Patients express sits at the center of this dementia and brain health question.
The overwhelming majority of Alzheimer’s disease patients continue their anti-amyloid treatment once it begins. In the landmark Clarity AD trial—the largest study of lecanemab, a disease-modifying Alzheimer’s drug—95% of patients who completed the 18-month core study chose to continue treatment in the open-label extension phase. Four years into treatment, 478 patients remained on lecanemab therapy, demonstrating that when patients experience the drug’s benefits and tolerate it well, they actively choose to keep taking it rather than stop.
This patient preference reflects both clinical efficacy and a manageable safety profile that has sustained over years of continuous use. This article explores what drives patients’ decisions to stay on Alzheimer’s disease-modifying treatments, the clinical evidence supporting those choices, and recent advances that are making treatment continuation easier. We’ll examine the long-term safety data, the cognitive benefits that accumulate over time, and how new delivery methods—such as at-home subcutaneous injections—are removing barriers that previously interrupted treatment for some patients.
Table of Contents
- What Does 95% Patient Continuation Really Tell Us About Alzheimer’s Drug Acceptance?
- How Does Long-Term Treatment Duration Change the Benefit Patients Experience?
- What Safety Profile Allows Patients to Stay on Treatment for Years?
- How Does Treatment Delivery Method Affect Whether Patients Continue Taking Alzheimer’s Drugs?
- When Should Patients Discontinue Alzheimer’s Treatment, and What Happens If They Do?
- What Does Patient Preference Tell Us About Subjective Experience Beyond Clinical Measures?
- What’s Ahead for Patient Continuation of Alzheimer’s Treatments?
- Conclusion
What Does 95% Patient Continuation Really Tell Us About Alzheimer’s Drug Acceptance?
A 95% continuation rate is remarkable in chronic disease treatment. To put this in perspective: in most long-term medication studies, patient adherence drops as weeks turn into months. Patients stop because of side effects, inconvenience, cost, or loss of faith that the drug is working. The near-universal choice to stay on lecanemab after the initial 18-month trial suggests something powerful: patients and their families can perceive the treatment’s benefit. The Clarity AD trial showed that lecanemab slowed cognitive decline by 0.45 points on the Clinical Dementia Rating Scale (CDR-SB) over 18 months—a statistically significant difference (P=0.00005)—compared to placebo. While this may sound modest, it represents a meaningful delay in symptom progression when measured against the natural course of early Alzheimer’s disease. The persistence of this patient preference across years of treatment is equally striking.
After four years of continuous lecanemab therapy, 478 patients from the trial were still receiving the drug. This isn’t just short-term enthusiasm; it’s sustained confidence. Patients and caregivers who initially chose to continue treatment kept making that same choice at each follow-up visit, year after year. This pattern suggests that they observed tangible benefits or at minimum didn’t experience side effects severe enough to warrant stopping. However, it’s important to note that this study population represents people who tolerated the drug initially and responded well enough to enroll in an extended trial. The 95% continuation rate reflects those who could continue, not necessarily all patients who started lecanemab. Some patients in the core trial may have discontinued due to safety concerns (such as amyloid-related imaging abnormalities, or ARIA) and did not enter the extension phase. The real-world continuation rate among all treated patients would likely be somewhat lower, though still likely to be substantial.
How Does Long-Term Treatment Duration Change the Benefit Patients Experience?
One of the most important findings from extended lecanemab data is that cognitive benefits do not plateau—they increase over time. After three years of treatment, patients showed a 1.01-point reduction in cognitive decline on the CDR-SB scale compared to what would be expected based on historical decline rates in untreated populations. By four years, that benefit had grown to a 1.75-point reduction. In practical terms, this means a patient who might normally experience progressive cognitive decline is maintaining better function for longer. This extended benefit creates a powerful incentive to continue treatment. If the drug were merely slowing decline initially but then providing no additional benefit, patients might reasonably stop after a few years.
Instead, the evidence suggests that staying on treatment delivers cumulative protection. Patients who remain on lecanemab longer are more likely to maintain higher cognitive function than those who discontinue, though this assumes they’re tolerating the drug well and responding to it. There is, however, an important caveat: the evidence for continued benefit assumes ongoing treatment. Discontinuing lecanemab is not well-studied in clinical trials, and it’s unclear whether cognitive benefits are preserved, partially reversed, or rapidly lost if a patient stops the drug. This uncertainty is one reason why clinical guidance emphasizes that treatment discontinuation should only be considered if there is a clear absence or loss of treatment response—essentially, if the drug simply isn’t working for that individual. For patients experiencing ongoing benefit, the data support continuation.
What Safety Profile Allows Patients to Stay on Treatment for Years?
Patient continuation depends critically on safety. Lecanemab’s infusion-based form requires patients to visit an infusion center every two weeks, which itself is a burden that can discourage continuation. More importantly, the drug carries a risk of amyloid-related imaging abnormalities (ARIA)—changes visible on brain MRI thought to relate to the drug’s mechanism of clearing amyloid protein. These can appear as brain microhemorrhages (ARIA-H) or amyloid-related edema (ARIA-E). Both are serious concerns that required careful monitoring and, in some cases, treatment discontinuation. The good news from the four-year safety data is that no new safety signals emerged during the extended treatment period, and ARIA rates actually decreased after the initial 12 months.
