Lack of diversity impacts research into Alzheimer’s and dementia

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A National Institutes of Allergy and Infectious Diseases clinical trial admissions coordinator collects information from a volunteer to create a medical record. Credit: NIAID

Alzheimer’s research has been in the news a lot lately, and not for the right reasons. The controversial decision by the Food and Drug Administration (FDA) to approve the drug Aduhelm left many people wondering how, when, or even if it should be used on people battling Alzheimer’s disease. Now a new study is raising questions about many of the clinical trials used to test medications like Aduhelm.

The research, published in the journal Jama Neurology, looked at 302 studies on dementia published in 2018 and 2019. Most of these studies were carried out in North America or Europe, and almost 90 percent of those studied were white.

In an accompanying editorial in the journal, Dr. Cerise Elliott, PhD, of the National Institute on Aging (NIA) in Bethesda, Maryland, and co-authors wrote that this limited the value of the studies: “This, combined with the fact that only 22% of the studies they analyzed even reported on race and ethnicity, and of those, a median 89% of participants were white, reflects the fact that recruitment for research participation is challenging; however, it is unacceptable that studies continue to fail to report participant demographics and that publishers allow such omissions.”

That bias is made all the more glaring by the fact that recent data from the Centers for Disease Control and Prevention shows that among people 65 and older, the Black community has the highest prevalence of Alzheimer’s disease and related dementias (13.8%), followed by Latinx (12.2%), non-Hispanic white (10.3%), American Indian and Alaskan Native (9.1%), and Asian and Pacific Islander (8.4%) populations.

The researchers admitted that the limited sample size – more than 40 percent of the studies they looked at included fewer than 50 patients – could have impacted their findings. Even so this clearly suggests there is a huge divide between the people at greatest risk of developing Alzheimer’s, or some other form of dementia, and the people being studied.

In the editorial, Elliott and his colleagues wrote that without a more diverse and balanced patient population this kind of research: “will continue to underrepresent people most affected by the disease and perpetuate systems that exclude important valuable knowledge about the disease.”


There are more details on this in Medpage Today.

An editorial in the New England Journal of Medicine highlights how this kind of bias is all too common in medical research.

“For years, the Journal has published studies that simply do not include enough participants from the racial and ethnic groups that are disproportionately affected by the illnesses being studied to support any conclusions about their treatment. In the United States, for example, Black Americans have high rates of hypertension and chronic kidney disease, Hispanic Americans have the highest prevalence of nonalcoholic fatty liver disease, Native Americans are disproportionately likely to have metabolic syndrome, and Asian Americans are at particular risk for hepatitis B infection and subsequent cirrhosis, but these groups are frequently underrepresented in clinical trials and cohort studies.”

“For too long, we have tolerated conditions that actively exclude groups from critical resources in health care delivery, research, and education. This exclusion has tragic consequences and undermines confidence in the institutions and the people who are conducting biomedical research. And clinicians cannot know how to optimally prevent and treat disease in members of communities that have not been studied.”

The encouraging news is that, finally, people are recognizing the problem and trying to come up with ways to correct it. The not so encouraging is that it took a pandemic to get us to pay attention.

At CIRM we are committed to being part of the solution. We are now requiring everyone who applies to us for funding to have a written plan on Diversity, Equity and Inclusion, laying out how their work will reflect the diversity of California. We know this will be challenging for all of us. But the alternative, doing nothing, is no longer acceptable.