Efeitos do envelhecimento na atividade do córtex cerebral durante o andar usual, adaptativo e com tarefa dupla
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2019-07-26
Autores
Sousa, Priscila Nobrega de [UNESP]
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Universidade Estadual Paulista (Unesp)
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Introdução: Apesar dos correlatos neurais dos comprometimentos do andar associados ao envelhecimento não serem completamente compreendidos, estudos recentes apontam que idosos apresentam maior ativação do córtex pré-frontal (via indireta) durante o andar. Entretanto, os estudos existentes não consideram o processo de envelhecimento em um espectro mais amplo e, ao contrário, apresentam comparações limitadas a extremos de idade (adulto jovem X idoso). A compreensão da atividade neural do controle do andar no envelhecimento é importante para a identificação do momento em que as alterações inerentes ao envelhecimento afetam a atividade do córtex cerebral. Assim os objetivos deste estudo foram: (i) investigar os efeitos do envelhecimento na atividade do córtex pré-frontal (CPF) durante o andar usual, adaptativo e com tarefa dupla; e (ii) analisar a associação entre a atividade cortical e medidas do andar e de funções cognitivas. Materiais e Método: Noventa participantes foram avaliados, sendo 15 participantes sadios em cada grupo etário: 20-25, 30-35, 40-45, 50-55, 60-65 e 70-75 anos. Foram realizadas avaliações cognitivas, do andar e da atividade do CPF. Um sistema portátil de espectroscopia funcional de luz próxima ao infravermelho foi utilizado para o registro da atividade do CPF enquanto os participantes andavam em um circuito em três condições: andar usual, adaptativo (ultrapassagem de obstáculos) e com tarefa dupla. Um carpete com sensores de pressão foi posicionado em uma das retas do circuito para o registro dos parâmetros espaço-temporais do andar. ANCOVAs foram empregadas para analisar as diferenças nas concentrações de oxihemoglobina entre os grupos e condições, controlando pela velocidade do andar usual; ANOVAs two-way foram utilizadas para analisar as diferenças dos parâmetros do andar e do desempenho na tarefa cognitiva; e testes de correlação de Pearson foram aplicados para analisar a associação entre as medidas da atividade cortical, do andar e de funções cognitivas. Resultados: A atividade do CPF aumentou de maneira crescente entre os grupos etários, com algumas particularidades para cada condição do andar.. O grupo G60 apresentou maior ativação do CPF em comparação com o grupo G30 no andar usual. Os grupos G50 e G60 apresentaram maior ativação do CPF em comparação com o grupo G20 no andar adaptativo. Os grupos G30, G50, G60 e G70 apresentaram maior ativação do CPF em comparação com o grupo G20 no andar com tarefa dupla. O grupo G70 apresentou pior desempenho cognitivo e do andar em comparação com os outros grupos. Ainda, a maior ativação do CPF foi correlacionada com pior performance do andar e pior função cognitiva (função executiva). Conclusão: O processo de envelhecimento provoca aumento gradativo da participação da via indireta no controle do andar e este aumento é influenciado pela tarefa locomotora realizada. Ainda, a ativação do CPF como mecanismo compensatório se torna ineficiente a partir da sétima década de vida. Esta ineficiência pode estar associada com comprometimentos da função executiva, que estão mais exacerbados nos indivíduos do grupo G70. De maneira geral, a menor ativação do córtex pré-frontal está relacionada com melhor performance do andar e melhor função executiva.
