Alzheimer’s disease is the most common cause of dementia, affecting millions of people around the world. It slowly damages memory, thinking, and the ability to carry out everyday tasks.
One of the biggest challenges facing doctors is that the disease begins many years before symptoms become obvious. By the time memory problems appear, changes inside the brain have often been developing for a decade or more.
Because of this, researchers are searching for better ways to detect Alzheimer’s disease as early as possible. A new study from the University of Pittsburgh School of Medicine suggests that a newer brain imaging method may identify one of the most important signs of Alzheimer’s earlier and more accurately than the technique currently used in clinical practice.
The findings were published in The Lancet and focused on a protein called tau. Scientists increasingly view tau as one of the most important biological markers of Alzheimer’s disease.
While another protein called amyloid has received attention for many years, researchers now believe that tau is more closely linked to memory decline, cognitive problems, and future disease progression.
Inside healthy brain cells, tau helps support the structure of neurons. In Alzheimer’s disease, however, tau proteins become abnormal and form tangled clumps inside brain cells. These tangles interfere with normal brain function and are strongly associated with worsening symptoms.
To detect tau, doctors use PET scans combined with special compounds called tracers. These tracers attach to tau proteins and light up on brain scans, allowing doctors to see where abnormal protein deposits have accumulated.
In this study, researchers compared two different tau tracers. One was Flortaucipir, the tracer currently approved for clinical use in the United States. The other was MK6240, a newer tracer that is mainly used in research studies and clinical trials.
The research team conducted a large multicenter study involving 775 participants. Of these, 682 completed all study procedures. Participants received both tau scans within a short period of time, as well as amyloid PET scans and detailed cognitive testing. This design allowed researchers to compare the two tracers under nearly identical conditions.
The results were striking. The newer tracer, MK6240, detected tau accumulation much more often than Flortaucipir.
Among people who showed amyloid buildup but still had normal thinking abilities, MK6240 identified more than twice as many cases of tau positivity. In practical terms, the newer tracer found 23 additional tau-positive individuals for every 100 people scanned.
The differences were also seen among participants who already had memory problems or other cognitive symptoms. MK6240 identified substantially more cases of tau involvement than the standard tracer. This suggests that the newer scan may be better at detecting disease activity across multiple stages of Alzheimer’s disease.
Researchers believe this matters because the presence of both amyloid plaques and tau tangles appears to create the conditions that allow Alzheimer’s disease to progress. Many people have amyloid in their brains but never develop dementia. Tau may be the factor that helps determine who is truly on the path toward Alzheimer’s-related decline.
Better detection of tau could therefore help doctors identify people who are more likely to benefit from emerging treatments. It could also help avoid unnecessary tests and treatments for people who are unlikely to develop symptoms.
The study’s authors note that tau imaging may become increasingly important as new therapies are developed. More accurate staging of disease biology could allow doctors to make better decisions about treatment eligibility, clinical trial enrollment, and long-term care planning.
However, the researchers caution that MK6240 has not yet received approval from the U.S. Food and Drug Administration for routine clinical use. More research and regulatory review will be needed before it becomes widely available.
One of the major strengths of the study is its head-to-head design. Every participant received both scans within a short time frame, making the comparison highly reliable. A limitation is that the study focused on imaging results rather than long-term patient outcomes.
Future research will need to determine whether the additional cases detected by MK6240 translate into better predictions of who will eventually develop Alzheimer’s symptoms.
Overall, the findings suggest that advances in brain imaging may help doctors identify Alzheimer’s disease earlier than ever before. If confirmed in future studies, the newer tracer could become an important tool for detecting the disease at its earliest stages, when interventions may have the greatest chance of success.
The study was published in The Lancet.
Source: University of Pittsburgh School of Medicine.
