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Influence of dual-task on sit-to-stand-to-sit postural control in Parkinson's disease Ângela Fernandes PDF

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Preview Influence of dual-task on sit-to-stand-to-sit postural control in Parkinson's disease Ângela Fernandes

Title: Influence of dual-task on sit-to-stand-to-sit postural control in Parkinson’s disease Ângela Fernandes (PhD) Escola Superior da Tecnologia de Saúde do Instituto Politécnico do Porto, Área Científica de Terapia Ocupacional, Centro de Estudo do Movimento e da Atividade Humana, PORTUGAL Faculdade de Engenharia, Universidade do Porto, PORTUGAL E-mail: [email protected] Andreia S. P. Sousa (PhD) Escola Superior da Tecnologia de Saúde do Instituto Politécnico do Porto, Área Científica de Fisioterapia, Centro de Estudo do Movimento e da Atividade Humana, PORTUGAL E-mail: [email protected]   Joana Couras (BSc) Escola Superior de Tecnologia da Saúde do Instituto Politécnico do Porto, Área Cientifica de Terapia Ocupacional, PORTUGAL E-mail: [email protected] Nuno Rocha (PhD) Escola Superior da Tecnologia de Saúde do Instituto Politécnico do Porto, Área Científica de Terapia Ocupacional, Laboratório de Reabilitação Psicossocial, Centro de Estudo do Movimento e da Atividade Humana, PORTUGAL 1 E-mail: [email protected] João Manuel R. S. Tavares (PhD) Instituto de Ciência e Inovação em Engenharia Mecânica e Engenharia Industrial, Departamento de Engenharia Mecânica, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, PORTUGAL E-mail: [email protected] Phone: +351 22 508 1487 / FAX: Phone: +351 22 508 1445 (corresponding author) 1   Abstract   2   Postural control deficits are the most disabling aspects of Parkinson's disease (PD), 3   resulting in decreased mobility and functional independence. The aim of this study was 4   to assess the postural control stability, revealed by variables based on the centre of 5   pressure (CoP), in individuals with PD while performing a sit-to-stand-to-sit sequence 6   under single- and dual-task conditions.   7   An observational, analytical and cross-sectional study was performed. The sample 8   consisted of 9 individuals with PD and 9 healthy controls. A force platform was used to 9   measure the CoP displacement and velocity during the sit-to-stand-to-sit sequence. The 10   results were statistically analysed.   11   Individuals with PD required greater durations for the sit-to-stand-to-sit sequence than 12   the controls (p<0.05). The anteroposterior and mediolateral CoP displacement were 13   higher in the individuals with PD (p<0.05). However, only the anteroposterior CoP 14   velocity in the stand-to-sit phase (p=0.006) was lower in the same individuals. 15   Comparing the single- and dual-task conditions in both groups, the duration, the 16   anteroposterior CoP displacement and velocity were higher in the dual-task condition 17   (p<0.05). 18   The individuals with PD presented reduced postural control stability during the sit-to- 19   stand-to-sit sequence, especially when under the dual-task condition. These individuals 20   have deficits not only in motor performance, but also in cognitive performance when 21   performing the sit-to-stand-to-sit sequence in their daily life tasks. Moreover, both 22   deficits tend to be intensified when two tasks are performed simultaneously. 23     24   Keywords:  Dual-task; Parkinson's; Postural Control; Sit-to-Stand-to-Sit.   25   1 26   1. INTRODUCTION 27   Parkinson's disease (PD) is considered the second most common neurodegenerative 28   disorder, affecting about 1% of the world's current population (1, 2). Some projections 29   indicate a large increase of this prevalence over the coming decades (2). 30   At the moment, the aetiology is explained by genetic predisposition and the presence of 31   toxic environmental factors (3, 4). The majority of individuals with PD present an 32   inadequate interaction between systems responsible for body balance, including the 33   vestibular, visual and proprioceptive systems. Consequently, these individuals tend to 34   shift their centre of gravity forward, and therefore, have difficulty to perform 35   compensatory movements to require balance (5). The transition from sitting to standing 36   and standing to sitting are components of some everyday functional tasks that are highly 37   demanding from a postural control perspective. In fact, the sit-to-stand-to-sit (STSTS) 38   sequence implies the involvement of anticipatory postural adjustments (APAs) to 39   movement performance (6-8). Hence, the study concerning the STSTS sequence can 40   contribute to clarify postural control requirements during daily activities. The variability 41   and efficiency of functional movements require an appropriate postural control that 42   depends on APAs to maintain stability of internal and external disturbances, taking into 43   account the context and the task (9). The planning of APAs involves various structures 44   of the central nervous system (CNS), such as the pre-motor cortex, supplementary 45   motor area, basal ganglia and cerebellum (10, 11) that, through independent channels, 46   convey information to the reticular formation, such as the pedunculopontine nucleus, 47   which is important to modulate the APAs (12). The neural connection between the basal 48   ganglia and the pedunculopontine nucleus is through the corticostriatal-pallidum- 49   pedunculopontine circuit, which is compromised in individuals with PD leading to 50   postural control deficits. This is manifested in the changes in the activation of postural 2 51   muscles in the form of APAs (10, 13-15). As the CNS is responsible for the motor 52   modulation