Frequently Asked Questions

Frequently Asked Questions

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An investigational medicine is a drug that is still being tested in research studies. The US Food and Drug Administration (FDA) is allowing the use of this drug for research purposes. Investigational means it has not yet been approved by regulatory authorities for use by doctors in their everyday practice.

A placebo looks just like the investigational drug but does not have any active medicine in it. The placebo will be given in the exact same way as the investigational drug. 

A placebo is used in research studies as a way of comparing a group that takes the investigational drug with a group whose study treatment does not contain active medicine. By using a placebo, it helps researchers see how well the investigational drug works and how safe it is. 

Magnetic resonance imaging (MRI) is a medical imaging technique that uses a magnetic field and computer-generated radio waves to create detailed images of the organs and tissues in the  body.

Most MRI machines are large, tube-shaped magnets. When you lie inside an MRI machine, the magnetic field temporarily realigns water molecules in your body. Radio waves cause these aligned atoms to produce faint signals, which are used to create cross-sectional MRI images — like slices in a loaf of bread.

The MRI machine can also produce 3D images that can be viewed from different angles.


This study is being done to see if an investigational drug may stop or slow down the appearance of memory and thinking problems associated with Alzheimer’s disease. The study will test the investigational drug in people who do not have any symptoms of the disease but who have early changes in their brain that are related to Alzheimer’s disease. The study will also compare people who have received the investigational drug with people who have received the placebo. This is to help researchers see how well the investigational drug works and how safe it is. 

By participating in this study, you will help answer the following research questions:

  • Does the investigational drug slow down the appearance of memory and thinking problems of Alzheimer’s disease?
  • How does the investigational drug compare with placebo?
  • What are the side effects you may experience?

If you join the TRAILBLAZER-ALZ 3 Study, you will have both in-person and virtual appointments over about a 4-year period. Virtual appointments will take place online using a study tablet provided by the sponsor (for example, via a video call), at your home, or at a convenient location.

An appointment may be made up of various parts and may take place over more than 1 day.

  • You will have study drug infusions (investigational or placebo) at an infusion center once each month for up to 9 months. You will also have blood samples and other health checks done during in-person visits.
  • You will have at least 4 MRI scans at an imaging center: one during your baseline screening process, one at about 3 weeks after the first infusion, one at about 3 months into the study, and one at about 5 months into the study. If you choose to join the study extension, you will have  4 more MRI scans.
  • Clinical assessments will be completed by the study participant and study partner. A cognitive test and a clinical interview will be done on your study device as a virtual appointment. You will also have contact with the research team by phone.

The TRAILBLAZER-ALZ 3 Study is made up of 4 parts and may last around 4 years. 

  • Screening: Screening may take place up to 12 weeks.
  • Study Treatment Period: The study treatment period takes around 9 months and includes IV infusions of the study drug (investigational medicine or placebo) about once each month.
  • Follow-Up Period: The follow-up period lasts around 3 years and includes virtual appointments by video call about every 6 months.
  • Study Extension: The study extension lasts around 11 months and may be offered to people who were assigned to receive placebo so they can receive the investigational drug, if it is shown to be effective in the TRAILBLAZER-ALZ 3 Study. 

In a research study, people are randomly assigned (like by flipping a coin) to one group (or arm) of the study, or another. In one group, people will receive an investigational drug. In the other, people will receive a placebo that looks like the drug, but has no actual medicine in it. This type of research study helps researchers and doctors know whether the drug works.

If you join this study, you will have a 50/50 chance of getting the investigational drug.  About half of the people in TRAILBLAZER-ALZ 3 will be randomly assigned to receive the investigational drug, and the other half will receive placebo. The placebo will be given in the exact same way as the investigational drug. 


You and your study partner will not know which group you are assigned to. People assigned to the placebo group receive the same monitoring and care as those who receive the investigational drug.

For people with Alzheimer’s disease, an unwanted substance called “amyloid beta” (or “amyloid ß”) builds up and forms plaques in the brain. It is believed that the build-up of amyloid plaques disrupts how brain cells function and leads to cell death. This study will examine whether the investigational drug, by removing amyloid plaques, can slow the progress of Alzheimer’s symptoms. The investigational drug will be given during study appointments through an intravenous infusion, or IV. The infusion will take about 30 minutes, with a 30-minute observational period afterwards.

You will be asked about any side effects during your health check conversations. If you have any concerns, please contact the primary investigator or study coordinator. 

In the case of an emergency, please contact the primary investigator with the phone number provided in your informed consent form. 

Study partners play a very important role in this study. As a study partner:

  • You will be asked to answer questions about the study participant’s day-to-day life and whether you notice changes in their memory or thinking at study appointments. These appointments will happen virtually, as a video call from your home using a study tablet that is provided. You must be willing to receive calls from the research team and seek their guidance between virtual appointments, as needed.
  • You will need to use the study tablet provided to you to join virtual clinical assessment appointments, as video calls from your home, and answer questions about the study participant’s wellbeing. Allow 1–2 hours for these appointments. These happen about every 6 months.

The information the study partner provides is vitally important for the purposes of this study, so your responses to some of the questionnaires will be audio and video recorded.

If you begin the study and no longer wish to participate, you can withdraw your consent at any time. However, the study participant cannot be in this study without a study partner. If you are unable or unwilling to participate, they may also need to leave the study or find another study partner.

As a study partner, you will need to consent to participate in the study. 


Once your study participant qualifies for the study, your key role in the study will be to answer questions about the study participant every 6 months. You will be interviewed by a member of the research team through a video call using the study tablet provided to you. You will also answer questions using the study tablet. You and your study participant will need to allow time to prepare for each interview and time to complete the interviews. These interviews will be recorded and must be scheduled on a different day than the participant's infusion day. You do not have to be in the same location as the study participant.

More than 3,000 people in the United States will take part in this study as participants. Along with their study partners, this means that more than 6,000 people will be a part of the TRAILBLAZER-ALZ 3 Study. 


Participation is optional, but if you and your study partner do volunteer, both of you would be joining an important effort to find a new treatment Alzheimer’s disease for you and your loved ones.

Continue to be curious about your health.

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