroticism, Extraversion, Openness, Agreeableness and Conscientiousness, would moderate the beneficial effects of workplace stimulation on cognitive outcomes.Methods: We analyzed data from the population-based LIFE-Adult-Study (n = 6529). Cognitive outcomes were assessed via the Trail-Making Test (TMTA, TMTB) and the Verbal Fluency Test. Personality was assessed via the Personality Adjective List (16 AM). Mental demands were classified with the indices Verbal and Executive based on the O*NET database.Results: Multivariate regression analyses showed only two significant moderation effects of personality, i.e. in individuals with low scores on Conscientiousness/Openness, index Verbal was connected to better TMTB performance, while this effect disappeared for individuals with high values on the personality trait. However, the additional explained variance remained marginal.Conclusion: The findings suggest that personality does not modify associations between high mental demands at work and better cognitive functioning in old age; however, there is a tendency that high levels of Openness and Conscientiousness may offset effects of mental demands.
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Affiliation(s)
- Felix S Hussenoeder
- Institute of Social Medicine, Occupational Health and Public Health, University of Leipzig, Leipzig, Germany
| | - Ines Conrad
- Institute of Social Medicine, Occupational Health and Public Health, University of Leipzig, Leipzig, Germany
| | - Susanne Roehr
- Institute of Social Medicine, Occupational Health and Public Health, University of Leipzig, Leipzig, Germany
| | - Heide Glaesmer
- Department of Medical Psychology and Medical Sociology, University of Leipzig, Leipzig, Germany
| | - Andreas Hinz
- Department of Medical Psychology and Medical Sociology, University of Leipzig, Leipzig, Germany
| | - Cornelia Enzenbach
- Institute for Medical Informatics, Statistics and Epidemiology (IMISE), University of Leipzig, Leipzig, Germany
| | - Christoph Engel
- Institute for Medical Informatics, Statistics and Epidemiology (IMISE), University of Leipzig, Leipzig, Germany
| | - Veronika Witte
- Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Matthias L Schroeter
- Clinic for Cognitive Neurology, Max-Planck-Institute for Human Cognitive and Brain Sciences and University Hospital Leipzig, Leipzig, Germany
| | - Markus Loeffler
- Institute for Medical Informatics, Statistics and Epidemiology (IMISE), University of Leipzig, Leipzig, Germany
| | - Joachim Thiery
- Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University of Leipzig, Leipzig, Germany
| | - Arno Villringer
- Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Steffi G Riedel-Heller
- Institute of Social Medicine, Occupational Health and Public Health, University of Leipzig, Leipzig, Germany
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Danielewska ME, Placek MM, Kicińska AK, Rękas M. Using the entropy of the corneal pulse signal to distinguish healthy eyes from eyes affected by primary open-angle glaucoma. Physiol Meas 2020; 41:055011. [PMID: 32299068 DOI: 10.1088/1361-6579/ab89c8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The purpose of this study was to evaluate whether the complexity of the corneal pulse (CP) signal can be used to differentiate patients with primary open-angle glaucoma (POAG) from healthy subjects. APPROACH The study sample consisted of 28 patients with POAG and a control, age-matched group of 30 subjects. After standard ophthalmic examination, the CP signal from a randomly selected eye of each participant was measured using non-contact ultrasonic micro-displacement measurement technology. After pre-processing, the complexity of the CP signal was estimated using refined composite multiscale fuzzy entropy (RCMFE) up to scale factor 50. The average RCMFE values were computed from three repeated measurements of the CP signals for each participant and each scale factor. MAIN RESULTS The complexity of the CP signal in glaucomatous eyes was higher than that observed in healthy ones. Also, RCMFE of the CP signal was found to differentiate (statistically significantly) between the two groups for scales in the range from 26 to 43. For these scales, the one for which the lowest p-value (t-test, p = 0.017) was obtained when comparing RCMFE between the two groups was selected as the optimal scale. Next, a receiver operating characteristic analysis for the optimal scale showed that the proposed approach of calculating the multiscale entropy of the CP signal has some potential to discriminate between patients with POAG and healthy controls (sensitivity, specificity and accuracy of 0.643, 0.700 and 0.672, respectively). SIGNIFICANCE In conclusion, RCMFE, as a complexity measure, may be considered an auxiliary indicator to support glaucoma diagnostics.
