RESUMEN

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 (∼ 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).

Asunto(s)

Ejercicio Físico , Marcha , Enfermedad de Parkinson , Estimulación Transcraneal de Corriente Directa , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Cruzados , Ejercicio Físico/fisiología , Prueba de Esfuerzo , Terapia por Ejercicio/métodos , Marcha/fisiología , Corteza Motora/fisiopatología , Enfermedad de Parkinson/terapia , Enfermedad de Parkinson/fisiopatología , Corteza Prefrontal/fisiopatología , Corteza Prefrontal/fisiología , Calidad de Vida , Ensayos Clínicos Controlados Aleatorios como Asunto , Estimulación Transcraneal de Corriente Directa/métodos

RESUMEN

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.

Asunto(s)

Enfermedad de Parkinson , Estimulación Transcraneal de Corriente Directa , Humanos , Estimulación Transcraneal de Corriente Directa/métodos , Proyectos Piloto , Enfermedad de Parkinson/terapia , Equilibrio Postural/fisiología , Método Doble Ciego

RESUMEN

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.

Asunto(s)

Enfermedad de Parkinson , Corteza Sensoriomotora , Humanos , Anciano , Caminata , Locomoción , Algoritmos

RESUMEN

Introdução: os comprometimentos do andar em idosos com doença de Parkinson (DP) estão associados à elevada ocorrência de quedas e à redução dos níveis de independência. O objetivo do estudo foi comparar a resposta dos parâmetros do andar em idosos com doença de Parkinson (DP), durante, imediatamente após e até uma hora após o término de uma sessão de treinamento do andar com e sem dicas auditivas rítmicas, utilizando três ritmos diferentes para o grupo dica (10% abaixo da cadência preferida, cadência preferida e 10% acima) e um ritmo diferente para o grupo controle (velocidade usual de cada participante). Métodos: vinte e nove idosos foram aleatoriamente distribuídos em dois grupos: "controle" e "dica". As sessões de intervenção tiveram 30 minutos de duração e a diferença entre os grupos foi a utilização de dicas auditivas rítmicas oferecidas por um metrônomo no grupo dica. O andar foi avaliado antes, durante e até uma hora após a sessão de intervenção. Resultados: os grupos apresentaram desempenhos similares ao longo das avaliações, com aumento do comprimento do passo e redução da variabilidade da duração do passo. Conclusão: a sessão de intervenção com dicas auditivas rítmicas apresentou efeitos similares aos da sessão de treino sem dica para o andar de idosos com DP.(AU)

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Introduction: Gait impairments in older people with Parkinson's disease (PD) are associated with a high occurrence of falls and reduced levels of patients' independence. The objective of the study was to compare the response of gait parameters in older people with Parkinson's disease (PD), during, immediately after, and up to 1h after the end of a single locomotion training session with and without rhythmic auditory cues, using 3 different rhythms for the tip group (10% below the preferred cadence, preferred cadence and 10% above) and 1 different rhythm for the control group (usual speed of each participant). Materials and method: 29 older people were randomly assigned to two groups: Control and "Cue". The intervention sessions lasted 30 minutes and the difference between the groups was the use of rhythmic auditory cues offered by a metro-nome in the Cue group. Gait was assessed before, during, and up to 1 hour after the intervention session. Results: The groups showed similar performances throughout the assessments, with increased step length and reduced step time variability in response to the intervention (compared to the baseline assessment). Conclusion: The intervention session with rhythmic auditory cues had similar effects on gait as the session without cues in older people with PD.(AU)

Asunto(s)

Masculino , Femenino , Anciano , Anciano de 80 o más Años , Enfermedad de Parkinson , Envejecimiento , Enfermedades Neurodegenerativas , Locomoción

RESUMEN

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.

Asunto(s)

Enfermedades del Sistema Nervioso , Rehabilitación de Accidente Cerebrovascular , Accidente Cerebrovascular , Estimulación Transcraneal de Corriente Directa , Actividades Cotidianas , Humanos , Enfermedades del Sistema Nervioso/terapia , Rehabilitación de Accidente Cerebrovascular/métodos , Estimulación Transcraneal de Corriente Directa/métodos

RESUMEN

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.

Asunto(s)

Trastornos Neurológicos de la Marcha , Enfermedad de Parkinson , Anciano , Marcha , Humanos , Equilibrio Postural/fisiología , Temblor

RESUMEN

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.

RESUMEN

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.

