Cohort Study of Adult Patients With Down Syndrome at Risk of Developing Alzheimer's Disease (TriAL21)

The aim of the study is to describe and follow a cohort of patients with Down syndrome without diagnosis of Alzheimer's disease at inclusion, in order to identify factors influencing the age of onset of the disease. The total study duration will be approximately 4 years. * Inclusion period : 2 years * Follow-up period per patient : 2 years Patients will be then followed during 10 years for routine medical follow-up. In case of Alzheimer's disease onset during this period, all data regarding diagnosis of AD will be collected for the study. Data about dementia evolution and mortality in case of AD diagnosis during the study will also be collected during this follow-up period.