The purpose of this study is to assess the safety and efficacy on cognitive impairment and functioning of several doses of PXT00864 (new fixed combination of acamprosate and baclofen at low dose) in patients with mild Alzheimer Disease.

Inclusion Criteria:

• Male or female patients aged ≥ 60 years.
• Patient with a diagnosis of probable AD
• Progressive decline in cognition for more than six months which story is documented in patient medical records
• A Mini-Mental State Examination (MMSE) score of 20-26
• With a minimum of educational background
• Naïve to anti-dementia treatment
• MRI assessment which corroborates the clinical diagnosis (hippocampal atrophy) and excludes other potential causes of dementia especially cerebrovascular lesions
• If available, Cerebral Spinal Fluid (CSF) classical biomarkers should be at levels which corroborate the clinical diagnosis
• Ambulatory patient living at home with a caregiver available and living in the same household or interacting with the patient daily and available if necessary to ensure administration of the investigational product
• Absence of major or severe depressive disease
• Patient with a willingness to participate in this study and who have signed an informed consent form

Exclusion Criteria:

• Early onset of dementia, i.e. before 60 years old to avoid hereditary AD forms
• Significant neurological disease other than AD
• Major psychiatric disorder or syndrome (schizophrenia or bipolar disorder)
• Seizure disorders
• Other infectious, metabolic or systemic diseases affecting central nervous system
• Other active clinically significant illness
• Hospitalization or change of chronic concomitant medications one month prior to screening
• Patients with severe respiratory, hepatic or renal failure or with any other significantly potentially disabling abnormality detected during screening
• Known hypersensitivity to the tested treatment including active substance and excipients.
• Patients participating in another study and exposed to any investigational therapy within the 30 days prior to the entry in this study.
• Patient without medical care insurance