D.Phil. (Psychology) / Please refer to full text to view abstract

Abstract: Tourettes syndrom är en neuropsykiatrisk funktionsnedsättning som kännetecknas av motoriska och vokala tics. Sedan covid- 19 pandemin har Tourettes syndrom spridits sig på sociala medier som en trend bland ungdomar och detta har uppmärksammats av forskare som nu försöker ta reda på vad spridningen bero på.    Syftet med denna litteraturstudie har varit att kartlägga vad tidigare forskning beskriver om Tourettes syndroms samband i sociala medier.    Metoden som används var en litteraturstudie med hjälp av scoping metoden som följer Arksey & O´Malleys (2005) sexstegsmodell. Sökresulteten gav oss 13 artiklar som hittades i databasen libsearch.    Resultaten visar på att man har sätt ett samband mellan sociala medier användningen och Tourettes syndrom. Resultatet visar även på att det tics liknande beteendet kan ha med MSI (mass socogenic illness) att göra. Slutligen visar resultatet också på att spridningen av tic liknande beteende har ökat sedan covid- 19 pandemin till följd av restriktionerna och förhållningsreglerna kring den sociala distansen. / Abstract: Tourette's syndrome is a neuropsychiatric disability characterized by its motor and vocal tics. Since the covid-19 pandemic, Tourette syndrome has spread on social media as a trend among young people. This trend has been noticed by researchers who are now trying to find out what caused the spread. The purpose of this scoping study has been to map what previous research describes about Tourette syndrome's connection to social media. The method used was a literature study using the metod scoping study that follows Arksey & O'Malley's (2005) six-step model. The search result gave us 13 articles that were found in the database libsearch. The results show that a connection is made between social media use and Tourette's syndrome. The result also shows that the tick-like behavior can be related to MSI (mass socogenic illness). Finally, the results show that the spread of similar behavior has increased since the covid-19 pandemic.

Le contrôle postural et la perception des limites de la stabilité sont des processus complexes qui nécessitent le traitement et l’intégration d’informations sensorielles multimodales. Pendant l’enfance, le développement de la stabilité posturale s’effectue de façon non-monotonique. Plusieurs auteurs ont suggéré que ce profil non linéaire serait provoqué par une période de recalibration des systèmes sensoriels. Cette phase, nommée période de transition, est observée vers l’âge de 6-7 ans. Nous disposons toutefois de très peu d’information sur le rôle spécifique des afférences et des mécanismes d’intégration sensorielle au cours du développement postural. Les dysfonctions dans les noyaux gris centraux, telles que ceux observés dans la maladie de Parkinson, ont été associées à divers déficits dans le contrôle de la posture, dans le traitement et l’intégration sensoriel plus particulièrement, au niveau des informations proprioceptives. De plus, les limites fonctionnelles de la stabilité posturale des personnes atteintes de la maladie de Parkinson sont significativement réduites. Cependant, les connaissances concernant comment certaines pathologies des noyaux gris centraux, telles que le syndrome Gilles de la Tourette (SGT) et la maladie de Huntington (MH) affectent la capacité d’utiliser les informations sensorielles pour contrôler la posture demeurent à ce jour, incomplètes. Cette thèse porte sur le rôle des noyaux gris centraux dans les processus de traitements et d’intégration sensorielle, particulièrement les afférences proprioceptives dans le contrôle de la posture au cours du développement de l’enfant en santé, atteint du SGT et chez l’adulte atteint de la MH avec et sans symptôme clinique. Notre protocole expérimental a été testé chez ces trois populations (enfants en santé, SGT et MH). Nous avons utilisé des mesures quantitatives à partir de données issues d’une plateforme de force afin d’évaluer les ajustements posturaux dans les limites de la stabilité posturale. Les participants devaient s’incliner le plus loin possible dans quatre différentes directions (avant, arrière, droite et gauche) et maintenir l’inclinaison posturale maximale pendant 10 secondes. Afin de tester la capacité à traiter et à intégrer les informations sensorielles, la tâche expérimentale a été exécutée dans trois conditions sensorielles : 1) yeux ouverts, 2) yeux fermés et 3) yeux fermés, debout sur une mousse. Ainsi, la contribution relative de la proprioception pour le contrôle postural augmente à travers les conditions sensorielles. Dans la première étude, nous avons évalué la capacité à traiter et à intégrer les informations sensorielles avant (4 ans) et après (8-10 ans) la période de transition comparativement aux adultes. Dans la deuxième et la troisième étude, nous avons également évalué le traitement et l’intégration des informations sensorielles chez les patients atteints de désordres des noyaux gris centraux. La deuxième étude portera spécifiquement sur les adolescents atteints du SGT et la troisième, sur la MH avant et après l’apparition des symptômes cliniques. En somme, les résultats de la première étude ont démontré que la performance des enfants est affectée de façon similaire par les différentes conditions sensorielles avant et après la période de transition. Toutefois, le profil de développement des