Fresh clinical research has raised hopes that the Alzheimer’s treatment donanemab may provide significantly longer protection against cognitive decline than previously believed.
Scientists reported that the drug could delay the progression of the disease by as much as three years in some patients, while also dramatically reducing one of the key forms of brain damage associated with Alzheimer’s.
Earlier studies suggested the treatment benefited only around 35 percent of patients, with improvements lasting between four and seven months.
However, the latest findings indicate that its effects may continue long after treatment has ended, offering renewed optimism for people diagnosed in the early stages of the disease.
Researchers Track Patients Over Three Years
The findings were presented at the Alzheimer’s Association International Conference (AAIC) in London, where researchers shared results from a study involving approximately 1,200 people with dementia.
Roughly half of the participants received donanemab through intravenous infusions over an 18-month period, while the remaining patients formed a matched comparison group that did not receive the treatment.
Researchers evaluated both groups using established cognitive assessments measuring memory, reasoning and thinking abilities.
By the end of the treatment period, patients receiving donanemab showed noticeably better cognitive outcomes than those who had not received the drug.
Follow-up assessments revealed that after three years, the difference between the two groups had grown even larger, suggesting the therapy’s protective effects continued beyond the active treatment phase.
Brain Biomarkers Show Significant Improvement
Researchers also examined biological markers linked to Alzheimer’s disease and found encouraging results.
One important protein, known as tau, is naturally present in the brain but accumulates abnormally in people with Alzheimer’s, contributing to nerve cell damage.
Scientists measured blood levels of a marker called p-tau217, which reflects tau activity.
After 17 months of treatment, patients given donanemab experienced a substantial decline in p-tau217 levels, while the marker continued to increase among untreated participants.
Brain imaging also revealed a striking reduction in amyloid plaques—another defining feature of Alzheimer’s disease.
Among patients with mild cognitive impairment, harmful amyloid deposits were reduced by approximately 90 percent, indicating that the therapy successfully removed much of the protein buildup linked to disease progression.
Experts Say Early Treatment May Deliver Greater Benefits
Hilary Evans-Newton, Chief Executive of Alzheimer’s Research UK, said the new evidence suggests that the advantages of donanemab may persist for years after therapy concludes.
According to Evans-Newton, the results add to growing evidence supporting both donanemab and lecanemab—the two Alzheimer’s medicines currently licensed in the UK—as treatments capable of slowing disease progression, particularly when patients begin therapy during the earliest stages of illness.
The findings could also strengthen arguments that the drug provides better long-term value than previously estimated.
Availability Remains Limited Despite UK Approval
Although donanemab received approval for use in the United Kingdom in 2024, it has yet to become available through the National Health Service.
The National Institute for Health and Care Excellence (NICE) concluded that the treatment’s clinical benefits did not justify its high cost, preventing routine NHS funding.
Patients seeking private treatment typically require infusions every two to four weeks, with annual costs reaching tens of thousands of pounds.
Safety Concerns Continue to Influence Decisions
Despite the encouraging clinical results, safety remains a major consideration.
Donanemab has been associated with brain swelling and bleeding, complications that can become severe in some patients.
Previous clinical trials reported three deaths linked to these side effects, although researchers noted that the overall fatality rate was fewer than two deaths per 1,000 participants.
Medical experts continue working to improve the treatment’s safety profile while monitoring patients closely during therapy.
Previous Review Found Only Modest Clinical Impact
The latest results contrast with conclusions from a major review published in April by researchers from the Cochrane Collaboration.
That analysis examined 17 clinical trials involving more than 20,000 patients receiving amyloid-removing drugs.
While the review confirmed that such therapies can slow Alzheimer’s progression, researchers concluded that the overall improvements remained below the threshold most patients would clearly notice in daily life.
The review also highlighted ongoing concerns about treatment-related risks, particularly brain swelling and bleeding.
Growing Need for Effective Alzheimer’s Treatments
Alzheimer’s disease remains the leading cause of dementia, affecting an estimated one million people across the UK.
Health experts project that the number of people living with dementia could rise to around 1.4 million by 2040 as the population ages.
The latest findings are expected to fuel further discussion among regulators, clinicians and health policymakers over whether long-term benefits demonstrated in newer research justify broader access to therapies such as donanemab, particularly for patients diagnosed before significant brain damage has occurred.
Summary
New research suggests that donanemab may offer much longer-lasting protection against Alzheimer’s disease than previously believed, potentially delaying cognitive decline for up to three years while reducing amyloid plaque buildup by about 90 percent in some patients.
Although the drug is licensed in the UK, it remains unavailable on the NHS because of cost-effectiveness concerns and ongoing safety risks, including brain bleeding.
The findings could influence future decisions about expanding access to Alzheimer’s treatments as dementia cases continue to rise.
