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Theory of Mind in schizophrenia: focusing on the role of non-verbal communication and motor function
Theory of Mind in schizophrenia: focusing on the role of non-verbal communication and motor function
Theory of Mind, known as the ability to infer mental states of others, is crucial to one’s social functioning. Despite Theory of Mind impairment being a well-recognized feature of schizophrenia, precise underlying mechanisms are still unclear. An abundance of cognitive testing methods along with several neurophysiological techniques aiming to evaluate Theory of Mind have been developed, however, there is no universal agreement as to the most accurate way to detect cognitive impairment. Both verbal and non-verbal communication methods are crucial for Theory of Mind function, yet the non-verbal skills develop earlier during childhood and prevail throughout life, which makes them fundamental for social cognitive development. Most of the existing studies evaluate Theory of Mind as a whole entity using a single testing modality, and without differentiating between the components. Therefore, the aim of the current thesis was to establish the significance of the non-verbal aspect of Theory of Mind in schizophrenia using cognitive testing, as well as neurophysiological and autonomic parameters. Study 1 evaluated both the verbal and the non-verbal testing methods to evaluate Theory of Mind impairment in schizophrenia. As predicted, all schizophrenia patients performed worse than the healthy controls, with the non-verbal test being the most sensitive to Theory of Mind impairment. Furthermore, the severity of psychopathological symptoms inversely correlated with the non-verbal test performance only. Study 2 investigated the neurophysiological aspect of Theory of Mind in schizophrenia using the EEG mu rhythm analysis during a motor imagery task. EEG mu rhythm suppression has previously been shown to reflect the function of Theory of Mind via the mirror neuron system (Pineda & Hecht, 2009). In our experiment, schizophrenia subjects demonstrated decreased EEG mu rhythm suppression compared to healthy controls. Study 3 analyzed the association of Theory of Mind test performance with both neurophysiological and autonomic parameters in first episode psychosis, chronic schizophrenia and the healthy subjects. Neither of the parameters differed substantially between the two patient groups. However, implementation of both neurophysiological and autonomic predictors led to a successful classification of subjects into the schizophrenia group and the healthy group. Our findings indicate that non-verbal communication plays a crucial role in Theory of Mind in schizophrenia. Theory of Mind deficit is detectable throughout the course of disease using both non-verbal cognitive and neurophysiological testing methods, suggesting that Theory of Mind impairment is a trait of schizophrenia. Furthermore, as the brain motor cortex is responsible both for the voluntary movement and the mirror neuron system, schizophrenia-related motor disturbances might be related to the malfunctioning Theory of Mind. All of the above provides further insight into the underlying mechanisms of schizophrenia.
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Morozova, Alexandra
2023
English
Universitätsbibliothek der Ludwig-Maximilians-Universität München
Morozova, Alexandra (2023): Theory of Mind in schizophrenia: focusing on the role of non-verbal communication and motor function. Dissertation, LMU München: Faculty of Medicine
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Abstract

Theory of Mind, known as the ability to infer mental states of others, is crucial to one’s social functioning. Despite Theory of Mind impairment being a well-recognized feature of schizophrenia, precise underlying mechanisms are still unclear. An abundance of cognitive testing methods along with several neurophysiological techniques aiming to evaluate Theory of Mind have been developed, however, there is no universal agreement as to the most accurate way to detect cognitive impairment. Both verbal and non-verbal communication methods are crucial for Theory of Mind function, yet the non-verbal skills develop earlier during childhood and prevail throughout life, which makes them fundamental for social cognitive development. Most of the existing studies evaluate Theory of Mind as a whole entity using a single testing modality, and without differentiating between the components. Therefore, the aim of the current thesis was to establish the significance of the non-verbal aspect of Theory of Mind in schizophrenia using cognitive testing, as well as neurophysiological and autonomic parameters. Study 1 evaluated both the verbal and the non-verbal testing methods to evaluate Theory of Mind impairment in schizophrenia. As predicted, all schizophrenia patients performed worse than the healthy controls, with the non-verbal test being the most sensitive to Theory of Mind impairment. Furthermore, the severity of psychopathological symptoms inversely correlated with the non-verbal test performance only. Study 2 investigated the neurophysiological aspect of Theory of Mind in schizophrenia using the EEG mu rhythm analysis during a motor imagery task. EEG mu rhythm suppression has previously been shown to reflect the function of Theory of Mind via the mirror neuron system (Pineda & Hecht, 2009). In our experiment, schizophrenia subjects demonstrated decreased EEG mu rhythm suppression compared to healthy controls. Study 3 analyzed the association of Theory of Mind test performance with both neurophysiological and autonomic parameters in first episode psychosis, chronic schizophrenia and the healthy subjects. Neither of the parameters differed substantially between the two patient groups. However, implementation of both neurophysiological and autonomic predictors led to a successful classification of subjects into the schizophrenia group and the healthy group. Our findings indicate that non-verbal communication plays a crucial role in Theory of Mind in schizophrenia. Theory of Mind deficit is detectable throughout the course of disease using both non-verbal cognitive and neurophysiological testing methods, suggesting that Theory of Mind impairment is a trait of schizophrenia. Furthermore, as the brain motor cortex is responsible both for the voluntary movement and the mirror neuron system, schizophrenia-related motor disturbances might be related to the malfunctioning Theory of Mind. All of the above provides further insight into the underlying mechanisms of schizophrenia.