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Affiliation(s)
- Monika E Danielewska
- Department of Biomedical Engineering, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
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Chien JH, Mukherjee M, Siu KC, Stergiou N. Locomotor Sensory Organization Test: How Sensory Conflict Affects the Temporal Structure of Sway Variability During Gait. Ann Biomed Eng 2015; 44:1625-35. [PMID: 26329924 DOI: 10.1007/s10439-015-1440-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 08/26/2015] [Indexed: 01/11/2023]
Abstract
When maintaining postural stability temporally under increased sensory conflict, a more rigid response is used where the available degrees of freedom are essentially frozen. The current study investigated if such a strategy is also utilized during more dynamic situations of postural control as is the case with walking. This study attempted to answer this question by using the Locomotor Sensory Organization Test (LSOT). This apparatus incorporates SOT inspired perturbations of the visual and the somatosensory system. Ten healthy young adults performed the six conditions of the traditional SOT and the corresponding six conditions on the LSOT. The temporal structure of sway variability was evaluated from all conditions. The results showed that in the anterior posterior direction somatosensory input is crucial for postural control for both walking and standing; visual input also had an effect but was not as prominent as the somatosensory input. In the medial lateral direction and with respect to walking, visual input has a much larger effect than somatosensory input. This is possibly due to the added contributions by peripheral vision during walking; in standing such contributions may not be as significant for postural control. In sum, as sensory conflict increases more rigid and regular sway patterns are found during standing confirming the previous results presented in the literature, however the opposite was the case with walking where more exploratory and adaptive movement patterns are present.
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Affiliation(s)
- Jung Hung Chien
- Biomechanics Research Building, College of Education, University of Nebraska at Omaha, 6160 University Drive, Omaha, NE, 68182, USA
- Department of Environmental, Agricultural & Occupational Health, College of Public Health, University of Nebraska Medical Center, Omaha, NE, USA
| | - Mukul Mukherjee
- Biomechanics Research Building, College of Education, University of Nebraska at Omaha, 6160 University Drive, Omaha, NE, 68182, USA
| | - Ka-Chun Siu
- Division of Physical Therapy Education, College of Allied Health, University of Nebraska Medical Center, Omaha, NE, USA
| | - Nicholas Stergiou
- Biomechanics Research Building, College of Education, University of Nebraska at Omaha, 6160 University Drive, Omaha, NE, 68182, USA.
- Department of Environmental, Agricultural & Occupational Health, College of Public Health, University of Nebraska Medical Center, Omaha, NE, USA.
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Then FS, Luck T, Luppa M, Arélin K, Schroeter ML, Engel C, Löffler M, Thiery J, Villringer A, Riedel-Heller SG. Association between mental demands at work and cognitive functioning in the general population - results of the health study of the Leipzig research center for civilization diseases (LIFE). J Occup Med Toxicol 2014; 9:23. [PMID: 24914403 PMCID: PMC4049483 DOI: 10.1186/1745-6673-9-23] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 05/13/2014] [Indexed: 01/28/2023] Open
Abstract
Background The level of mental demands in the workplace is rising. The present study investigated whether and how mental demands at work are associated with cognitive functioning in the general population. Methods The analysis is based on data of the Health Study of the Leipzig Research Centre for Civilization Disease (LIFE). 2,725 participants aged 40–80 years underwent cognitive testing (Trail-Making Test, Verbal Fluency Test) and provided information on their occupational situation. Participants over the age of 65 years additionally completed the Mini-Mental State Examination. Mental demands at work were rated by a standardized classification system (O*NET). The association between mental demands and cognitive functioning was analyzed using Generalized Linear Modeling (GENLIN) adjusted for age, gender, self-regulation, working hour status, education, and health-related factors. Results Univariate as well as multivariate analyses demonstrated significant and highly consistent effects of higher mental demands on better performance in cognitive testing. The results also indicated that the effects are independent of education and intelligence. Moreover, analyses of retired individuals implied a significant association between high mental demands at work of the job they once held and a better cognitive functioning in old age. Conclusions In sum, our findings suggest a significant association between high mental demands at work and better cognitive functioning. In this sense, higher levels of mental demands – as brought about by technological changes in the working environment – may also have beneficial effects for the society as they could increase cognitive capacity levels and might even delay cognitive decline in old age.
