Tidigare forskning har funnit samband mellan gång och kognitiv funktion, men sambandet mellan lindrig kognitiv svikt (MCI) och gång är inte helt klarlagt. Syftet med den föreliggande examensuppsatsen var således att undersöka hur gångvariabler och gångvariabilitet är påverkat hos personer med MCI i relation till kognitivt friska individer. Studien genomfördes i det pågående projektet the Healthy Ageing Initiative vid Umeå Universitet. Totalt 1937 personer inkluderades i studien. Samtliga var 70 år gamla och bosatta i Umeå kommun. Totalt 112 personer bedömdes ha MCI utifrån instrumentet Mini-Mental State Examination (MMSE). Gånganalys genomfördes med den elektroniska gångmattan GAITRite® system och deltagarna utförde fyra gångförsök: egenvald hastighet, snabb hastighet, kognitiv dual task och motorisk dual task. Resultatet visade att det finns skillnader mellan grupper vad gäller både spatiala och temporala aspekter, främst i de tre första försöken. Exempelvis uppvisade gruppen MCI lägre gånghastighet, kortare steg och kliv samt längre double support och kortare swing. Gruppen MCI uppvisade högre variabilitet under kognitiv dual task. Ett flertal gång- och variabilitets-variabler under kognitiv dual task kunde, enligt logistisk regression, predicera sannolikheten att ha MCI. Resultaten indikerar att gången hos de med MCI kan ge ökad fallrisk. / Previous research has found a connection between gait and cognitive function. However, the relationship between mild cognitive impairment (MCI) and gait has not been fully explored. Thus, the aim of this study was to examine how spatiotemporal gait parameters, and gait variability, are affected in people with MCI compared to cognitively healthy individuals (CHI). The study was carried out in cooperation with the Healthy Ageing Initiative research project, Umeå University, Sweden. A total of 1937 participants were included in the study. All participants were 70-years old and residents of the municipality Umeå. A total of 112 participants were classified as having MCI, as measured with the Mini-Mental State Examination (MMSE). Gait analysis was performed with the GAITRite® system, and participants performed four trials: preferred pace, fast pace, cognitive dual task and motor dual task. Results showed group differences in both spatial and temporal aspects of gait, especially during the first three trials. For example, participants with MCI walked more slowly, had shorter steps and strides, as well as a longer duration of the double support phase and lower duration of the swing phase. Participants with MCI revealed higher gait variability during cognitive dual task. Several of these variability variables, as well as spatiotemporal variables, could predict probability of having MCI, as seen through logistic regression. Results indicate that the gait observed in MCI could be related to a higher risk of falling.

De nombreux troubles ont un retentissement sur le contrôle de l’équilibre dynamique au cours de la marche. Qu’ils soient d’origine traumatique, neurologique, ou liés à la sénescence, ils limitent plus ou moins la stabilité, c’est-à-dire la capacité des sujets à récupérer de perturbations internes ou externes, et peuvent conduire à la chute. Chez les enfants, la stabilité est de plus liée aux étapes développementales. Son interprétation nécessite donc de différencier ce qui relève de l’instabilité développementale et de l’instabilité pathologique. Les techniques instrumentées d’analyse du mouvement permettent un enregistrement fiable et précis des paramètres de la marche. Des index ont été développés pour faciliter l’évaluation clinique de la marche des patients mais aucun d’entre eux ne quantifie l’aspect stabilité.Ce travail de thèse a conduit à la production d’un score quantifiant la stabilité au travers de la variabilité des paramètres spatiotemporels, enregistrés par une piste de marche électronique. Ce score, dénommé Gait Variability Index (GVI), a été appliqué à des populations, asymptomatiques et pathologiques, représentatives des différents âges de la vie : l’enfant, l’adulte et la personne âgée. Les résultats obtenus chez des patients affectés de paralysie cérébrale, d’ataxie de Friedreich ou cérébrolésés démontrent que le GVI est un outil cohérent pour l’évaluation de l’instabilité. Outre l’intérêt clinique qu’il représente, celui-ci ouvre différentes perspectives pour son application et invite à la réflexion quant à la nature perturbatrice ou régulatrice de la variabilité. / Many pathologies affect balance control during gait. Traumatic, neurological or age-related disorders can all limit more or less the stability, which is the capacity of subjects to recover from perturbations, and can lead to falls. For children, the stability is related to the developmental stages and its interpretation requires differentiating what pertains to the developmental instability and to the pathological instability. Instrumented movement analysis allows a reliable and precise recording of the gait parameters. Indexes were developed to improve the clinical evaluation of the patients walking but no one of them quantifies the stability feature.This thesis led to the production of a score quantifying the stability through variability of the spatiotemporal parameters, recorded by an electronic walkway system. The score, called Gait Variability Index (GVI), has been applied to asymptomatic and pathological populations, representative of the various ages of life: children, adults and elderly persons. Results for patients affected by cerebral palsy, Friedreich’s ataxia or after stroke demonstrate that the GVI is a coherent tool for the evaluation of instability. Beyond the clinical interest, it opens various studies perspectives in gait analysis, and is thought-provoking about the disruptive or regulating nature of variability.