Real-world studies sits at the center of this dementia and brain health question.

Real-world studies are now tracking the effectiveness of newly approved Alzheimer’s drugs with concrete data, and the results show that lecanemab (Leqembi) and donanemab (Kisunla) do slow cognitive decline in actual patients—though more modestly than early marketing suggested and with meaningful safety concerns. By early 2024, over 3,000 patients had already enrolled in lecanemab treatment in the United States, giving researchers their first opportunity to observe how these drugs perform outside the controlled setting of clinical trials. As of 2026, enough real-world data has accumulated to move beyond “does it work?” to the more nuanced questions doctors and patients actually need answered: How much does it help? Who benefits most? What side effects should I expect? This article examines what real-world studies reveal about approved anti-amyloid drugs, compares them to earlier Alzheimer’s treatments, and explores the emerging pipeline of 138 drugs currently in 182 clinical trials worldwide.

What Do Real-World Studies Show About Lecanemab and Donanemab?
How Effective Are These Drugs Compared to Previous Alzheimer’s Treatments?
What Safety Concerns Emerge in Real-World Use?
Which Patients Benefit Most From These Medications?
What Are the Practical Barriers to Treatment Access?
What’s in the Emerging Treatment Pipeline?
Real-World Effectiveness vs. Media Hype
Conclusion

What Do Real-World Studies Show About Lecanemab and Donanemab?

Both lecanemab and donanemab demonstrate measurable slowing of cognitive decline in real-world settings, though the effect sizes differ. Lecanemab, administered as intravenous infusions every two weeks, showed cognitive benefit on multiple standardized measures including the ADCOMS scale and clinical Dementia Rating Scale. Donanemab, which Eli Lilly developed as a monthly infusion, showed statistically significant reduction in clinical decline at the 76-week mark on the Integrated Alzheimer’s Disease Rating Scale and Clinical Dementia Rating Scale – Sum of Boxes—meaning patients on donanemab declined more slowly than those on placebo over the study period. The difference between the two drugs matters: a network meta-analysis comparing multiple Alzheimer’s treatments found that donanemab showed nearly three times greater effect size on cognitive measures compared to lecanemab and the discontinued drug aducanumab, suggesting donanemab may slow decline more substantially, though both are genuine advances.

Real-world data collection is only now reaching sufficient maturity to understand how these benefits translate into daily life outside clinical trials. The FDA and academic researchers are designing frameworks to continuously monitor drug effectiveness using evolving biomarker data from actual patients in community hospitals and memory clinics. This matters because clinical trial participants are often healthier, more adherent to treatment, and more closely monitored than typical patients seen in routine care. Early real-world monitoring through FDA adverse event reporting systems shows both lecanemab and donanemab are being used in everyday practice, providing evidence that the drugs’ benefits extend beyond trial settings—though some real-world complications have emerged.

What Do Real-World Studies Show About Lecanemab and Donanemab?

How Effective Are These Drugs Compared to Previous Alzheimer’s Treatments?

Before lecanemab and donanemab, the Alzheimer’s treatment landscape included donepezil (Aricept), rivastigmine (Exelon), and galantamine, which are acetylcholinesterase inhibitors that provide modest symptom relief for some patients but do not slow underlying disease progression. The anti-amyloid drugs represent a fundamentally different approach: rather than merely managing symptoms, they target amyloid plaques—the protein clumps believed to trigger neurodegeneration. On standard cognitive measures like the ADAS-Cog 14 (a 14-item cognitive test), both lecanemab and donanemab outperformed placebo significantly, and PET imaging confirmed they reduced amyloid burden in the brain, a marker of drug target engagement. However, the clinical meaningfulness of these improvements deserves scrutiny.

A typical patient on donanemab showed measurable cognitive benefit over 76 weeks, but “measurable” does not mean dramatic—decline slowed by months rather than halted entirely. For comparison, donepezil temporarily stabilizes cognition for perhaps six months to a year in some patients with mild to moderate dementia, after which decline resumes. The new anti-amyloid drugs appear to extend the window of modest stability, but they are not cures. Additionally, the FDA approved lecanemab and donanemab specifically for mild cognitive impairment and mild dementia stages, not moderate or advanced dementia, limiting their applicability to earlier disease stages. One emerging alternative, valiltramiprosate (ALZ-801), represents an oral treatment option for patients with high genetic risk (APOE4 carriers) and showed clinically meaningful effects on slowing cognitive and functional decline while preserving brain volume—offering a different pathway for at-risk populations.

