Cohort of Patients with Alzheimer's Disease and Their Families.

o Inclusion criteria: AD patients: * Probable Alzheimer's disease (clinical and biological NINCDS-ADRDA 2011 criteria) * Mild-moderate AD (MMSE ≥15) * Sufficiently fluent in French in order to answer study questionnaires * Agrees to undergo medical examinations at baseline, 12 and 24 months, as outlined in the protocol * Affiliated to French social security * Written informed consent Caregivers: * Caregiver (defined as assisting the patient in activities of daily living for at least 6 hours per week during the last 6 months) to an AD patient having agreed to participate in the study * Age ≥18 years. * Sufficiently fluent in French in order to answer study questionnaires * Agrees to answer regular questionnaires about their own or the AD patient's health (during visits at study centres or via a secure internet website/postal questionnaires) * Affiliated to French social security * Written informed consent First-degree relatives: * First degree relative of an AD patient having agreed to participate in the study * Age ≥18 years. * Sufficiently fluent in French in order to answer study questionnaires * Agrees to undergo medical examinations at baseline, 12 and 24 months, as outlined in the protocol * Agrees to answer regular questionnaires about their own health (via a secure internet website or via postal questionnaires) * Affiliated to French social security * Written informed consent In order to be included in the study, a familial cluster must be comprised of 2 to 5 people, as follows: * Familial cluster of 2 people: 1 AD patient and 1 first-degree relative who also meets the caregiver inclusion criteria, OR * Familial cluster of 3 to 5 people: 1 AD patient, 1 caregiver (does not need to be a relative of the patient), 1 to 3 first-degree relatives of the patient * Exclusion criteria: AD patients: * Other brain disorders * Autosomal dominant form of AD * Under legal protection measure (guardianship, curators, safeguard of justice…) * Institutionalized * Life expectancy \<2 years Caregivers: * Under legal protection measure (guardianship, curators, safeguard of justice…) * Diagnosed with a major neurocognitive disorder First-degree relatives: * Related to a patient with an autosomal dominant form of dementia * Carrier of an autosomal dominant dementia mutation * Under legal protection measure (guardianship, curators, safeguard of justice…) * Diagnosed with a major neurocognitive disorder