Inclusion Criteria:  Male or female patient aged ≥ 45 years Enrolled in a social health insurance scheme Diagnosed with probable DLB according to McKeith et al. criteria, 2017, or McKeith et al. 2020 criteria for the prodromal stage A Mini Mental State Examination (MMSE; Folstein et al., 1983) score ≥ to 18 in the last 6 months (prodromal stage or a major neurocognitive disorder (dementia syndrome) at moderate stage) MMSE score ≥ to 15 at the inclusion visit Presence of clinically significant cognitive fluctuations Caregivers of eligible patients do have to be able to stay with the patient for at least 4 hours a day, 3 days a week, and have to be able to provide requested information and accompany the patient to the certain visits. The patient must be able to understand the objectives and risks of the study and has to be able to give dated and signed informed consent. In the case of a designed guardian or curator, the guardian or curator will sign the consent. For women of childbearing age, effective contraception throughout the study is required  Exclusion criteria:  History of generalized seizures (epilepsy) Pharmacological treatment for cognitive fluctuations in DLB with dose modifications that have taken place less than 2 months before the first visit of the protocol (anticholinesterase and neuroleptics) Anti-epileptic drug treatment "Keppra" (Levetiracetam) History of psychosis or severe depression unrelated to DLB History of brain surgery (tumour removal, electrode implantation, certain strokes as judged by the investigator, oedema...) Patients with any contraindication for MRI scans (claustrophobia, pacemaker, cochlear implant, mechanical heart valve, metallic prostheses, neurostimulators, other non-removably implanted electronic medical devices etc.) Subject unable to understand the aims and risks of the study and patients unable to give full informed consent Having a MMSE score < to 18 in the last 6 months (prodromal stage or mild to moderate dementia) MMSE score < to 15 at the inclusion visit Patients in an emergency or life-threatening situation Patients under court protection Pregnancy Breastfeeding Patients in exclusion period (determined by a previous or current study)