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The neural correlates of locomotion impairments observed in people with Parkinson's disease (PD) are not fully understood. We investigated whether people with PD present distinct brain electrocortical activity during usual walking and the approach phase of obstacle avoidance when compared to healthy individuals. Fifteen people with PD and fourteen older adults walked overground in two conditions: usual walking and obstacle crossing. Scalp electroencephalography (EEG) was recorded using a mobile 64-channel EEG system. Independent components were clustered using a k-means clustering algorithm. Outcome measures included absolute power in several frequency bands and alpha/beta ratio. During the usual walk, people with PD presented a greater alpha/beta ratio in the left sensorimotor cortex than healthy individuals. While approaching obstacles, both groups reduced alpha and beta power in the premotor and right sensorimotor cortices (balance demand) and increased gamma power in the primary visual cortex (visual demand). Only people with PD reduced alpha power and alpha/beta ratio in the left sensorimotor cortex when approaching obstacles. These findings suggest that PD affects the cortical control of usual walking, leading to a greater proportion of low-frequency (alpha) neuronal firing in the sensorimotor cortex. Moreover, the planning for obstacle avoidance changes the electrocortical dynamics associated with increased balance and visual demands. People with PD rely on increased sensorimotor integration to modulate locomotion.
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Doença de Parkinson , Córtex Sensório-Motor , Humanos , Idoso , Caminhada , Locomoção , AlgoritmosRESUMO
Falls are associated with impairment in postural control in people with Parkinson's disease (PwPD). We aimed to predict the fall risk through models combining postural responses with clinical and cognitive measures. Also, we compared the center of pressure (CoP) between PwPD fallers and non-fallers after unpredictable external perturbations. We expected that CoP parameters combined with clinical and cognitive measures would predict fall risk. Seventy-five individuals participated in the study. CoP parameters were measured during postural responses through five trials with unpredictable translations of the support-surface in posterior direction. Range and peak of CoP were analyzed in two periods: early and late responses. Time to peak (negative peak) and recovery time were analyzed regardless of the periods. Models included the CoP parameters in early (model 1), late responses (model 2), and temporal parameters (model 3). Clinical and cognitive measures were entered into all models. Twenty-nine participants fell at least once, and 46 PwPD did not fall during 12 months following the postural assessment. Range of CoP in late responses was associated with fall risk (p = .046). However, although statistically non-significant, this parameter indicated low accuracy in predicting fall risk (area under the curve = 0.58). Fallers presented a higher range of CoP in early responses than non-fallers (p = .033). In conclusion, although an association was observed between fall risk and range of CoP in late responses, this parameter indicated low accuracy in predicting fall risk in PwPD. Also, fallers demonstrate worse postural control during early responses after external perturbations than non-fallers, measured by CoP parameters.
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Doença de Parkinson , Acidentes por Quedas , Suscetibilidade a Doenças , Humanos , Equilíbrio PosturalRESUMO
BACKGROUND: Pharmacologic therapy is the primary treatment used to manage Parkinson's disease (PD) symptoms. However, it becomes less effective with time and some symptoms do not respond to medication. Complementary interventions are therefore required for PD. Recent studies have implemented transcranial direct current stimulation (tDCS) in combination with other modalities of interventions, such as physical and cognitive training. Although the combination of tDCS with physical and cognitive training seems promising, the existing studies present mixed results. Therefore, a systematic review of the literature is necessary. AIMS: This systematic review aims to (i) assess the clinical effects of tDCS when applied in combination with physical or cognitive therapies in people with PD and; (ii) analyze how specific details of the intervention protocols may relate to findings. METHODS: The search strategy detailed the technique of stimulation, population and combined interventions (i.e. cognitive and/or physical training). Only controlled studies were included. RESULTS: Seventeen of an initial yield of 408 studies satisfied the criteria. Studies involved small sample sizes. tDCS protocols and characteristics of combined interventions varied. The reviewed studies suggest that synergistic effects may be obtained for cognition, upper limb function, gait/mobility and posture when tDCS is combined with cognitive and/or motor interventions in PD. CONCLUSION: The reported results encourage further research to better understand the therapeutic utility of tDCS and to inform optimal clinical use in PD. Future studies in this field should focus on determining optimal stimulation parameters and intervention characteristics for maximal benefits in people with PD.
