The aim of the MAPEG 2 study is to explore gustatory function and to follow its evolution in the 4 following groups of participants:

• Healthy subjects
• Participants with isolated cognitive complaint
• Participants with minor neurocognitive disorder
• Participants with mild and moderate Alzheimer-type major neurocognitive disorders

For this purpose, we want to compare the results of the following tests:

• Subjective taste tests (tasting solutions, answering food preference questionnaires),
• Gustatory evoked potential (GEP) parameters, recorded by electrodes placed on the scalp,
• And nutritional parameters (hormones of food intake by blood test, measurement of the global body composition).

Identifying and following the evolution of early taste disorders in case of cognitive disorders could improve the diagnosis of Alzheimer's disease in two ways:

• To allow an early diagnosis of Alzheimer's disease, and thus improve its management,
• To define groups of subjects at risk of developing Alzheimer's disease in later years.

Inclusion Criteria:

• Person who has given oral consent.
• For patients with mild to moderate Alzheimer's disease, the primary caregiver and the patient will be asked to provide oral consent
• Person of legal age
• Body Mass Index (BMI) < 30 kg/m².
• For the healthy group: absence of cognitive complaints and normal neurological assessment
• Patients meeting the criteria for isolated cognitive complaint: presence of cognitive complaint but normal neuropsychological evaluation
• Patients meeting diagnostic criteria for minor cognitive impairment: imaging (brain MRI) and neuropsychological assessment with a Clinical Dementia Rating (CDR) score of 0.5
• Patients meeting diagnostic criteria for mild to moderate Alzheimer's disease: imaging (brain MRI), neuropsychobiological criteria (consultation with neuropsychological assessment, CSF biomarkers), MMSE score ≥ 20 and CDR score of 1 or 1.5
• Fasting for at least 2 hours before GEP measurement

Exclusion Criteria:

• MMSE score<15
• Known COVID-19 infection within 6 months prior to inclusion
• Person not affiliated to national health insurance system
• Person under a legal protection measure (curatorship, guardianship)
• Person subject to a measure of legal protection
• Pregnant, parturient or breastfeeding women
• Subjects with a pacemaker (contraindication to bioelectrical impedance measurement)
• Adult unable to express consent or to perform cognitive tests.
• Active smoker (> 4 cigarettes per day on a regular basis)
• Diabetic subject (type 1 or type 2)
• Subject with acute or chronic ENT disease
• Treatment interfering with gustation
• Brain MRI showing another cause of neurocognitive disorder (except for vascular lesions Fazekas 1 accepted)