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Affiliation(s)
- Francisca S Then
- Institute of Social Medicine, Occupational Health and Public Health (ISAP), Medical Faculty, University of Leipzig, Philipp-Rosenthal-Str. 55, 04103 Leipzig, Germany ; LIFE - Leipzig Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
| | - Tobias Luck
- Institute of Social Medicine, Occupational Health and Public Health (ISAP), Medical Faculty, University of Leipzig, Philipp-Rosenthal-Str. 55, 04103 Leipzig, Germany ; LIFE - Leipzig Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
| | - Melanie Luppa
- Institute of Social Medicine, Occupational Health and Public Health (ISAP), Medical Faculty, University of Leipzig, Philipp-Rosenthal-Str. 55, 04103 Leipzig, Germany
| | - Katrin Arélin
- LIFE - Leipzig Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany ; Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, and Clinic for Cognitive Neurology, University Hospital Leipzig, Leipzig, Germany
| | - Matthias L Schroeter
- LIFE - Leipzig Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany ; Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, and Clinic for Cognitive Neurology, University Hospital Leipzig, Leipzig, Germany
| | - Christoph Engel
- LIFE - Leipzig Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany ; Institute for Medical Informatics, Statistics and Epidemiology (IMISE), University of Leipzig, Leipzig, Germany
| | - Markus Löffler
- LIFE - Leipzig Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany ; Institute for Medical Informatics, Statistics and Epidemiology (IMISE), University of Leipzig, Leipzig, Germany
| | - Joachim Thiery
- Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics (ILM), University of Leipzig, Leipzig, Germany
| | - Arno Villringer
- Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, and Clinic for Cognitive Neurology, University Hospital Leipzig, Leipzig, Germany
| | - Steffi G Riedel-Heller
- Institute of Social Medicine, Occupational Health and Public Health (ISAP), Medical Faculty, University of Leipzig, Philipp-Rosenthal-Str. 55, 04103 Leipzig, Germany
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Karmakar C, Khandoker A, Begg R, Palaniswami M. Understanding ageing effects using complexity analysis of foot–ground clearance during walking. Comput Methods Biomech Biomed Engin 2013; 16:554-64. [DOI: 10.1080/10255842.2011.628943] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Sosnoff JJ, Newell KM. Aging and motor variability: a test of the neural noise hypothesis. Exp Aging Res 2011; 37:377-97. [PMID: 21800971 DOI: 10.1080/0361073x.2011.590754] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Experimental tests of the neural noise hypothesis of aging, which holds that aging-related increments in motor variability are due to increases in white noise in the perceptual-motor system, were conducted. Young (20-29 years old) and old (60-69 and 70-79 years old) adults performed several perceptual-motor tasks. Older adults were progressively more variable in their performance outcome, but there was no age-related difference in white noise in the motor output. Older adults had a greater frequency-dependent structure in their motor variability that was associated with performance decrements. The findings challenge the main tenet of the neural noise hypothesis of aging in that the increased variability of older adults was due to a decreased ability to adapt to the constraints of the task rather than an increment of neural noise per se.
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Affiliation(s)
- Jacob J Sosnoff
- Department of Kinesiology and Community Health and Beckman Institute of Advanced Science and Technology, University of Illinois at Urbana-Champaign, USA.
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Turnock MJE, Layne CS. Variations in linear and nonlinear postural measurements under achilles tendon vibration and unstable support-surface conditions. J Mot Behav 2010; 42:61-9. [PMID: 20018587 DOI: 10.1080/00222890903397103] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Reduced support-surface stability has been shown to attenuate the effect of Achilles tendon vibration on backward body displacement. In the present study, 20 participants performed a quiet, upright standing task on a stable and sway-referenced support, with and without vibration. The authors calculated equilibrium scores (ES), approximate entropy (ApEn), and mean and peak power spectral density frequencies of center-of-pressure variations. It was found that ES values decreased with the addition of vibration and in the sway-referenced support condition. ApEn values decreased with the addition of vibration but only with a stable support. Conversely, mean and peak frequencies increased with the addition of vibration, independent of support stability. These results suggest that the role of ankle proprioceptive input changes depending on support-surface characteristics and demonstrate the value of using both linear and nonlinear measures of postural sway.
