The aim of this study is to understand regional variations in acetylcholine esterase activity in Alzheimer's disease. In this study the aim is to identify by PET the physiological values of the regional activity of acetylcholine esterase using the 11C PM4 tracer and to study by PET and 11C PM4 the brain activity of acetylcholine esterase in a group of patients with Alzheimer's disease, enrolled according to the inclusion and exclusion criteria. The PET data will be correlated with the clinical, neuropsychological and morphological data acquired by MRI and with the clinical-cognitive outcome.

Inclusion Criteria:

• patients diagnosed with Alzheimer's disease;
• patients must have undergone an instrumental morphological examination to exclude other neurological pathologies.

Exclusion Criteria:

• positive history of major head trauma;
• clinically active somatic diseases.

Patients diagnosed with Alzheimer's disease who are eligible for therapy with acetylcholine esterase inhibitors but not yet undergoing treatment.