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Doença de Parkinson/terapia , Estimulação Transcraniana por Corrente Contínua/métodos , Humanos , MasculinoRESUMO
The aim of this study was to investigate obstacle clearance and its variability in individuals with Alzheimer dementia (AD) as well as healthy elderly individuals while they approached and crossed an obstacle in their path. Fifteen people with AD and 15 age-matched/sex-matched healthy individuals (control group) participated in this study. Clinical assessment of both groups was performed by a neuropsychiatrist. Spatial-temporal parameters of 5 trials of unobstructed walking and 5 trials of obstacle crossing during walking (approach and crossing phases) were measured using a 3-dimensional optoelectronic system. The results indicated that individuals with AD showed higher variability in the approach phase for stride length and the horizontal distance from their trailing limb foot to the obstacle. However, their gait variability in the crossing phase was similar to the control group. In addition, the individuals with AD were found to walk slowly and with a short stride length in both conditions. In conclusion, individuals with AD had increased gait variability while approaching an obstacle during walking, indicating a deficit in planning to avoid obstacles that could be related to cognitive disorders. However, gait variability during the crossing phase may not be indicative of cognitive disorders in AD.
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Doença de Alzheimer/diagnóstico , Doença de Alzheimer/psicologia , Transtornos Cognitivos/diagnóstico , Transtornos Cognitivos/psicologia , Marcha , Caminhada/psicologia , Idoso , Idoso de 80 Anos ou mais , Feminino , Marcha/fisiologia , Humanos , Masculino , Desempenho Psicomotor/fisiologia , Comportamento Espacial/fisiologia , Caminhada/fisiologiaRESUMO
BACKGROUND: Near-infrared spectroscopy (NIRS) technology has allowed for the measurement of cerebral and skeletal muscle oxygenation simultaneously during exercise. Since this technology has been growing and is now successfully used in laboratory and sports settings, this systematic review aimed to synthesize the evidence and enhance an integrative understanding of blood flow adjustments and oxygen (O2) changes (i.e., the balance between O2 delivery and O2 consumption) within the cerebral and muscle systems during exercise. METHODS: A systematic review was conducted using PubMed, Embase, Scopus, and Web of Science databases to search for relevant studies that simultaneously investigated cerebral and muscle hemodynamic changes using the near-infrared spectroscopy system during exercise. This review considered manuscripts written in English and available before February 9, 2023. Each step of screening involved evaluation by 2 independent authors, with disagreements resolved by a third author. The Joanna Briggs Institute Critical Appraisal Checklist was used to assess the methodological quality of the studies. RESULTS: Twenty studies were included, of which 80% had good methodological quality, and involved 290 young or middle-aged adults. Different types of exercises were used to assess cerebral and muscle hemodynamic changes, such as cycling (nâ¯=â¯11), treadmill (nâ¯=â¯1), knee extension (nâ¯=â¯5), isometric contraction of biceps brachii (nâ¯=â¯3), and duet swim routines (nâ¯=â¯1). The cerebral hemodynamics analysis was focused on the frontal cortex (nâ¯=â¯20), while in the muscle, the analysis involved vastus lateralis (nâ¯=â¯18), gastrocnemius (nâ¯=â¯3), biceps brachii (nâ¯=â¯5), deltoid (nâ¯=â¯1), and intercostal muscle (nâ¯=â¯1). Overall, muscle deoxygenation increases during exercise, reaching a plateau in voluntary exhaustion, while in the brain, oxyhemoglobin concentration increases with exercise intensity, reaching a plateau or declining at the exhaustion point. CONCLUSION: Muscle and cerebral oxygenation respond differently to exercise, with muscle increasing O2 utilization and cerebral tissue increasing O2 delivery during exercise. However, at the exhaustion point, both muscle and cerebral oxygenation become compromised. This is characterized by a reduction in blood flow and a decrease in O2 extraction in the muscle, while in the brain, oxygenation reaches a plateau or decline, potentially resulting in motor failure during exercise.