What Safety Concerns Emerge in Real-World Use?

The most significant safety concern with anti-amyloid drugs is amyloid-related imaging abnormalities (ARIA), which includes brain swelling (amyloid-related imaging abnormalities edema) and microhemorrhages. In lecanemab trials, 17.3% of patients experienced brain swelling or microhemorrhages detected on MRI scans. Donanemab showed higher rates, with up to 30.5% of trial participants experiencing brain abnormalities—a substantial proportion that demands careful patient selection and monitoring. Most ARIA cases were asymptomatic and detected only through routine MRI screening, but some patients experienced cognitive worsening, headache, or confusion that was reversible after stopping the drug.

A critical real-world observation is that both lecanemab and donanemab were significantly less tolerable than placebo overall in clinical trials, meaning more patients discontinued these drugs due to side effects or burden of infusions compared to the placebo group. This real-world intolerance matters: a drug only helps patients who stay on it. Monthly or biweekly infusions require sustained commitment, and the mandatory monthly or biweekly MRI screening (at least initially) adds time and expense. Real-world safety tracking through FDA adverse event reporting is now comparing lecanemab and other anti-amyloid drugs to identify patterns that clinical trials might have missed, particularly in older patients or those with multiple comorbidities. One recent negative finding warrants mention: large-scale trials of semaglutide (a GLP-1 drug) showed it did not significantly slow Alzheimer’s disease progression, dampening earlier enthusiasm for repurposing diabetes medications in cognitive decline.

What Safety Concerns Emerge in Real-World Use?

Which Patients Benefit Most From These Medications?

Patient selection is crucial because not all mild cognitive impairment progresses to dementia, and not all patients with early symptoms tolerate anti-amyloid drugs well. Lecanemab and donanemab were approved for mild cognitive impairment and mild dementia due to amyloid pathology, but “mild cognitive impairment” is itself a heterogeneous diagnosis—some patients with this label will progress rapidly while others decline very slowly or remain stable. Biomarker confirmation (amyloid PET imaging or tau PET) helps identify patients with confirmed amyloid pathology who are more likely to progress, but many primary care practices cannot access these expensive imaging studies. Genetic risk (APOE4 carrier status) identifies higher-risk individuals, as does the presence of tau tangles on PET imaging, though only specialists typically have access to this level of testing.

Early enrollment data showed that 3,000+ patients had registered for lecanemab treatment by early 2024, suggesting high demand among cognitively declining older adults and their families. In real-world settings, gastroenterologists, neurologists, primary care physicians, and memory specialists have begun prescribing these drugs, sometimes with and sometimes without comprehensive biomarker testing. The practical reality is that access to amyloid imaging varies by geography and insurance, so real-world effectiveness depends partly on patient resources and medical sophistication. Patients with better access to specialty care and amyloid imaging confirmation are more likely to be appropriate candidates; patients in underresourced areas may receive treatment based on clinical assessment alone, potentially including those without confirmed amyloid pathology.

What Are the Practical Barriers to Treatment Access?

Beyond side effects, practical barriers significantly limit real-world effectiveness of these drugs. Lecanemab requires biweekly intravenous infusions for 18 months, donanemab requires monthly infusions, and both historically required frequent in-person MRI screening to detect ARIA early. Elderly patients with mobility limitations, transportation barriers, or cognitive impairment may struggle with biweekly or monthly infusions. Insurance coverage remains inconsistent, and these drugs are expensive: lecanemab costs approximately $26,500 annually, donanemab similar rates, and insurance companies have gradually expanded coverage as real-world safety data accumulated. However, high out-of-pocket costs or prior authorization requirements may delay or prevent treatment initiation.

An emerging real-world advantage comes from lecanemab’s new subcutaneous formulation, which shows equivalent efficacy to intravenous infusions but can potentially be administered at home via automated injection systems. This development addresses one of the largest real-world barriers—the time and logistical burden of frequent hospital or clinic visits. If at-home lecanemab administration becomes widely available, real-world effectiveness may improve substantially because patient adherence typically increases when treatment becomes more convenient. Conversely, the safety monitoring requirement (MRI imaging to detect ARIA) remains a barrier that affects real-world access regardless of administration route. Patients who tolerate the treatment regimen and remain adherent for the full duration show cognitive benefits; those who drop out due to burden, side effects, or access barriers gain no benefit.

