Memória de trabalho visuoespacial e posicionamento do pé no início do andar em pacientes com doença de Parkinson
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2017-12-14
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Universidade Estadual Paulista (Unesp)
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A doença de Parkinson (DP) é a segunda doença neurodegenerativa mais comum, que acomete aproximadamente 0,3% da população mundial. A morte dos neurônios dopaminérgicos na substância negra leva aos seus sinais/sintomas motores característicos da DP. Além dos sinais/sintomas motores destacam-se também os não motores como alterações de humor, cognição, ansiedade e depressão. As alterações cognitivas incluem comprometimentos das funções executivas e da memória de trabalho (MT) verbal e visuoespacial. Déficits na MT visuoespacial parecem estar associados aos comprometimentos do andar em pacientes com DP, principalmente no início do andar, porém esta relação ainda é pouco conhecida. O objetivo deste estudo foi analisar o impacto da MT no posicionamento do pé em alvos com diferentes tempos para iniciar o andar em pacientes com DP e idosos neurologicamente sadios (NS). Participaram do estudo 20 idosos com DP e 18 NS avaliados quanto à função cognitiva geral, capacidade de armazenamento na MT e central executiva da MT por meio dos testes Digit Span, Blocos de Corsi e Clox I e II. A tarefa foi realizada sob condições que combinaram o tempo para início do andar (250ms, 500ms, 1s ou 2s) após a exposição inicial do alvo (5s) e a localização do alvo (direita, esquerda e central). Para a análise cinemática, o sistema optoeletrônico capturou as trajetórias dos emissores infravermelhos que foram fixados no pé direito dos participantes. A estatística descritiva (média ± desvio ou erro padrão) foi empregada para a apresentação das variáveis de caracterização dos grupos e das variáveis dependentes. Na análise estatística foram utilizados os testes de Shapiro-Wilk e de Levene para verificar a normalidade e a homogeneidade dos dados. Para a comparação entre os grupos, testes t para amostras independentes (idade, massa corporal e estatura) e o teste U de Mann-Whitney (variáveis cognitivas) foram empregados. Para o erro absoluto, erro variável e erro constante foram realizadas ANOVAS two-way (grupo X condição), com medidas repetidas para condição. O teste de Bonferroni foi empregado para localizar possíveis diferenças significativas. Os grupos não apresentaram diferença significativa para idade, peso e altura. Nas variáveis cognitivas apenas encontrou-se diferença no MEEM. Para variáveis de posicionamento do pé sobre o alvo, ausência de efeito principal de grupo (GDP X GC) e de interação entre grupo e os fatores de tempo e posição do alvo para os três erros. No sentido médio-lateral, os participantes apresentaram menor erro absoluto e maior erro variável para o alvo posicionado à esquerda, nas condições de 250ms e 2s. Ainda, para o alvo posicionado à direita, observou-se maior erro constante anteroposterior e médio-lateral comparados aos outros alvos. Na condição de maior tempo, 2s, os participantes posicionaram o pé antes do alvo em comparação ao tempo de 500ms, indicado pelo maior erro constante nesta condição. Os participantes apresentaram menor erro absoluto médio-lateral na condição de tempo de 1s e erro absoluto anteroposterior na condição de tempo de 2s para o alvo posicionado no centro nas condições com maior tempo. Finalmente, não houve correlação entre as variáveis de (erro absoluto, constante e variável) com a capacidade de armazenamento de informações verbais e visuoespaciais e os processos de controle executivo da MT. Concluindo-se que pacientes com DP e idosos NS apresentam desempenho semelhante ao posicionar o pé sobre o alvo. Quando os alvos estão posicionados lateralmente, o desempenho da tarefa é prejudicado, principalmente no alvo da esquerda, diminuindo a acurácia e a precisão. Ainda, tempos muito longos (2s) ou curtos (250ms) parecem influenciar negativamente no desempenho da tarefa devido ao longo tempo de armazenamento da informação visual e curto tempo para a realização da ação motora, respectivamente.
