Alzheimer’s disease is now the leading cause of death for people living with Down syndrome over the age of 35, and yet, recent drug trials and treatments often do not include them.

That’s according to a new analysis published last month in The Journal of the American Medical Association.

Thanks to advances in medical treatment and health care, people with Down syndrome are living longer than ever before. But “virtually all” people living with Down syndrome develop amyloid plaques before reaching 40, with an average onset of dementia at 54, according to the report.

“With this change in life expectancy, Alzheimer’s disease is now the leading cause of mortality in adults with Down syndrome older than 35, being the proximate cause of death in 70% of cases,” wrote the study’s authors, Michael Rafii and Juan Fortea.

Despite the prevalence of the disease and deaths associated with it, people living with Down syndrome have “limited access to expert clinical evaluation for dementia, let alone these newly approved therapeutics.”

“Ensuring equitable access should therefore be the priority, while balanced with safety. It is imperative that controlled data are acquired to estimate the safety of these medications without precluding access,” Rafi added.

That is complicated by the fact that some drugs used to treat Alzheimer’s have not been assessed or approved for people living with Down syndrome. For example, researchers have advised against treating people with Down syndrome with the drug lecanemab until safety studies are completed.

“The expectation that all drugs approved for Alzheimer disease in the general population will have a clinical trial in persons with Down syndrome (even safety data) may be unrealistic and might preclude access to the growing number of treatments for Alzheimer disease,” the researchers wrote. “Conversely, bridging studies are imperative to ensure that life-saving amyloid-lowering therapies for Alzheimer disease are safe in this unique population.”

The study’s authors noted the ongoing “inflection point” in the study of Alzheimer’s disease, “where the biomarker similarities between sporadic Alzheimer disease and the genetic forms … are well characterized, and cohorts with thousands of individuals with Down syndrome are being observed, using harmonized protocols across the world.”

As such, the authors called for more study and treatment for people living with Down syndrome.

“In this era of diversity, equity, and inclusion, now is the time to bring these new, disease-modifying treatments to individuals who have been left behind for far too long,” the study’s authors wrote. “We would address an ethical imperative and take advantage of a unique opportunity to not only improve the lives of people with Down syndrome, but also those in the general population.”