The search for earlier and more accurate ways to detect Alzheimer’s disease has become one of the biggest goals in modern medicine.
Alzheimer’s affects memory, thinking, and behavior, and currently there is no cure. Researchers believe that finding the disease before symptoms become severe may be one of the best ways to improve patient outcomes.
A major new study from the University of Pittsburgh School of Medicine has now shown that a newer brain scan may detect a key sign of Alzheimer’s disease earlier than the imaging method currently used in hospitals and clinics.
The findings, published in The Lancet, could influence how doctors diagnose Alzheimer’s disease and determine who may benefit from future treatments.
Alzheimer’s disease is characterized by the buildup of abnormal proteins in the brain. Two proteins are especially important: amyloid and tau. For many years, amyloid received most of the attention because it forms plaques that are commonly found in the brains of people with Alzheimer’s.
More recently, researchers have shifted their focus toward tau. Evidence suggests that tau is more directly connected to memory loss and cognitive decline. While many people can have amyloid deposits without developing dementia, the presence of tau tangles appears to be much more closely linked to disease progression.
This growing understanding has increased interest in brain scans that can detect tau. Such scans use radioactive tracers that attach to tau proteins and make them visible during PET imaging.
In the new study, researchers compared two tau tracers. Flortaucipir is the standard tracer currently approved for routine clinical use. MK6240 is a newer tracer that has mostly been used in research settings and clinical trials.
To determine which tracer performs better, researchers enrolled 775 participants and obtained complete data from 682 of them. Each participant underwent two separate tau PET scans, one using Flortaucipir and another using MK6240. They also received amyloid scans and detailed cognitive assessments within a 45-day period.
Because each participant received both scans, researchers could directly compare how the tracers performed in the same person at nearly the same point in time. This approach minimized the possibility that disease progression would influence the results.
The newer tracer consistently detected more tau pathology. Among participants who had amyloid buildup but no noticeable cognitive problems, MK6240 identified more than twice as many tau-positive cases as the standard tracer.
The pattern continued among people who already had mild cognitive impairment or dementia symptoms. MK6240 found evidence of tau involvement in substantially more individuals than Flortaucipir. This suggests that the newer tracer may be more sensitive and capable of detecting smaller amounts of abnormal tau accumulation.
Researchers say this difference could have important consequences. If a scan fails to detect early tau buildup, some people may not be identified as being at high risk for future Alzheimer’s disease. More sensitive imaging could allow doctors to recognize disease processes earlier and monitor progression more accurately.
The findings are also relevant because new Alzheimer’s therapies are being developed and approved. Some of these treatments target amyloid, but researchers increasingly recognize that tau provides valuable information about how far the disease has progressed.
More accurate tau detection could help determine which patients are most likely to benefit from treatment. It could also improve the selection of participants for clinical trials, allowing researchers to study therapies in the people most likely to develop symptoms.
Despite the promising results, MK6240 is not yet approved for routine clinical use. Additional studies and regulatory evaluations will be required before it becomes available outside research settings.
The study’s greatest strength is its large sample size and direct comparison of the two tracers in the same individuals.
This provides strong evidence that the observed differences reflect the tracers themselves rather than changes in disease over time. A limitation is that researchers have not yet shown whether detecting more tau-positive cases ultimately improves patient outcomes or treatment decisions.
Even so, the study represents an important step forward in Alzheimer’s research. As scientists continue to develop better diagnostic tools and treatments, more sensitive tau imaging could play a central role in identifying disease earlier and understanding how it progresses.
The results suggest that future Alzheimer’s diagnosis may rely increasingly on detecting tau changes long before symptoms become obvious.
The study was published in The Lancet.
Source: University of Pittsburgh School of Medicine.
