Positron-Emission Tomography, Alzheimer's Disease

Patients for brain imaging:- patient and designee capable of giving fully informed consent in writing- patient fulfils DSM-IV and NINCDS-ADRDA criteria for probable Alzheimer's disease. Other forms of dementia excluded- males or postmenopausal females aged >/= 50 yearsHealthy volunteers for brain imaging: - able to give fully informed consent in writing- absence of any sign of dementia/cognitive impairment in neuropsychological examinations- males or postmenopausal females aged >/= 50 years Healthy volunteers for whole body imaging:- able to give fully informed consent in writing - males or postmenopausal females aged >/= 60 years - no significant disease or drug use

For all healthy volunteers and patients:- Any disease, condition, or concomitant medications that significantly compromises the function of the body systems and could result in excessive accumulation, impaired metabolism, altered excretion of the radiotracer, or might interfere with the conduct of the study or interpretation of the results