This is part one of a two-part story on diversity in Alzheimer's disease research, which will examine the lack of basic research in nonwhite and female patients. The second story explores the importance of long-term engagement to recruit diverse patients in need of timely diagnosis and treatment.

No new drugs have been approved for Alzheimer's disease in 15 years, and as pharmaceutical companies struggle to make progress against the devastating disease, minorities have been left out of the conversation.

The prevalence of Alzheimer's disease is only expected to grow, according to the Alzheimer's Association's annual report. Most research efforts are focused on early detection and risk prevention, but minorities may not directly benefit from pharmaceutical companies' drug development, experts have observed, pointing to majority-white clinical trials.

Eli Lilly and Co., which has considerably narrowed its Alzheimer's pipeline after multiple failures, recruited 83% white participants in a phase 3 drug trial for a therapy called solanezumab. The trial, which concluded with failure in 2016, enrolled about 7% Asian and less than 2% black or African American patients, according to Lilly's data presentation. No Hispanic participation was reported.

Anavex Life Sciences Corp., a smaller drugmaker, recruited all white participants in a 32-patient phase 2a study for its Alzheimer's drug candidate Anavex 2-73. Fellow small-cap biotechnology company Vivoryon Therapeutics AG is still holding out hope for its Alzheimer's drug candidate but has not reported patient demographics in publicly available clinical data.

Remaining big players in the space, Biogen Inc. and partner Eisai Co. Ltd., have not provided patient demographics in data presentations either, disclosing only disease characteristics. The two drugmakers previously abandoned several late-stage trials due to likely failure, only to revive the drug candidate, called aducanumab, in October.

Meanwhile, Roche Holding AG's drug candidate crenezumab, which failed in the pharma giant's trials, is being used in a 252-patient study in Colombia. The study has enrolled cognitively healthy individuals with a known mutation that leads to a high risk of early onset of Alzheimer's. The Alzheimer's Prevention Initiative trial, led by the Banner Institute and National Institute on Aging, specifically sought out these Colombian descendants who had inherited the gene mutation PSEN1.

While the neurodegenerative disease impacts all populations, African American and Hispanic populations have a higher rate of onset.

"One of the primary reasons [minorities] don't participate in research is no one ever asks them," said Stephanie Monroe, executive director of Us Against Alzheimer's African American network. "We're looking at intrinsic bias that prevents healthcare professionals from asking."

For communities of color, clinical trial research is one matter, but basic research into how the disease might affect different population groups is also not inclusive. Alzheimer's as a whole is still not well-understood in any demographic.

Root problems

African Americans are two to three times more likely to develop Alzheimer's than white Americans, but tend to be diagnosed in later stages of the disease. Hispanics similarly are 1.5 times more likely than whites to have Alzheimer's, but are less likely than whites to receive a diagnosis. On average, Alzheimer's symptoms develop in Hispanics approximately seven years earlier than in non-Hispanic whites, the Alzheimer's Prevention Initiative said in a report.

According to the National Institute of Aging's Cerise Elliott, research and data on how dementias manifest in racial and ethnic groups is missing, which could lead to a misdiagnosis even when patients are screened. Elliott is program director for the National Institute of Aging's dementias of aging branch in the division of neuroscience.

By 2060, minority populations will represent 45% of the U.S. population aged 65 years and older. The unmet need for communities of color is exacerbated by the overall phenomenon of delayed or lack of diagnosis, plus the fact that few clinical trials are conducted for moderate to severe Alzheimer's disease — an area with "very little hope," according to Global Alzheimer's Platform Foundation President John Dwyer.

Moreover, Monroe said unusual memory changes can be accepted as normal in African American and Latino communities. These communities already face a healthcare provider shortage, according to Jason Resendez, Us Against Alzheimer's chief of staff and executive director of Latinos Against Alzheimer's.

"The scope of the challenge is big," Resendez said. "There … hasn't really been a concerted effort to address that under-diagnosis, specifically among communities of color."

Resendez said Latinos Against Alzheimer's has launched a learning network system to better understand provider behavior and skills to identify where knowledge gaps exist.

"We really haven't seen providers embrace the notion that when you diagnose earlier there are things you can do … to slow progression of disease," said Women Against Alzheimer's President Jill Lesser. The medical community remains far behind in understanding symptoms of cognitive decline and ensuring timely and accurate diagnosis, she added.

Another area lacking clarity is how Alzheimer's affects women differently than men. Elliott believes the differences could stem from the fact that women tend to live longer than men, but biological differences between men and women may play a role as well.

Specifically, the hormone estrogen might have a connection to brain aging. Lesser suggested that, in post-menopausal women, development of chronic diseases such as anxiety, depression and cardiovascular disease may be predictors for decline associated with Alzheimer's.

Comorbidities, or co-occurring diseases, are common in those living with Alzheimer's, particularly those with lower socioeconomic status. According to Dwyer, socioeconomic status and geographic location figure greatly in cognitive health, as those factors may indicate how many jobs an individual might hold, or whether the individual has access to a healthy diet.

But as in cancer, the prevalence of Alzheimer's in minorities suggests an overlap in disproportionate poverty, which on its own creates difficulties accessing treatment and timely diagnosis.

"It's much more about your ZIP code than your genetic code," Dwyer said. "I think it's true in Alzheimer's as well as in hypertension, diabetes and other chronic diseases. … The poor are at a unique disadvantage in some respects to maintain cognitive health."