Researchers looked past statistics to see how new Alzheimer’s treatments impacted patients’ daily life. (Chinnapong/Shutterstock)

ST. LOUIS — For decades, researchers have searched for effective treatments for Alzheimer’s disease, a devastating neurodegenerative condition that affects memory, thinking, and the ability to perform everyday activities. The recent approval of new medications offers a glimmer of hope, but questions remain about how much these treatments actually help patients in meaningful ways. A new study from the Washington University School of Medicine provides a fresh perspective on this question, focusing on what matters most to patients and their families: maintaining independence in daily life.

When pharmaceutical companies test new Alzheimer’s treatments, they typically measure success using clinical scales that may not translate clearly to real-world benefits. The Clinical Dementia Rating Sum of Boxes (CDR-SB) is one such scale frequently used in clinical trials. But what does a small improvement on this scale actually mean for patients and their families? Does it translate to more time living independently? More days being able to manage finances, drive, or prepare meals?

These questions drove researchers to conduct a detailed analysis examining how scores on clinical tests relate to practical outcomes that patients and families deeply value—specifically, how long people can maintain independence in their daily activities. Their findings, published in the peer-reviewed journal Alzheimer’s & Dementia: Translational Research & Clinical Interventions provide a new framework for understanding treatment benefits.

“What we were trying to do was figure out how to give people a piece of information that would be meaningful to them and help them make decisions about their care,” says senior author Dr. Sarah Hartz, Ph.D., a professor of psychiatry at WashU Medicine, in a statement. “What people want to know is how long they will be able to live independently, not something abstract like the percent change in decline.”

Which Alzheimer’s drugs provide the biggest benefits?

The study found that two recently approved medications, lecanemab and donanemab, could potentially extend independence in daily activities by approximately 10 months for patients in the early stages of Alzheimer’s disease. This finding helps translate abstract clinical trial results into tangible benefits that patients and families can understand when making treatment decisions.

Alzheimer’s disease progressively damages the brain, leading to a decline in memory, thinking, and eventually the ability to perform everyday tasks. The disease follows a typical progression from mild cognitive impairment to increasing dependency in daily activities. For many families, maintaining independence for as long as possible is a primary goal, allowing loved ones to continue living at home, managing their own affairs, and preserving their dignity and quality of life.

The study focused on individuals with early onset of Alzheimer’s disease who would be eligible for the new anti-amyloid treatments. These treatments target and remove amyloid plaques in the brain, one of the hallmarks of Alzheimer’s disease. Lecanemab (approved in July 2023) and donanemab (approved in July 2024) have shown modest but statistically significant effects in slowing disease progression in clinical trials.

However, the clinical meaningfulness of these treatments has been debated. Some experts have questioned whether the small improvements seen on clinical scales justify the treatments’ costs, potential side effects, and the burden of regular intravenous infusions. These medications can cost tens of thousands of dollars annually and carry risks of side effects, including brain swelling or bleeding that are usually mild but can occasionally be serious.

Making the right decision

Patients and their families face difficult decisions when considering these new treatments. As the study authors note, they must decide whether to undergo a treatment that will not make them better or even stop the disease progression. At best, it will only slow the decline. The treatment requires biweekly or monthly infusions and carries risks that should be carefully considered.

“My patients want to know, ‘How long can I drive? How long will I be able to take care of my own personal hygiene? How much time would this treatment give me?’” says co-author Dr. Suzanne Schindler, Ph.D., an associate professor of neurology and a WashU Medicine physician who treats people with Alzheimer’s disease. “The question of whether or not these drugs would be helpful for any particular person is complicated and has to do with not only medical factors but the patient’s priorities, preferences, and risk tolerance.”

The Washington University researchers sought to bridge this gap between clinical trial measurements and real-world outcomes. They asked: How do scores on the CDR-SB scale relate to independence in daily activities, and how much additional independence might these new treatments provide?

The research team studied 282 participants from the Knight Alzheimer Disease Research Center who had either very mild or mild Alzheimer’s disease with confirmed amyloid pathology (the abnormal protein deposits characteristic of the disease). The participants were followed for an average of 2.9 years, with researchers regularly assessing their cognitive abilities and functional independence.

The study looked at two types of daily activities. First, instrumental activities of daily living (IADLs) include managing finances, driving or arranging transportation, remembering medications and appointments, and preparing meals. These activities represent the practical skills needed for independent living. Second, basic activities of daily living (BADLs) include fundamental self-care tasks like bathing, dressing, and grooming.

By analyzing how CDR-SB scores related to independence in these activities over time, the researchers identified critical thresholds. They found that loss of independence in IADLs typically occurred when a person’s CDR-SB score exceeded 4.5, while loss of independence in basic self-care activities occurred much later, when the CDR-SB score exceeded 11.5.

The researchers then used data from clinical trials of lecanemab and donanemab to estimate how much these treatments might delay reaching these critical thresholds. For someone with early Alzheimer’s disease (baseline CDR-SB score of 2), treatment with lecanemab could potentially extend independence in IADLs by approximately 10 months. For those treated with donanemab who had low or medium levels of tau protein (another Alzheimer’s biomarker), independence might be extended by approximately 13 months.

Using their analysis of disease progression and treatment effects, the researchers provided more specific estimates for patients at different stages. A typical person with very mild symptoms could expect to live independently for another 29 months without treatment, compared to 39 months with lecanemab and 37 months with donanemab.

For people with more advanced symptoms who were already having difficulty living independently, the focus shifted to how long they could maintain independence in basic self-care activities. The researchers calculated that a typical person at this stage could expect to manage self-care independently for an additional 26 months if treated with lecanemab, and 19 months with donanemab.

Assisted living is costly

Rather than focusing solely on statistical improvements in test scores, patients and families can now better understand the potential real-world benefits: additional months of being able to manage finances, drive, remember medications, and prepare meals independently.

In the United States, the average annual cost of assisted living is over $56,000, while nursing home care averages around $100,000 per year. Extending independence could potentially reduce these costs and the tremendous burden on family caregivers, who provided an estimated 18 billion hours of unpaid assistance in 2022, valued at $339.5 billion.

The study’s findings may also help clinicians have more informed conversations with patients and families about treatment options. When discussing whether to pursue these new medications, they can now frame the discussion around the potential for extended independence rather than abstract improvements on clinical scales.

It’s important to note that the effects of these treatments vary based on a person’s disease stage and biological factors. For example, individuals with higher levels of tau protein in their brains showed less benefit from donanemab treatment. Those who start treatment earlier in the disease course (with lower CDR-SB scores) generally gain more additional months of independence than those who start treatment at later stages.

“The purpose of this study is not to advocate for or against these medications,” adds Dr. Hartz. “The purpose of the paper is to put the impact of these medications into context in ways that can help people make the decisions that are best for themselves and their family members.”

For patients with Alzheimer’s disease and their families, maintaining independence isn’t just about convenience; it’s about preserving dignity, quality of life, and personal identity for as long as possible. This research helps clarify what these new treatments might actually mean in the daily lives of those affected by this devastating disease. This study provides patients and clinicians with practical information to weigh treatment benefits against costs and risks, helping them navigate the complex terrain of Alzheimer’s care decisions.