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Encéfalo , Exercício Físico , Músculo Esquelético , Consumo de Oxigênio , Espectroscopia de Luz Próxima ao Infravermelho , Humanos , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiologia , Músculo Esquelético/irrigação sanguínea , Consumo de Oxigênio/fisiologia , Exercício Físico/fisiologia , Encéfalo/metabolismo , Encéfalo/fisiologia , Encéfalo/irrigação sanguínea , Hemodinâmica/fisiologia , Oxigênio/metabolismo , Oxigênio/sangue , Circulação Cerebrovascular/fisiologia , AdultoRESUMO
BACKGROUND: Impairments in postural responses to perturbation are common in people with Parkinson's disease (PwPD) and lack effective treatment. We recently showed that a single session of transcranial direct current stimulation (tDCS) promotes acute improvement of postural response to perturbation in PwPD. However, the effects of multiple tDCS sessions remain unclear. RESEARCH QUESTION: What is the efficacy of eight sessions of anodal tDCS on postural responses to external perturbation in PwPD? METHODS: Twenty-two PwPD participated in this randomized, double-blind, parallel-arm, and sham-controlled study. Participants were randomly distributed into active (a-tDCS; n=11) or sham stimulation (s-tDCS; n=11). Eight tDCS sessions were applied over the primary motor cortex (M1), with the a-tDCS group receiving 2â¯mA for 20â¯minutes. Postural responses to external perturbations were assessed before, 48â¯hours after, and one month after (follow-up) the completion of tDCS sessions. Primary outcome measures included the onset latency of medial gastrocnemius (MG) muscle and range of center of pressure. Secondary outcomes included electromyography and CoP parameters, and prefrontal cortex (PFC) activity. RESULTS: ANOVA revealed a trend for Group*Moment interaction for MG onset latency (p=0.058). a-tDCS tended to have shorter MG onset latency at post-test (p=0.040; SRM = -0.63) compared to pre-test. For the secondary outcomes, only a-tDCS decreased the time taken to recover balance after the perturbation at post-test and follow-up compared to pre-test (both p<0.001; SRM=-1.42 and -1.53, respectively). Also, only a-tDCS demonstrated lower PFC activity at post-test compared to pre-test (p=0.017; SRM = -0.82) and follow-up (p=0.001). SIGNIFICANCE: Eight sessions of tDCS over M1 improved postural response to perturbation in PwPD. Some benefits lasted for at least a month. Neuromuscular and behavioral changes observed after the intervention were accompanied by decreased PFC activity (executive-attentional control), suggesting that tDCS applied over M1 can improve movement automaticity.
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Gait impairments negatively affect the quality of life of people with Parkinson's disease (PwPD). Aerobic exercise (AE) is an alternative to alleviate these impairments and its combination with transcranial direct current stimulation (tDCS) has demonstrated synergistic effects. However, the effect of multitarget tDCS application (i.e., motor, and prefrontal cortices simultaneously) combined with physical exercise on gait impairments is still little known. Thus, the proposed randomized clinical trial will verify the acute effects of AE combined with tDCS applied on motor and prefrontal cortices separately and simultaneously on gait (spatial-temporal and cortical activity parameters) in PwPD. Twenty-four PwPD in Hoehn & Yahr stages I-III will be recruited for this crossover study. PwPD will practice AE on treadmill simultaneously with the application of anodal tDCS during four intervention sessions on different days (â¼ one week of interval). Active tDCS will be applied to the primary motor cortex, prefrontal cortex, and both areas simultaneously (multitarget), with an intensity of 2 mA for 20 min. For sham, the stimulation will remain at 2 mA for 10 s. The AE will last a total of 30 min, consisting of warm-up, main part (20 min with application of tDCS), and recovery. Exercise intensity will be controlled by heart rate. Spatial-temporal and cortical activity parameters will be acquired before and after each session during overground walking, walking with obstacle avoidance, and walking with a cognitive dual task at self-preferred velocity. An accelerometer will be positioned on the fifth lumbar vertebra to obtain the spatial-temporal parameters (i.e., step length, duration, velocity, and swing phase duration). Prefrontal cortex activity will be recorded from a portable functional near-infrared spectroscopy system and oxygenated and deoxygenated hemoglobin concentrations will be analyzed. Two-way ANOVAs with repeated measures for stimulation and moment will be performed. The findings of the study may contribute to improving gait in PwPD. Trial registration: Brazilian Clinical Trials Registry (RBR-738zkp7).
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Exercício Físico , Marcha , Doença de Parkinson , Estimulação Transcraniana por Corrente Contínua , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Cross-Over , Exercício Físico/fisiologia , Teste de Esforço , Terapia por Exercício/métodos , Marcha/fisiologia , Córtex Motor/fisiopatologia , Doença de Parkinson/terapia , Doença de Parkinson/fisiopatologia , Córtex Pré-Frontal/fisiopatologia , Córtex Pré-Frontal/fisiologia , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Estimulação Transcraniana por Corrente Contínua/métodosRESUMO
BACKGROUND: Balance impairments in people with Parkinson's disease (PD) demonstrated mainly in challenging postural tasks, such as increased body oscillation may be attributed to the deficits in the brain structures functionality involved in postural control (e.g., motor cortex, midbrain, and brainstem). Although promising results, the effect of transcranial direct current stimulation (tDCS) on postural control in people with PD is unclear, especially in objective measures such as the center of pressure (CoP) parameters. Thus, we analyzed the effects of a single session of tDCS on the CoP parameters during the adapted tandem position in people with PD. METHODS: Nineteen people with PD participated in this crossover, randomized, and double-blind study. Anodal tDCS was applied over the primary motor cortex in two conditions of stimulation (2 mA/active and sham) on two different days for 20 min immediately before the postural control evaluation. Participants remained standing in an adapted tandem position for the postural control assessment for 30 s (three trials). CoP parameters were acquired by a force plate. RESULTS: No significant differences were demonstrated between stimulation conditions (p-value range = 0.15-0.89). CONCLUSIONS: Our results suggested that a single session of tDCS with 2 mA does not improve the postural control of people with PD during adapted tandem.