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Affiliation(s)
- Matthew J E Turnock
- International Space University, Department of Health and Human Performance, Center for Neuromotor and Biomechanics Research, University of Houston, Houston, Texas 77004, USA
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Sample entropy tracks changes in electroencephalogram power spectrum with sleep state and aging. J Clin Neurophysiol 2009; 26:257-66. [PMID: 19590434 DOI: 10.1097/wnp.0b013e3181b2f1e3] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The regularity of electroencephalogram signals was compared between middle-aged (47.2 +/- 2.0 years) and elderly (78.4 +/- 3.8 years) female subjects in wake, nonrapid eye movement stages 2 and 3 (S-2, S-3), and rapid eye movement sleep. Signals from C3A2 leads of healthy subjects, acquired from polysomnograms obtained from the Sleep Heart Health Study, were analyzed using both sample entropy (SaEn) and power spectral analysis (delta, theta, alpha, and beta frequency band powers). SaEn changed systematically and significantly (P < 0.001) with sleep state in both age groups, following the relationships wake > rapid eye movement > S-2 > S-3. SaEn was found to be negatively correlated with delta power and positively correlated with beta power. Small changes in SaEn seem to reflect changes in spectral content rather than changes in regularity of the signal. A better predictor of SaEn than the frequency band powers was the logarithm of the power ratio (alpha + beta)/(delta + theta). Thus, SaEn seems to reflect the balance between sleep-promoting and alertness-promoting mechanisms. SaEn of the elderly was larger than that of middle-aged subjects in S-2 (P = 0.029) and rapid eye movement (P = 0.001), suggesting that cortical state is shifted toward alertness in elderly subjects in these sleep states compared with the middle-aged subjects.
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Nonlinear analysis of sitting postural sway indicates developmental delay in infants. Clin Biomech (Bristol, Avon) 2009; 24:564-70. [PMID: 19493596 DOI: 10.1016/j.clinbiomech.2009.05.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 04/28/2009] [Accepted: 05/03/2009] [Indexed: 02/07/2023]
Abstract
BACKGROUND Upright sitting is one of the first developmental motor milestones achieved by infants, and sitting postural sway provides a window into the developing motor control system. A variety of posture sway measures can be used, but the optimal measures for infant development have not been identified. METHODS We have collected sitting postural sway data from two groups of infants, one with typical development (n=33), and one with delayed development and either diagnosed with or at risk for cerebral palsy (n=26), when the infants had developed to the point where they could just maintain sitting for about 10s. Postural sway data was collected while infants were sitting on a force platform, and the center of pressure was analyzed using both linear and nonlinear measures. FINDINGS Our results showed that a nonlinear measure, the largest Lyapunov exponent, was the only parameter of postural sway that revealed significant differences between infants with typical versus delayed development. The largest Lyapunov exponent was found to be higher for typically developing infants, indicating less repeated patterning in their movement coordination. INTERPRETATIONS A nonlinear measure such as largest Lyapunov exponent may be useful as an identifier of pathology and as a yardstick for the success of therapeutic interventions.
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Hausdorff JM. Gait dynamics in Parkinson's disease: common and distinct behavior among stride length, gait variability, and fractal-like scaling. CHAOS (WOODBURY, N.Y.) 2009; 19:026113. [PMID: 19566273 PMCID: PMC2719464 DOI: 10.1063/1.3147408] [Citation(s) in RCA: 360] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Accepted: 05/11/2009] [Indexed: 05/06/2023]
Abstract
Parkinson's disease (PD) is a common, debilitating neurodegenerative disease. Gait disturbances are a frequent cause of disability and impairment for patients with PD. This article provides a brief introduction to PD and describes the gait changes typically seen in patients with this disease. A major focus of this report is an update on the study of the fractal properties of gait in PD, the relationship between this feature of gait and stride length and gait variability, and the effects of different experimental conditions on these three gait properties. Implications of these findings are also briefly described. This update highlights the idea that while stride length, gait variability, and fractal scaling of gait are all impaired in PD, distinct mechanisms likely contribute to and are responsible for the regulation of these disparate gait properties.
