Alzheimer’s disease has received significant attention in recent years, particularly following debates over new treatments and how best to use them. Yet another challenge continues to receive far less attention: many Alzheimer’s studies fail to include the populations most affected by the disease.

A recent study published in JAMA Neurology highlights the scope of that problem and underscores the need for greater diversity in medical research.

The Diversity Gap in Alzheimer’s Research

Researchers reviewed 302 dementia studies published in 2018 and 2019.

Most of those studies took place in North America or Europe. Among studies that reported participant demographics, nearly 90 percent of participants were white.

The researchers also found that only 22 percent of studies reported race and ethnicity information at all.

In an accompanying editorial, researchers from the National Institute on Aging argued that this lack of representation limits the value of the findings.

Without accurate demographic data, scientists cannot determine whether treatments work equally well across different populations.

Why Representation Matters

The lack of diversity becomes even more concerning when compared with Alzheimer’s prevalence rates.

According to data from the Centers for Disease Control and Prevention, Alzheimer’s disease and related dementias affect some communities at disproportionately high rates.

Among adults age 65 and older:

• Black Americans experience the highest prevalence.
• Latino populations also face elevated rates.
• White, Native American, Alaska Native, Asian, and Pacific Islander populations experience lower rates.

Despite these disparities, many of the people at greatest risk remain underrepresented in research studies.

As a result, scientists may miss important biological, environmental, cultural, or healthcare factors that influence disease risk and treatment outcomes.

The Consequences of Underrepresentation

The researchers acknowledged limitations in their analysis.

More than 40 percent of the studies reviewed enrolled fewer than 50 participants. Small sample sizes can weaken any conclusions.

Even so, the findings point to a larger systemic problem.

When research populations fail to reflect real-world patient populations, the resulting evidence becomes less useful.

Researchers, clinicians, and patients all benefit from studies that include participants from diverse racial, ethnic, and socioeconomic backgrounds.

As the editorial authors noted, continued underrepresentation risks excluding valuable knowledge about the disease and limiting progress toward effective treatments.

A Challenge Across Medical Research

The issue extends well beyond Alzheimer’s disease.

A separate editorial in the New England Journal of Medicine highlighted similar patterns across many areas of medicine.

Historically, clinical trials have often failed to include enough participants from communities that experience the highest burden of disease.

Examples include:

• Black Americans and hypertension.
• Hispanic Americans and nonalcoholic fatty liver disease.
• Native Americans and metabolic syndrome.
• Asian Americans and hepatitis B.

When these populations remain underrepresented, researchers cannot fully understand how diseases develop or how treatments perform across diverse groups.

The result is a healthcare system that serves some populations better than others.

Building More Equitable Research

The encouraging news is that awareness of this problem continues to grow.

Researchers, funding agencies, journals, and healthcare organizations increasingly recognize that diversity is essential to high-quality science.

Representative studies produce stronger evidence. They also help ensure that new therapies benefit everyone who may need them.

At CIRM, diversity, equity, and inclusion are central to that effort.

All applicants seeking CIRM funding must submit a written Diversity, Equity, and Inclusion (DEI) plan. These plans outline how researchers will ensure their work reflects California’s diverse communities.

This requirement creates challenges, but it also creates accountability.

The alternative, continuing to exclude the very populations most affected by disease, is no longer acceptable.

Better Science Requires Broader Participation

Diversity is not simply a matter of fairness. It is a matter of scientific rigor.

Researchers cannot develop therapies for all patients if they study only a narrow segment of the population.

By expanding participation in clinical research, scientists can generate more reliable data, improve patient outcomes, and build greater trust in medicine.

As Alzheimer’s research moves forward, ensuring that studies reflect the communities most affected by the disease will be essential.

Better representation leads to better science. And better science leads to better treatments for everyone.