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Doença de Parkinson , Estimulação Transcraniana por Corrente Contínua , Humanos , Estimulação Transcraniana por Corrente Contínua/métodos , Projetos Piloto , Doença de Parkinson/terapia , Equilíbrio Postural/fisiologia , Método Duplo-CegoRESUMO
Postural instability is common in neurological diseases. Although transcranial direct current stimulation (tDCS) seems to be a promising complementary therapy, emerging evidence indicates mixed results and protocols' characteristics. We conducted a systematic review and meta-analysis on PubMed, EMBASE, Scopus, and Web of Science to synthesize key findings of the effectiveness of single and multiple sessions of tDCS alone and combined with other interventions on balance in adults with neurological disorders. Thirty-seven studies were included in the systematic review and 33 in the meta-analysis. The reviewed studies did not personalize the stimulation protocol to individual needs/characteristics. A random-effects meta-analysis indicated that tDCS alone (SMD = -0.44; 95%CI = -0.69/-0.19; p < 0.001) and combined with another intervention (SMD = -0.31; 95%CI = -0.51/-0.11; p = 0.002) improved balance in adults with neurological disorders (small to moderate effect sizes). Balance improvements were evidenced regardless of the number of sessions and targeted area. In summary, tDCS is a promising therapy for balance rehabilitation in adults with neurological disorders. However, further clinical trials should identify factors that influence responsiveness to tDCS for a more tailored approach, which may optimize the clinical use of tDCS.
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Doenças do Sistema Nervoso , Reabilitação do Acidente Vascular Cerebral , Acidente Vascular Cerebral , Estimulação Transcraniana por Corrente Contínua , Atividades Cotidianas , Humanos , Doenças do Sistema Nervoso/terapia , Reabilitação do Acidente Vascular Cerebral/métodos , Estimulação Transcraniana por Corrente Contínua/métodosRESUMO
BACKGROUND: Postural response impairments in postural instability and gait disorders (PIGD) subtype patients may be attributed to Parkinson's disease (PD)-deterioration in central-set (programing/modulating of central outputs during motor responses). Although additional information improves some PD motor impairments, an unanswered question is whether additional information can benefit postural response in PIGD subtype. OBJECTIVE: To analyze the effect of cumulative additional information on postural responses after perturbation in PIGD and neurologically healthy older adults (CG). METHODS: Perturbations were applied in 16 PIGD and 19 CG by the support-base translation. Participants performed 3 blocks of 5 trials without additional information (B1-B3, Day 1) and 5 trials of each cumulative additional information (C1-C4, Day 2): information about perturbation (C1), visual (C2), verbal (C3), and somatosensory information (C4). Electromyography and center of pressure (CoP) parameters were analyzed by ANOVAs with Group (PIGD × CG) and Block (B1 × B2 × B3) and with Group (PIGD × CG) and Condition (B3 × C1 × C2 × C3 × C4). RESULTS: PIGD decreased the range of CoP in B3 while CG decreased both range of CoP and the integral of antagonist's muscle activity (iEMG) in B2. Also, PIGD decreased the recovery time in C4 while CG increased the iEMG of agonist's muscle in C2 and antagonist's muscle in all conditions except C2. CONCLUSION: Additional information provided before postural control assessment influences the postural response in PIGD and CG differently. PIGD demonstrated inflexibility of central-set in modulating the neuromuscular control regardless of additional information. CG presents a flexible system evidenced by the increase of agonist muscle iEMG when provided visual information.
