Srijani DattaGupta – srijani.dattagupta@gmail.com
July 25th, 2025
Edited by the YNPS Publications team.
Abstract
Alzheimer’s disease often goes unnoticed until the brain has already sustained significant damage. That delay in diagnosis doesn’t just affect treatment—it also means people lose valuable time to understand what’s happening and make plans for the future. In recent years, researchers have turned to biomarkers in an effort to change that. These are biological indicators that can show changes in the brain even before symptoms appear. Some come from imaging, like PET scans. Others are found in spinal fluid or blood. There are also genetic markers, like APOE4, that may indicate a higher risk. Each of these tools offers something valuable, but they also have limitations. Some are expensive, some are difficult to access, and others are still undergoing testing. Still, their potential to shift diagnosis earlier makes them a key area of focus. This paper explores how far biomarker research has come, what’s proving effective, and where it may be headed next.
Introduction
Alzheimer’s disease doesn’t appear all at once. It develops gradually, and by the time memory loss or confusion becomes noticeable, significant damage has often already occurred in the brain. That delay makes treatment more difficult and robs patients of time they could have used to prepare or seek help earlier.
To change that, scientists have been studying biomarkers— signals inside the body that can indicate disease. Some of these are visible in brain scans. Others appear in spinal fluid or blood. There are also genetic markers that help identify individuals who may be more likely to develop Alzheimer’s later in life.
This paper examines these diagnostic tools in detail. It breaks down what each type of biomarker reveals, how reliable they are, and how they might help patients and families face Alzheimer’s with greater time for decision-making—and broader treatment options..
Methodology
To understand how biomarkers are being used in Alzheimer’s research, this paper reviews studies published over the past ten years. Most sources come from peer-reviewed journals, including Nature Medicine, Frontiers in Aging Neuroscience, and Nature Reviews Neurology. Searches were done through PubMed, Google Scholar, and ScienceDirect, using terms like
“Alzheimer’s biomarkers,” “amyloid-beta,” “PET imaging,” “APOE4 gene,” and “plasma p-tau.”
The focus was on three main categories of biomarkers: imaging, fluid-based, and genetic. Studies were chosen based on how clearly they explained the role of biomarkers in early detection and how well they connected their findings to real-world applications.
This review doesn’t include original experiments, but it brings together key findings from existing research to give a clear picture of where things stand—and where they might be headed.
Results
1. Imaging Biomarkers
Doctors often turn to brain scans when looking for early signs of Alzheimer’s. PET scans can show where proteins like amyloid and tau are building up—changes that tend to appear years before memory loss begins. MRI scans work a bit differently. Instead of looking for specific proteins, they capture changes in brain structure, such as shrinkage in areas linked to memory. Both are helpful, especially in spotting the disease early, but they aren’t easy for everyone to access. These scans are expensive, time consuming , and require equipment which isn’t available in every hospital or clinic. For many people, especially in under-resourced settings, they simply aren’t an option.
2. Fluid-Based Biomarkers
Researchers have also been studying changes in spinal fluid and blood to detect signs of Alzheimer’s. Tests on spinal fluid can reveal patterns—such as lower levels of amyloid-beta or higher levels of tau—that indicate disease. But getting that sample means doing a spinal tap, which isn’t something everyone’s comfortable with. Blood tests are now emerging as a less invasive alternative. Some of them measure the same kinds of proteins and could one day be used more widely. So far, early results are promising, but most of these blood tests are still in development. They aren’t ready for routine clinical use just yet.
3. Genetic Biomarkers
Genetic testing offers another way to assess Alzheimer’s risk. The APOE4 gene, in particular, is one of the most well-known genetic risk factors. People who carry it are more likely to develop the disease later in life—but not everyone who has the gene develops Alzheimer’s, and not everyone with Alzheimer’s has the gene. Other genes like TREM2 and APP are also being studied, though they are less common. Genetic tests can help people understand their personal risk, but that kind of information can be hard to sit with. It often raises tough questions about what to do next and whether knowing actually helps or just adds stress.
