NCT02820896

Who might be able to join this trial:

For all participants:

• Your total body weight is between 45 and 120 kilograms (roughly 99 to 265 pounds)
• You agree not to donate blood or blood products for the entire study and for 1 year after your last dose of the study drug
• You are generally in good health, with no significant concerns found during a medical check-up, physical exam, heart tracing (ECG), blood tests, or vital signs
• Your routine blood and urine test results are within normal ranges (or any differences are considered not medically important by the doctor)
• You test negative for certain drugs of abuse at your initial screening and at check-in
• You agree to use highly effective birth control measures during the study

For healthy participants (no Alzheimer's disease):

• You are between 18 and 80 years old
• You have no history of noticeable memory or thinking decline, and neither you nor the doctor has serious concerns about your mental abilities

For participants who may need a spinal fluid sample (lumbar puncture):

• You have no medical reasons that would make a lumbar puncture (a procedure to collect fluid from your spine) unsafe for you, such as blood clotting problems, blood thinning medication, low platelet counts, previous spine surgery, or other concerns (confirm with trial site)

For participants with Alzheimer's disease:

• You are between 50 and 80 years old
• You are able to complete study assessments either on your own or with help from a caregiver
• You have a caregiver who knows you well, sees you regularly, can accurately describe your thinking and daily abilities, is willing to attend clinic visits, and signs the required consent form
• You have good enough vision and hearing to complete memory and thinking tests, in the doctor's judgment
• You have been formally diagnosed with probable Alzheimer's disease dementia based on recognised medical guidelines
• Your score on a standard memory screening test (called the MMSE) is between 16 and 28 out of 30
• Your score on a standard dementia rating scale (called the CDR-GS) is 0.5, 1.0, or 2.0
• A brain scan (called an amyloid PET scan) shows the presence of amyloid, a protein associated with Alzheimer's disease
• If you are already taking Alzheimer's medications (such as a cholinesterase inhibitor or memantine), you have been on a stable dose for at least 4 weeks before screening and do not plan to change or stop them during the study

Who may not be able to join:

For all participants:

• You are pregnant, breastfeeding, or planning to become pregnant within 16 weeks of your last dose of the study drug
• You have taken part in another clinical trial within the last 30 days, or have taken an experimental oral medication within 30 days (or 5 half-lives, whichever is longer), or a biologic experimental treatment within 12 weeks (or 5 half-lives, whichever is longer) before the study starts
• You have received any non-experimental vaccine within 2 weeks before starting the study, or until 2 weeks after your last dose
• You had surgery or were hospitalised in the 4 weeks before screening
• You have a procedure or surgery planned during the study
• You received a blood transfusion within 8 weeks before screening
• You donated or lost a significant amount of blood (50–499 mL within 30 days, or more than 499 mL within 56 days) before taking the study drug
• You have very difficult veins to access for blood draws
• You have tested positive for hepatitis C, hepatitis B, or HIV
• You have had problems with alcohol or illegal drug use in the past 12 months, in the doctor's judgment
• You have taken herbal or nutritional supplements (other than standard vitamins and calcium) within 7 days before your study dose
• You have a past history of seizures, a serious brain injury, schizophrenia, schizoaffective disorder, or bipolar disorder
• The doctor considers you to be at risk of suicide
• You have had a serious infection requiring oral or intravenous (IV) antibiotics within 30 days before screening
• You have a serious medical condition, abnormal lab results, or a