5 Reasons We Don’t Have a Cure for Alzheimer’s Disease

3. Brains are almost impenetrable.

The human brain is protected by the blood-brain barrier, a layer of cells separating the brain from harmful things in the blood. Imagine a security guard letting oxygen and important hormones in, but blocking bacteria, viruses and toxins from reaching the delicate cells of the brain. Unfortunately, that barrier shuts out a lot of potentially helpful drugs, too. “Your immediate problem is that only 20 percent of the compounds … cross the blood-brain barrier,” Ballard says. Scientists are testing some clever workarounds, attaching the drugs to nanoparticles or tucking them inside little water-friendly packages called hydrogels to smuggle the drugs past the brain’s security system.

4. Treating a symptom isn’t treating a disease.

Most of the medications for people with Alzheimer’s aim at the symptoms, not the cause of the disease. Once diagnosed with dementia, a patient may receive drugs like a cholinesterase inhibitor or memantine to adjust levels of some brain chemicals and ease some problems.

“You give a patient something that helps his symptoms,” Espay says. But that’s a bit like taking Tylenol because you have the flu and a fever. The drug brings the fever down and makes you more comfortable. But the fever is just a symptom; you still have the flu.

It’s no small thing to treat those symptoms, Ballard points out. For people with moderate dementia, “I think the maintenance of function is perhaps most important,” he says. It’s “the difference between, say, being able to walk a few steps independently and needing a hoist to be moved. That’s a huge impact on independence and quality of life.”

The recently approved Leqembi and other antibody drugs still being tested, however, go after the cause of the disease. These drugs bind to and clear away the sticky amyloid plaques. If those plaques are the cause of Alzheimer’s disease, scientists could be on to something.

​But there’s probably more involved in this disease. So, researchers are pursuing many potential players in the disease, such as inflammation and microglia — small cells that are a kind of clean-up crew in the brain. Some studies are even targeting circadian rhythms (the body’s internal clock) or hormones like estrogen that might play a role in the disease. ​

5. There’s not a lot of funding for Alzheimer’s research.

Part of the problem comes back to the lack of clarity on the cause of Alzheimer’s and the steep costs of developing a single drug. Ballard says it’s also a problem that there’s less awareness around dementia — and less hope.

“People are now beginning to become aware of [dementia], but they still see it as a death sentence,” he says. “The more you have hope and the more treatments potentially can do something, the easier it is to persuade people to invest in it.”

The U.S. government will spend about $3.7 billion on Alzheimer’s and dementia research in 2023, according to the National Institutes of Health. This is a big increase from 2015, when the federal government funded $631 million in research. But it’s also not much more than the $3.3 billion that will be spent on HIV/AIDS. Around 119,000 people died from Alzheimer’s disease in 2022. Compare that to the 18,000 people diagnosed with HIV that died of any cause in 2020, the latest year data is available. Because of a lot of research and funding, many people are living long, healthy lives with HIV. With more funding and research for Alzheimer’s disease, some day it might, like HIV, go from a death sentence to a manageable condition.

The new antibody treatments have Ballard feeling optimistic. “We’re starting to get some treatments that start looking like [they have] benefit,” he says. While the trials are limited, and focus on people with early disease, any small success gives people hope. Hope, he adds, sparks more research, and eventually, more treatments.