What are clinical trials and how do they work?

By Alzheimer's Prevention Bulletin


Every month the Alzheimer’s Prevention Bulletin brings you articles about Alzheimer’s disease clinical trials, new study results, novel treatments and other news about cognitive decline and dementia. This month we delve deeper into how clinical trials work and how participating in a trial advances medical research.

Clinical trials study a new treatment, such as a medication, medical device or other intervention, developed to treat a specific illness or condition. Some trials aim to treat disease while others study new methods to prevent disease. Scientists and researchers use clinical trials to determine if a treatment is effective and safe for use.

Phases of Clinical Trials

Clinical trials for medications or a medical device occur in phases to help researchers determine the safety, side effects and effectiveness of a treatment.

  • Phase I trials test the safety of a treatment, look for side effects and determine dosage. These trials often involve just a small number of participants.
  • Phase II trials use a larger group of people to look at the effectiveness of a treatment. Researchers gather data to determine if a drug or medical device works for people with a specific disease or condition.
  • Phase III trials continue to gather evidence on safety and effectiveness in a larger, broader, and more diverse population. The trials may test different dosages of a drug or even look at the drug in combination with other medications. Positive results in a Phase III trial can lead to approval from the Federal Drug Administration (FDA).
  • Phase IV trials, often called post-marketing studies, are usually required by the FDA after approval. In this phase, researchers continue to monitor people using the medication or device to determine long-term safety and effectiveness.

Trial Safety

When participating in a clinical trial, individuals are randomly assigned (like a coin flip) to either receive the intervention (such as a study drug, active medical device or the “active” form of the intervention being studied) or a placebo. This allows researchers to compare similar individuals over time who are and are not receiving the intervention and determine if the intervention is effective. Most trials are double-blinded, meaning that the participants and researchers do not know who receives the intervention and who gets the placebo. This information is revealed at the end of the study period.

To protect the safety of the participants, a separate and independent Data Safety and Monitoring Committee can see who is receiving the trial medication and reviews the data regularly. The committee can intervene at any time if they observe concerns such as side effects that need to be addressed.

Is a clinical trial right for you?

Study participants are the most important part of any successful trial. If you’re interested in participating in a clinical trial, you will rightly have questions. It is important to fully understand the trial requirements and have an opportunity to discuss all aspects of the trial with medical experts and your family.

Once you decide to participate, you must meet study criteria. All trials have participation guidelines to ensure the results meet research requirements. Guidelines may include age, disease stage, support from family or friends, the presence of other health conditions and current medications.

Participating in a clinical trial can allow you to play a more active role in your health. At the same time, it can help researchers learn more about treating or preventing certain diseases and medical problems.

Alzheimer’s prevention trials have a specific focus to prevent future generations from suffering the debilitating effects of the disease. Learn more about the many Alzheimer’s prevention trials currently recruiting participants on the Alzheimer’s Prevention Registry website.

Are you interested in joining a clinical trial or study? Check out this infographic to learn more.