Asunto(s)

Electromiografía/estadística & datos numéricos , Enfermedad de Parkinson/cirugía , Equilibrio Postural , Estimulación Transcraneal de Corriente Directa/estadística & datos numéricos , Anciano , Cognición , Femenino , Humanos , Masculino , Persona de Mediana Edad , Enfermedad de Parkinson/fisiopatología , Periodo Preoperatorio , Resultado del Tratamiento

RESUMEN

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.

Asunto(s)

Espectroscopía Infrarroja Corta , Caminata , Anciano , Marcha , Humanos , Corteza Prefrontal , Velocidad al Caminar , Adulto Joven

RESUMEN

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.

Asunto(s)

Cognición/fisiología , Ejercicio Físico/fisiología , Marcha/fisiología , Enfermedad de Parkinson/terapia , Corteza Prefrontal/fisiopatología , Estimulación Transcraneal de Corriente Directa , Anciano , Estudios Cruzados , Método Doble Ciego , Femenino , Neuroimagen Funcional , Humanos , Masculino , Pruebas de Estado Mental y Demencia , Persona de Mediana Edad , Enfermedad de Parkinson/diagnóstico por imagen , Enfermedad de Parkinson/fisiopatología , Enfermedad de Parkinson/psicología , Corteza Prefrontal/diagnóstico por imagen , Espectroscopía Infrarroja Corta , Resultado del Tratamiento , Caminata/fisiología

RESUMEN

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.

Asunto(s)

Enfermedad de Parkinson , Equilibrio Postural , Adaptación Fisiológica , Anciano , Electromiografía , Habituación Psicofisiológica , Humanos , Enfermedad de Parkinson/tratamiento farmacológico

RESUMEN

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.

Asunto(s)

Corteza Cerebral/fisiopatología , Dopaminérgicos/farmacología , Trastornos Neurológicos de la Marcha , Enfermedad de Parkinson , Desempeño Psicomotor , Caminata , Anciano , Corteza Cerebral/diagnóstico por imagen , Electroencefalografía , Femenino , Trastornos Neurológicos de la Marcha/diagnóstico por imagen , Trastornos Neurológicos de la Marcha/tratamiento farmacológico , Trastornos Neurológicos de la Marcha/etiología , Trastornos Neurológicos de la Marcha/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Enfermedad de Parkinson/complicaciones , Enfermedad de Parkinson/diagnóstico por imagen , Enfermedad de Parkinson/tratamiento farmacológico , Enfermedad de Parkinson/fisiopatología , Corteza Prefrontal/efectos de los fármacos , Corteza Prefrontal/fisiopatología , Desempeño Psicomotor/efectos de los fármacos , Desempeño Psicomotor/fisiología , Índice de Severidad de la Enfermedad , Espectroscopía Infrarroja Corta , Caminata/fisiología

RESUMEN

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.

Asunto(s)

Enfermedad de Parkinson , Accidentes por Caídas , Susceptibilidad a Enfermedades , Humanos , Equilibrio Postural

RESUMEN

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.

Asunto(s)

Trastornos Neurológicos de la Marcha , Oxihemoglobinas/análisis , Enfermedad de Parkinson , Equilibrio Postural/fisiología , Corteza Prefrontal , Temblor , Anciano , Electroencefalografía/métodos , Neuroimagen Funcional/métodos , Análisis de la Marcha/métodos , Trastornos Neurológicos de la Marcha/metabolismo , Trastornos Neurológicos de la Marcha/fisiopatología , Humanos , Enfermedad de Parkinson/clasificación , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/fisiopatología , Corteza Prefrontal/metabolismo , Corteza Prefrontal/fisiopatología , Espectroscopía Infrarroja Corta/métodos , Temblor/metabolismo , Temblor/fisiopatología , Caminata/fisiología , Caminata/psicología

