The purpose of this study is to compare characteristics of gait and balance measured among patients with Alzheimer's disease or related disorders separated into 3 groups according to the stage of disease (i.e., pre-dementia, mild and moderate dementia stages); to determine the effects of anti-dementia drugs and vitamin D on cognitive motor abnormalities; and to establish a database at Angers University Memory Centre.

Although gait disorders are frequently associated with Alzheimer's disease and related disorders (ADRD), few studies have focused on cognitive motor effects of anti-dementia drugs and vitamin D.

The objectives of this study are to

• Compare characteristics of gait and balance measured among patients with ADRD separated into 3 groups according to stages of disease (i.e., pre-dementia, mild and moderate dementia stages)
• To determine the effects of anti-dementia drugs and vitamin D on cognitive motor abnormalities
• To determine whether motor abnormalities could be associated with cognitive impairments, specifically executive dysfunctions
• To establish a database at Angers University Memory Center.

Inclusion Criteria:

• All elderly patients from the University Memory Center of Angers University Hospital.
• Able to walk without any walking aid on 15 meters
• Mini-Mental Status Examination score > 10
• Being affiliated to a social security regime

Exclusion Criteria:

• Mini-Mental Status Examination score ≤ 10
• Subject suffering from pre-existing impellent disturbances
• History of cerebrovascular accident or other cerebro-spinal pathology
• Poor workmanship of the written or oral French language
• Use of walking aid such as walking frame with wheels or tricycle.
• Acute medical or surgical disease in the past 3 months
• Refusal to participate (or trustworthy person)
• Near visual acuity < 2/10

All patients of the University Memory Center of Angers University Hospital with respect to the eligibility criteria