A growing debate is emerging within the scientific community over whether Alzheimer's disease should be diagnosed before any symptoms appear.
The discussion has been fuelled by recent advances in both treatment and diagnosis. Until recently, Alzheimer's was largely diagnosed through progressive memory loss and cognitive decline. However, two major developments have changed that picture.
New treatments and new tests
The first milestone came in 2021, when the US Food and Drug Administration (FDA) approved the first of three monoclonal-antibody treatments designed to slow the progression of Alzheimer's disease. These therapies target amyloid, a protein that accumulates in the brain and forms the plaques associated with the disease. Two of the treatments are currently available on the market.
The second breakthrough came in May 2025, when the FDA approved the first blood biomarker test capable of detecting pathological changes linked to Alzheimer's disease.
Blood tests developed in recent years are now approaching the accuracy of PET scans and cerebrospinal fluid analysis. Three additional approvals have followed since then.
"For the first time, we have simple blood tests that can tell you whether you have Alzheimer's," Bill Gates has remarked.
Hope and uncertainty
These developments have created optimism that Alzheimer's could one day be detected and treated before dementia develops.
The reasoning is straightforward: if doctors can identify the biological process of the disease before symptoms emerge, and if treatments are available to slow its progression, then preventing dementia may become possible.
However, according to Howard Feldman, a neurologist at the University of California, around one in four people over the age of 65 who show no signs of cognitive decline already have amyloid accumulation in the brain.
Globally, that could translate into hundreds of millions of people potentially being classified as at risk.
Yet the presence of amyloid does not guarantee that Alzheimer's disease will develop.
Researchers estimate that only 5% to 10% of these individuals will develop Alzheimer's within the next five years. Lifetime risk estimates range from approximately 25% to 33%.
The scientific disagreement
This uncertainty sits at the heart of the debate.
Supporters of the new approach argue that diagnosis should occur before symptoms appear. By the time dementia develops, substantial neurodegeneration has already taken place and lost neural connections and memories cannot be restored. From this perspective, intervention must happen as early as possible.
Critics, however, caution that amyloid accumulation does not necessarily mean a person will develop dementia.
Furthermore, there is currently no proof that treating symptom-free individuals who test positive for Alzheimer's biomarkers can prevent the disease altogether.
In other words, they argue there is a risk of giving people a future diagnosis, with all the psychological burden that may entail, without having a proven preventive treatment to offer.
More than a debate over definitions
The disagreement extends beyond the definition of Alzheimer's itself.
It also concerns the effectiveness of the new treatments and whether detecting the disease decades before symptoms appear ultimately benefits patients.
For now, that question remains unanswered.
Source: Vita.gr
