Cerebral Oxygenation During Gait in Elderly

Ageing is accompanied by a cognitive decline altering gait and increasing the risk of falling. Physical activity could reduce this cognitive decline by an improvement in the oxygen supply to the brain. At the moment, the effect of physical activity on brain oxygenation during walking in elderly has never been described. Moreover, the increase in cognitive request during a dual task could lead to an increase in the risk of falling. In this context, the investigators of Orleans's hospital want to examine the effect of the physical activity level of elderly on their brain oxygenation during walking and during a dual task. Moreover, Parkinson' patients could display an impairment of gait and cognitive function. Attentional task and dual task situation are particularly impaired in this pathology. This is why the investigators of Orleans's hospital want to also examine cerebral activation of these patients during walking and during a dual task. The hemodynamic cerebral activation will be studied using the near infrared spectroscopy at the level of the prefrontal cortex. This non-invasive technic allows the evaluation of the regional oxyhemoglobin and deoxyhemoglobin variations induced by cerebral activation.