mécanismes responsables des ajustements posturaux de l’axe antéropostérieur est plus précoce comparativement à ceux de l’axe médiolatéral. Ainsi, nos résultats ne supportent pas l’hypothèse de la période de recalibration des systèmes sensoriels pendant cette période ontogénétique mais suggèrent que la période de transition peut être expliquée par la maturation précoce des mécanismes d’ajustements posturaux dans l’axe antéropostérieur. Dans l’ensemble, les résultats de nos études chez les populations atteintes de désordres des noyaux gris centraux (MH et SGT) démontrent non seulement qu’ils ont des déficits posturaux mais également que les ajustements posturaux dans les deux axes sont affectés par les conditions sensorielles. Pour la première fois, nos études démontrent des déficits globaux de traitements et d’intégration sensorielle accentués pour les signaux proprioceptifs. Ces résultats sont similaires à ceux observés dans la maladie de Parkinson. De plus, les adolescents atteints du SGT éprouvent également des troubles posturaux marqués dans la condition visuelle ce qui suggère des déficits d’intégrations visuelles et/ou multimodaux. / Postural control and the perception of the stability limits are complex mechanisms requiring the processing and integration of multimodal sensory information. During childhood, the development of postural control skills improves in a non-monotonic manner. Many researchers suggested that this non linear profile is caused by the recalibration of sensory systems. This recalibration phase, named transition period, is generally observed at 6-7 years of age. However, the exact cause of this critical turning point remains undetermined. Moreover, very little is known about the specific role of sensory information and sensorimotor mechanisms during postural development. Basal ganglia disorders such as Parkinson’s disease are associated with postural control impairments and deficits in the processing and integration of sensory information, especially in proprioception. Moreover, the limits of stability are significantly reduced in Parkinson’s disease. However, the knowledge on how other basal ganglia dysfunctions such as Gilles de la Tourette syndrome (GTS) and Huntington’s disease (HD) impact on the ability to process and integrate sensory information for postural control is still limited. In this thesis, we explored the role of basal ganglia in the processing an integration of sensory information, particularly proprioceptive signals for the postural control during the development of healthy children, in adolescents with GTS and in adults with premanifest and manifest HD. Our stability limits protocol was used to test the postural control skills of these three populations. We calculated center of pressure displacements obtained from a force plate and we investigated postural adjustments during the maximum leaning posture. The participants were asked to lean as far as possible and maintain this position during 10 seconds in different directions (forward, backward, rightward or leftward). This task simulates functional positions that frequently occur in daily life. In order to test the ability to process and integrate sensory information for postural control, the stability limits task was assessed in three sensory conditions: 1) eyes open, 2) eyes closed and 3) eyes closed while standing on foam. Thus, the relative contribution of proprioceptive signals for postural control increased across sensory conditions. In the first study, we investigated the children’s ability to process and integrate sensory information for postural control before (4 years old) and after (8 to 10 years old) the transition period compared to adults. In the second and third studies, the ability to process and integrate sensory information for postural control was assessed in participants with basal ganglia disorders, namely adolescents with GTS and adults with manifest and premanifest HD. In sum, our ontogenetic study indicated that the younger children (4 years old) were not differentially affected by sensory conditions than the older children (8 to 10 years old). Thus, our results do not support the hypothesis that an important recalibration of sensorial systems takes place during the transition period. However, the results revealed axis-dependent differences among the groups in postural control. Until the age of 10, children have a reduced ability to perform appropriate center of pressure adjustments along the mediolateral direction compared to adults. In contrast, the ability to produce precise center of pressure adjustments along the anteroposterior axis was already developed at 4 years of age, but it reached the adult level of performance after the transition period. Altogether, the assessment of participants with basal ganglia disorders indicated that they have postural adjustment impairments in both movement axes and are affected by sensory conditions. For the first time, we reported global deficits in the processing and integration of sensory information, especially in proprioception in GTS and in premanifest and manifest HD. These results are similar to those reported for Parkinson’s disease patients. Moreover, the adolescents with GTS also displayed marked postural control abnormalities in the visual condition which might be explained by either deficit in the processing of visual information and/or in multimodal sensory integration mechanisms.

