Aerobic exercise on the treadmill combined with transcranial direct current stimulation on the gait of people with Parkinson's disease: A protocol for a randomized clinical trial.

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).

Cerebral and muscle tissue oxygenation during exercise in healthy adults: A systematic review.

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 (n = 11), treadmill (n = 1), knee extension (n = 5), isometric contraction of biceps brachii (n = 3), and duet swim routines (n = 1). The cerebral hemodynamics analysis was focused on the frontal cortex (n = 20), while in the muscle, the analysis involved vastus lateralis (n = 18), gastrocnemius (n = 3), biceps brachii (n = 5), deltoid (n = 1), and intercostal muscle (n = 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.

The Association between Perceived Stress, Quality of Life, and Level of Physical Activity in Public School Teachers.

Chronic high stress levels related to work impact the quality of life (QoL). Although physical activity improves QoL, it is not clear whether this life study habit could attenuate possible relationships between QoL and stress in public school teachers. The sample for this study was made up of 231 teachers from public schools. QoL was assessed using the Short-Form Health Survey and physical activity via Baecke's questionnaire. A Likert scale assessed stress level perception. Poisson Regression analyzed the association between stress level and QoL domains adjusted for sex, age, and socioeconomic conditions (model 1). In model 2, physical activity level was inserted in addition to model 1. Seven out of eight domains of QoL, except the domain of pain, were associated with high levels of stress (all p < 0.05-model 1). However, in model 2, the associations of the high levels of stress with general health status (p = 0.052) and functional capacity (p = 0.081) domains of QoL were mitigated. Our results indicated that physical activity mitigated the relationship between higher levels of stress and lower perception of general health status and functional capacity domains in secondary public school teachers.

Postural control of prolonged standing in people with Parkinson's disease.

People with Parkinson's disease (pwPD) have reduced adaptability to postural control during prolonged standing compared to neurologically healthy individuals (control). Objective. The study aimed to characterize postural changes during prolonged standing and their effect on postural control in pwPD compared to control. We recorded the body sway of the second lumbar vertebra of 23 pwPD and 23 control while they performed prolonged standing (15 min). The number and amplitude of the body sway patterns (shifts, fidgets, and drifts), the root mean square, velocity, and frequency of the body sway were analyzed. The number of shifts in the anterior-posterior (AP) and medial-lateral (ML) directions was greater for the pwPD than the control. In addition, the amplitudes of shifts in the AP direction and fidgets in the AP and ML directions were greater for the pwPD than the control. Our results show that: (1) A larger number of shifts of body sway suggest references positions are frequently changing; (2) Fidgets is a pumping mechanism and can be sensory-demand action to restore mechanoreceptors activity on the foot sole; and (3) No drift changes may suggest there is no slow migration of reference position. We conclude that pwPD exhibits different behavior than healthy ones during prolonged standing, suggesting that prolonged standing could distinguish individuals with Parkinson's disease.

Electrocortical Dynamics of Usual Walking and the Planning to Step over Obstacles in Parkinson's Disease.

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.

Transcranial direct current stimulation suggests not improving postural control during adapted tandem position in people with Parkinson's disease: A pilot study.

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.

Association between Diet and Adiposity in Adults: Influence of Sedentary Behavior Patterns.

This study analyzed the influence of sedentary behavior (SB) on the association between dietary patterns and adiposity in community-dwelling adults. Eight hundred and forty-three adults (age: 56.5 ± 18.3 years) participated in this cross-sectional epidemiological study. Dietary patterns were evaluated using self-report questions regarding the weekly frequency of consumption of certain foods. Adiposity was determined using anthropometric measurements of weight, waist circumference, and height. SB was evaluated according to the time spent on screen devices. The usual physical activity level and socioeconomic status were considered confounding factors. Associations were determined using multivariate linear models with simultaneous adjustments for confounding variables. A statistical analysis indicated that fruit consumption was negatively related to the body mass index, regardless of the adjustment for SB domains. Red meat consumption was positively related to the body mass index, and fried food consumption was positively related to the waist-to-height ratio, regardless of the adjustment for SB domains. The consumption of fried food was positively associated with global and central adiposity after the adjustments for confounding factors and time spent on screen devices. We concluded that dietary habits are related to adiposity in adults. However, SB domains seem to influence the relationship between body adiposity and dietary habits, mainly regarding the consumption of fried foods.