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Affiliation(s)
- Jeffrey M Hausdorff
- Movement Disorders Unit, Department of Neurology, Tel Aviv Sourasky Medical Center, Tel-Aviv 64239, Israel.
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Khandoker AH, Jelinek HF, Palaniswami M. Identifying diabetic patients with cardiac autonomic neuropathy by heart rate complexity analysis. Biomed Eng Online 2009; 8:3. [PMID: 19178728 PMCID: PMC2645418 DOI: 10.1186/1475-925x-8-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Accepted: 01/29/2009] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Cardiac autonomic neuropathy (CAN) in diabetes has been called a "silent killer", because so few patients realize that they suffer from it, and yet its effect can be lethal. Early sub clinical detection of CAN and intervention are of prime importance for risk stratification in preventing sudden death due to silent myocardial infarction. This study presents the usefulness of heart rate variability (HRV) and complexity analyses from short term ECG recordings as a screening tool for CAN. METHODS A total of 17 sets of ECG recordings during supine rest were acquired from diabetic subjects with CAN (CAN+) and without CAN (CAN-) and analyzed. Poincaré plot indexes as well as traditional time and frequency, and the sample entropy (SampEn) measure were used for analyzing variability (short and long term) and complexity of HRV respectively. RESULTS Reduced (p > 0.05)_Poincaré plot patterns and lower (p < 0.05) SampEn values were found in CAN+ group, which could be a practical diagnostic and prognostic marker. Classification Trees methodology generated a simple decision tree for CAN+ prediction including SampEn and Poincaré plot indexes with a sensitivity reaching 100% and a specificity of 75% (percentage of agreement 88.24%). CONCLUSION Our results demonstrate the potential utility of SampEn (a complexity based estimator) of HRV in identifying asymptomatic CAN.
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Affiliation(s)
- Ahsan H Khandoker
- Dept, of Electrical & Electronic Engineering, The University of Melbourne, Parkville, Victoria, Australia.
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16
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Abstract
Laboratory experiments show us that the deleterious character of accumulated novel age-specific mutations is reduced and made less variable with increased age. While theories of aging predict that the frequency of deleterious mutations at mutation-selection equilibrium will increase with the mutation's age of effect, they do not account for these age-related changes in the distribution of de novo mutational effects. Furthermore, no model predicts why this dependence of mutational effects upon age exists. Because the nature of mutational distributions plays a critical role in shaping patterns of senescence, we need to develop aging theory that explains and incorporates these effects. Here we propose a model that explains the age dependency of mutational effects by extending Fisher's geometrical model of adaptation to include a temporal dimension. Using a combination of simple analytical arguments and simulations, we show that our model predicts age-specific mutational distributions that are consistent with observations from mutation-accumulation experiments. Simulations show us that these age-specific mutational effects may generate patterns of senescence at mutation-selection equilibrium that are consistent with observed demographic patterns that are otherwise difficult to explain.