RESUMEN

BACKGROUND: Habituation of postural response to perturbations is impaired in people with Parkinson's disease (PD) due to deficits in cortico-basal pathways. Although transcranial direct current stimulation (tDCS) modulate cortico-basal networks, it remains unclear if it can benefit postural control in PD. OBJECTIVE: To analyze the effect of different intensities of anodal tDCS on postural responses and prefrontal cortex (PFC) activity during the habituation to the external perturbation in patients with PD (n = 24). METHODS: Anodal tDCS was applied over the primary motor cortex (M1) with 1 mA, 2 mA, and sham stimulation in 3 different sessions (~2 weeks apart) during 20 minutes immediately before the postural assessment. External perturbation (7 trials) was applied by a support base posterior translation (20 cm/s and 5 cm). Primary outcome measures included lower limb electromyography and center of pressure parameters. Measures of PFC activity are reported as exploratory outcomes. Analyses of variance (Stimulation Condition × Trial) were performed. RESULTS: Habituation of perturbation was evidenced independent of the stimulation conditions. Both active stimulation intensities had shorter recovery time and a trend for lower cortical activity in the stimulated hemisphere when compared to sham condition. Shorter onset latency of the medial gastrocnemius as well as lower cortical activity in the nonstimulated hemisphere were only observed after 2 mA concerning the sham condition. CONCLUSIONS: tDCS over M1 improved the postural response to external perturbation in PD, with better response observed for 2 mA compared with 1 mA. However, tDCS seems to be inefficient in modifying the habituation of perturbation.

Asunto(s)

Corteza Motora/fisiopatología , Enfermedad de Parkinson/fisiopatología , Equilibrio Postural , Corteza Prefrontal/fisiopatología , Anciano , Electromiografía , Femenino , Habituación Psicofisiológica , Humanos , Masculino , Persona de Mediana Edad , Estimulación Transcraneal de Corriente Directa

RESUMEN

BACKGROUND: Declines in gait parameters are common with aging and more pronounced in tasks with increased executive demand. However, the neural correlates of age-related gait impairments are not fully understood yet. OBJECTIVES: To investigate (a) the effects of aging on prefrontal cortex (PFC) activity and gait parameters during usual walking, obstacle crossing and dual-task walking and (b) the association between PFC activity and measures of gait and executive function. METHODS: Eighty-eight healthy individuals were distributed into 6 age-groups: 20-25 (G20), 30-35 (G30), 40-45 (G40), 50-55 (G50), 60-65 (G60), and 70-75 years (G70). Participants walked overground under 3 conditions: usual walking, obstacle crossing, and dual-task walking. Changes in oxygenated and deoxygenated hemoglobin in the PFC were recorded using functional near-infrared spectroscopy. Gait spatiotemporal parameters were assessed using an electronic walkway. Executive function was assessed through validated tests. RESULTS: Between-group differences on PFC activity were observed for all conditions. Multiple groups (ie, G30, G50, G60, and G70) showed increased PFC activity in at least one of the walking conditions. Young adults (G20 and G30) had the lowest levels of PFC activity while G60 had the highest levels. Only G70 showed reduced executive function and gait impairments (which were more pronounced during obstacle crossing and dual-task walking). PFC activity was related to gait and executive function. CONCLUSIONS: Aging causes a gradual increase in PFC activity during walking. This compensatory mechanism may reach the resource ceiling in the 70s, when reduced executive function limits its efficiency and gait impairments are observed.

Asunto(s)

Envejecimiento/fisiología , Función Ejecutiva/fisiología , Corteza Prefrontal/fisiología , Desempeño Psicomotor/fisiología , Caminata/fisiología , Adulto , Anciano , Femenino , Neuroimagen Funcional , Marcha/fisiología , Humanos , Masculino , Persona de Mediana Edad , Corteza Prefrontal/diagnóstico por imagen , Espectroscopía Infrarroja Corta , Adulto Joven

RESUMEN

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.

Asunto(s)

Enfermedad de Parkinson/terapia , Estimulación Transcraneal de Corriente Directa/métodos , Humanos , Masculino

RESUMEN

Background. Although dopaminergic medication improves dual task walking in people with Parkinson disease (PD), the underlying neural mechanisms are not yet fully understood. As prefrontal cognitive resources are involved in dual task walking, evaluation of the prefrontal cortex (PFC) is required. Objective. To investigate the effect of dopaminergic medication on PFC activity and gait parameters during dual task walking in people with PD. Methods. A total of 20 individuals with PD (69.8 ± 5.9 years) and 30 healthy older people (68.0 ± 5.6 years) performed 2 walking conditions: single and dual task (walking while performing a digit vigilance task). A mobile functional near infrared spectroscopy system and an electronic sensor carpet were used to analyze PFC activation and gait parameters, respectively. Relative concentrations of oxygenated hemoglobin (HbO2) from the left and right PFC were measured. Results. People with PD in the off state did not present changes in HbO2 level in the left PFC across walking conditions. In contrast, in the on state, they presented increased HbO2 levels during dual task compared with single task. Regardless of medication state, people with PD presented increased HbO2 levels in the right PFC during dual task walking compared with single task. The control group demonstrated increased PFC activity in both hemispheres during dual task compared with single task. People with PD showed increases in both step length and velocity in the on state compared with the off state. Conclusions. PD limits the activation of the left PFC during dual task walking, and dopaminergic medication facilitates its recruitment.