circuits, which are compromised in individuals with PD, there is a decrease 53   in postural control and consequently, repercussions in the performance of tasks, like 54   STSTS sequences (16-18). This decreased postural control was demonstrated through 55   CoP displacement variables. The CoP displacement reflects the orientation of body 56   segments and corrective responses that control the centre of mass over the base of 57   support (19), resulting from the combination of descending motor commands and the 58   mechanical properties of the surrounding muscles (20). In situations of dual-task, the 59   use of cortical resources to perform motor tasks can affect or influence the performance 60   of one or both tasks (21-23). Despite the importance of the postural control stability for 61   the STSTS sequence performance and the impact of PD on the postural control system, 62   few studies have assessed these issues and only the sit-to-stand sequence has been 63   addressed. Additionally, no study has evaluated this task under high cognitive 64   demanding conditions. Based on these facts, the objective of the present study was to 65   analyse the postural control stability in individuals with PD in single- and dual-task 66   conditions. More specifically, the postural stability was assessed through representative 67   CoP displacement variables in the anteroposterior and mediolateral directions 68   (displacements and velocities), in the five phases of the STSTS sequence in single- and 69   dual-task conditions. Based on the results obtained by Bhatt et al. (16) and on the neural 70   dysfunction involving postural control pathways, a reduced postural control stability in 71   individuals with PD can be hypothesised during the preforming of the STSTS sequence. 72   This reduced stability would be amplified in these individuals when the STSTS 73   sequence is performed in the dual-task condition. 74       75   2. MATERIALS AND METHODS 3 76   2.1. Study Design and Participants 77   A cross-sectional study was implemented using a non-probabilistic (24) sample of 9 78   individuals with PD and 9 healthy controls, aged between 52 and 80 years old. The 79   individuals diagnosed with PD were patients from the Parkinson's Association, Porto, in 80   Portugal, while the healthy controls were community-dwelling volunteers, mainly from 81   Porto. 82   Subjects were excluded if they presented one of the following criteria: severe cognitive 83   impairment (screened using the Montreal Cognitive Assessment (MoCA) test (25)); 84   incapable of performing the sit-to-stand or stand-to-sit sequence independently; and 85   unable to speak. Severely disabled PD patients (> 3 Hoehn and Yahr scale (26)), 86   patients diagnosed with any other neuromuscular disease, and those who had undergone 87   deep brain stimulation through subthalamic surgery or were taking cholinergic 88   medication were also excluded. Healthy controls that had been diagnosed as adults with 89   any neuromuscular disorder or that could not be considered sedentary according to the 90   Centre for Disease Control for the American College of Sports Medicine, were also 91   excluded (27). 92   A trained researcher conducted the data collection based on a structured protocol. The 93   study was approved by the Ethical Review Board of “Escola Superior de Tecnologia da 94   Saúde - Instituto Politécnico do Porto”, in Portugal. Written informed consent, 95   according to the Helsinki Declaration, was obtained from all participants.     96     97   2.2. Instruments 98   The data collected from all participants included the sociodemographic characteristics 99   age, gender, height, weight and level of education, and years of disease, cognitive 100   performance (assessed using the MoCA test), Hoehn and Yahr scale and the CoP data 4 101   acquired using a force platform (model FP4060-8 from Bertec Corporation (USA)) 102   under the single- and dual-task conditions. 103   The scale of Hoehn & Yahr (1967) evaluates the severity of overall dysfunction in 104   individuals with PD. It is a 7-point scale, in which each point represents a different 105   stage of the disease (stages 1 to 5, including 1.5 and 2.5). The scale increases with the 106   severity of dysfunction along with the stage of the disease (26). The MoCA test consists 107   of eight fields: visuospatial, nomination, memory, attention, language, abstraction, 108   deferred evocation and orientation. The performance of an individual is calculated by 109   the addition of the scores obtained in each of the domains, and the maximum that can be 110   reached is equal to 30 points (25, 28). 111   For the evaluation of the postural control, the data from the force platform was acquired 112   at a sampling rate of 1000 Hz (29). The platform was connected to a Bertec AM 6300 113   amplifier (USA) and in turn, this was connected to an analog-digital converter from 114   Biopac Systems, Inc. (USA), and to an analog board of Qualysis Track Manager 115   (Sweden) that can be used for stabilometric analyses. The stabilometric measurements 116   comprise the assessment of balance in the orthostatic position through body movements, 117   taking into account the anteroposterior (Fx), mediolateral (Fy) and vertical (Fz) 118   components of the ground reaction force. For this, it is necessary to monitor the 119   movement of the CoP in the anteroposterior (CoPAP) and mediolateral (CoPML) 120   directions (30). The signal related to the CoP movement was filtered using a fourth- 121   order Butterworth low pass filter with a cut-off frequency of 20 Hz (31). 