Introdução: O Transtorno Obsessivo-Compulsivo (TOC) é reconhecido como um transtorno heterogêneo. Esta heterogeneidade dificulta a interpretação dos resultados dos estudos. A descrição de grupos de pacientes mais homogêneos pode facilitar a identificação desta busca, já que pode identificar fenótipos que sejam hereditários e válidos do ponto de vista genético. A abordagem categorial e dimensional são estratégias reconhecidas para a identificação de subgrupos mais homogêneos de pacientes. Dentro da abordagem categorial, o subgrupo de pacientes com início precoce dos sintomas obsessivo-compulsivo (SOC), e o subgrupo de TOC associado a transtorno de tiques apresentam características clínicas semelhantes, com evidências de sobreposição destas características entre os dois grupos. Os objetivos deste estudo foram: investigar características demográficas e clínicas dos pacientes com TOC de início precoce (GP) e TOC de início tardio (GT); e pesquisar características demográficas e clínicas dos pacientes com TOC de início precoce (GP) com tiques e pacientes com TOC de início precoce (GP) sem tiques. Metodologia: Trezentos e trinta pacientes com diagnóstico de TOC de acordo com o DSM-IV foram avaliados diretamente com os seguintes instrumentos: Entrevista Clínica Estruturada para o DSM-IV - Transtornos do Eixo I; Escala Yale-Brown de Sintomas Obsessivo-Compulsivos - Y-BOCS; Escala Dimensional para Avaliação de Presença e Gravidade de Sintomas Obsessivo-Compulsivos DY-BOCS; Escala de Avaliação Global de Tiques desenvolvida pelo Yale Child Study Center - YGTSS. Foi considerado TOC de início precoce se os sintomas dos pacientes tiveram início até os 10 anos de idade (160 pacientes). Os pacientes com início de sintomas entre 11 e 17 anos (95 pacientes) foram denominados grupo intermediário, enquanto aqueles após os 17 anos foram chamados grupo de início tardio (75 pacientes). Resultados: os pacientes do GP se diferenciaram dos pacientes do GT por apresentar maior freqüência do sexo masculino; maior freqüência de história familiar de SOC em familiares de primeiro grau; maiores escores da escala Y-BOCS para compulsões e Y-BOCS total; maior chance de ter obsessões de contaminação; maior chance de ter compulsões de repetição, colecionismo, diversas e compulsões do tipo tic-like; menor chance de ter compulsões de contagem; maior chance de apresentar sintomas da dimensão de \"colecionismo\"; maior gravidade nas dimensões de \"agressão/violência\", \"diversas\" e escore global da escala DY-BOCS; maior número médio de comorbidades; maior probabilidade de ocorrência de transtorno de ansiedade de separação, fobia social, transtorno dismórfico corporal e transtorno de tiques; menor chance de apresentar transtorno de estress pós-traumático; e maior chance de ter redução de 35% dos sintomas na escala Y-BOCS. O GP com tiques se diferenciou do GP sem tiques por apresentar maior prevalência de fenômenos sensoriais; menor chance e menor gravidade de ter a dimensão de \"contaminação/limpeza\" e menor gravidade no escore global da escala DY-BOCS; menor chance de apresentar transtorno de humor, transtorno unipolar, transtornos ansiosos, fobia social e skin picking, e maior a chance de apresentar diminuição de 35% dos sintomas na escala Y-BOCS. Os resultados sugeriram que as diferenças encontradas entre os grupos precoce, intermediário e tardio foram devidas à própria idade de início, e outras diferenças foram devidas à presença de tiques. / Introduction: Obsessive-compulsive disorder (OCD) is recognized as a heterogeneous condition. This heterogeneity obscures the interpretation of the results of the studies. The description of more homogeneous groups of patients can facilitate the identification of this search, since it can identify phenotypes that are hereditary and valid to the genetic point of view. Categorical and dimensional approaches are recognized strategies for the identification of more homogeneous subgroups of patients. Regarding the categorical approach, the subgroup of patients with early age at onset of the