Alzheimer's Matters Blog

Alzheimer’s Clinical Trials, Explained

May 4, 2018

Category: Developing Drugs


Clinical trials are an important and growing part of our funding at the Alzheimer’s Drug Discovery Foundation (ADDF). Trials are the final stages of a drug’s development. After years of hard work in the lab, researchers can finally test their potential drugs in people. Some drugs never make it this far and those that do face a rigorous process before they can be submitted to the FDA for approval.

The process begins with an investigational new drug (IND) application, which is required by the FDA before human testing can begin. IND applications involve strict regulatory guidelines including manufacturing requirements to ensure human subjects will be protected from potential harm. The ADDF is one of the few research funders that supports IND application studies. We understand their importance and the associated expenses, so we do all we can to help researchers navigate the process successfully. 

Alzheimer’s clinical trials happen in three phases—each phase tests different aspects of a drug’s safety and effectiveness at treating Alzheimer’s in people. Those with positive results after phase 3 can apply for FDA approval.  (Most programs we fund follow the U.S. FDA guidelines. We do fund trials in the European Union and several other countries, where the regulatory process may vary slightly.)


Phase 1. In phase 1 clinical trials, a drug is tested in people for the first time. These early-stage trials evaluate a drug’s safety and potential side effects. Phase 1 trials often also examine how a drug is metabolized by the body (i.e., pharmacodynamics and pharmacokinetics). These trials are short and involve a small number of (often healthy) people.

Phase 2. In phase 2 trials, drugs are tested for efficacy. If earlier trials proved that the drug was safe in healthy people, it can then be given to small groups of patients who have Alzheimer’s disease or those most at risk for developing it, such as people with mild cognitive impairment. In this stage, researchers evaluate whether the drug affects its intended target and if that helps slow or stop the disease. They also continue to evaluate its safety. The U.S. National Library of Medicine notes that in phase 2 trials, “participants receiving the drug may be compared to similar participants receiving a different treatment, usually an inactive substance (called a placebo) or a different drug.”

Phase 3. Phase 3 trials include many more patients, are of longer duration, and are therefore more expensive than the previous two phases. Phase 3 trials may include different populations of patients (e.g., Alzheimer’s patients with and without the APOE4 gene) given different doses of medication. Very few drugs have made it this far in Alzheimer’s, though the ADDF’s investments are changing that. 

There are more drugs for Alzheimer’s in clinical trials than ever before. Not every idea advances this far, but more and more of the programs the ADDF supports are reaching the clinic. These drugs are designed to slow, stop, or possibly even reverse the course of Alzheimer’s. And they could be available to patients in just a few years.

Howard Fillit, MD is the Founding Executive Director and Chief Science Officer at the ADDF.