Memantine - Communication Study

Inclusion Criteria: * Male or female outpatient at least 50 years of age and at least 8 years of education. * The patient should have German as a mother-tongue or at least speak the language fluently in order to achieve similar scores in verbal tasks. * Current diagnosis of probable Alzheimer's disease consistent with NINCDS- ADRDA criteria or with DSM IV TR criteria for Dementia of the Alzheimer's type. * Mini Mental State Examination (MMSE) total score is less than 20 * Patients treated with any acetylcholinesterase inhibitor (AChEI) may be included, when treatment has started at least 6 months prior screening and was stable during the last 3 months. Exclusion Criteria: * Any type of evident aphasia, which may interfere with patient's communication difficulties caused by Alzheimer's disease * History of severe drug allergy, or hypersensitivity, or patients with known hypersensitivity to amantadine, lactose. * Evidence (including CT/MRI results) of any clinically significant central nervous system disease other than Alzheimer's disease. * Modified Hachinski Ischemia score greater than 4 at screening. * Current evidence of clinically significant systemic disease * Known or suspected history of alcoholism or drug abuse within the past 10 years. * Previous treatment with memantine or participation in an investigational study with memantine.