Comparison of Quality of Life in Breast Cancer Survivors with and without Persistent Depressive Symptoms: A 12-Month Follow-Up Study.

Although breast cancer treatments reduce mortality, their adverse effects can increase depression which impacts one's quality of life (QoL). Physical activity (PA) seems to improve the QoL of breast cancer survivors (BCS). However, an unanswered question is the influence of PA on the QoL in BCS with depressive symptoms. Thus, we analyzed the influence of PA on the QoL in BCS with persistent depressive symptoms during 12 months of follow-up. The sample included 70 female BCS. Depression and QoL domains (i.e., functional capacity, physical limitations, body pain, general health status, vitality, social and emotional aspects, and mental health) were assessed at baseline and follow-up periods by the Hospital Anxiety and Depression Scale and SF-36, respectively. Habitual PA was assessed by Baecke's questionnaire. Our results indicate a prevalence of 17.1% of depressive symptoms. Non-depressives BCS improved their physical limitations and general health status domains over time, but there were no observed differences in depressive BCS. BCS with persistent depressive symptoms (baseline and follow-up) showed worse QoL scores than non-depressives in all domains, regardless of confounding factors. When adjusted for PA, the difference between BCS depressives and non-depressives lost its significance in the functional capacity domain. In conclusion, habitual PA practice positively influenced the functional capacity domain of the QoL in BCS.

Resposta dos parâmentros do andar após intervenção com dicas auditivas rítmicas em idosos com doença de Parkinson / Response of gait parameters after intervention with rhythmic auditory cues in older people with parkinson's disease

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)

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)

Association between Different Domains of Sedentary Behavior and Health-Related Quality of Life in Adults: A Longitudinal Study.

Extended periods of time on screen devices and sitting are the main activities that characterize sedentary behavior (SB), which negatively impacts the quality of life. This negative influence was demonstrated mainly by cross-sectional studies performed in high-income countries in which the effects of screen time on health-related quality of life (HRQoL) is not considered. Thus, we analyzed the association between the different domains of SB (i.e., subdomains of screen time-television, computer, cellphone) and the HRQoL in adults that live in Brazil during two years of follow-up. The sample included 331 adults. Subdomains of screen time (i.e., watching television, using computers, and cellphones) and of HRQoL (i.e., physical functioning, role-physical, bodily pain, general health, vitality, social functioning, role-emotional, mental health, and current health perception) were assessed by a structured questionnaire and SF-36, respectively. Our results indicate a significant increase in screen time during the two years of follow-up. Linear regression models indicated that although domains of SB were differently associated with HRQoL, in general, screen time was negatively associated with social functioning and positively associated with physical functioning during locomotion and activities of daily living (ADL), role-physical (i.e., physical issues during work and ADLs), and role-emotional (i.e., emotional issues during work and ADLs) after the two-year follow-up. In conclusion, screen time may positively or negatively influence some domains of HRQoL in adults.

Transcranial direct current stimulation for balance rehabilitation in neurological disorders: A systematic review and meta-analysis.

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.

Cumulative additional information does not improve the neuromuscular control during postural responses to perturbations in postural instability/gait disorders subtype of Parkinson's disease.

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.

tDCS application for postural control in Parkinson's disease: Effects are associated with baseline characteristics.

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.

Prefrontal Cortical Activity During Preferred and Fast Walking in Young and Older Adults: An fNIRS Study.

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.

Being physically active minimizes the effects of leg muscle fatigue on obstacle negotiation in people with Parkinson's disease.

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.

Does the impaired postural control in Parkinson's disease affect the habituation to non-sequential external perturbation trials?

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.

Aerobic Exercise Combined With Transcranial Direct Current Stimulation Over the Prefrontal Cortex in Parkinson Disease: Effects on Cortical Activity, Gait, and Cognition.

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.

Cortical Activity Underlying Gait Improvements Achieved With Dopaminergic Medication During Usual Walking and Obstacle Avoidance in Parkinson Disease.

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.

Center of pressure responses to unpredictable external perturbations indicate low accuracy in predicting fall risk in people with Parkinson's disease.

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.

Is Cortical Activation During Walking Different Between Parkinson's Disease Motor Subtypes?

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.