Approximately one million of Spaniards suffer from AlzhEimer´s Disease (AD) and this figure is expected to triple by 20150. The approved treatments modulate neurotransmission in general and are not specific or anatomically directed. In AD there is a dysfunction in cognitive and memory circuits. It has been shown that the deep brain stimulation (DBS) can specially modulate circuits in such a way that is modulable, and this approach is safe. The safety of this treatment and its biological effects are convincing enough to require further study of possible therapeutic effects of DBS in AD. The objectives are: To evaluate the security of DBS in AD (main objective). To study the influence of DBS in the progress of AD, to compare the effects of DBS on the brain metabolism neural connectivity and hubs using MEG, and to compare the effects between two different groups: fornix and Basal nucleus of Meynert (BNM). To achieve this, a prospective, double-blind comparison study between groups will be conducted, to evaluate the effects of DBS in 6 patients: group I (fornix) and group II ( BNM).

Inclusion Criteria:

• Age: Between 50-80 years old
• Diagnosis criteria of Alzheimer disease (Dubois criteria) in the previous 2 years
• Presence of tau, p-tau or Aβ in cerebrospinal fluid or positive amiloid-PET scan
• Clinical dementia rating scale (CDR): 1
• Use of cholinesterase inhibitors and/or memantine during one year at least, and worsening in neuropsychologic tests in spite of the treatment
• Informed consent (patient and caregiver or legal representative)

Exclusion Criteria:

• Brain structural disorders: primary or metastatic tumor, Hydrocephalus, stroke, brain abscess or cerebral malformation
• Vascular dementia (NINCDS-AIREN criteria)
• Neurodegenerative disease other than AD
• Psychiatric disease
• Epilepsy
• Severe or unstable comorbidity (mellitus diabetes, high blood pressure…)