Asunto(s)

Dopaminérgicos/farmacología , Función Ejecutiva/efectos de los fármacos , Marcha/efectos de los fármacos , Levodopa/farmacología , Enfermedad de Parkinson/tratamiento farmacológico , Corteza Prefrontal/efectos de los fármacos , Desempeño Psicomotor/efectos de los fármacos , Anciano , Función Ejecutiva/fisiología , Femenino , Neuroimagen Funcional , Marcha/fisiología , Humanos , Masculino , Persona de Mediana Edad , Enfermedad de Parkinson/fisiopatología , Corteza Prefrontal/diagnóstico por imagen , Corteza Prefrontal/fisiopatología , Desempeño Psicomotor/fisiología , Espectroscopía Infrarroja Corta

RESUMEN

Gait asymmetry during unobstructed walking in people with Parkinson's disease (PD) has been well documented. However, under complex situations, such as environments with double obstacles, gait asymmetry remains poorly understood in PD. Therefore, the aim of this study was to analyze inter-limb asymmetry while crossing a single obstacle and double obstacles (with different distances between them) in people with PD and healthy older adults. Nineteen people with PD and 19 healthy older people performed three conditions: (i) walking with one obstacle (Single); (ii) walking with two obstacles with a 50 cm distance between them (Double-50); (iii) walking with two obstacles with a 108 cm distance between them (Double-108). The participants performed the obstacle crossing with both lower limbs. Asymmetry Index was calculated. We found that people with PD presented higher leading and trailing toe clearance asymmetry than healthy older people. In addition, participants increased asymmetry in the Double-50 compared to Single condition. It can be concluded that people with PD show higher asymmetry during obstacle crossing compared to healthy older people, independently of the number of obstacles. In addition, a challenging environment induces asymmetry during obstacle crossing in both people with PD and healthy older people.

Asunto(s)

Envejecimiento/fisiología , Marcha/fisiología , Enfermedad de Parkinson/fisiopatología , Accidentes por Caídas , Anciano , Fenómenos Biomecánicos , Femenino , Análisis de la Marcha , Humanos , Masculino , Persona de Mediana Edad , Proyectos Piloto

RESUMEN

ABSTRACT Introduction Cognitive components are necessary to maintain posture during external perturbations. However, few studies have investigated postural control when external perturbations are associated with a concomitant cognitive task (DT). Objectives To analyze the behavior of reactive adjustments after perturbation with different intensities and displacements in active young adults; and to analyze the influence of DT on predictive and reactive adjustments in different perturbation conditions. Methods Twenty-eight physically active young adults stood on an item of equipment that produced displacements of the base. Four experimental conditions were introduced in a single task (ST) and DT (cognitive-report how many times a pre-established number appeared in the audio): 1 (5 cm and 10 cm/s); 2 (5 cm and 25 cm/s); 3 (12 cm and 10 cm/s) and 4 (12 cm and 25 cm/s). Three attempts were carried out for each condition (total=24). Center of pressure (CoP) parameters were analyzed considering the following windows: predictive (-250 to +50 ms), reactive 1 (+50 to +200 ms) and reactive 2 (+200 to +700 ms), in comparison to the start of the CoP activity. One-way ANOVAs were performed to analyze predictive adjustments, while two-way ANOVAs with factor for task (STxDT) and condition (1x2x3x4), with repeated measurements, were performed for the reactive adjustments. Results One-way ANOVA (predictive) indicated that the subjects had higher CoP parameters in ST vs DT. In reactive adjustments 1 and 2, ANOVA indicated greater CoP parameters in condition 2 and 4 when compared to 1 and 3, and in the ST vs DT. The subjects took longer to recover stable position in conditions 1 and 3 than in conditions 2 and 4. Conclusion Perturbation intensity has a greater influence on postural adjustments to maintain balance than on magnitude. Moreover, the association of cognitive tasks with external perturbation decreases CoP oscillation. Therefore, cognitive resources play an important role in postural control after perturbation. Level of evidence III; Study of nonconsecutive patients, with no "gold" standard applied uniformly.

