This research focuses on the activity of an enzymatic protein: glucocerebrosidase, in dementia with lewy bodies (DLB). Indeed, the mutation of the GBA gene responsible for a decrease in the activity of glucocerebrosidase is the most frequent known genetic risk factor in DLB. However, mutations of the GBA gene are known in another pathology, Gaucher disease, in which treatments have been developed.

The objective of this research is to determine if glucocerebrosidase activity is decreased in DLB. This hypothesis could open up a therapeutic perspective, with treatments already used in Gaucher disease.

Population: 118 patients and 118 control subjects Act of research: blood test

Objectifs :

• Comparison of glucocerebrosidase activity between patients and controls
• Search for variants or mutations of the GBA gene and correlation with glucocerebrosidase activity
• Correlation between clinical characteristics (UPDRS motor scale, MMSE cognitive scale) and GCase activity in patients
• Identification of macrophage abnormalities and the impact of treatments targeting the GBA pathway on the deregulation of biomarkers in patient macrophages.

Inclusion Criteria for patients :

• Male or female aged ≥ 50 years old
• Presence of an accompanying person
• Dementia with lewy bodies according to the revised criteria of Mc Keith 2017

Inclusion Criteria for controls:

• Male or female aged ≥ 50 years old
• Absence of cognitive impairment and clinical element for a neurodegenerative disease

Exclusion Criteria for patients:

• Other neurodegenerative disease
• Gaucher disease

Exclusion Criteria for controls:

• Neurodegenerative disease
• Cognitive impairment of all causes

118 patients and 118 control subjects Patients and controls (often an accompanying person) will be selected during a routine visit for the patient's DLB