The prevalence of neurodegenerative diseases will increase over the next decades driven by ageing population. It seems important to develop reliable, replicable and accessible diagnostic tools.

This is a prospective study whose objective is to study the spatio-temporal parameters of gait in patients with Alzheimer's and Lewy body diseases. 64 patients were included in this study. A comparison of the two pathologies was conducted, followed by an analysis based on four groups (mild, severe Alzheimer's disease, mild, severe Lewy body disease) and a study of the severity of the diseases. To study these parameters, we used the Gaitrite treadmill.

The analysis of spatio-temporal parameters of walking in Alzheimer's disease and Lewy body disease enables to identify discriminating variables between the two pathologies. The probability of suffering from an Alzheimer's disease decreases with the pace increase but increases with variations in length of the step, and with the rotation of the foot. While the probability of suffering from Lewy body disease increases with the pace, variations in the step duration, and the duration of double support.

These results are interesting but do not allow to establish a diagnostic score for these two diseases. The monitoring of the variations of these parameters at individual level would probably be more relevant and would enable to detect dual pathologies.

Inclusion Criteria:

• Patient over 50
• Hospitalized patient in day hospital
• Patient with an etiological diagnosis of his cognitive disorder
• Patient having a neuropsychological assessment
• Patient able to walk without technical help
• Patient having agreed to participate in the study

Exclusion Criteria:

- Refusal to participate in the study

Patient over the age of 50 with a gait disorder