Altogether, these three types of biomarkers—imaging, fluid, and genetic—are helping to shift how Alzheimer’s is diagnosed. The hope is to catch the disease early, possibly even before the first symptoms appear. But while science is moving forward, not everyone has access to these tools. Many of the most accurate tests are still limited by cost, location, or both. Until that changes, early detection will remain out of reach for many people who could benefit most.
Discussion
In the past, Alzheimer’s disease was often diagnosed only after symptoms—such as memory loss or confusion—became too noticeable to ignore. By then, the brain had already undergone significant changes. The introduction of biomarkers has started to change that timeline. Now, it may be possible to detect the disease earlier, sometimes before symptoms appear. But while this might sound like a straightforward improvement, it raises new questions about accessibility, accuracy, and emotional impact.
Each type of biomarker offers a different way to look at the disease. PET scans can show buildups of amyloid plaques and tau proteins, both linked to Alzheimer’s, but they’re expensive and often only available in larger hospitals or research centers. MRI scans, while more widely used, may not always show clear signs of the disease in its early stages. And although spinal fluid tests are useful, they involve an invasive procedure that isn’t ideal for routine screening.
Blood-based biomarkers are beginning to attract more attention. They offer a less invasive way to measure the same proteins, and early results suggest they could match the accuracy of spinal fluid tests. But they’re still being tested, and for now, most of these blood tests aren’t available in everyday clinical settings.
Genetic testing works differently. It doesn’t diagnose the disease directly, but it can show whether someone is at higher risk. The APOE4 gene is the most widely studied example. Carrying one or two copies increases risk, but not everyone with the gene will develop Alzheimer’s—and some people without it still do.
Even if all of these biomarkers become more accurate, there’s still the problem of access. Tests like PET scans are expensive. Others, like spinal taps, aren’t easy to perform in primary care settings. For people in rural areas or under-resourced clinics, early detection might still be out of reach. And that raises another question: how useful is early detection if only a few people can benefit from it?
There’s also the question of how people respond to this kind of information. Learning that someone has biomarkers for Alzheimer’s, even if they’re still healthy, can bring up stress, fear, and uncertainty. What are they supposed to do with that information? Should they change their plans, or just wait and see? These aren’t just medical concerns—they’re deeply personal ones.
Because of this, future approaches may depend less on a single test and more on combinations. Using multiple biomarkers—imaging, fluid, genetic—together might give doctors a fuller picture. It could also make it easier to track the progression of the disease and the efficiency of the treatments.
So while biomarkers are far from perfect, their growing use reflects something important: a shift toward earlier, more proactive care. But for that shift to matter, it has to reach more people—and be paired with guidance that helps them navigate what the results actually mean.
Conclusion
In recent years, Alzheimer’s research has begun to move in a new direction. Instead of waiting for memory loss or confusion to appear, scientists are focusing on catching the disease earlier—sometimes long before symptoms begin. This shift has brought biomarkers into focus. Brain scans, spinal fluid tests, blood work, and genetic screening each offer a glimpse into what’s happening beneath the surface. Together, they form a larger picture. But on their own, none of these tools can fully capture the complexity of the disease—or make detection truly accessible to everyone.
Much of the conversation so far has centered on clinical accuracy, diagnostic methods, and biological markers. But there’s more to early detection than just science. It also raises practical and emotional questions that don’t have easy answers. What does it mean to learn something before it starts to show? How do families prepare for something they can’t yet see? What kind of support should follow that kind of news?
The future of Alzheimer’s diagnosis will likely depend on how these tools are used together—and how easily they can be brought into everyday care. Just as importantly, it will depend on whether people at risk can actually access them. And when they do, whether the systems in place help them understand what the results mean and what their options are.
Recognizing Alzheimer’s earlier is a step forward. But what happens next—the way that knowledge is delivered, used, and supported—may end up mattering just as much.
Works Cited
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Hampel, H., O’Bryant, S. E., Molinuevo, J. L., Zetterberg, H., Masters, C. L., Lista, S., … & Blennow, K. (2018). Blood-based biomarkers for Alzheimer disease: Mapping the road to the clinic. Nature Reviews Neurology, 14(11), 639–652. https://doi.org/10.1038/s41582-018-0079-7
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