Positron Emission Tomography (PET) Study With [11C]AZD2995 and [11C]AZD2184, Candidate PET Ligands for β Amyloid

Inclusion Criteria: * Alzheimer´s Disease patients - 50-85 years- mild to moderate AD, clinical progression of AD over 12 months. * Healthy male volunteers: - Age 20-50 years, Body Mass Index: 18-30 kg/m2. * Clinically normal physical findings including normal blood pressure and pulse rate. Exclusion Criteria: * Alzheimer´s Disease patients: * significant cerebrovascular disease or depression, central nervous system infarct or infection or lesions * clinically significant illness within 2 weeks before the study start. * administration of any investigational product with effect on brain beta amyloid levels within 3 months prior to study and/or participation in a PET investigation other than study D0180C00011 as part of a scientific study during the past 12 months,. * Healthy volunteers; - clinically significant illness within 2 weeks before the study start, history of psychiatric or somatic disease/condition that may interfere.- first degree relative with dementia. Obvious deterioration of memory functions.