The pathophysiology of AD is complex. In addition to amyloid plaques and neurofibrillary degeneration, there is a metabolic alteration of the energy pathways, oxidative phosphorylation and glycolysis, which are involved in brain function. Several authors have shown a series of early metabolic dysregulations via an increase in phosphorylation at the origin of neuronal death.

Ultra-high field imaging (7T MRI) may allow, with its better spatial resolution and advanced imaging techniques, to shed light on the mechanisms of progression of Alzheimer's disease. A Magnetic Resonance Spectroscopy (MRS) examination can be coupled to brain MRI without additional risk for the patient. Multinuclear 1H-31P metabolic imaging is a promising tool that can provide information on the metabolic evolutionary profile of AD. Thus, we propose a longitudinal study in patients with early-stage AD on 7T MRI-MRS.

Inclusion Criteria:

• French-speaking patients aged 60 to 90 years,

• Patient in the context of Alzheimer's disease * for which imaging after MRI is prescribed as part of the usual diagnostic process,

  *Alzheimer's disease is diagnosed by the doctor of the memory consultation and is defined by :Evidence of a storage disorder in verbal episodic memory at LR/RI defined by a sum of LR < 17/48 and sum of RT < 40/48 +/- Impairment of executive functions possible (BREF, TMT grefex, verbal fluencies) +/- Impairment of instrumental functions possible (Grémots noun naming, Rey's figure, Mahieux's Battery).

• MMSE score ≥18,

• Written informed consent after the patient has been informed,

• Progressive decline for at least 6 months.

Exclusion Criteria:

--Partially or completely illiterate patient unable to read and write,

• Patient with an absolute contraindication to 7T MRI
• Severe psychiatric pathology not balanced,
• Non-degenerative neurological disease (stroke, multiple sclerosis ...),
• Patient with tumor or inflammatory pathology, or vascular leukopathy visualized in MRI (Fazekas score > 3)