obsessive-compulsive symptoms (OCS), and the tic-related-OCD subgroup present similar clinical characteristics, with evidences of an overlap of these characteristics between the two groups. The aims of this study were: to investigate clinical and demographic characteristics of the early age at onset subgroup (EO), compared to the late onset subgroup (LO); and to investigate demographic and clinical characteristics of early age at onset OCD patients, with and without comorbid tic disorders. Methodology: Three hundred and thirty patients with the diagnosis of OCD according to the DSM-IV were directly assessed with the following instruments: Structured Clinical Interview for DSM-IV Axis I Disorders-patient edition - SCID-I/P; Yale-Brown Obsessive-Compulsive Scale - Y-BOCS; Dimensional Yale-Brown Obsessive-Compulsive Scale - DY-BOCS and Yale Global Tics Severity Scale - YGTSS. We considered early age at onset when OCS began before the age of 10 (160 patients). Patients with age at onset between 11 and 17 years old were termed intermediate group (95 patients), whereas those with age at onset after 17 years old were designated as late onset OCD (75 patients). Results: EO patients differed from LO patients in terms of presenting higher frequency of the male gender; higher frequency of a family history of OCS; higher Y-BOCS for compulsions and total Y-BOCS scores; higher chance of presenting contamination obsessions, repeating, hoarding, miscellaneous and tic-like compulsions; lower chance of having counting compulsions; higher probability of presenting symptoms of \"hoarding\" dimension; higher severity in \"aggression/violence\" and \"miscellaneous\" dimensions and global DY-BOCS scale score; higher mean number of comorbidities; higher probability of presenting separation anxiety disorder, social phobia, body dysmorphic disorder and tic disorders; lower chance of presenting posttraumatic stress disorder; and a higher chance of having a 35% reduction on the Y-BOCS scale. The EO subgroup with tic disorders differed from the EO without tics for presenting higher chance of having sensory phenomena, somatic obsessions; lower chance and lower score in the DY-BOCS scale; lower chance of presenting mood disorder, depressive disorder, anxiety disorders, social phobia and skin picking; higher chance of having a 35% reduction on the Y-BOCS scale. Results suggested that the differences found among early, intermediated and late onset groups with early onset were secondary to the own age at onset, and other differences were secondary to the presence of tics.

A web-based survey was conducted that included 97 practicing school psychologists in California. The results from the survey indicated that the majority (88%) of respondents were knowledgeable about Tourette Syndrome. Many respondents (28%) had never worked with a student with Tourette’s, 20% had at least one case, and 52% indicated that they had worked with more than two cases in their careers as school psychologists. The majority of respondents indicated that their school psychology program did not adequately train them to assess or counsel students with Tourette’s. The majority of participants also did not feel confident to work with students with Tourette’s. As found in the study, school psychologists are in need of training to better serve children with Tourette Syndrome. Children, whether diagnosed with Tourette Syndrome or not, may exhibit difficulties making academic progress because of tic related issues, as well as comorbid disorders such as Attention Deficit Hyperactivity Disorder (ADHD) and Obsessive Compulsive Disorder (OCD). Schools typically are where students spend many hours of their day, and where those who are knowledgeable about Tourette’s can identify and provide needed supports depending on the student’s needs. Therefore, school psychologists play a key role in facilitating proper education regarding Tourette’s to students, teachers, staff, and families, as well as providing academic, behavioral, emotional, and social support a student may need.