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Transtornos Neurológicos da Marcha , Doença de Parkinson , Idoso , Marcha , Humanos , Equilíbrio Postural/fisiologia , TremorRESUMO
INTRODUCTION: Transcranial direct current stimulation (tDCS) improves postural response to perturbation in patients with Parkinson's disease (PwPD). However, the influence of baseline characteristics such as clinical/cognitive and postural performance on the response to tDCS remains unclear. OBJECTIVE: To investigate whether baseline level of postural control (performance during sham condition) and clinical/cognitive characteristics are associated with tDCS-related changes in postural responses to external perturbations in PwPD. METHODS: Twenty-four PwPD participated in this study. Clinical assessment included disease severity, disease duration, levodopa equivalent dose and global cognition. Anodal tDCS protocols targeting the primary motor cortex were applied in two separate sessions (at least 2 weeks apart): active (2 mA for 20 min) and sham stimulation. Seven trials with the backward translation of the support base (20 cm/s and 5 cm) were performed after tDCS. Postural outcomes included the recovery time to stable position and onset latency of the medial gastrocnemius (MG). Pearson and Spearman correlation tests were performed. RESULTS: No significant correlations were observed between clinical/cognitive characteristics and tDCS-related changes in postural responses. Negative associations were observed between the baseline level of postural control and tDCS-related changes in postural responses for the recovery time (r = -0.657; p < 0.001) and the MG onset latency (rs = -0.539; p = 0.007). PwPD with worse baseline postural control demonstrated greater improvement after active stimulation. CONCLUSIONS: Findings suggest that tDCS-related effects on postural response to perturbation are related to the baseline level of postural control, but not to clinical characteristics in PwPD. Those with worse baseline postural control responded better to tDCS.
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Eletromiografia/estatística & dados numéricos , Doença de Parkinson/cirurgia , Equilíbrio Postural , Estimulação Transcraniana por Corrente Contínua/estatística & dados numéricos , Idoso , Cognição , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doença de Parkinson/fisiopatologia , Período Pré-Operatório , Resultado do TratamentoRESUMO
It is challenging for people with Parkinson's disease (PwPD) to adjust their gait to perturbations, including fatigue. Obstacle negotiation increases the risk of tripping and falling in PD. Being physically active can improve gait control and the ability to negotiate obstacles while walking under fatigue state. We thus determined the effects of Parkinson's disease, fatigue, and level of physical activity on gait during the approach to and crossing an obstacle during gait. Forty participants were stratified to people with Parkinson's disease active and inactive, and control individuals active and inactive. Participants walked on an 8 m walkway and stepped over an obstacle placed at the middle (4 m). They performed three trials before and after repeated sit-to-stand (rSTS)-induced fatigue state. Maximum voluntary force was assessed before and after rSTS. We measured the length, width, duration, and velocity of the approach (stride before obstacle) and crossing (step over the obstacle) phases and the leading and trailing placements and clearance during crossing phase. Fatigue trait was determined by multidimensional fatigue inventory. Before rSTS, people with Parkinson's disease inactive vs. other subgroups approached the obstacle using 18-28% shorter, wider and slower steps and crossed the obstacle slower (all p < 0.04). After rSTS, people with Parkinson's disease inactive increased (23-34%) stride length and velocity and decreased (-21%) the step width (p < 0.01). People with Parkinson's disease approached the obstacle similarly to control individuals. Physical activity minimizes Parkinson's disease-typical gait impairments during obstacle negotiation and affords a protective effect against fatigue-effects on obstacle negotiation.
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Doença de Parkinson , Marcha , Humanos , Perna (Membro) , Fadiga Muscular , Negociação , Doença de Parkinson/complicações , CaminhadaRESUMO
Background: Postural control and cognition are affected by aging. We investigated whether cognitive distraction influenced neural activity differently in young and older adults during a game-like mediolateral weight-shifting task with a personalized task load. Methods: Seventeen healthy young and 17 older adults performed a balance game, involving hitting virtual wasps, serial subtractions and a combination of both (dual-task). A motion analysis system estimated each subject's center of mass position. Cortical activity in five regions was assessed by measuring oxygenated hemoglobin (HbO2) with a functional Near-Infrared Spectroscopy system. Results: When adding cognitive load to the game, weight-shifting speed decreased irrespective of age, but older adults reduced the wasp-hits more than young adults. Accompanying these changes, older adults decreased HbO2 in the left pre-frontal cortex (PFC) and frontal eye fields (FEF) compared to single-tasking, a finding not seen in young adults. Additionally, lower HbO2 levels were found during dual-tasking compared to the summed activation of the two single tasks in all regions except for the right PFC. These relative reductions were specific for the older age group in the left premotor cortex (PMC), the right supplementary motor area (SMA), and the left FEF. Conclusion: Older adults showed more compromised neural activity than young adults when adding a distraction to a challenging balance game. We interpret these changes as competitive downgrading of neural activity underpinning the age-related deterioration of game performance during dual-tasking. Future work needs to ascertain if older adults can train their neural flexibility to withstand balance challenges during daily life activities.