What Are the Practical Barriers to Treatment Access?

What’s in the Emerging Treatment Pipeline?

The therapeutic pipeline for Alzheimer’s is dramatically expanding. As of 2025, 138 drugs are being assessed in 182 clinical trials worldwide—a significant increase from 2024—suggesting that multiple pathways to slowing or treating Alzheimer’s are being explored simultaneously. Roche’s trontinemab represents a novel mechanism, with Phase I/II results showing 92% of treated patients had no measurable amyloid plaques after 28 weeks and low rates of ARIA, suggesting potentially better tolerability than lecanemab or donanemab. Two Phase III trials (TRONTIER 1 and TRONTIER 2) are currently underway to confirm these early findings.

Merck’s MK-2214 represents a different approach, targeting tau rather than amyloid, and received FDA Fast Track Designation based on promising first-in-human data, potentially offering benefits to patients whose tau pathology drives disease more than amyloid. Twelve additional drugs are expected to complete Phase 3 trials in 2025, including dextromethorphan/quinidine, nabilone, simufilam, nilotinib, piromelatine, and masupirdine. This diversity reflects a major shift in Alzheimer’s research: rather than betting everything on amyloid targeting, researchers are pursuing multiple biological mechanisms including tau aggregation, neuroinflammation, and neuroprotection. For patients and families, this expanding pipeline means better treatment options may become available within 12-24 months, and combination therapies (e.g., amyloid-targeting drug plus tau-targeting drug) may eventually offer greater efficacy than single-agent approaches.

Real-World Effectiveness vs. Media Hype

Media coverage of lecanemab and donanemab often emphasizes the dramatic language of “slowing Alzheimer’s” or “halting cognitive decline,” which can mislead patients into expecting disease reversal or complete halt to progression. Real-world data shows a more modest reality: these drugs slow decline measurably over 12-18 months, giving patients an extended window of milder impairment. For some patients and families, even modest slowing is meaningful—a few extra months of independence, clearer thinking, or preserved ability to recognize loved ones. For others, the burden of treatment, risk of brain swelling, and cost may outweigh modest cognitive benefits.

The answer depends entirely on individual values and circumstances, not on clinical trial efficacy statistics alone. Looking forward, the field is moving toward precision medicine: using biomarker testing (amyloid PET, tau PET, blood biomarkers) to identify which patients have which pathology driving their symptoms, then matching them to mechanism-specific treatments. A patient with pure amyloid pathology might receive an amyloid-targeting drug; one with prominent tau pathology might receive a tau-targeting drug; those with multiple pathologies might eventually receive combination therapy. This approach, enabled by real-world data and improved biomarkers, offers genuine promise to match treatments to individual biology rather than administering a one-size-fits-all approach to all patients with cognitive impairment.

Conclusion

Real-world studies now confirm that FDA-approved anti-amyloid drugs like lecanemab and donanemab do slow cognitive decline in early Alzheimer’s disease, but the benefits are measurable rather than dramatic—extending the period of mild impairment by several months rather than halting disease progression entirely. Safety concerns including brain swelling in up to 30% of donanemab-treated patients, the burden of frequent infusions, and inconsistent insurance coverage significantly limit real-world effectiveness despite clinical trial efficacy. The expanding pipeline of 138 drugs in 182 trials, including promising agents targeting tau and other pathways, suggests that better and more tolerable treatments will become available in coming years, eventually enabling precision medicine approaches that match specific drugs to specific disease mechanisms in individual patients.

For patients and families facing early cognitive impairment, the realistic conversation should focus on whether the measurable slowing of decline justifies the practical burden, expense, and safety risk for that particular person’s circumstances. Specialists increasingly have tools to identify who might benefit most (biomarker-positive patients with confirmed amyloid pathology in mild stages), and real-world monitoring will continue refining safety protocols. Discussing realistic expectations, exploring whether amyloid imaging is available and covered, understanding local access to infusion infrastructure, and reassessing tolerability over time are all essential components of real-world decision-making that clinical trials alone cannot capture.