<p>A total population of 4,479 children (7-15 years of age) attended school in Ludvika & Smedjebacken in 2000. All the school children and their parents were asked to fill in a questionnaire concerning different tics A three-stage procedure was used: tic identification, interview, and clinical assessment.</p><p>Tourette syndrome, according to DSM IV criteria was found in 25 (0.6%) of the children, another 34 (0.8%) suffered from chronic motor tics (CMT), 24 (0.4%) from chronic vocal tics (CVT) and 214 (4.8%) children had had transient tics (TT) during the last year. Altogether 297 (6.6%) children had or had had some tic disorder. </p><p>Twenty-five controls without tics and 25 children with TT of the same age, sex and school as the TS children were randomly chosen. They were together with the 34 children with CMT and the 24 children with CVT examined with use of a broad battery of instruments. </p><p>The mean age of the first symptoms of TS was significantly lower than the onset of chronic motor/vocal tics. A younger age of onset of TS indicated more severe tics. Eighty per cent had a first-degree relative with a psychiatric disorder such as tic disorder, obsessive-compulsive behaviour, attentiondeficit/hyperactivity disorder (ADHD), or depression. A non-significant increase with regard to reduced optimality score in the pre-, peri-, or neonatal periods was found in children with TS compared to controls. No differences were found concerning socio-economic status. Psychiatric comorbid disorders were found in 92% of the children with TS. ADHD was most common. Patterns of psychiatric comorbidity were similar in children with TS and CVT. Children with TS perform poorer than the population in general with respect to cognitive functioning and self-perception.</p><p>The results are discussed as they relate to the need for case identification, diagnosis, intervention, and treatment. </p>

A total population of 4,479 children (7-15 years of age) attended school in Ludvika &amp; Smedjebacken in 2000. All the school children and their parents were asked to fill in a questionnaire concerning different tics A three-stage procedure was used: tic identification, interview, and clinical assessment. Tourette syndrome, according to DSM IV criteria was found in 25 (0.6%) of the children, another 34 (0.8%) suffered from chronic motor tics (CMT), 24 (0.4%) from chronic vocal tics (CVT) and 214 (4.8%) children had had transient tics (TT) during the last year. Altogether 297 (6.6%) children had or had had some tic disorder. Twenty-five controls without tics and 25 children with TT of the same age, sex and school as the TS children were randomly chosen. They were together with the 34 children with CMT and the 24 children with CVT examined with use of a broad battery of instruments. The mean age of the first symptoms of TS was significantly lower than the onset of chronic motor/vocal tics. A younger age of onset of TS indicated more severe tics. Eighty per cent had a first-degree relative with a psychiatric disorder such as tic disorder, obsessive-compulsive behaviour, attentiondeficit/hyperactivity disorder (ADHD), or depression. A non-significant increase with regard to reduced optimality score in the pre-, peri-, or neonatal periods was found in children with TS compared to controls. No differences were found concerning socio-economic status. Psychiatric comorbid disorders were found in 92% of the children with TS. ADHD was most common. Patterns of psychiatric comorbidity were similar in children with TS and CVT. Children with TS perform poorer than the population in general with respect to cognitive functioning and self-perception. The results are discussed as they relate to the need for case identification, diagnosis, intervention, and treatment.