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Background: Walking in the "real world" involves motor and cognitive processes. In relation to this, declines in both motor function and cognition contribute to age-related gait dysfunction. Transcranial direct current stimulation (tDCS) and treadmill walking (STW) have potential to improve gait, particularly during dual-task walking (DTW); walking whilst performing a cognitive task. Our aims were to analyze effects of combined anodal tDCS + STW intervention on cortical activity and gait during DTW. Methods: Twenty-three young adults (YA) and 21 older adults (OA) were randomly allocated to active or sham tDCS stimulation groups. Participants performed 5-min of mixed treadmill walking (alternating 30 s bouts of STW and DTW) before and after a 20-min intervention of active or sham tDCS + STW. Anodal electrodes were placed over the left prefrontal cortex (PFC) and the vertex (Cz) using 9 cm2 electrodes at 0.6 mA. Cortical activity of the PFC, primary motor cortex (M1), premotor cortex (PMC), and supplementary motor area (SMA) bilaterally were recorded using a functional near-infrared spectroscopy (fNIRS) system. Oxygenated hemoglobin (HbO2) levels were analyzed as indicators of cortical activity. An accelerometer measured gait parameters. We calculated the difference between DTW and STW for HbO2 and gait parameters. We applied linear mixed effects models which included age group (YA vs. OA), stimulation condition (sham vs. active), and time (pre- vs. post-intervention) as fixed effects. Treadmill belt speed was a covariate. Partial correlation tests were also performed. Results: A main effect of age group was observed. OA displayed higher activity bilaterally in the PFC and M1, unilaterally in the right PMC and higher gait variability than YA. M1 activity decreased in both YA and OA following active tDCS + STW. There was no overall effect of tDCS + STW on PFC activity or gait parameters. However, negative correlations were observed between changes in left PFC and stride length variability following active tDCS + STW intervention. Conclusion: Increased activity in multiple cortical areas during DTW in OA may act as a compensatory mechanism. Reduction in M1 activity following active tDCS + STW with no observed gait changes suggests improved neural efficiency.
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BACKGROUND: Social anxiety caused by the presence of an evaluator can impair balance performance in older women. However, it is unknown whether co-performing balance tasks with a partner mitigates this effect. RESEARCH QUESTION: Does the presence of a partner mitigate the effect of social anxiety on static and dynamic balance assessment in older women? METHODS: Twenty-one older women (mean age 66.5 (SD = 5.2) years) performed nine balance tasks under three conditions: (a) Alone (no evaluator present); (b) Evaluator (male evaluator present); (c) Partner (evaluator + performing tasks in parallel with partner). Participants were split into two groups post-hoc: Affected (n = 10) and Unaffected (n = 11), based on their emotional response to the presence of the evaluator (increased self-reported anxiety and fear). RESULTS: The affected group took a longer time to complete tandem walking with eyes open in the Evaluator vs. Alone condition, but not in the Partner condition. Both groups increased anterior-posterior trunk angular velocity during tandem walking with eyes closed in the Evaluator vs. Alone condition, but not in the Partner condition. SIGNIFICANCE: Social anxiety impairs the balance performance of older women, particularly in those most affected by the evaluator, and during more dynamic modified gait tasks that challenge balance while walking. However, co-performing balance tasks with a partner reduced the effects of social anxiety, suggesting that social support may help to mitigate some of the potential 'white coat' effects experienced during clinical balance assessments.
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Ansiedade/fisiopatologia , Marcha/fisiologia , Equilíbrio Postural/fisiologia , Caminhada/fisiologia , Idoso , Feminino , Humanos , Análise e Desempenho de TarefasRESUMO
Parkinson's disease (PD) is often classified into tremor dominant (TD) and postural instability gait disorder (PIGD) subtypes. Degeneration of subcortical/cortical pathways is different between PD subtypes, which leads to differences in motor behavior. However, the influence of PD subtype on cortical activity during walking remains poorly understood. Therefore, we aimed to investigate the influence of PD motor subtypes on cortical activity during unobstructed walking and obstacle avoidance. Seventeen PIGD and 19 TD patients performed unobstructed walking and obstacle avoidance conditions. Brain activity was measured using a mobile functional near-infrared spectroscopy-electroencephalography (EEG) systems, and gait parameters were analyzed using an electronic carpet. Concentrations of oxygenated hemoglobin (HbO2) of the prefrontal cortex (PFC) and EEG absolute power from alpha, beta, and gamma bands in FCz, Cz, CPz, and Oz channels were calculated. These EEG channels correspond to supplementary motor area, primary motor cortex, posterior parietal cortex, and visual cortex, respectively. Postural instability gait disorder patients presented higher PFC activity than TD patients, regardless of the walking condition. Tremor dominant patients presented reduced beta power in the Cz channel during obstacle avoidance compared to unobstructed walking. Both TD and PIGD patients decreased alpha and beta power in the FCz and CPz channels. In conclusion, PIGD patients need to recruit additional cognitive resources from the PFC for walking. Both TD and PIGD patients presented changes in the activation of brain areas related to motor/sensorimotor areas in order to maintain balance control during obstacle avoidance, being that TD patients presented further changes in the motor area (Cz channel) to avoid obstacles.