122   The attention level and consequently, the motor control perturbations were attained 123   through a cognitive secondary task, namely the Stroop colour word test. This test 124   consists in the enunciation of the visual colour instead of the written one. The number 5 125   of errors and the number of named items were used for analysis (32) during a pre- 126   defined time (60 seconds) for both groups. 127     128   2.3. Procedures 129   After an explanation of all the procedures involved, all individuals performed the study 130   with shorts and standard shoes (33). The height of the chair seat was adjusted to 100% 131   of the lower leg length (from the knee joint to the ground), and 2/3 of the femur 132   supported on the seat was used as a reference for the subjects to be considered in the 133   sitting position. In the single-task condition, the subjects were asked to rise from sitting 134   with a self-selected speed without using their upper limbs (34), then remain for 60 135   seconds in the standing position, looking at a point two meters away at eye level. After 136   this interval, subjects were instructed to sit, again without any kind of support and at a 137   self-selected speed. In the dual-task condition, all the previous procedures were 138   repeated; however, the subjects were required to perform the Stroop test during the 139   performing of the STSTS sequence (28). The test words in different colours were 140   projected on a wall at eye level. The subjects were instructed to name the colour instead 141   of reading the word and no other specific instructions were given. The words were 142   present according to each participant’s responses during a pre-defined period of 60 143   seconds. A one minute rest between each trial was allowed, and the necessary 144   repetitions were performed in order to obtain three valid trials for each subject. 145   The CoP displacement variables were analysed over the five phases of the STSTS 146   sequence. For this, the sit-to-stand-to sit sequence was divided into five phases: sitting 147   phase - phase 1, sit-to-stand phase - phase 2, standing phase - phase 3, stand-to-sit phase 148   - phase 4, and sitting phase - phase 5. The procedures used to identify the phases are 149   shown in Table 1. 6 150   < Insert Table 1 about here > 151   152   The data acquisition was always performed by the same investigator to ensure the 153   reproducibility of the procedures. The data analysis was performed using the Matlab 154   software (MathWorks, USA) and Acqknowledge software (Biopac Systems, Inc. USA). 155       156   2.4. Statistical Analysis 157   Descriptive statistical analyses were performed using proportions and measures of 158   central tendency and dispersion. 159   The independent sample t test and Chi square test were performed to examine whether 160   there were significant differences between the groups in terms of the sociodemographic 161   and anthropometric variables. The multiple analysis of variance (MANOVA) test was used 162   to analyse the interaction between the groups (PD and controls) and the conditions 163   (single- and dual-task). The Bonferroni analysis was used as a post-hoc test to 164   determine the differences in single- and dual- task conditions in each group and to 165   determine for each condition the differences between the groups (PD and controls). The 166   number of errors and the number of correctly named items for the Stroop test were used 167   as covariates in the analysis. Two-tailed tests were used in all analyses, and p < 0.05 168   was adopted for statistical significance. All statistical analyses were conducted using 169   IBM SPSS Statistics 22.0 (SPSS, Inc., Chicago, IL, USA). 170   171   3. RESULTS 172   The 9 PD individuals (66.7% male) had a mean age of 66 years old (standard deviation 173   (SD) = 8.2), a mean education of 7.7 years (SD = 5.6) and a mean number of years with 174   PD 10.22 (SD 5.38). Most of these participants were classified in stage 1 and 1.5 of the 7 175   Hoehn and Yahr scale. The 9 healthy controls (44.4% male) had a mean age of 63.9 176   years (SD = 8.1) and a mean education of 7.8 years (SD = 4.6). The Mann-Whitney test 177   and chi-square test showed no significant differences between the two groups studied, 178   Table 2. 179   180   < Insert Table 2 about here > 181   182   The MANOVA test showed that in phase 1, no significant differences were found 183   between the groups (between-subjects) or conditions (within-subjects) and also no 184   significant interaction was found between group and condition, Table 3. 185   186   < Insert Table 3 about here > 187   188   In phase 2, a significant difference between the groups was found. The individuals with 189   PD presented a greater duration (p=0.047) compared to the healthy controls. The Post- 190   hoc analysis showed that these differences occurred only in the dual-task condition 191   (p=0.005). However, no differences between conditions or any significant interaction 192   between groups and conditions were found. 193   In phase 3, the differences between groups were found in terms of the duration and 194   CoPAP displacement. The duration was significantly greater in the PD individuals than 195   in the healthy controls (p<0.001). These differences occurred both under single- 196   (p<0.001) and dual-task (p=0.004) conditions. The CoPAP displacement was 197   significantly higher in the individuals with PD in comparison to the healthy controls 198   (0.015). The Post-hoc analysis showed that these differences occurred under the dual- 8

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Title: Influence of dual-task on sit-to-stand-to-sit postural control in Parkinson's disease. Ângela Fernandes (PhD). Escola Superior da Tecnologia de
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