<p>Among some researchers, there is an emerging conceptualization of chronic tic disorders (CTDs) as conditions that are partially rooted in avoidance of tic-related private experiences (i.e., painful or difficult thoughts and feelings) and internal sensations (i.e., premonitory urges to tic). The first specific aim of the present research was to investigate the possibility that experiential avoidance is related to tic severity and perceived quality of life in individuals with CTDs. The second aim was to determine whether the efficacy of Habit Reversal Training (HRT), the most prevalent and effective behavioral intervention for CTDs to date, might be enhanced by combining it with Acceptance and Commitment Therapy (ACT), an intervention that directly targets experiential avoidance. These aims were addressed by conducting two related studies. Study I, an online survey, included 239 adults (<italic>M</italic> = 37.6 years; <italic>SD</italic> = 13.8 years) who reported having been previously diagnosed with a CTD. Results showed that levels of premonitory urges, as well as both general and tic-specific experiential avoidance, were significantly positively related to tic severity. General and tic-specific experiential avoidance were also significantly negatively related to perceived quality of life. Psychometric analyses of two novel measures developed for Study I (i.e., the Yale Global Tic Severity Scale-Self-Report Version and the Acceptance and Action Questionnaire-Tic-Specific Version) demonstrated excellent internal consistency and convergent validity. Study II, a multi-site pilot investigation, involved 13 adolescents (<italic>M</italic> = 15.4 years; <italic>SD</italic> = 1.3 years) who were treated with either HRT alone or a novel HRT+ACT intervention. Results suggest that the HRT+ACT treatment is feasible, highly acceptable to both patients and parents, and as effective as HRT alone at reducing tic severity from pre-treatment through week 22 follow-up. Participants in both groups reported clinically significant post-treatment decreases in general and tic-specific experiential avoidance and improvements in overall functioning. Researchers concluded that experiential avoidance plays an important role in tic expression and overall functioning for individuals with CTDs. Results support additional development and testing of the promising HRT+ACT intervention, to evaluate its efficacy alone and in comparison to other relevant psychosocial and pharmacological interventions.</p> / Dissertation

No description available.

Le contrôle postural et la perception des limites de la stabilité sont des processus complexes qui nécessitent le traitement et l’intégration d’informations sensorielles multimodales. Pendant l’enfance, le développement de la stabilité posturale s’effectue de façon non-monotonique. Plusieurs auteurs ont suggéré que ce profil non linéaire serait provoqué par une période de recalibration des systèmes sensoriels. Cette phase, nommée période de transition, est observée vers l’âge de 6-7 ans. Nous disposons toutefois de très peu d’information sur le rôle spécifique des afférences et des mécanismes d’intégration sensorielle au cours du développement postural. Les dysfonctions dans les noyaux gris centraux, telles que ceux observés dans la maladie de Parkinson, ont été associées à divers déficits dans le contrôle de la posture, dans le traitement et l’intégration sensoriel plus particulièrement, au niveau des informations proprioceptives. De plus, les limites fonctionnelles de la stabilité posturale des personnes atteintes de la maladie de Parkinson sont significativement réduites. Cependant, les connaissances concernant comment certaines pathologies des noyaux gris centraux, telles que le syndrome Gilles de la Tourette (SGT) et la maladie de Huntington (MH) affectent la capacité d’utiliser les informations sensorielles pour contrôler la posture demeurent à ce jour, incomplètes. Cette thèse porte sur le rôle des noyaux gris centraux dans les processus de traitements et d’intégration sensorielle, particulièrement les afférences proprioceptives dans le contrôle de la posture au cours du développement de l’enfant en santé, atteint du SGT et chez l’adulte atteint de la MH avec et sans symptôme clinique. Notre protocole expérimental a été testé chez ces trois populations (enfants en santé, SGT et MH). Nous avons utilisé des mesures quantitatives à partir de données issues d’une plateforme de force afin d’évaluer les ajustements posturaux dans les limites de la stabilité posturale. Les participants devaient s’incliner le plus loin possible dans quatre différentes directions (avant, arrière, droite et gauche) et maintenir l’inclinaison posturale maximale pendant 10 secondes. Afin de tester la capacité à traiter et à intégrer les informations sensorielles, la tâche expérimentale a été exécutée dans trois conditions sensorielles : 1) yeux ouverts, 2) yeux fermés et 3) yeux fermés, debout sur une mousse. Ainsi, la contribution relative de la proprioception pour le contrôle postural augmente à travers les conditions sensorielles. Dans la première étude, nous avons évalué la capacité à traiter et à intégrer les informations sensorielles avant (4 ans) et après (8-10 ans) la période de transition comparativement aux adultes. Dans la deuxième et la troisième étude, nous avons également évalué le traitement et l’intégration des informations sensorielles chez les patients atteints de désordres des noyaux gris centraux. La deuxième étude portera spécifiquement sur les adolescents atteints du SGT et la troisième, sur la MH avant et après l’apparition des symptômes cliniques. En somme, les