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Transtornos Neurológicos da Marcha , Oxiemoglobinas/análise , Doença de Parkinson , Equilíbrio Postural/fisiologia , Córtex Pré-Frontal , Tremor , Idoso , Eletroencefalografia/métodos , Neuroimagem Funcional/métodos , Análise da Marcha/métodos , Transtornos Neurológicos da Marcha/metabolismo , Transtornos Neurológicos da Marcha/fisiopatologia , Humanos , Doença de Parkinson/classificação , Doença de Parkinson/metabolismo , Doença de Parkinson/fisiopatologia , Córtex Pré-Frontal/metabolismo , Córtex Pré-Frontal/fisiopatologia , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Tremor/metabolismo , Tremor/fisiopatologia , Caminhada/fisiologia , Caminhada/psicologiaRESUMO
BACKGROUND: How people with Parkinson's disease habituate their postural response to unpredictable translation perturbation is not totally understood. We compared the capacity to change the postural responses after unexpected external perturbation and investigated the habituation plateaus of postural responses to non-sequential perturbation trials in people with Parkinson's disease and healthy older adults. METHODS: In people with Parkinson's disease (n = 37) and older adults (n = 20), sudden posterior support-surface translational were applied in 7 out of 17 randomized trials to ensure perturbation unpredictability. Electromyography and center of pressure parameters of postural response were analyzed by ANOVAs (Group vs. Trials). Two simple planned contrasts were performed to determine at which trial the responses first significantly habituate, and by which trials the habituation plateaus. FINDINGS: Older adults demonstrated a first response change in trial 5 and habituation plateaus after trial 4, while for people with Parkinson's disease, the first change occurred in trial 2 and habituation plateau after trial 5 observed by center of pressure range. People with Parkinson's disease demonstrated a greater center of pressure range in trial 1 compared to older adults. Independent of trial, people with Parkinson's disease vs. older adults demonstrated a greater ankle muscle co-activation and recovery time. INTERPRETATION: Despite the greater center of pressure range in the first trial, people with Parkinson's disease can habituate to unpredictable perturbations. This is reflected by little, to no difference in the time-course of adaptation for all but 2 parameters that showed only marginal differences between people with Parkinson's disease and older adults.
Assuntos
Doença de Parkinson , Equilíbrio Postural , Adaptação Fisiológica , Idoso , Eletromiografia , Habituação Psicofisiológica , Humanos , Doença de Parkinson/tratamento farmacológicoRESUMO
BACKGROUND: Dopaminergic medication improves gait in people with Parkinson disease (PD). However, it remains unclear if dopaminergic medication modulates cortical activity while walking. OBJECTIVE: We investigated the effects of dopaminergic medication on cortical activity during unobstructed walking and obstacle avoidance in people with PD. METHODS: A total of 23 individuals with PD, in both off (PDOFF) and on (PDON) medication states, and 30 healthy older adults (control group [CG]) performed unobstructed walking and obstacle avoidance conditions. Cortical activity was acquired through a combined functional near-infrared spectroscopy electroencephalography (EEG) system, along with gait parameters, through an electronic carpet. Prefrontal cortex (PFC) oxygenated hemoglobin (HbO2) and EEG absolute power from FCz, Cz, and CPz channels were calculated. RESULTS: HbO2 concentration reduced for people with PDOFF during obstacle avoidance compared with unobstructed walking. In contrast, both people with PDON and the CG had increased HbO2 concentration when avoiding obstacles compared with unobstructed walking. Dopaminergic medication increased step length, step velocity, and ß and γ power in the CPz channel, regardless of walking condition. Moreover, dopaminergic-related changes (ie, on-off) in FCz/CPz γ power were associated with dopaminergic-related changes in step length for both walking conditions. CONCLUSIONS: PD compromises the activation of the PFC during obstacle avoidance, and dopaminergic medication facilitates its recruitment. In addition, PD medication increases sensorimotor integration during walking by increasing posterior parietal cortex (CPz) activity. Increased γ power in the CPz and FCz channels is correlated with step length improvements achieved with dopaminergic medication during unobstructed walking and obstacle avoidance in PD.
