A Two-part Multiple Dose Study to Assess the Safety and Effects of AZD3293 in Healthy Elderly and Alzheimer's Patients

Inclusion Criteria: * Part 1: Healthy elderly male and female (of non-childbearing potential) subjects. * Part 2: Male and non-fertile female AD patients. * Body mass index (BMI) between 19 and 30 kg/m2 and weigh at least 50 kg and no more than 100 kg. * Part 2: Clinical diagnosis of probable AD according to the NINCDS-ADRDA criteria. * Part 2: Manifestation of AD symptoms at least 6 months before randomization. Exclusion Criteria: * Part 1: History or presence of psychiatric disease/condition, GI, renal, hepatic, cardiovascular, psychiatric, or retinal diseases or disorders. * Part 2: Significant disease affecting the CNS other than Alzheimer's disease, including but not limited to other dementias, other significant neurological or major psychiatric disease. * History of use of antipsychotic drugs , or chronic use of antidepressant or anxiolytic drugs. * Frequent use (more than 2 days per week during the last 12 weeks) of tobacco or other nicotine products. * History of neurological disease, including seizures, recent memory impairment, or clinically significant head injury.