RESUMO
Tremor is the most common movement disorder characterized by repetitive and stereotyped movements. The analysis of hand-drawing movements is commonly used in the evaluation of patients with tremor. The data collection conducted under kinetic conditions and while performing a voluntary movement highlights the kinetic tremor. Most investigations on tremor attempt to understand its relation to neuromuscular dysfunctions. Therefore, there is a lack of studies that aim to investigate the complex relation between the physiological tremor and aging, especially in kinetic conditions. In this context, the main motivation of this research was to generalize the results obtained in Almeida et al., a study that quantified age-related changes in the kinetic tremor of clinically healthy individuals. For this, a number of features extracted from tremor activity, obtained from digitized drawings of Archimedes' spirals, were analyzed. The analyses followed the sequence: Linearization of the Archimedes' spiral; Estimate of tremor activity; Data pre-processing; Feature extraction from the tremor activity; and Application of Linear Discriminant Analysis (LDA) technique as described in Almeida et al.. The generalization of the obtained results showed that the method based on LDA allows for a linear correlation between physiological kinetic tremor and aging.
Assuntos
Envelhecimento/fisiologia , Tremor/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Feminino , Humanos , Cinética , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
Tremor is the most common movement disorder characterized by repetitive and stereotyped movements. Most investigations on tremor attempt to understand its relation to neuromuscular dysfunctions. Therefore, there is a lack of studies that aim to investigate the complex relation between the physiological tremor and aging, especially in kinetic conditions. In this context, the main motivation of this research was to quantify age-related changes in the kinetic tremor of clinically healthy individuals. For this, a number of features extracted from tremor activity, obtained from digitized drawings of Archimedes' spirals, were analyzed. In total, 59 subjects participated in the experiments. These individuals were divided into seven groups according to their ages and two types of analysis were carried out. First, the tremor activity of young and elderly adults was investigated by means of traditional features commonly used in tremor analysis, and secondly, linear discriminant analysis (LDA) was employed for the study of the correlation between age and tremor. The results showed significant statistical differences between the kinetic tremor activity of the young and elderly groups. Furthermore, it was found that LDA allowed for the estimate of a unique feature, so-called LDA-value, which showed to be linearly correlated with age.
Assuntos
Envelhecimento , Atividade Motora , Tremor/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Cinética , Masculino , Pessoa de Meia-IdadeRESUMO
BACKGROUND: The human body adopts a number of strategies to maintain an upright position. The analysis of the human balance allows for the understanding and identification of such strategies. The displacement of the centre of pressure (COP) is a measure that has been successfully employed in studies regarding the postural control. Most of these investigations are related to the analysis of individuals suffering from neuromuscular disorders. Recent studies have shown that the elderly population is growing very fast in many countries all over the world, and therefore, researches that try to understand changes in this group are required. In this context, this study proposes the analysis of the postural control, measured by the displacement of the COP, in groups of young and elderly adults. METHODS: In total 59 subjects participated of this study. They were divided into seven groups according to their age. The displacement of the COP was collected for each subject standing on a force plate. Two experimental conditions, of 30 seconds each, were investigated: opened eyes and closed eyes. Traditional and recent digital signal processing tools were employed for feature computation from the displacement of the COP. Statistical analyses were carried out in order to identify significant differences between the features computed from the distinct groups that could allow for their discrimination. RESULTS: Our results showed that Linear Discrimination Analysis (LDA), which is one of the most popular feature extraction and classifier design techniques, could be successfully employed as a linear transformation, based on the linear combination of standard features for COP analysis, capable of estimating a unique feature, so-called LDA-value, from which it was possible to discriminate the investigated groups and show a high correlation between this feature and age. CONCLUSION: These results show that the analysis of features computed from the displacement of the COP are of great importance in studies trying to understand the ageing process. In particular, the LDA-value showed to be an adequate feature for assessment of changes in the postural control which can be related to functional changes that occur over the ageing.