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Khandoker AH, Palaniswami M, Begg RK. A comparative study on approximate entropy measure and poincaré plot indexes of minimum foot clearance variability in the elderly during walking. J Neuroeng Rehabil 2008; 5:4. [PMID: 18241348 PMCID: PMC2268940 DOI: 10.1186/1743-0003-5-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Accepted: 02/02/2008] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Trip-related falls which is a major problem in the elderly population, might be linked to declines in the balance control function due to ageing. Minimum foot clearance (MFC) which provides a more sensitive measure of the motor function of the locomotor system, has been identified as a potential gait parameter associated with trip-related falls in older population. This paper proposes nonlinear indexes (approximate entropy (ApEn) and Poincaré plot indexes) of MFC variability and investigates the relationship of MFC with derived indexes of elderly gait patterns. The main aim is to find MFC variability indexes that well correlate with balance impairments. METHODS MFC data during treadmill walking for 14 healthy elderly and 10 elderly participants with balance problems and a history of falls (falls risk) were analysed using a PEAK-2D motion analysis system. ApEn and Poincaré plot indexes of all MFC data sets were calculated and compared. RESULTS Significant relationships of mean MFC with Poincaré plot indexes (SD1, SD2) and ApEn (r = 0.70, p < 0.05; r = 0.86, p < 0.01; r = 0.74, p < 0.05) were found in the falls-risk elderly group. On the other hand, such relationships were absent in the healthy elderly group. In contrast, the ApEn values of MFC data series were significantly (p < 0.05) correlated with Poincaré plot indexes of MFC in the healthy elderly group, whereas correlations were absent in the falls-risk group. The ApEn values in the falls-risk group (mean ApEn = 0.18 +/- 0.03) was significantly (p < 0.05) higher than that in the healthy group (mean ApEn = 0.13 +/- 0.13). The higher ApEn values in the falls-risk group might indicate increased irregularities and randomness in their gait patterns and an indication of loss of gait control mechanism. ApEn values of randomly shuffled MFC data of falls risk subjects did not show any significant relationship with mean MFC. CONCLUSION Results have implication for quantifying gait dynamics in normal and pathological conditions, thus could be useful for the early diagnosis of at-risk gait. Further research should provide important information on whether falls prevention intervention can improve the gait performance of falls risk elderly by monitoring the change in MFC variability indexes.
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Affiliation(s)
- Ahsan H Khandoker
- Department of Electrical & Electronic Engineering, The Universityof Melbourne, VIC 3010, Australia
| | - Marimuthu Palaniswami
- Department of Electrical & Electronic Engineering, The Universityof Melbourne, VIC 3010, Australia
| | - Rezaul K Begg
- Biomechanics Unit, Centre for Ageing, Rehabilitation, Exercise and Sport, Victoria University, VIC 8001, Australia
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Sosnoff JJ, Newell KM. Are visual feedback delays responsible for aging-related increases in force variability? Exp Aging Res 2007; 33:399-415. [PMID: 17886015 DOI: 10.1080/03610730701525311] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The current investigation examined if age-related differences in the control of isometric force production are related to an increase in visual motor processing time. Young and old adults produced isometric force production to a visually displayed target while visual feedback delay was manipulated over a broad range (50 to 3200 ms). The force output of the oldest age group was more variable across the range of delays, but only demonstrated enhanced time dependent structure at short delays. It is concluded that age differences in visual motor processing time contribute to decrements in both the feedback and feedforward control of force output.
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Affiliation(s)
- Jacob J Sosnoff
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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Slobounov SM, Haibach PS, Newell KM. Aging-related temporal constraints to stability and instability in postural control. Eur Rev Aging Phys Act 2006. [DOI: 10.1007/s11556-006-0012-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Abstract
In this study, we review the evidence that older adults tend to have both a shorter time to lose stability in the maintenance of standing posture and the functionally related but inverse problem of needing more time to reacquire stability in transitioning to a postural state. These age-related time limitations to processes of stability are hypothesized to enhance the probability of falling with aging and the problems that can occur in the transition between activities, such as sitting to standing and standing to walking. The potential role of fitness and health variables in mediating the temporal constraints on the acquisition and loss of postural stability in aging is discussed.
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Kavanagh JJ, Barrett RS, Morrison S. Age-related differences in head and trunk coordination during walking. Hum Mov Sci 2005; 24:574-87. [PMID: 16125264 DOI: 10.1016/j.humov.2005.07.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2005] [Revised: 06/27/2005] [Accepted: 07/14/2005] [Indexed: 10/25/2022]
Abstract
The purpose of this study was to examine the effect of ageing on the pattern and structure of head and trunk accelerations during walking. Head and trunk accelerations of young (n=8; mean=23 years, SD=4 years) and elderly (n=8; mean=74 years, SD=3 years) individuals were measured using triaxial accelerometers while performing preferred speed walking. Accelerations were examined using power-spectral analysis and measures of signal smoothness, regularity and coupling. No differences in walking speed or signal regularity were detected between age groups. Compared to the young participants, the elderly had (1) a greater proportion of signal power above 6 Hz for the trunk, (2) a smaller difference in signal smoothness between the trunk and head, (3) less signal smoothness in the mediolateral direction, and (4) a greater degree of directional coupling for the head compared to the trunk. Overall these results suggest that the pattern of head accelerations was relatively unaffected by age, and that both age groups achieved similar levels of head stability despite differences in trunk acceleration characteristics. The manner in which head stability was achieved differed between age groups, with the elderly employing an upper body coordination strategy that enhanced coupling between acceleration directions of the head compared to the trunk. The findings of this study also suggest that an absence of age-related differences in signal complexity at one level of postural system, combined with differences at another level, may provide information about the way in which the motor system prioritises postural control during gait.
