The science of eligibility requirements

By Alzheimer's Prevention Bulletin

There is much to be learned about the development of Alzheimer’s disease and how to prevent or delay the onset of the disease – this is why so many research studies are looking for volunteers. For many, that begs the question, “Why don’t studies broaden their age requirements in order to find more participants?”

“We get asked that question a lot,” says Jessica Langbaum, PhD, Associate Director, Alzheimer’s Prevention Institute and Principal Scientist, Banner Alzheimer’s Institute. “The answer lies in the scientific rationale behind research study eligibility requirements. How do researchers determine which criteria make someone eligible (or not eligible) for a study? “It really depends on the goals and objectives of the study, says Dr. Langbaum. “Studies focused on identifying the earliest signs of the disease might be able to enroll people in their 40s or 50s, whereas with clinical trials, when the goal is to determine if a treatment delays or prevents the onset of the disease, researchers have to narrow the age criteria, enrolling people who are within a certain window of time for when symptoms of the disease might appear given that these types of studies only last 4-8 years.”

Although age is the biggest risk factor for Alzheimer’s disease, there are other factors which researchers might consider when designing their study. Whether a person has one of these other risk factors might make them eligible - or not eligible- for the study, again depending on the goals of the study. “Some studies are looking for people with a certain genetic profile, elevated levels of amyloid in their brain, or other characteristics such as having a family history of the disease,” says Langbaum. “When it comes to clinical trials, when researchers are often studying an experimental treatment, we often have to exclude people with certain medical conditions or who are on specific medications.”

What about people who want to participate in a study but can’t, either because they don’t meet the study’s eligibility criteria, or they live too far away from where the study is taking place? “The good news is that more and more studies are taking place online, which is often open to wider age ranges.”

With all these restrictions in place, recruitment for studies can be a daunting challenge for researchers. “Sometimes it is like looking for a needle in a haystack,” says Langbaum. “We may need to screen thousands of volunteers to find the few who can participate. This is why programs like the Alzheimer’s Prevention Registry are so helpful to researchers, allowing us to efficiently spread the word to hundreds of thousands of people about a particular study in need of participants.”

You can help spread the word about the Alzheimer’s Prevention Registry to loved ones as well as search for studies by clicking here.