Cochrane review on ineffectiveness of Alzheimer’s drug sparks backlash

Seven drugs with different outcomes grouped together for Cochrane’s evaluation… doubts raised over study validity

Treatments approved based on Phase III data have sufficient efficacy

“Anti-amyloid Alzheimer’s drugs show no clinically meaningful effect.”

The backlash is as fierce as the message itself. Last April, the Cochrane Database published the results of a systematic review and meta-analysis covering anti-amyloid targeted therapies.

The study concluded that these drugs, as a whole, failed to demonstrate clinically meaningful benefits in inhibiting cognitive and functional decline and raised significant safety concerns, such as amyloid-related imaging abnormalities (ARIA).

Cochrane is a nonprofit health research organization with over 11,000 experts from more than 190 countries worldwide, providing evidence to inform healthcare decision-making. Such an announcement in a prestigious academic journal naturally had a significant impact.

However, before assessing the value and validity of the study, the academic community has come forward to directly refute the results of the Cochrane meta-analysis.

It is true that the conclusions of a meta-analysis can vary completely depending on “how the data is pooled.”

Medical professionals argue that the core of the controversy surrounding this review lies in the fatal “methodological limitations” inherent in the study design.

Because the study produced results that fundamentally overturn the current landscape of clinical practice, it is also true that any misinterpretation could cause significant turmoil for patients with early-stage Alzheimer’s disease, whether they are about to begin treatment or are already undergoing it, as well as their families.

Integration of drugs with different development stages and regulatory status

The main criticism is this: the review analyzed in a single pool four drugs that failed to meet clinical endpoints (e.g., ‘bapineuzumab’), ‘aducanumab (withdrawn due to safety concerns),’ and currently approved ‘lecanemab’ and ‘donanemab.’

The argument is that grouping drugs with fundamentally different levels of development maturity, regulatory status, and mechanisms of action with equal weighting is scientifically inappropriate.

Furthermore, the review is criticized for indiscriminately combining exploratory early-stage clinical trials (Phase 2) with large-scale confirmatory trials (Phase 3). Small-scale Phase 2 data with low statistical power were treated on par with Phase 3 results involving thousands of participants, leading to a severe distortion of the overall effect estimate. As a result, positive signals from drugs like lecanemab or donanemab, whose efficacy was clearly demonstrated in individual clinical trials, were diluted by the vast amount of noise from drugs that had failed in the past.

Ji-won Seo, planning secretary of the Korean Dementia Association (Dongguk University Ilsan Hospital), stated, “If drugs at different development stages and regulatory statuses are combined, results will inevitably be diluted by the majority of data from failed drugs. It is not scientific to group successful drugs, failed candidates, and even those whose approvals have been revoked into the same basket and conclude that ‘the efficacy of this class is unclear.’”

Regulatory approvals are based on independent data

Global regulatory authorities worldwide evaluate new drugs based on the specific clinical data unique to each drug, rather than on a generalized impression of the entire class.

For example, lecanemab has been approved in over 50 countries worldwide, including the US FDA (July 2023), Japan PMDA (September 2023), China NMPA (January 2024), Korea MFDS (May 2024), UK MHRA (August 2024), and the European Commission (April 2025).

Donanemab has also received sequential marketing authorization in over 40 major countries worldwide, including the US (July 2024), Japan (September 2024), China (December 2024), and Europe (September 2025).

This global wave of approvals was made possible by thorough and independent reviews by regulatory agencies in each country, which evaluated the clinical evidence supporting these drugs’ ability to inhibit cognitive and functional decline, as well as the manageability of side effects such as ARIA. This means that, unlike the results of the Cochrane Review’s overly broad meta-analysis, their actual clinical value has already been validated worldwide.

The Cochrane review cited ARIA as a major safety concern. ARIA is divided into cerebral edema (ARIA-E) and microbleeds (ARIA-H). While these are side effects that require careful management in the ATT class, the majority are asymptomatic or mild and can be adequately managed through regular MRI monitoring.

These safety profiles have already been thoroughly reviewed during regulatory approval processes and are reflected in labeling and prescribing information.

Alzheimer’s disease is ultimately a fatal, progressive neurodegenerative disorder. Now that evidence has been established that intervention during the early symptomatic stage can slow disease progression, unfounded misconceptions can lead to negative outcomes, causing patients to miss the “golden window” for treatment.

Seo added, “With new treatments emerging in a field that previously had limited options, expectations for early diagnosis and treatment are increasing. However, following recent reports of research findings that were misinterpreted, many patients are expressing anxiety in the clinic or experiencing confusion when deciding on a treatment plan.”

Seo emphasized, “We must remember that each drug has been approved by regulatory authorities based on clear scientific evidence. If the optimal window for treatment is missed due to misunderstandings, it could later result in far greater burdens for patients and their families.”