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Affiliation(s)
- Justin J Kavanagh
- School of Physiotherapy and Exercise Science, Griffith University, Gold Coast, Queensland.
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21
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Abstract
Aging is associated with a progressive decline in physical and cognitive functions. The impact of age-dependent endocrine changes regulated by the central nervous system on the dynamics of neuronal behavior, neurodegeneration, cognition, biological rhythms, sexual behavior, and metabolism are reviewed. We also briefly review how functional deficits associated with increases in glucocorticoids and cytokines and declining production of sex steroids, GH, and IGF are likely exacerbated by age-dependent molecular misreading and alterations in components of signal transduction pathways and transcription factors.
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Affiliation(s)
- Roy G Smith
- Huffington Center on Aging, Baylor College of Medicine, One Baylor Plaza, M320, Houston, TX 77030, USA.
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Seely AJE, Macklem PT. Complex systems and the technology of variability analysis. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2004; 8:R367-84. [PMID: 15566580 PMCID: PMC1065053 DOI: 10.1186/cc2948] [Citation(s) in RCA: 240] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/21/2004] [Revised: 08/05/2004] [Accepted: 08/09/2004] [Indexed: 01/09/2023]
Abstract
Characteristic patterns of variation over time, namely rhythms, represent a defining feature of complex systems, one that is synonymous with life. Despite the intrinsic dynamic, interdependent and nonlinear relationships of their parts, complex biological systems exhibit robust systemic stability. Applied to critical care, it is the systemic properties of the host response to a physiological insult that manifest as health or illness and determine outcome in our patients. Variability analysis provides a novel technology with which to evaluate the overall properties of a complex system. This review highlights the means by which we scientifically measure variation, including analyses of overall variation (time domain analysis, frequency distribution, spectral power), frequency contribution (spectral analysis), scale invariant (fractal) behaviour (detrended fluctuation and power law analysis) and regularity (approximate and multiscale entropy). Each technique is presented with a definition, interpretation, clinical application, advantages, limitations and summary of its calculation. The ubiquitous association between altered variability and illness is highlighted, followed by an analysis of how variability analysis may significantly improve prognostication of severity of illness and guide therapeutic intervention in critically ill patients.
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Affiliation(s)
- Andrew J E Seely
- Thoracic Surgery and Critical Care Medicine, University of Ottawa, Ottawa, Ontario, Canada.
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Vaillancourt DE, Newell KM. Aging and the time and frequency structure of force output variability. J Appl Physiol (1985) 2003; 94:903-12. [PMID: 12571125 DOI: 10.1152/japplphysiol.00166.2002] [Citation(s) in RCA: 213] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study examined the time and frequency structure of force output in adult humans to determine whether the changes in complexity with age are dependent on external task demands. Healthy young (20-24 yr), old (60-69 yr), and older-old (75-90 yr) humans produced isometric force contractions to constant and sine wave targets that also varied in force level. First, force variability on each force task increased with advancing age. Second, both time and frequency analysis showed that the structure of the force output in the old and older-old adults was less complex in the constant-force level task and more complex in the sine wave force task. Third, the alterations in force output with aging were primarily due to low-frequency bands <4 Hz. These results support the postulation that the observed increase or decrease in physiological complexity with aging is influenced by the relatively fast time scale of external task demands (Vaillancourt DE and Newell KM. Neurobiol Aging 23: 1-11, 2002).
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Affiliation(s)
- David E Vaillancourt
- School of Kinesiology, University of Illinois at Chicago, Chicago, Illinois 60608, USA.
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