Patients with different types of dementia will be recruited and evaluated in national hospital departments for their usual neurological follow-ups. A blood sample will be proposed in the field of this research project, and the biological material will be stored at the DNA and Cell Bank of Institut de Fédératif Recherche (IFR) of Neurosciences (Pitié-Salpêtrière Hospital, Paris). The clinical research network is already set up for Alzheimer's disease and frontotemporal dementias, which permits an evaluation according to a clinical standardized protocol.