Parkinson's disease (PD) is the second most common neurodegenerative disease, affecting approximately 0.3% of the world's population. The death of dopaminergic neurons in the substantia nigra leads to the characteristic motor signals/symptoms in PD. Additionally, patients also show non-motor signs/symptoms such as impairments in mood, cognition, anxiety and depression. The cognitive changes are dependent on executive functions and among them are a verbal and visuospatial (WM) working memory. Deficits in visuospatial WM seem to be associated with gait impairment in patients with PD, especially in gait initiation, but this relationship is still poorly understood. The aim of this study was to analyze the impact of visuospatial WM on foot positioning on targets with different intervals to star walking after target exposure in patients with PD (PDG) and neurologically healthy (NH) older adults. Participants were 20 older adults with PD and 18 NH older adults (CG) who were assessed in regard to general cognitive function, storage capacity in WM and central executive of WM by means of the Span Digit, Corsi Blocks and Clox I and II tests. The experimental task was performed under conditions that combined the time to start walking (250ms, 500ms, 1s or 2s) after the initial target exposure target location (right, left and center). For kinematic analysis, the optoelectronic system captured trajectories of the infrared emitters that were fixed in the right foot of the participants. Descriptive statistic (mean ± standard deviation or error) was used to present variables for characterization of groups and dependent variables. In the statistical analysis of the Shapiro-Wilk and Levene test instruments to verify the normality and the homogeneity of the data. For a comparison between groups, testis for independent samples (age, body mass and stature) and Mann-Whitney test (cognitive variables) and employed. For absolute error, variable error and constant error, we performed two-way ANOVAs (group X condition), with repeated measures for the condition. The Bonferroni test was used to find possible significant differences. The groups did not present significant differences for age, weight and height. For the cognitive variables, we found significant difference for MEEM only, with PDG presenting lower score than the CG. For foot positioning variables, absence of main group effect (PGD X CG) and interaction between group and time and target position factors for the three errors. In the mid-lateral direction, the participants presented lower absolute error and greater variable error for the target positioned to the left, in the conditions of 250ms and 2s. Also, for the right-positioned target, greater anteroposterior and mid-lateral constant error were observed compared to the others targets. For longer time condition, 2s, participants positioned the foot before the target compared to the time of 500ms, indicated by the largest constant error in this condition. The participants presented lower absolute mid-lateral error in the 1s time condition and anteroposterior absolute error in the time condition of 2s for the target positioned in the center in the conditions with greater time. Finally, there was no correlation between the variables (absolute, constant and variable error) with the storage capacity of verbal and visuospatial information and the processes of executive control of WM. It was concluded that patients with PD and NH older people present similar performance for foot positioning. When the targets are positioned laterally, the performance of the task is impaired, especially in the left target, decreasing the precision and accuracy. Also, very long (2s) or short times (250ms) seem to negatively influence the performance of the task due to the long storage time of the visual information and short time to perform the motor action, respectively.
Parkinson's disease (PD) is the second most common neurodegenerative disease, affecting approximately 0.3% of the world's population. The death of dopaminergic neurons in the substantia nigra leads to the characteristic motor signals/symptoms in PD. Additionally, patients also show non-motor signs/symptoms such as impairments in mood, cognition, anxiety and depression. The cognitive changes are dependent on executive functions and among them are a verbal and visuospatial (WM) working memory. Deficits in visuospatial WM seem to be associated with gait impairment in patients with PD, especially in gait initiation, but this relationship is still poorly understood. The aim of this study was to analyze the impact of visuospatial WM on foot positioning on targets with different intervals to star walking after target exposure in patients with PD (PDG) and neurologically healthy (NH) older adults. Participants were 20 older adults with PD and 18 NH older adults (CG) who were assessed in regard to general cognitive function, storage capacity in WM and central executive of WM by means of the Span Digit, Corsi Blocks and Clox I and II tests. The experimental task was performed under conditions that combined the time to start walking (250ms, 500ms, 1s or 2s) after the initial target exposure target location (right, left and center). For kinematic analysis, the optoelectronic system captured trajectories of the infrared emitters that were fixed in the right foot of the participants. Descriptive statistic (mean ± standard deviation or error) was used to present variables for characterization of groups and dependent variables. In the statistical analysis of the Shapiro-Wilk and Levene test instruments to verify the normality and the homogeneity of the data. For a comparison between groups, testis for independent samples (age, body mass and stature) and Mann-Whitney test (cognitive variables) and employed. For absolute error, variable error and constant error, we performed two-way ANOVAs (group X condition), with repeated measures for the condition. The Bonferroni test was used to find possible significant differences. The groups did not present significant differences for age, weight and height. For the cognitive variables, we found significant difference for MEEM only, with PDG presenting lower score than the CG. For foot positioning variables, absence of main group effect (PGD X CG) and interaction between group and time and target position factors for the three errors. In the mid-lateral direction, the participants presented lower absolute error and greater variable error for the target positioned to the left, in the conditions of 250ms and 2s. Also, for the right-positioned target, greater anteroposterior and mid-lateral constant error were observed compared to the others targets. For longer time condition, 2s, participants positioned the foot before the target compared to the time of 500ms, indicated by the largest constant error in this condition. The participants presented lower absolute mid-lateral error in the 1s time condition and anteroposterior absolute error in the time condition of 2s for the target positioned in the center in the conditions with greater time. Finally, there was no correlation between the variables (absolute, constant and variable error) with the storage capacity of verbal and visuospatial information and the processes of executive control of WM. It was concluded that patients with PD and NH older people present similar performance for foot positioning. When the targets are positioned laterally, the performance of the task is impaired, especially in the left target, decreasing the precision and accuracy. Also, very long (2s) or short times (250ms) seem to negatively influence the performance of the task due to the long storage time of the visual information and short time to perform the motor action, respectively.
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Palavras-chave
Doença de Parkinson, Memória de trabalho visuoespacial, Iniciar o andar, Parkinson’s disease, Visuospatial working memory, Gait initiation