résultats de la première étude ont démontré que la performance des enfants est affectée de façon similaire par les différentes conditions sensorielles avant et après la période de transition. Toutefois, le profil de développement des mécanismes responsables des ajustements posturaux de l’axe antéropostérieur est plus précoce comparativement à ceux de l’axe médiolatéral. Ainsi, nos résultats ne supportent pas l’hypothèse de la période de recalibration des systèmes sensoriels pendant cette période ontogénétique mais suggèrent que la période de transition peut être expliquée par la maturation précoce des mécanismes d’ajustements posturaux dans l’axe antéropostérieur. Dans l’ensemble, les résultats de nos études chez les populations atteintes de désordres des noyaux gris centraux (MH et SGT) démontrent non seulement qu’ils ont des déficits posturaux mais également que les ajustements posturaux dans les deux axes sont affectés par les conditions sensorielles. Pour la première fois, nos études démontrent des déficits globaux de traitements et d’intégration sensorielle accentués pour les signaux proprioceptifs. Ces résultats sont similaires à ceux observés dans la maladie de Parkinson. De plus, les adolescents atteints du SGT éprouvent également des troubles posturaux marqués dans la condition visuelle ce qui suggère des déficits d’intégrations visuelles et/ou multimodaux. / Postural control and the perception of the stability limits are complex mechanisms requiring the processing and integration of multimodal sensory information. During childhood, the development of postural control skills improves in a non-monotonic manner. Many researchers suggested that this non linear profile is caused by the recalibration of sensory systems. This recalibration phase, named transition period, is generally observed at 6-7 years of age. However, the exact cause of this critical turning point remains undetermined. Moreover, very little is known about the specific role of sensory information and sensorimotor mechanisms during postural development. Basal ganglia disorders such as Parkinson’s disease are associated with postural control impairments and deficits in the processing and integration of sensory information, especially in proprioception. Moreover, the limits of stability are significantly reduced in Parkinson’s disease. However, the knowledge on how other basal ganglia dysfunctions such as Gilles de la Tourette syndrome (GTS) and Huntington’s disease (HD) impact on the ability to process and integrate sensory information for postural control is still limited. In this thesis, we explored the role of basal ganglia in the processing an integration of sensory information, particularly proprioceptive signals for the postural control during the development of healthy children, in adolescents with GTS and in adults with premanifest and manifest HD. Our stability limits protocol was used to test the postural control skills of these three populations. We calculated center of pressure displacements obtained from a force plate and we investigated postural adjustments during the maximum leaning posture. The participants were asked to lean as far as possible and maintain this position during 10 seconds in different directions (forward, backward, rightward or leftward). This task simulates functional positions that frequently occur in daily life. In order to test the ability to process and integrate sensory information for postural control, the stability limits task was assessed in three sensory conditions: 1) eyes open, 2) eyes closed and 3) eyes closed while standing on foam. Thus, the relative contribution of proprioceptive signals for postural control increased across sensory conditions. In the first study, we investigated the children’s ability to process and integrate sensory information for postural control before (4 years old) and after (8 to 10 years old) the transition period compared to adults. In the second and third studies, the ability to process and integrate sensory information for postural control was assessed in participants with basal ganglia disorders, namely adolescents with GTS and adults with manifest and premanifest HD. In sum, our ontogenetic study indicated that the younger children (4 years old) were not differentially affected by sensory conditions than the older children (8 to 10 years old). Thus, our results do not support the hypothesis that an important recalibration of sensorial systems takes place during the transition period. However, the results revealed axis-dependent differences among the groups in postural control. Until the age of 10, children have a reduced ability to perform appropriate center of pressure adjustments along the mediolateral direction compared to adults. In contrast, the ability to produce precise center of pressure adjustments along the anteroposterior axis was already developed at 4 years of age, but it reached the adult level of performance after the transition period. Altogether, the assessment of participants with basal ganglia disorders indicated that they have postural adjustment impairments in both movement axes and are affected by sensory conditions. For the first time, we reported global deficits in the processing and integration of sensory information, especially in proprioception in GTS and in premanifest and manifest HD. These results are similar to those reported for Parkinson’s disease patients. Moreover, the adolescents with GTS also displayed marked postural control abnormalities in the visual condition which might be explained by either deficit in the processing of visual information and/or in multimodal sensory integration mechanisms.