Assuntos
Córtex Cerebral/fisiopatologia , Dopaminérgicos/farmacologia , Transtornos Neurológicos da Marcha , Doença de Parkinson , Desempenho Psicomotor , Caminhada , Idoso , Córtex Cerebral/diagnóstico por imagem , Eletroencefalografia , Feminino , Transtornos Neurológicos da Marcha/diagnóstico por imagem , Transtornos Neurológicos da Marcha/tratamento farmacológico , Transtornos Neurológicos da Marcha/etiologia , Transtornos Neurológicos da Marcha/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Doença de Parkinson/complicações , Doença de Parkinson/diagnóstico por imagem , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/fisiopatologia , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/fisiopatologia , Desempenho Psicomotor/efeitos dos fármacos , Desempenho Psicomotor/fisiologia , Índice de Gravidade de Doença , Espectroscopia de Luz Próxima ao Infravermelho , Caminhada/fisiologiaRESUMO
BACKGROUND: Since people with Parkinson disease (PD) rely on limited prefrontal executive resources for the control of gait, interventions targeting the prefrontal cortex (PFC) may help in managing PD-related gait impairments. Transcranial direct current stimulation (tDCS) can be used to modulate PFC excitability and improve prefrontal cognitive functions and gait. OBJECTIVE: We investigated the effects of adding anodal tDCS applied over the PFC to a session of aerobic exercise on gait, cognition, and PFC activity while walking in people with PD. METHODS: A total of 20 people with PD participated in this randomized, double-blinded, sham-controlled crossover study. Participants attended two 30-minute sessions of aerobic exercise (cycling at moderate intensity) combined with different tDCS conditions (active- or sham-tDCS), 1 week apart. The order of sessions was counterbalanced across the sample. Anodal tDCS (2 mA for 20 minutes [active-tDCS] or 10 s [sham-tDCS]) targeted the PFC in the most affected hemisphere. Spatiotemporal gait parameters, cognitive functions, and PFC activity while walking were assessed before and immediately after each session. RESULTS: Compared with the pre-assessment, participants decreased step time variability (effect size: -0.4), shortened simple and choice reaction times (effect sizes: -0.73 and -0.57, respectively), and increased PFC activity in the stimulated hemisphere while walking (effect size: 0.54) only after aerobic exercise + active-tDCS. CONCLUSION: The addition of anodal tDCS over the PFC to a session of aerobic exercise led to immediate positive effects on gait variability, processing speed, and executive control of walking in people with PD.
Assuntos
Cognição/fisiologia , Exercício Físico/fisiologia , Marcha/fisiologia , Doença de Parkinson/terapia , Córtex Pré-Frontal/fisiopatologia , Estimulação Transcraniana por Corrente Contínua , Idoso , Estudos Cross-Over , Método Duplo-Cego , Feminino , Neuroimagem Funcional , Humanos , Masculino , Testes de Estado Mental e Demência , Pessoa de Meia-Idade , Doença de Parkinson/diagnóstico por imagem , Doença de Parkinson/fisiopatologia , Doença de Parkinson/psicologia , Córtex Pré-Frontal/diagnóstico por imagem , Espectroscopia de Luz Próxima ao Infravermelho , Resultado do Tratamento , Caminhada/fisiologiaRESUMO
Age-related changes may affect the performance during fast walking speed. Although, several studies have been focused on the contribution of the prefrontal cortex (PFC) during challenging walking tasks, the neural mechanism underling fast walking speed in older people remain poorly understood. Therefore, the aim of this study was to investigate the influence of aging on PFC activity during overground walking at preferred and fast speeds. Twenty-five older adults (67.37 ± 5.31 years) and 24 young adults (22.70 ± 1.30 years) walked overground in two conditions: preferred speed and fast walking speed. Five trials were performed for each condition. A wireless functional near-infrared spectroscopy (fNIRS) system measured PFC activity. Gait parameters were evaluated using the GAITRite system. Overall, older adults presented higher PFC activity than young adults in both conditions. Speed-related change in PFC activity was observed for older adults, but not for young adults. Older adults significantly increased activity in the left PFC from the preferred to fast walking condition whereas young adults had similar levels of PFC activity across conditions. Our findings suggest that older adults need to recruit additional prefrontal cognitive resources to control walking, indicating a compensatory mechanism. In addition, left PFC seems to be involved in the modulation of gait speed in older adults.