Introduction: Although the neural correlates of walking impairments associated with aging are not fully understood, recent studies indicate that the older adults present greater activation of the prefrontal cortex during walking. However, existing studies do not consider the aging process in a broader spectrum and, on the contrary, present limited comparisons to extremes of age (younger X older adult). Understanding the neural activity of walking control in aging is important to identify when the inherent changes in aging affect the activity of the cerebral cortex. Thus, the aims of this study were: (i) to investigate the effects of aging on the activity of the prefrontal cortex (PFC) during usual, adaptive and dual task walking; and (ii) to analyze the association of cortical activity with walk measures and cognitive functions. Materials and Methods: Ninety participants were evaluated, with 15 healthy participants in each age group: 20-25, 30-35, 40-45, 50-55, 60-65 and 70-75 years. Cognitive, walking and PFC activity assessments were performed. A portable near infrared functional spectroscopy system was used to record PFC activity while participants walked on a circuit in three conditions: usual, adaptive (obstacle avoidance) and dual task walking. A carpet with pressure sensors was positioned in one of the straight lines of the circuit to record walk parameters. ANCOVAs were used to analyze differences in oxyhemoglobin concentrations between groups and conditions; Two-way ANOVAs were used to analyze differences in walking parameters and performance in the cognitive task; and Pearson's correlation tests were applied to analyze the association between measures of cortical activity, walk and cognitive functions. Results: PFC activation occurred in an increasing way between the age groups, with some peculiarities for each walking condition. The G60 group presented greater activation of the PFC compared to the G30 group in the usual walking. The G50 and G60 groups showed greater PFC activation compared to the G20 group on the adaptive walking. The G30, G50, G60 and G70 groups showed greater activation of PFC compared to the G20 group in the dual task walking. The G70 group had worse cognitive and walking performance compared to the other groups. Also, the greater PFC activation was correlated with worse walking performance and cognitive function (executive function). Conclusion: The aging process causes a gradual increase in the participation of the indirect pathway in the walking control and this increase is influenced by the locomotor task performed. Also, the activation of the PFC as compensatory mechanism becomes inefficient from the seventh decade of life. This inefficiency may be associated with executive function impairments, which are more exacerbated in individuals of the G70 group. In general, the lower activation of the prefrontal cortex is related to better walking performance and better executive function.
Introduction: Although the neural correlates of walking impairments associated with aging are not fully understood, recent studies indicate that the older adults present greater activation of the prefrontal cortex during walking. However, existing studies do not consider the aging process in a broader spectrum and, on the contrary, present limited comparisons to extremes of age (younger X older adult). Understanding the neural activity of walking control in aging is important to identify when the inherent changes in aging affect the activity of the cerebral cortex. Thus, the aims of this study were: (i) to investigate the effects of aging on the activity of the prefrontal cortex (PFC) during usual, adaptive and dual task walking; and (ii) to analyze the association of cortical activity with walk measures and cognitive functions. Materials and Methods: Ninety participants were evaluated, with 15 healthy participants in each age group: 20-25, 30-35, 40-45, 50-55, 60-65 and 70-75 years. Cognitive, walking and PFC activity assessments were performed. A portable near infrared functional spectroscopy system was used to record PFC activity while participants walked on a circuit in three conditions: usual, adaptive (obstacle avoidance) and dual task walking. A carpet with pressure sensors was positioned in one of the straight lines of the circuit to record walk parameters. ANCOVAs were used to analyze differences in oxyhemoglobin concentrations between groups and conditions; Two-way ANOVAs were used to analyze differences in walking parameters and performance in the cognitive task; and Pearson's correlation tests were applied to analyze the association between measures of cortical activity, walk and cognitive functions. Results: PFC activation occurred in an increasing way between the age groups, with some peculiarities for each walking condition. The G60 group presented greater activation of the PFC compared to the G30 group in the usual walking. The G50 and G60 groups showed greater PFC activation compared to the G20 group on the adaptive walking. The G30, G50, G60 and G70 groups showed greater activation of PFC compared to the G20 group in the dual task walking. The G70 group had worse cognitive and walking performance compared to the other groups. Also, the greater PFC activation was correlated with worse walking performance and cognitive function (executive function). Conclusion: The aging process causes a gradual increase in the participation of the indirect pathway in the walking control and this increase is influenced by the locomotor task performed. Also, the activation of the PFC as compensatory mechanism becomes inefficient from the seventh decade of life. This inefficiency may be associated with executive function impairments, which are more exacerbated in individuals of the G70 group. In general, the lower activation of the prefrontal cortex is related to better walking performance and better executive function.
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Palavras-chave
Envelhecimento, Locomoção, fNIRS, Córtex pré-frontal, Aging, Locomotion, Prefrontal cortex