Memory Center - Clinical Trials

Clinical Trials and Research

Clinical research is medical research involving people. It includes clinical studies, which use long-term observation and analysis in large groups to determine how a disease or condition may occur and progress, and clinical trials, which test possible interventions to diagnose, prevent, treat, and someday cure a disease.

Clinical studies observe people in normal settings, with less direct intervention than in clinical trials. Researchers gather baseline information, group volunteers according to broad characteristics, and compare changes over time. Studies of Alzheimer’s disease may help identify new possibilities for clinical trials. The National Institute on Aging (NIA), part of the National Institutes of Health (NIH), sponsors several major ongoing studies.

Clinical trials test interventions such as drugs or devices, as well as prevention methods and changes in diet or lifestyle. (See examples below.) Drug testing is the focus of many clinical trials. Currently, more than 90 drugs are in clinical trials for Alzheimer’s disease, and more are in the pipeline awaiting Food and Drug Administration (FDA) approval to enter human testing.

FDA-approved clinical trials are always preceded by laboratory analyses in test tubes and in tissue culture, followed by studies in laboratory animals to test for safety and efficacy. If these show favorable results, the FDA gives approval for the treatment or intervention to be tested in humans. Clinical trials advance through four well-defined phases to test the treatment, find appropriate dosage, and monitor side effects in increasing numbers of people. If investigators find an intervention safe and effective after undergoing the first three phases, the FDA decides whether to approve it for clinical use. In Phase IV, the FDA continues to monitor the effects of a new drug after its approval for marketing and clinical use. If problems occur, approval may be withdrawn and the drug recalled. After the efficacy of a drug for one health condition is established, Phase IV studies can evaluate the activity of the drug in other conditions.

Why Placebos Are Important

The “gold standard” for testing interventions in people is the randomized, placebo-controlled clinical trial, because it is designed to reduce error or bias. Volunteers are randomly assigned—that is, selected by chance—to either a test group receiving the experimental intervention or a control group receiving a placebo, an inactive substance resembling the drug tested.

Comparing results indicates whether changes in the test group result from the treatment. In many trials, no one—not even the research team—knows who gets the treatment, the placebo, or another intervention. When the participant, family members, and staff all are “blind” to the treatment, the study is called a double-blind, placebo-controlled clinical trial.

Placebo and test groups are equally important, as shown in the results of numerous clinical trials. For example, early research suggested that ginkgo biloba, an herbal supplement, might be effective in delaying dementia. To find out, NIA sponsored a 6-year, Phase III clinical trial with more than 3,000 participants age 75 and older. In 2008, scientists reported no significant differences in effect on dementia in adults who received ginkgo biloba or placebo.

This result was disappointing, but scientists gained a wealth of information to inform future research. For example, researchers learned more about subgroups of participants who may be at greater risk for developing dementia, and ginkgo's possible effects on cardiovascular disease, cancer, depression and other age-related conditions. They also gained insights on issues related to the design and conduct of large dementia prevention trials in older adults, such as the number of participants needed to provide clinically significant measures on outcomes like occurrence of dementia.

Participating in a Trial or Study

How Can People Find Out About Alzheimer’s Disease Trials and Studies?

Information about Alzheimer’s disease clinical trials and studies is available through a number of sources. First, talk to your doctor, who may know about local or specific research studies that may be right for you. NIA-supported Alzheimer’s Disease Centers or specialized memory or neurological clinics in your community may also be conducting trials. You might also learn of clinical trials through newspapers or other media. To search more widely for trials or studies, you can also visit web sites like See the “For More Information” section at the end of this fact sheet for resources and contact information.

Benefits of Volunteering

  • Help others, including future family generations, who may be at risk for Alzheimer’s disease
  • Receive regular monitoring by Alzheimer’s professionals
  • Learn more about the disease from experts
  • Get information about support groups and resources

What Happens When a Person Joins a Clinical Trial?

First, it is important to learn as much as you can about the trial. Staff members at the research center are trained to explain the trial in detail and describe possible risks and benefits. They clarify participants’ rights. Participants and their families can have this information repeated until they are sure they understand it.

After questions are answered, participants sign an informed consent form, which contains key facts about the trial. Next, they are screened by clinical staff to see whether they meet criteria to participate in the trial. Screening examines the characteristics people must have to participate in a particular trial, as well as characteristics that may exclude them. The screening may involve cognitive and physical tests that provide baseline information to compare with future changes. If participants meet all criteria, they are enrolled in the trial.

Informed Consent

Each participant must sign an informed consent agreement, affirming that he or she understands the trial and is willing to participate. Laws and regulations regarding informed consent differ across States and institutions, but they are all meant to ensure participant safety and protection, and to prevent unethical experimentation on vulnerable populations.

Right To Withdraw

Volunteers can withdraw from a trial or study anytime they or their physician feels it is in their best interests. For example, a new health condition in a volunteer may require medications that are risky if combined with experimental treatments.

Clinical Trials and Studies Need All Kinds of People

Clinical trials and studies are a partnership between researchers and volunteer participants, who work together to answer questions about humans we can answer in no other way. Ensuring that those answers are correct requires including volunteers of all kinds: men and women, African Americans, Latinos, Native Americans, Asian Americans, whites, people with Alzheimer’s or a family history of the disease, people with conditions that may lead to Alzheimer’s, and those without the disease (controls).

An intervention may work differently in one group than in another. Without adequate representation of a particular group, questions about safety and effectiveness of a treatment in that group may remain unanswered. In addition to diversity, the number of people included in research can affect results. Changes or effects seen in smaller groups may or may not show up significantly in larger groups.

CISCRP is an independent, national nonprofit organization working to promote greater understanding and awareness of clinical research participation and the role it plays in public health.