This is a meaningful finding: it suggests that patients who pass through the first year of treatment without developing severe ARIA are at lower risk for these complications during subsequent years. Patients remained on stable monitoring protocols, but the trajectory of safety problems was favorable. However, ARIA-E (brain swelling) occurred in some patients and required dose adjustment or discontinuation. Similarly, ARIA-H (microhemorrhages) occurred in a minority of patients. While continuation rates were high among those who enrolled in the extension, some patients from the original trial did not continue because of these safety issues. For patients with certain risk factors—such as presence of the APOE4 genetic variant, history of microinfarcts, or older age—the benefit-to-risk calculation may differ. Treatment decisions should always be individualized based on MRI findings and neurological assessment.
How Does Treatment Delivery Method Affect Whether Patients Continue Taking Alzheimer’s Drugs?
The original form of lecanemab required patients to attend an infusion center every two weeks for a 60-minute infusion. For patients who live far from medical centers, who lack reliable transportation, or who struggle with the time commitment, this became a reason to stop treatment. Even patients benefiting from the drug sometimes discontinued simply because the logistics became unmanageable. In 2025-2026, the FDA approved a new form of lecanemab—a subcutaneous weekly injection that patients can administer at home. This addresses a major barrier to continuation. Rather than a twice-monthly clinic visit, patients (or caregivers) inject the drug themselves once weekly.
This change is expected to substantially improve continuation rates by removing the logistical burden. For someone with early cognitive impairment, the difference between traveling to an infusion center twice monthly versus injecting at home once weekly is enormous. Research consistently shows that treatment convenience significantly impacts patient adherence to chronic medications. This shift highlights an important principle: the best treatment is the one patients actually take. A highly effective drug abandoned because of inconvenience is less valuable than a moderately effective drug that patients sustain. The development of at-home subcutaneous lecanemab represents progress not just in drug delivery, but in recognizing that patient compliance depends on removing barriers—not just on the drug’s efficacy alone.
When Should Patients Discontinue Alzheimer’s Treatment, and What Happens If They Do?
Clinical guidance is clear on one point: there is no routine reason to discontinue disease-modifying Alzheimer’s treatment in patients who are tolerating it well and showing response. Discontinuation should be considered only if there is an absence or loss of treatment response—meaning the drug is not slowing decline—or if a patient develops serious adverse effects that outweigh the benefit. The problem is that stopping treatment is poorly understood scientifically. We don’t have long-term data showing what happens to cognitive decline if a patient stops lecanemab after one year, three years, or five years of treatment.
Do the benefits persist? Are they gradually lost? Does decline accelerate back to baseline rate? These questions remain open. This uncertainty argues for treatment continuation in patients who are benefiting and tolerating the drug—stopping is a change with unknown consequences. Additionally, there is a practical limitation for patients considering discontinuation: restarting treatment after a gap is not well-characterized in trials. Some patients have restarted lecanemab after brief discontinuations, but long-term data on re-initiation after years off the drug are lacking. These unknowns, combined with evidence that benefits increase over years of continuous treatment, support the approach of continuing treatment rather than experimenting with stopping.
What Does Patient Preference Tell Us About Subjective Experience Beyond Clinical Measures?
The 95% continuation rate reflects more than just statistical benefit on a cognitive scale. It reflects patients’ and caregivers’ lived experience. Cognitive decline in Alzheimer’s disease is devastating. A patient who notices they can remember grandchildren’s names longer, or can follow a conversation more reliably, or can maintain independence in daily activities longer—these experiences matter deeply.
While the CDR-SB measures these outcomes objectively, the patient’s perception of benefit is what drives the decision to continue. Caregivers also play a crucial role in this preference. A caregiver who observes that their spouse is more functional, more engaged, or more autonomous for longer is motivated to support continuation of treatment. The decision to continue is rarely made by the patient alone; it’s usually a shared decision between patient, family, and physician. When all three parties perceive benefit—or at minimum, when the side effects are tolerable—continuation becomes the natural choice.
What’s Ahead for Patient Continuation of Alzheimer’s Treatments?
The approval of at-home lecanemab injection and ongoing development of other disease-modifying therapies suggest that continuation rates will likely improve as treatment burden decreases. Additional monoclonal antibodies targeting amyloid (such as donanemab) are also advancing through trials and regulatory approval. As patients have more options and as administration methods become more convenient, the barriers to long-term treatment continuation will fall further.
The trajectory from 2023 to 2026 reflects a critical shift in Alzheimer’s care: from a disease with only symptomatic treatments to a disease where early, sustained treatment can slow decline. The high patient preference for continuing lecanemab isn’t surprising once you consider the alternative—accepting progressive cognitive loss when a treatment exists that slows it. As these therapies become more accessible and more convenient, sustained treatment will likely become the norm rather than the exception.
Conclusion
Patients express a strong preference to continue Alzheimer’s disease-modifying treatment because they experience meaningful benefits with manageable safety profiles. The 95% continuation rate in the Clarity AD trial, sustained through four years of follow-up, reflects genuine clinical benefit: cognitive decline slowed by 0.45 points at 18 months, and by 1.75 points after four years of treatment. Safety concerns (primarily ARIA) were manageable, and new safety signals did not emerge during extended treatment—an important reassurance for patients committing to years of therapy.
Moving forward, the availability of at-home subcutaneous lecanemab injection will remove a major barrier to continuation and likely increase both initiation and long-term adherence. For patients and caregivers considering Alzheimer’s treatment, the evidence clearly supports sustained therapy in those who tolerate and respond to it. Discontinuation should be reserved for situations where treatment is not providing benefit or causing significant harm. The conversation with your neurologist or specialist should focus on which treatment option and delivery method best fits your life and values—because the best treatment is one you’ll actually take.
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For more, see Alzheimer’s Association — clinical trials.
