A Phase 3 Study of Rotigotine in Combination with Rivastigmine in Mild to Moderate Alzheimer's Disease

Inclusion Criteria: 1. Men and women (non-childbearing potential, as defined in Appendix 2) with a diagnosis of AD according to IWG criteria 2. Age 50-85 years 3. MRI or computerized tomography (CT) assessment, corroborating the clinical diagnosis of AD and excluding other potential causes of dementia, especially cerebrovascular lesions (see exclusion criteria, number 3) 4. Patients who show CSF biomarker data supporting the diagnosis of AD (for Czech Republic only: lumbar punctures can be performed for screening purposes), or patients with a positive Amyloid Pet Scan will qualify for the study 5. Stable on a treatment with rivastigmine transdermal patch for at least 3 months, of which at least the last month was at 9.5mg/day, or for one month, if the patient had received donepezil before rivastigmine 6. Mild to moderate stage of AD according to MMSE ≥18 and ≤26 7. Clinical Dementia Rating (CDR) total score of 0.5 or 1 (mild) 8. Evidence of frontal lobe dysfunctions as assessed by FAB ≤14 9. Absence of major depressive disease according to GDS of \< 5 10. Formal education for five or more years 11. Previous decline in cognition for more than six months as documented in patient medical records 12. A caregiver available and living in the same household or interacting with the patient and available if necessary to assure administration of drug 13. Patients living at home or nursing home setting without continuous nursing care 14. General health status acceptable for a participation in a 6-month clinical trial 15. Stable pharmacological treatment of any other chronic condition for at least one month prior to screening 16. No regular intake of prohibited medications 17. Signed informed consent by the patient. If there are any doubts that the patient is mentally capable of giving informed consent, the patient will be examined and verified to be mentally capable by an independent physician/ neurologist, prior to the initiation of any study specific procedure. Signed consent of the caregiver Exclusion Criteria: 1. Failure to perform screening or baseline examinations 2. Hospitalization or change of chronic concomitant medication one month prior to screening or during screening period 3. Clinical, laboratory or neuro-imaging findings consistent with: * other primary degenerative dementia (dementia with Lewy bodies, fronto- temporal dementia, Huntington's disease, Creutzfeldt-Jakob Disease, Down's syndrome, etc.); * other neurodegenerative condition (Parkinson's disease, amyotrophic lateral sclerosis, etc.); * orthostatic hypotension and autonomic disorders * cerebrovascular disease (major infarct, one strategic or multiple lacunar infarcts, extensive white matter lesions \> one quarter of the total white matter); * other central nervous system diseases (severe head trauma, tumors, subdural hematoma or other space occupying processes, etc.); * seizure disorder; * other infectious, metabolic, or systemic diseases affecting the central nervous system (syphilis, present hypothyroidism, present vitamin B12 or folate deficiency, serum electrolytes out of normal range, juvenile onset diabetes mellitus, etc.). 4. A current DSM-V diagnosis of active major depression, schizophrenia, or bipolar disorder 5. Any suicidal ideation or suicidal behavior in the C-SSRS (C-SSRS score \> 0) 6. Clinically significant, advanced, or unstable disease that may interfere with primary or secondary variable evaluations, and which may bias the assessment of the clinical or mental status of the patient or put the patient at special risk, such as: * history of any kind of psychosis * chronic liver disease, liver function test abnormalities or other signs of hepatic insufficiency (ALT, AST, Gamma GT, alkaline phosphatase \> 2.5 ULN); * respiratory insufficiency; * renal insufficiency (serum creatinine \>2 mg/dl) or creatinine clearance ≤ 30 mL/min according to Cockcroft-Gault formula). In case of creatinine clearance ≤30 mL/min, an alternative verification of the renal function must be completed using Cystatin C analysis. In case of normal level of Cystatin C, the patient can be included; * heart disease (myocardial infarction, unstable angina, heart failure, cardiomyopathy within six months before screening); * bradycardia (heart beat \<50/min.) or tachycardia (heart beat \>95/min); * hypertension (\>140/90 mm/Hg) or hypotension (\<90/60 mm/Hg) requiring treatment with more than three drugs; * AV block (type II / Mobitz II and type III), congenital long QT syndrome, sinus node dysfunction or prolonged QTcB-interval (males \>450 and females \>470 msec); * uncontrolled diabetes defined by HbA1c \>8.5; * malignancies within the last five years except skin malignancies (other than melanoma) or indolent prostate cancer; * metastases; * disability that may prevent the patient from completing all study requirements (e.g. blindness, deafness, severe language difficulty, etc.); * women who are fertile and of childbearing potential; * chronic daily drug intake of ≥ 14 days or expected for ≥ 14 days: * benzodiazepines, neuroleptics or major sedatives, * antiepileptics, * centrally active anti-hypertensive drugs (clonidine, l-methyl DOPA, guanidine, guanfacine, etc.), * opioid containing analgesics, * nootropic drugs (except Ginkgo Biloba); * suspected or known drug or alcohol abuse, i.e., more than approximately 60 g alcohol (approximately 1 liter of beer or 500 ml of wine) per day, indicated by elevated mean corpuscular volume (MCV) above normal value at screening; (Please advise all subjects that because of possible additive effects, patients should not be taking alcohol in combination with rotigotine). * suspected or known allergy to any components of the study treatments; * hypersensitivity to the active substance rotigotine or to any of the excipients contained in the patches (according to SmPC). * enrollment in another investigational stu