Over just the past few decades, the life expectancy of people with Down Syndrome (DS) has increased from less than 30 years to nearly 60. But for many, that remarkable advancement comes at a high price. As they live longer, up to ninety percent of people with DS will have Alzheimer’s Disease. It is, in fact, the leading cause of death among the 200,000 or more people in the US and the 400,000 people in Europe with DS.

Yet, the challenges of Alzheimer’s in this population are largely being ignored by the health care and social support systems in the US. Physicians don’t know how to diagnose it. Families get little assistance or advice in how to care for loved ones with Alzheimer’s. Few residential care settings will accept or are prepared to care for people with DS. And many parents of children with DS seem unwilling to even acknowledge the high incidence of Alzheimer’s and thus do little to prepare for it.

Just imagine: A severe disease strikes 90 percent of a population and most of us don’t even know it. And the medical establishment seems largely disinterested.

DS occurs when a person has an extra copy of Chromosome 21. By middle-age, nearly everyone with Down’s shows signs of Alzheimer’s Disease, including telltale plaques and tangles on the brain. They also began to exhibit symptoms such as memory loss and other cognitive impairment.

It is not entirely clear why. Researchers have found that a gene associated with Alzheimer’s is located on Chromosome 21. Because people with Down Syndrome have that extra chromosome, they may be more likely to have the Alzheimer’s gene too.

Yet, about 10 percent of people with DS do not appear to develop Alzheimer’s. Understanding why could better inform broader research into Alzheimer’s.

But there is tragically little research into either the causes of Alzheimer’s or treatments for those with DS.

While there currently are no proven drug therapies to cure or slow the progression of Alzheimer’s, there has been aggressive research in the subject for decades. After all, finding a cure would not only benefit society, it would make drug makers billions of dollars.

However, people with DS generally are excluded from clinical trials for anti-Alzheimer’s drugs.  According to government data, fewer than 10 Alzheimer’s interventional clinical trials (out of hundreds) are being conducted with the Down Syndrome population.

Some researchers say it is difficult to get informed consent from someone with an intellectual disability. That may be true in some cases, but in many are capable of providing consent.

While more researchers are working to understand the root causes of Alzheimer’s among those with DS, both in the US and overseas, these studies also remain limited. All this research could be extremely important in helping understand the causes of Alzheimer’s and how to treat it, both for those with DS and among the broader population.

Another Catch-22. The Centers for Medicare and Medicaid Services (CMS) tentatively decided that Medicare generally will not pay for the cost of Aduhelm, a newly developed drug for those with early-stage Alzheimer’s, until it sees positive results from new clinical trials. According to this decision, Medicare would pay only for those in the trials.

Where does that leave people with DS? Many have early-stage Alzheimer’s. But they are excluded from the trials. Thus, they cannot know whether the drug can provide any clinical benefit or whether they are at risk of dangerous side effects. And Medicare will not pay for the drug, which currently costs $28,000 annually.

But the challenges go beyond research. For example, physicians often fail to properly diagnose Alzheimer’s and other dementias even in the population-at-large. And it is especially true for people in their 50s or 60s who show early signs of cognitive decline.

But people with DS are a particular challenge. Some are non-verbal and can’t respond to the questions in a routine cognitive exam. In other cases, physicians fail to differentiate between Alzheimer’s and unrelated cognitive changes or behavioral health issues such as anxiety, depression, or social withdrawal.

As with the broader population, failing to diagnose Alzheimer’s at an early stage results in missed opportunities to manage the disease and support those living with it.

A new report by an expert panel suggests some solutions: Better assessment tools for people with Down’s Syndrome and other intellectual disabilities, more frequent screenings for those showing signs of cognitive impairment, and better training for physicians all can help.

These failures go beyond medical professionals and researchers, however. Margot Rhondeau of the National Down Syndrome Society says parents of children with DS need to recognize the very high likelihood that those children will confront Alzheimer’s as they age. “A lot of parents are in denial about Alzheimer’s,” she says. “Parents and caregivers need to become as knowledgeable as they can” about this issue.

So do the rest of us.