This study aims to determine factors related to diagnosis delay for patients with young onset dementia (first symptoms before 60 years old) who live in North of France.

Inclusion Criteria:

As part of this study, patients will be considered:

• Residing in the departments of Nord (59) and Pas-de-Calais (62),
• whose diagnosis of Alzheimer's disease or related illness (DLFT, DCL) was made and announced,
• Whose diagnosis of illness was made after 2007
• whose first symptoms appeared before the age of 60 Patients included in the COMAJ cohort and those who completed the Pathways medical and social booklet will have to meet these criteria to be selected for this study.

As part of the survey, caregivers of patients meeting the above criteria and the following two will be recruited:

• Having consulted or being followed by liberal neurologists or in hospital memory consultations (excluding CMRR-CNR-MAJ Lille) of the departments of Nord and Pas-de-Calais,
• Not monitored at the CMRR-CNR-MAJ Lille (ad hoc notice possible). The caregiver is defined as a family member or friend who helps regularly by doing the necessary tasks so that the sick person can keep as much autonomy as possible.

Exclusion Criteria:

• aged under 18
• no social coverage
• refusal to sign informed consent form

Patients with a diagnosis of Alzheimer disease, Lewy Bodies Dementia or FrontoTemporal Lobar Degeneration and their caregivers