The AT(N) system for describing biological changes in Alzheimer's disease: a plain language summary.

WHAT IS THIS SUMMARY ABOUT?: This is a plain language summary of an article published in . It explains how Alzheimer's disease is diagnosed. It also looks at whether a newer way to assess people with Alzheimer's disease could help improve how the condition is diagnosed, monitored, and treated.

WHY IS THIS IMPORTANT?: Alzheimer's disease is a long-term progressive brain disease that leads to difficulties with thinking and memory. It is a progressive condition, which means it gets worse over time. Biological changes occur in the brain of people with Alzheimer's disease. This includes a build-up of toxic protein clusters called amyloid plaques and tau tangles, gradual damage to the brain cells (neurodegeneration), and brain shrinkage due to loss of neurons. It is often due to multiple factors and doctors usually diagnose Alzheimer's disease by looking at a person's symptoms and ruling out other causes of dementia. However, research shows that people diagnosed in this way do not always have the biological changes in the brain that are related to Alzheimer's disease. This means that some people may be misdiagnosed. Additionally, there may be a delay in the appearance of Alzheimer's symptoms, by which point changes in the brain may be severe. For example, people with Alzheimer's disease show biological changes in the brain, years before symptoms appear.

WHAT ARE THE KEY TAKEAWAYS?: An assessment of biological changes in the brain, by measuring substances that indicate disease progress (biomarkers), may offer a fuller picture of a person's Alzheimer's disease, how advanced it is, and which treatments are likely to work best. A recently developed classification scheme known as the AT(N) system provides a way to assess and describe the biological changes in amyloid (A), tau (T), and neurodegeneration (N) that occur in people with Alzheimer's disease. The goal is to include biomarker testing in clinical practice to help physicians and practitioners diagnose, monitor, and treat people with Alzheimer's disease more effectively. The AT(N) system is being used for various purposes in clinical studies, and has the potential to assist physicians and practitioners in early detection, accurate diagnosis, staging, and treatment selection for people with Alzheimer's disease.