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RESUMO Introdução Componentes cognitivos são necessários para manter a postura nas perturbações externas. Porém, poucos estudos investigaram o controle postural quando perturbações externas são associadas à tarefa cognitiva concomitante (TD). Objetivo Analisar o comportamento dos ajustes reativos após perturbação com diferentes intensidades e deslocamentos em adultos jovens ativos; e analisar a influência da TD nos ajustes preditivos e reativos em diferentes condições de perturbação. Métodos Permaneceram em pé sobre um equipamento que provocou deslocamento da base de suporte 28 adultos jovens fisicamente ativos. Quatro condições experimentais foram realizadas em tarefa simples (TS) e TD (cognitiva-reportar quantas vezes um número preestabelecido apareceu no áudio): uma (5cm e 10cm/s); duas (5cm e 25cm/s); três (12cm e 10cm/s) e quatro (12cm e 25cm/s). Foram realizadas três tentativas para cada condição (total=24). Os parâmetros do centro de pressão (CoP) foram analisados em janelamentos: preditivo (-250 a +50ms), reativo 1 (+50 a +200ms) e reativo 2 (+200 a +700ms), em relação ao início da atividade do CoP. ANOVAs one-way foram realizadas para análise dos ajustes preditivos. Já para os ajustes reativos, foram realizadas ANOVAs two-way com fator para tarefa (TS×TD) e condição (1×2×3×4) com medidas repetidas. Resultados ANOVA one-way (preditivo) apontou que os indivíduos apresentaram maiores parâmetros do CoP na TS em relação à TD. Nos reativos 1 e 2, a ANOVA apontou maiores parâmetros do CoP na segunda e na quarta condição quando comparada à primeira e à terceira, e na TS em relação às TD. Apresentaram maior tempo para recuperar a posição estável na primeira e na terceira condição em comparação à segunda e à quarta. Conclusão A intensidade da perturbação influencia mais nos ajustes posturais para manutenção do equilíbrio do que a magnitude. Ainda, as tarefas cognitivas concomitantes à perturbação externa diminuem a oscilação do CoP. Com isso, recursos cognitivos possuem relevância no controle postural após perturbação. Nível de evidência III; Estudos de pacientes não consecutivos, sem padrão de referência "ouro" aplicado uniformemente.

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RESUMEN Introducción Los componentes cognitivos son necesarios para mantener la postura en perturbaciones externas. Sin embargo, pocos estudios investigaron el control postural cuando son asociadas perturbaciones a la tarea cognitiva concomitante (TD). Objetivo Analizar el comportamiento de los ajustes reactivos después de una perturbación con diferentes intensidades y desplazamientos en adultos jóvenes activos; y analizar la influencia de la TD en ajustes predictivos y reactivos en diferentes condiciones de perturbación. Métodos Veintiocho adultos jóvenes físicamente activos permanecieron en pie sobre un equipo que provocó desplazamiento de la base de soporte. Cuatro condiciones experimentales fueron realizadas en tareas simples (TS) y TD (cognitiva-reportar cuántas veces un número preestablecido apareció en el audio): una (5 cm y 10 cm/s); dos (5 cm y 25 cm/s); tres (12 cm y 10 cm/s) y cuatro (12 cm y 25 cm/s). Fueron realizadas tres tentativas para cada condición (total=24). Los parámetros del centro de presión (CoP) fueron analizados en ventanas: predictiva (-250 a +50 ms), reactiva 1 (+50 a +200 ms) y reactiva 2 (+200 a +700 ms) en relación al inicio de la actividad del CoP. Fueron realizadas ANOVAs one-way para análisis de los ajustes predictivos. Fueron realizadas ANOVAs two-way con factor para tarea (TSxTD) y condición (1x2x3x4) con medidas repetidas para análisis de los ajustes reactivos. Resultados ANOVA one-way (predictivo) mostró que los individuos presentaron parámetros mayores de CoP en TS con relación a TD. En los reactivos 1 y 2, ANOVA mostró parámetros del CoP en la segunda y cuarta condición cuando comparada a la primera y la tercera, y en la TS con relación a las TD. Presentaron tiempo mayor para recuperar la posición estable en la primera y tercera condición en comparación a la segunda y la cuarta. Conclusión La intensidad de perturbación influencia más en los ajustes posturales para mantenimiento del equilibrio que la magnitud. Además, las tareas cognitivas concomitantes a la perturbación externa disminuyen la oscilación del CoP. Con eso, los recursos cognitivos poseen relevancia en el control postural después de la perturbación. Nivel de evidencia III; Estudios de pacientes no consecutivos, sin estándar de referencia "oro" aplicado uniformemente.